Aliphatic Chemistry Part 1

8/6/2019 Aliphatic Chemistry Part 1

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Part IALIPHATIC CHEMISTRY


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1Acetylenes, Allenes, and Olefins

BY R. S. ATKINSON

1 AcetylenesAreas of acetylenic chemistry reviewed recently include the base-catalysedisomerization of acetylenes,l nucleophilic additions to acetylenes,2additionsto activated triple bonds,3 synthetic and naturally occurring acetylene com-pounds as d r i i g ~ , ~llenic and acetylenic carotenoids,s linear polymers fromacetylenes: carbonylation of mono-olefinic and monoacetylenic hydro-carbons,and the combustion and oxidation of acetylene.* Severalbooks havealso a p ~ e a r e d . ~Synthesis.-The coupling reaction between acetylenic Grignard reagents andallylic halides yields acetylenic olefins which are of value for sterospecificconversion into acyclic isoprenoid polyenes.1 However, this coupling reactiongenerally leads to mixtures of allenic and acetylenic products. The lithiatedtrimethylsilylacetylene has been used to circumvent this prob1em.l Anothercomplementary methodI2 is trimethylsilylation of the crude reaction productafter treatment with one equivalent of Grignard reagent. Thus the allylic

R. J. Bushby, Quart . Rev. , 1970, 24, 5 8 5 .S. I. Miller and R. Tanaka, Selective Org. Transform., 1970, 1, 143.E. Winterfeld, Neure Method . Praep. Org. C hem., 1970, 6 , 230.K. E. Schulte and G. Ruecker, Fortschr. Arzneim ., 1970, 14, 387.B. C. L. Weedon, Rev. Pure. Ap pl . Chem. , 1970,20, 51.M. J. Benes, M . Janic, and J. Peska, Chem. lisry., 1970, 64, 1094 (Chern. Abs., 1970,74, 31 97931).Ya. T. Eidus, K. V. Puzitskii, A. L. Lapidus, and B. K. Nefedov, Rus s . Chem. Rev. ,1971,40,429.( a ) T. F. Rutledge, Acetylenic Compounds, Van Nostrand-Reinhold, New York,1968 ; ( b ) T. F. Rutledge, Acetylenes and Allenes, Van Nostrand-Reinhold, NewYork, 1969; (c) Chemistry of Acetylenes, ed. H. G. Viehe, Marcel Dekker, NewYork, 1969.

lo E. J. Corey, J. A. Katzenellenbogen,N. W. Gilman, S.A. Roman, and B. W. Erickson,J. Amer. Chem. Soc., 1968,90, 5618; E. J. Corey, J. A. Katzenellenbogen, and G. H.Posner, ibid., 1967, 89, 4245.l1 E. J. Corey and H. A. Kirst, Tetrahedron L efte rs, 1968, 5041.l2 R . E . Ireland, M. . Dawson, and C. A. Lipinski, Tetrahedron Letters, 1970, 2247.

* A. Williams and D. B. Smith, Chem. Rev. , 1970, 70, 267.


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4 AlQhatic, Alicyclic, and Saturated Heterocyclic Chemistrydibromide (1) gives the trimethylsilylated acetylene (2), from which the ene-diyne (3) is obtained in 50% overall yield.

BrMe

Selenium dioxide oxidation of aryl ketone semicarbazones (4) in aceticacid affords 1,2,3-~elenadiazoles5). Pyrolysis of the latter gives seleniumand the aryIacetylenes ( 6 ) in good yieldJ3 The same procedure has been usedto prepare cyclo-octyne in 34 % yield.14

The fragmentation reaction of Eschenmoser,15which gives acetylenes fromt oluene-p-sulphonyl hydrazones of ap-epoxy-ketones (Scheme l) , has beenadapted to the synthesis of acetylenesfrom ketones substituted with leavinggroups in the a-position [(7) -+(8)].16

,NH S0 A r

Scheme 1Cadiot-Chodkiewicz coupling of 1 bromoacetylenes with terminal acetyl-

enes in the presence of cuprous salts and amines is much slower when 1-chloroacetylenes are used.17 Conditions have been described for the intra-molecular coupling of the bromodiyne (9) to (10) in 40%yield using highdilution and complementing the Glaser reaction.l*l3 I . Lalezari, A. Shafiee, and M. Yalpani, Angew . C hem . Internat. Edn., 1970, 9, 464.l4 H. Meier and I. Menzel, Chern. Comm. , 1971, 1059.l5 A. Eschenmoser, D. Felix, and G. Ohlott, Helu. Chim. Acta , 1967,50,708; J. Schreiber,D. Felix, A. Eschenmoser, M . Winter, F. G. Gautschi, K . H . Schulte-Elte, E. Sundt,G. Ohloff, J . Kalvoda, H . Kaufm ann, P. Wieland, and G . Anner, ibid., p. 2101.l6 P. Wieland, Helu. Chim. Acta , 1970, 5 3 , 171.l7 J.-L. Phillipe, W. Chodkiewicz, and P. Cadiot, Tetrahedron Le tters, 1970, 1795.l* G. Eglinton and W. McCrae, Ado. Org. Chem. , 1963, 5 , 2 2 5 .


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Acety lenes, Allenes, and Olefins 5

Labile and unstable acetylenes are conveniently coupled with halogeno-acetylenes as their copper(I1) salts. The terminal acetylenes required, e . g .( 1 l), can be obtained by deformylation with base of the aldehydes obtainedby nickel peroxide oxidation of the corresponding alcohols (12).19 Iodo-

NiOz NaOHR(C=C),CH,OH + (CzC)2CHO+ ( C 4 ) P H(1 1)C6H6(12)

pyrazoles,20 odopyridines,21and iodonitrobenzenes22 ouple efficiently withacetylenes in the presence of copper, potassium carbonate, and pyridine.Copper acetylides also react with allylic halides to give ene-ynes (13) and thereaction is accelerated by the presence of halide or cyanide ion.23Similarly,reaction with acid chlorides giving acetylenic ketones (14) is catalysed byhalide salts and by addition of hexamethylphosphortriamide t a specific imeduring the reaction.24

RCGCCU + XCHz+C- - CZSCHZG=C-I I t i(13)(14)

R-CE&CU + RCOCI __+ RC=CCOR2R. F. Curtis and J. A. Taylor, J . Chem. SOC. C), 1971, 186.S . S . S . R . , S e r . khim., 1971, 8, 1764 (Chem. A b s . , 1971, 75, 15 1 724p).S . S . S . R . , Ser. khim., 1971, 8, 1833 (Chem. Abs . , 1971, 75, 151 645p).S .S .S .R . , Ser . khim., 971, 8, 1306 (Chem. Abs . , 1971, 75, 88 219k).J. F. Normant and M . Bourgain, Tetrahedron Le tters, 1970, 2659

2o S. F. Vasilevskii, M . S . Schvartsberg, and I . L. Kotlyarevskii, Izves t . Akad. Nauk21 M. S . Schvartsberg, A . N. Kozhevnikova, and I . L. Kotlyarevskii, Zzvest. A ka d. Nauk2 z M . S . Schvartsberg, A. A. Moroz, and I. L. Kotlyarevskii, Izvest . Akad. Nauk23 J. F. Normant, M . Bourgain, and A. M . Rone, Co m p t . rend., 1970, 270, C , 354.


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6 Aliphatic, Alicyclic, and Saturated Heterocyclic ChemistryA synthesis of p,p'-bridged tolans (15 ) has used the Fritsch-Buttenberg-

Wiechell (FBW) rearrangement of gem-dihalogeno-olefins with strong base.25The effect of diminishing n upon the U.V. spectrum of (15) has been deter-mined and for the o,p'-bridged acetylene and p,p'-bridged diacetylenes.26The FBW rearrangement has also been used to prepare dicyclopropylacetyl-ene from (16) with n-butyl-lithium?'

Br(C e)nOQ0=CC&HO

BuLi_I_)

Conversion of terminal olefins into alk-1-ynes by a bromination-dehydro-bromination sequence is often easier in theory than in practice. The use ofD M SO as solvent and methylsulphinyl carbanion or sodamide as the basegives excellent yields with little isomerization to alk-2-ynes. Moreover, con-ditions have also been found for transformation of alk-1-ynes into alk-2-ynes.2s

Selective hydro bora t ion of symmetrical conjugated diynes with dialkyl-boranes provides a route to acetylenic ketones in yields >70%. Protonolysisof the intermediate boranes also gives the corresponding cis-ene-ynes in highyield (Scheme 2).29

Reaction between acetylenic Grignard reagents and hydroximoyl chlorides(17) is known30 to give isoxazoles via intermediate ketoximes (18). The latter2526

27

T. Ando and M. Nakagawa, Bull. Chem. SOC. apan, 1971,44, 172.M . Kataoka, T. Ando, and M . Nakagawa, Bull. Chem. SOC.apan, 1971, 44, 177;M. Kataoka, T. Ando, and M . Nakagawa, ibid., p. 1909; F. Toda, T. Ando, M .Kataoka, and M. Nakagawa, ibid.,p. 1914.G . Kobrich and D. Merkel, Angew. Chem . Internat. Edrt., 1970, 9, 243.

28 J . Klein and E. Gurfinkel, Tetrahedron, 1970, 26, 2127.29 G . Zweifel and N. L. Polston, J . Amer. Chem. SOC., 970,92, 4068 .30 G . Palazzo, Gazzet ta , 1947,77, 214.


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Acetylenes, Allenes, and Olefins 7

1-1/ '\BRq H/ \p202-..,,,iR ' C H Z C C S R 'I I0 Scheme 2have now been isolated by working at low t empera t~ re .~~n 4,4,4-triethoxy-but-l-yne (19), obtained from propargylmagnesium bromide and tetraethylorthocarbonate, the carboxy-group, masked as an orthoester, is protectedfrom attack by basic reagents, and ready acetylene-allene interconversion isinhibited. Thus the lithio-derivative of (19) is acylated and converted intoenol-ether (20) by base-catalysed addition of alcohols. This represents exten-sion of carboxylic acid R by two acetyl units.32

II2 R ' C E C M g B r + R2CCI+ 1C=CCR2 + R 1 C E C I INI IN'OH HO/

(17) (18) \Ah

HC--LCH2(0Et),(19)

RCOCH-CCHZC(OEt),1(20)OEt

BuLi L ~ C E C C H ~ C ( O E ~ ) ~0 0

EtO-- CC-=CCH,C(OEt),II0A safe and convenient preparati~n~~f dichloroacetylene uses a liquidmedium and reduces explosion hazards. All the six homo- and hetero-di-halogenoacetylenes (21) have been obtained pure and characterized by theiri.r. and Raman spectra.34Chlorofluoroacetylenehas also been synthesizedby

X--C-Y(21)

X = CI, Br, or IY = C1, Br, or I

31 Z. Hamlet, M. Rampersad, and D. J. Shearing, Tetrahedron Letters, 1970, 2101;see also S. Morrocchi, A. Ricca, A . Zanarotti, G. Bianchi, R . Gandolfi, and P.Grunanger, ibid., 1969, 3329.33 R . Finding and U. Schmidt, Angew. Chem. Internat. Edn., 1970, 9, 456.33 J. Siegel, R. A. Jones, and L. Kurlansik, J . Org. Chem. , 1970, 35, 3199.34 E. Kloster-Jenson, Tetrahedron, 1971, 27, 33 .


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8 Aliphatic, Alicyclic, and Satura ted Heterocyclic Chemistrybase treatment of 1 l-dichloro-2-fluoroethylene (22). It is a very unstableexplosive com pou nd which ad ds regiospecifically t o ethers in the absence ofinitiat0rs.3~Trichloroethylene reacts with NN-disubstituted lithium amidesF c1 FC=C __f F-CI __f F-C=CCl- \ /H/ LiNRa ether /c=c\clMeCH

(22) Me OEt OEtICH IH aan d secondary amines t o for m chloroketen aminals (23). Up on further treat-ment with strong base, the latter undergo HCI cc-elimination and oniumrearrangement t o afford yne-diamines (24) in high

c1 c1 Li\ / R2NLi-R,NH \ / ___t ClCkCNRa/c=c\clc1/c=c\H c1____j IR8N NRa

LiNRz-ether /\ / \R~N-CEC-NRS - %====ct--- lCH=C NRIR7N\R (23)(24)Acetylenic sulphoxides and sulphones are obtained by oxidation of themore readily available acetylenic sulphides using m-chloroperbenzoic acida t -2 0 OC in chloroform. Alternatively, the sulphoxides may be prepared bydehydrohalogenation of chlorovinylsulphoxides (25): A useful preparative

PhC(CI)=CHSOMe ___f PhC=CSOMe (89 %)KOtBuTHF(25)

route to acetylenic acids (26) uses aroylmalonates as starting materials.Treatment with arenesulphonic anhydrides yields the intermediate enolsulphonates, a nd decarboxylative elimina tion of the derived diacids gives (26)in 80% overall yieldsF8The synthesis of the hexadehydro[l8]annulene (27), and hence of [181-annulene, has been improved.39 Although cycloheptyne h as no t been

35 S. Y. elavarenne and H. G. Viehe, Chem. Ber. , 1970, 103, 1198.36 S. Y. elavarenne and H. G. Viehe, Chem. Ber. , 1970, 103, 1209.a G. A. Russell and L. A. Ochrymowycz, J . Org. Chem., 1970, 35 , 2106.I. Fleming and C. R. Owen, J . Chem. SOC. C ) , 1971, 2013.3 @ H. P. Figeys and M. Gelbcke, Tetrahedron Letters, 1970, 5139.


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Ace?).Ienes, A llenes, and O l e j k s 9Ar Ar

\ (ArSO,),O \/C=C(CozR)zC-CH(COaR)Z -

(26)IrsopoAr

/0C=C(COgH)z ___+ A r C k C C O e H\/

isolated, the thiacycloheptyne (29) has been prepared in low yield by oxida-tion of bishydrazone (28).40ArSOzO

( 2 5 ) (291Asymmetric synthesis of acetylenic alcohols is possible by reduction of thecorresponding ketones w ith lithium aluminium hydride complexed with sug arderivatives; the optical yields are 4-7 The trimethylether of the

naturally occurring robustol (30), from the leaves of Greuillea robusta A .Cu nn., ha s been synthesized in 55 % yield via cupric aceta te oxidative cycliza-tion of the diacetylene (31).42OM C OMC

(3114 0 A . Krebs and H. Kimling, Tetrahedron Letters , 1970, 761.41 S.R. Landor, B. J. Miller, and A . R. Tatchell, J . Chem. SOC. C ) , 1971, 2339.4 2 J. R. C a nnon , P. W. C h o w , B. W. Metcalf, A . J. Power, and M . W. Fuller , TetrahedronLetters, 1970, 325.


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10 Aliphatic, Alicyclic, and Saturated Heterocylic ChemistryCycloaddition Reactions.-The use of dimethylacetylene dicarboxylate(DMAD) in cycloaddition reactions with various substrates is illustrated inthe Table.

1,2,3-Trirnethylindole and D M A D yield the benzazepine (32) and thedienone (33); the suggested mechanism is shown in Scheme 3.43 A reaction

E = C02M eMe(33)Scheme 3

BU~G=C-NO~

p3 F. Fried, J . B.

+Q -

Taylor, and R.Westwood, Chem. Comm., 1971, 1226.


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Acetylenes, Allenes, and O l e - n s 11Table Reactions of dime thy ace ty enedicarboxy la te with various substratesStartingmaterial Products Re f.

a

OH

c*

aa

e

fh4


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12 Aliphatic, Alicyclic, and Saturated Heterocyclic ChemistryStartingmaterial Products Ref:

x

i

M e 0pc02Me

C 0 2 M e E EMeC&

E

H2NYNH2H 1

CJ CHNz!-70X 0 0X E = C02Me


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Ace tylenes, Allenes, und Ole jnsStartingmateria I Products

RI IR' C

13ReJ

n

0 E' = CO2Et* No n.m.r. data reported in abstract(a) J. E. Baldwin and R. K. Pinschmidt, Chem. Comm. , 1971, 820; (6) L.-C. Lin, P.-W.Yang, H.-Y. Huang, and C.-C. Hsieh, Hua Hsueh, 1970, (1-2), 1 (Chem. Abs. , 1970 ,74 ,76 149d); (c) T. Uyehara, M. Funamizu, and Y. Kitahara, Che m. and Ind., 1970, 1500;( d ) H. Wynberg and R. Helder, Tetrahedron Letters , 1971, 4317; ( e )T. W. Doyle, Canad.J. Chem., 1970, 48, 1633; (f) . M. Acheson and J. N. Bridson, Chem. Com m., 1971,1225; see also M . 4 . Lin, and V. Snieckus,J. Org. Chem., 1971, 36, 645; ( g ) G. H. Wahiand K. Weiss,J. Org. Chem., 1970, 35, 3902; ( h ) D. L. Coffen, TetrahedronLettem, 1970,2633; ( i ) L. J. Kricka and J. M. Vernon, Chem. Comm., 1971 ,942; see also C. 0.Bender,R. Bonnett, and R. G. Smith, J. Chem. S a c . ( C ) , 1970, 1251; ( j ) A . C. Day, C. G. Scales,0. J. R. Hodder, and C. K. Prout, Chem. Comm. , 1970, 1225; (k) J. D. Brewer, W. J.Davidson, J. A. Elix, and R. A. Leppik, Austral. J. Chem., 1971,24, 1883; I ) A. S . Katnerand E. A. Ziege, Chem. Comm. , 1971 ,864;(m) . M. Acton, K. J. Ryan, and L. Goodman,Chem. Comm., 1970, 313; (n) Y. Hayasi, M. Kobayasi, and H. Nozaki, Tetrahedron1970 ,26 ,4353 .similar to the formation of benzazepines from indoles accounts for cyclo-addition of nitroacetylenes to cyclic enamines, affording the ring-openednitrocycloheptadienylamine (34), which can be hydrolysed to the cyclo-heptenone with acid.44The product from the reaction of nitroacetylene (35) with ynamine (36)is not the stabilized cyclobutadiene (37)45 but the isomeric nitrile oxide(38).44 The nucleophilic ynamines also cycloadd to carbonyl groups and to

INM e 2(38)

44 V. Jagar and H. E. Viehe, Angew. Chem . Internat. Edn., 1970, 9, 794.45 R. Gompper and G. Seybold, Angew. Chem . Internat. Edn ., 1968,7 , 824; M. Neuen-schwander and A. Niederhauser, Helv. Chim. Acta, 1970, 5 3 , 519.


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14 Aliphatic, Alicyclic, and Saturated Heterocyclic Chem istryacyclic imines to give a~rylamide~~nd acrylan1idines,4~espectively (Scheme4); cyclic imines give the two-carbon ring expansion.

R'- - N R ~

R3\/ ==CR'CONR2ZR4

R S NR?,\ /R4c=cR'c \NR'

Scheme 4Cycloaddition of acetylenes with various substituted isocyanates follows adiversity of pathways depending on the substitution of both reactants. Thus

cycloaddition of the ethynylogous acid amide (39) with N-carbonyliso-cyanates gives oxazinones (40).4* By contrast, one mole of N-benzoyliso-cyanate reacts with one mole of ethyl propiolate to yield (41), but in a 2: 1

0I tMe2N-C=C-COMe + RC-N=C=O __+(39)

R = Ph or O EtPhC?0

MeoN O A R

'COtEtI (41)

P h $ t r oH20MeNCOPh0 (42)

molar ratio with 3-methoxypropyne to yield (42).49 The extremely48 R. Fuks and H. G. Viehe, Chem. Ber . , 1970,103, 564.47 R . Fuks and H. G . Viehe, Chem. Ber . , 1970,103, 573.4 9 B. A. Arbuzov, N. N. Zobova, and F. B . Balabanova, Izvest . Akad. Nauk S.S.S.R.H.-J. Gais and K. Hafrer, Tetrahedron Le tters, 1970, 5101.Ser . khim. , 1970, 7 , 1570 (C he m. A h . , 1970, 74, 76 350).


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Ace tylenes, Allenes, and Olefins 15electrophilic halogenosulphonylisocyanates react differently again : (43)reacts with but-2-yne in a 2 : 1 molar ratio to give (44)50whereas X-rayanalysis shows the structure of the product from chlorosulphonylisocyanateand hex-3-yne to be (45).61

O=C=NSOeF 4 M r C r C M e ---+(43)

(44)

(45)1,3-Dipolar addition of cyanoacetylene to the ylide (46) gives the cyano-

indolizine (47), dehydrogenation being effected by the acetyleneF2 The1,3-dipolar addition of azlactones (48) to D M A D proceeds via prior tauto-merism to the mesoionic oxazolium 5-oxide (49); pyrroles are the products ofsubsequent elimination of carbon dioxide.53

C N

6 o K . Claus and H . Jensen, Tetrahedron Le tters, 1970, 119.51 E. J. Moriconi, J. G . White, R . W . Franck, J. Jansing, J. F. Kelley, R.A. Salomone,52 T. Sasaki, K . Kanematsu, and Y . Yukimoto, J . Chem. SOC. C ) , 1970, 481.63 H . Gotthardt, R . Huisgen, and H . 0 . Bayer, J . Amer. Chem. S o c . , 1970, 92, 4340.

and Y . Shimakawa, Tetrahedron Le tters, 1970, 27 .


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16 Aliphatic, Alicyclic, artd Saturated Heterocyclic ChemistryThe Diels-Alder addition product (50) from butadiene and 1 Zdibenzoyl-

acetylene is a versatile precursor for preparation of isoindoles, isobenzo-furans, and isobenz~thiophens.~~0 P h@"'- H 2 0 R N H z , @CPh

P11 (50) Ph

P h

PI1Other Additions to the Acetylenic Bond.-Nucleophilic, Acetophenoneoxime and D M A D react to yield the 1:1 adduct (51), which undergoes aClaisen-type rearrangement on heating to the pyrrole (52).55Similarly, theadduct (53) from phenylamidoxime and D M A D is thermally rearranged tothe imidazolone (54).56 The driving force in both these rearrangements is themaking of a C-C bond at the expense of breaking a N-0 bond. Adducts

M e ,OII p h y M C 0 2 M e

N\O C O z M eh'C=N + M e O z C C E C C 0 2 M e -+/

(51)

(53) (54)5 4 J. D. White, M . E. Mann, H. D. Kirschenbaum, and A . Mitra, J . O r g . Chem., 1971,5 5 T. Sheradsky, Tetrahedron Letter s, 1970, 25.5 8 N. D. Heindel and M. C. Chun, Chem. Comm., 1971, 664 .

36, 1048.


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Acetylenes, Allenes, and OlefinsC 0 2 M e C . U . M eI1\ &CO-.Me pwJO aM e&ei(55) 1

17

(55) of N-allylanilines with D M A D also undergo a hetero-Cope rearrange-ment to give anilinofumarates, which are converted into quinolones (56)under the conditions of the rea~tion.~The stereochemistry of nucleophilic addition to activated triple bonds is

related to the nature of the activating groups.2 In the case of the trifluoro-methyl substituted acetylenes where activation is by the inductive effectalone, addition is predominantly trans, e.g. methoxide-catalysed addition ofmethanol to hexafluorobut-Zyne gives (57).58 trans-Addition is also observed

H\ /MeO- + F , C C C C F 3+ c=c/ \M e 0 CF,(57)

F3C

in the nucleophilic addition of thiols to ethyls~lphonylacet~lene~~o give (58)in a kinetically controlled reaction; isomerization at 100C gave the transproducts (59).

H H EtSO2 H\ / 100C \ /RS- + EtSO,C=CH __f c=c + c=c( 5 8 ) (59)

EtSO, SR H/ SRCopper alkyls, prepared from RMgBr and CuBr, react with terminalalkynesto give dienes (60) by two successive sterospecific additions. No metal-hydro-

gen exchange occurs in ether and the reaction can be limited to the first step;bubbling oxygen into the solution promotes the coupling reaction whose57 G . Schmidt and E. Winterfeldt, Chem. B e r . , 1971, 104, 2483.58 E . K . Raunio and T. G . Frey, J . Org. Chem. , 1971,36, 345.59 E. N. Prilezhaeva, V . I. Laba, V. I . Snegotskii, and R . I . Shekhtman, Izuest . Akad .Nnuk S . S . S . R . , Ser . khiin., 1970, 7 , 1602 (Chem. A b s . , 1970, 74, 3285k).


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18 Aliphatic, Alicyclic, and Saturated Heterocyclic ChemistryR1 c u R' D\ / DZO \ /

H- c=c\/c=c\ H R2RlCu + R2C=CH +R2(61) (62)R' c u R2 H\ / \ / Rl- -\ /

R2 R1 c=cR2\H

B u n C r C H + EtCuMgBr2 '' - l o "" B (1)ii , O,, -F 10 'C , 1h E t

stereospecificity is illustrated by the reactions (1) and (2). The vinylcopperintermediate (61) is identified by hydrolysis with D,O to give the deuterio-olefin (62) or by iodination to provide iodo-olefins, mono- or di-substitutedon C-2 (63) and (64). The more reactive ally1 bromide may also add to theintermediate copper complex [reaction (3)].6O

i , ether, 1h , - 0 "CEtCuMgBr, + h n C E C H -i . HMPT,\,,Br, 15Addition of Grignard reagents to alkenes and alkynes is known to be pro-moted by the presence of hydroxy-functions near the multiple bonds. The

OO J. F.Normant and M. ourgain, Tetrahedron Letters, 1971, 2583.


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Acetylenes, Allenes, and Olefins 19stereochemistry of addition appears to be trans [e.g. (65)] with cis-additionproducts resulting from a side-reaction-probably addition to an allenol (66)formed by Grignard-promoted isomerization of the alkynol. The trans-addition eliminates a mechanism such as (67).6f Similarly, suitably locatedtertiary amine functions can cause addition of Grignard reagents to other-wise unreactive multiple bonds, e.g. (68) -+ (69).s2

(6Sj

Electrophilic. Electrophilic addition of bromine to acetylenes has receivedmuch less attention than the corresponding reaction with olefins. At lowbromine concentration and in the absence of bromide ion, the rate of bromina-tion of ring-substituted phenylacetylenes correlates well with d aIues. Thep value of -5.17 is interpreted in terms of a transition state leading to a vinylcation intermediate (70) and, in agreement, addition is non-stereospecific.

A r = y-XCOH4In contrast, a cyclic bromonium io n is postulated in alkylacetylene bromina-tion with the isolation of trans-dibromides from hex-3-ynes and hex- l-yne~.~~

A kinetic and product study of the reaction of diphenylacetylenes withtriphenylaluminium is interpreted as monomeric aluminium attacking theacetylene electrophilically in the rate-determining step (71); cis-Additionproducts are obtained.** Vinylalanes, formed by addition of aluminium

F. W. von Rein and H. G. Richey, Tetrahedron Letters, 1971, 3777, 3781; 1. G .Richey and S . S. Szucs, ibid., p. 3785.e2 H . G. Richey, W. F. Erickson, and A. S . Heyn, Tetrahedron Letter s, 1971, 2183.63 J. A. Pincock and K . Yates, Canad. J . Chem., 1970 ,48, 3332.J. J. Eisch and C . K . Hordis, J . Amer . Chem. Sac., 1971, 93, 2974, 4496.


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20 Aliphatic, Alicyclic, and Saturated Heterocyclic Chemistryalkyls to acetylenes, are known to add to disubstituted acetylenes to producetrans,trans-dienes, e.g. (72), after hydroly~is.~~erminal alkynes do not

(71) X = Me,N, MeO, etc .Et Et\ // \E t k C E t + RzAlH- =CH AlRz

E t m C E t

EtI

Et Et Et /=C H/ H+ / \H G C t H c=cEt Et Et Et

(72)undergo this reaction owing to metalation, but the derived terminal alanes(73) are also converted by cuprous chloride into isomerically pure trans,trans-1,3-dienes (74).66Hydroalumination has also been used to convert alk-1-ynes

R H R1 H HR ~ A I H / CUClRIC=CH + C=C/ \ T H F / \ /H AIR: H c=c

H R1(73) (74)

into alkylcyclopropanes and trans-2-alkyl-1-halogeno-cyclopropanes75),cleavage of the carbon-aluminium bond occurring with retention of con-figuration.g765 G. Wilke and H . Miiller, Annalen, 1960, 629, 222.66 G.Zweifel and R . L. Miller, J . Arner. Chem. SOC.,1970, 92, 6679.13 G .ZweifeI, G. M . Clark, and C. Whitney, J . Arner. Chem. SOC. , 971, 93, 1305.


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Monohydroboration of terminal alkynes with bulky hydroboranes (76)places the boron exclusively at the terminal position of the triple bond. Addi-tion to unsymmetrically disubstituted alkynes is markedly affected by thetriple bond substituent size. Protonolysis or oxidation with H202onverts

the alkynes into alkenes and ketones (aldehydes), respectively.68 Hydro-boration of hex-1 -yne with bis (trans-2-methylcyclohexyl)borane (77) givesthe vinylborane (78). Treatment of (78) successively with 6N-NaOH andiodine gave (79) in 85 % yield.69 Migration of the cyclohexyl group occurswith retention of configuration at the ring. Inversion at the migrationterminus is known from previous A complementary method forintroducing truns-olefinic groups on to cycloalkane rings is treatment ofa-halogenovinylboranes (80) with sodium methoxide followed by pro-ton01ysis 69

The products of addition of sulphur dichloride to diphenylacetylene arestrongly dependent on the solvent. In ether, the unstable vinylsulphenylG. Zweifel, G. M . Clark, and N. L. Polston, J . Amer. Chem. SOC., 971, 93, 3395.

68 G. Zweifel, R. P. Fischer, J. T. Snow, and C. C. Whitney, J . Amer. Chem. SOC., 971,93, 6309.'O G . Zweifel. H. Arzoumanian, and C. C. Whitney, J . Amer. Chem.SOC., 967,89, 3652 .


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22 Aliphatic, Alicyclic, and Saturated Heterocyclic Chemistry

/Y M e(79)

( ( y M e ) : H z: (oI,Me):,-\ I3U"/-


23/78

Acetylenes, Allenes, and Olejins 23preparation of trans-unsymmetrical vinyl halides, which are themselvessynthetically useful.1

In the presence of superacids, alkynes generate vinyl cations which aretrapped by carbon monoxide. Thus a mixture of but-2-yne and carbon mon-oxide, when bubbled into FS0,H-SbF, in an n.m.r. tube, gave (85), (86), and(87) (Scheme 5); (85) was explained by attack of adventitious water. Cur-iously, the stereochemistryof (86) implies attack of carbon monoxide upon

Me---Me iH+Me OH2 Me M e CO\ / HZO \ + + / c o \

/\c-c + C=C-Me+ CH=C + C=CMe,M e H/ \M e H1 lC0 +MeCH,CMe Me co\ // \c=c1+OH Me( 8 5 ) (86 )Scheme 5

the more hindered side of the (presumably linear) vinyl cation intermediate.The methyl migration required to explain (87) is also ~nexpected.~~inylcations are also involved in the reaction of t-butylacetylene with anhydrousHCl at room temperature (Scheme 6); (88) and (89) are minor products fromcyclodimerization of the vinyl cation intermediate.74

Acid-catalysed intramolecular cyclization of (90) gives the enone (9 1).None of the isomeric (92) was obtained, although it is stable under the re-action conditions. 573 1 . Hogeveen and C. F. Roobeek, Tetrahedron Letters , 1971, 3343.7 L K. Griesbaum, Z . Rehman, and U-I. Zfihorszky, Angew. Chem. Internat. Edn., 1970,7 b C . E. Harding and H. Hanack, Tetrahedron Letters , 1971, 1253.9, 812.


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24 Aliphatic, Alicyclic, and Saturated Heterocyclic ChemistryM e

MeCI IIM ~ - C - B U ~Ic1 IMe2C-CMe2 :t CICHeCH-CMesIC1I 1c 1 c1

(85) (89) Scheme 6

Acetylenic bond participation occurs in the biogenetic-like cyclizations(93)+ 94) and (95)4 96), the vinyl cation in the former case beingtrapped by ethylene ~arbonate.'~

Acetolysis of 1,3-di-t-butylpropargyl osylate (97) shows an eight-fold rateenhancement by comparison with a model compound (98). The major prod-ucts were the acetate (99) and the rearranged olefins (100) and (101). Noneof the other products was allenic: hence the positive charge density residesmostly at C-1 in the propargyl cation.77

7 6 W. S . Johnson, M . B. Gravestock, R . J. Parry, R. F. Myers, T. A. Bryson, and D. H .Miles, J . Amer. Chem. SOC.,1971,93, 4332; W. S. Johnson, M. B . Gravestock, andB. E. McCarry, ibid.,p . 4334.7 7 R . S. Macomber, Tetrahedron Le tters, 1970,4639.


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@'Me

(93)

0H(95)

J

RadicaZ Addition. Free-radical addition of toluene-p-sulphonyl iodide ormethanesulphonyl iodide to acetylenes proceeds readily and stereoselectivelywhen the two are mixed in ether and ill~n iinated. '~he high yields of crystal-line products (102) obtained imply that in the mechanism (Scheme 7), chaintransfer by the sulphonyl iodide (k3)s much faster than isomerization of theintermediate vinyl radical ( k 2 ) . The trans-addition was confirmed byzinc-acetic acid reduction to the sulphone, and by X-ray analysis of one ofthe adducts.

7 8 W . E . Truce and G .C.Wolf, J . Org. Chem. , 1971, 36, 1727.3


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26 Aliphatic, Alicyclic, and Saturated Heterocyclic Chem istryR1

RSOp + RIC=CH C==C - e=cA-%3R c S 0 2 R\ /C=C

k - 2 / \H\H R'

Scheme 7The kinetically controlled radical addition of ethyl mercaptan to ethoxy-

acetylene is also trans and sterospecific at low conversions to give cis-l-ethoxy-2-(ethy1thio)ethylene (103).79EtS OEt\ /

H/-\,(103)In the peroxide-catalysed reaction of pentamethyldisilanewith pentamethyl-disilanylacetylene, abstraction of hydrogen from an intermediate vinyl

radical (104) must occur to account for acetylene (105) as one of the prod-ucts.8O Trialkylboranes are known to undergo facile 1,4-addition to manyMe,Si2C=CH + Me5Si2.__+ Me,Si2d=CHSi2Me,

1(l 04)ButO.

Me,Si,CH=CHSi,Me,JMe,Si2GzCSi2Me,(105)

ap-olefinic carbonyl compounds. Acetylacetylene does not react spon-taneously with trialkylboranes but the radical reaction, as in the case of 8-substituted olefinic carbonyl compounds, may be induced by the presence ofcatalytic amounts of oxygen. Hydrolysis of the intermediate allenic compound(106) produces a@-unsaturatedmethyl ketones in good yield.a1

OBRZ0 2 /

THF \R3B + H C kC C O M e + CH=C=C(106) M e/" /Az.RCH=C

COMe7D D. K . W edegaertner, R . M . Kopchik, and J. A . Kampmeier, J . Amer. Chem. SOC.,1971, 93, 6891.8 o H . Sakurai and M . Yamagata, Chem. Comm ., 1970, 1144.A. Suzuki, S. Nozawa, M . Itoh, H . C. Brown, G. W . Kabalka, and G . W. Holland,J . A m e r . Chem. SOC.,970,92, 3503.


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Ace tylenes, Allenes, and Olefins 27Addition of benzyne to tricyclo[4,1 0,O2s7]heptane107) gives the formal[,2 + ,,2 + a2] cycloaddition product (108) in 61% yield.82The mechanismis believed to involve a biradical intermediate (109) with attack on theC-1-C-7 bond taking place from inside the flap as shown, afeature which is

characteristic of these reactions.83 Dicyanoacetylene reacts with (1 10) toform (1 1 ), and in principle attack takes place here inside the flap at eithera or b. The isolation of (111) shows that reaction has occurred at b and thatthe initial radical addition is fairly sensitive to steric effects.82

-+

,H

a

Other Reactions of Acetylenes .-Several recent papers have been concernedwith the mechanism of nucleophilic displacement at acetylenic carb0n.8~In the halide displacement from halogenoacetylenes, substitution is feasibleby either a-addition and p-elimination [reaction (4)] or by attack on thehalogen atom with subsequent attack by the acetylide anion [reaction (5)l.82 P. G . Gassman and G . D. Richmond, J . Amer. Chem. SOC., 970, 92, 2 0 9 0 .83 P . G . Gassman, Accounts Chem. R es. , 1971, 4, 128.A. Fuji and S . I . Miller, J . Amer. Chem. SOC.,971, 93, 3694.


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28 Aliphatic, Alicyclic, and Saturated Heterocyclic Chemistryn -n* / i

B- (4)-C-C-X ---+ RC=C & -GEC-B

R-CEC-X - C r C - t BX 2; R-Cr C-B (5 )7B-

21

Viehe and Delavarenne have ~u g g e s t e d ~ ~ ** ~third possibility which includesp-addition, a-elimination, and onium rearrangement [reaction ( 6 ) ] similarto the mechanism of the Frisch-Buttenberg-Wiechell rearrangement. Their

RC=C----+ R-CEC-B (6)\ /B

4-

evidence is that addition of thiophenolate anion in protonic solvents to t-butylchloroacetylene gives (1 12) and (1 13). The latter are thermodynamicallyunstable with respect to (114) but all three isomers yield the acetylene (115)on treatment with lithium diethylamide. This acetylene is also obtained on

(113)

C=C--SPh(1 15)+112), (113), and (1 14) L i N r l f +

addition of thiophenolate anion to t-butylchloroacetylene in aprotic solvents,and the inference is that the mechanism in reaction (7) is operating, assumingthat a drastic change in mechanism does not occur with absence of proton-donating solvents. The validity and generality of this mechanism remains tobe proved.85 H . G . Viehe and S . Y. elavarenne, Chem. Ber. , 1970,103, 1216.


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Acetylenes, Allenes, and Olefins--l-cI=c--c.] LG:+ ;=c;

I CIP h S

29

r.c:=c:I_f ';";c.=c .-+ + C E C S P h/ \ /., s11sI'll

The reaction of phenylhalogenoacetyleneswith trialkyl phosphite gives theacetylenic phosphonate by an Arbuzov reaction. Halogenoacetylenes aremore reactive than the corresponding alkyl, aryl, or vinyl halides towardstriethylphosphite, and the mechanism has been studied by using ethanol as atrapping agent.84*86he results were interpreted as a nucleophilic attack byphosphite on halogen [as in reaction ( 5 ) ] , the acetylide anion being trappedbyadded ethanol (Scheme 8). At least one other mechanism is operating and this+(RO),P + XCGCPh __+ (RO),PX G C P h X = C1or BrFOHylcohol of

+ +X- + (R0)4P + HC=CPh (RO),P-CECPh + X-i(RO),PO + H C S C P h + RX (RO),P(O)C=CPh + R XScheme 8is the major pathway in the case of phenylchloroacetylene in dilute THFsolution. This is believed to be an attack on the or-carbon and subsequent ,!I-elimination [reaction (4)].

Phenylethynyl ethers may be obtained from phenylchloroacetylene bytreatment with alkoxide ion in aprotic solvents.s7A detailed study of thereaction of phenylchloroacetylene has shown the latter to be triphilic to-wards methoxide ion with 99 % of the attack occurring at the carbon bearingthe chlorine. With phenylbromoacetylene the corresponding figure is 83 %.88

Acetylenes generally react with carbenes to form cyclopropenes. Whetherthis is a reaction via a singlet carbene or a two-step process via a biradicalcannot be determined from the product, as is the case in the trapping witholefins. Isolation of indenes (116) from the reaction of acetylenes with di-phenylcarbene generated photochemically from the diazo-compound, how-ever, was considered to be evidence for the intermediacy of a triplet carbene.8e P. Simpson and D. W . Burt, Tetrahedron Letters, 1970, 4799; D. W. Burt and P.Simpson, J . Chem. SOC. C ) , 1971, 2872.R . Tanaka and S. I . Miller, Tetrahedron Le tters, 1971, 1753.* * R . Tanaka , M. Rodgers, R . Simonaitis, and S . 1. Miller, Tetrahedron, 1 9 7 1 ,2 7 ,2 6 5 1 .


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30 Aliphatic, Alicyclic, and Saturated Heterocyclic ChemistryThe cyclopropenes (117) were shown not to be intermediates in the reac-t ion.89

J,R

Among Cope rearrangements involving acetylenes is the thermolysis ofhex-5-en-l-yn-3-01. The products were all considered to be derived by further

reaction of the primary oxy-Cope rearrangement product (118). TheArrhenius energy of 30 f kcal and AS* f - 4 e.u. are indicative of a con-certed reaction via a cyclic transition state and suggest that participationof thetriple bonds in electrocyclic reactions leads to increased rates by comparisonwith the corresponding 01efins.~~imilarly, thermolysis of p-hydroxyacetyl-enes (119) gives carbonyl and allenic products resulting from a retro-enereaction (1,5-sigmatropic hydrogen shift).g1O B M . E. Hendrick, W. J. Baron, and M. Jones, J . Amer. Chem. SOC., 971, 93 , 1554.O 0 A. Viola and J. H. MacMillan, J . Amer . Chem. SOC., 971,93, 2404.91 A. Viola, J. H. MacMillan, R. J. Proverb, and B . L. Yates, J . Amer. Chem. SOC., 971,93, 6967.


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Acetylenes, AIlenes, and Olejns 31

Cyclization of the aromatic acetylenic aldehyde (120) with acid gives therearranged allenyldihydroisoquinoline 1 21).'2

Allylboranes react with monosubstituted acetylenes and protonolysis ofthe resulting vinylboranes is a general method for synthesisof 1,4-substitutedpentadienes (122).93Using alkoxyacetylenes (R = OAlk) theresultingalkoxy-pentadienes can be hydrolysed to the non-conjugated enones.

Oxidation of acetylenes with N-bromosuccinimide in DMSO gives a-dicarbonyl compounds in some cases. The yield using diphenylacetylene ispractically q~anti ta tive.~' xidation with peracid has been studied usingdi-t-butylacetylene,and the products obtained compared with those obtainedby decomposition of the related diazoketone (123). The primary productsfrom the former were the ap-unsaturated ketone (124) and the cyclopropyl-ketone (125). An almost identical ratio of products (124) and (125) was

(123) (124) (125)s2 M. Sainsbury, S . F. Dyke, D. W. Brown, and R. G . Kinsman, Tetrahedron, 1970,26,93 B. M. Mikhailov, Yu. N. Bubnov, S. A . Korobeinikova, and S. I . Frolov, J . Organo-9 4 S . Wolfe, W . R . Pilgrim, T. F. Garrard, and P. Chamberlain, Canad. J . Chem.. 1971,

5265.metallic Chem., 1971, 27, 165.49, 1099.


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32 Aliphatic, Alicyclic, and Saturated Heterocyclic Chemistryobtained from decomposition of the diazoketone, implying a common inter-mediate ketocarbene for both reactions. Although similar products wereobtained from analogous reactions using (126) and cyclodecyne (127), thedistributions were different.95

( 1 27)Oxidat ion of secondary-tert iary

to furanones (129).96( 126)

acetylenic glycols (128) provides a route

R? ,R2

(128) (129 )An attempt to convert the aldehyde (130) into the corresponding ester(131) by the method of Coreyg7gave, in addition, the ester (132) and its

transformation products. Ester (132) was also obtained in the absence ofMn02, and the mechanism via (133) is supported by studies using NaCNin MeOD.98

\ IeOlI-CX-X l I l O ~Ph-CZX-CII=C H C H O Ph- C=C- C H z C H C O : !E t(130) (131)

4--- C N(133)Oxidation of internal acetylenes with ruthenium tetroxide gives the corre-

sponding diketones with some of the acids resulting from cleavage.99DMAD reacts with ethylene trithiocarbonate (134) to give ethylene and the

1,3-dithiole-2-thione (135).looFurther study has indicated that acetylenesO 5 J . Ciabattoni, R. A . Campbell, C. A. Renner, and P. W. Concannon, J . Amer . Chem.9 6 M . F. Shostakovskii,T. A. Favorskaya, A . S.Medvedeva, L. P. Safronova, and V. K .g7 E. J. Corey, N. W . Gilman, and B. E. Ganem, J . A m er . Chem. Soc . , 1968, 90 , 5616.g* P.-H. Bonnet and F. Bohlmann, Chem. Ber., 1971, 104, 1616.H. Gopal and A. J. Gordon, Tetrahedron Letters , 1971, 2941.

SOC., 970,92, 3826.Voranov, Zhur. org . khim. , 1970, 6, 2377 (Chem. Abs . , 1970,14, 64 134g).

lo o D. B. J . Easton and D. Leaver, Chem. Conim. , 1965, 585.


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Acetylenes, Allenes, and Olefins 33bearing electron-withdrawing groups and the -C(==S)S- unit are necessaryfor the success of this reaction. Thus (136) reacts to give (137), but the SS'-ethylene dithiocarbonate was unreactive. Bromocyanoacetylene reactsanomalously to give (138). No mechanisms have been advanced for thesereactions."'

TJCO.C,y + MeO?CC=CCOLMc -* ;.'t',C':tl&.\MCOJ2

(154) x = Y = s(136) x -= 0,k' == s (135) X = Y = S(137) X = S,Y = 0

(138)t-Butyl isocyanide reacts with acetylenes in the presence of nickel acetate,and the pyrrole derivatives (139) are formed in high yield.lo2

R2\aRR2/R1 , NHCMe3CMe3RlC'CR2 + McJCNC Ni(oAc)S + NHCMt.3 N (IOMCZNC (139)It is often difficult to induce selective addition to double bonds in the

presence of triple bonds because of the reactivity of the latter. Dicobalt octa-carbonyl selectively adds to a triple bond in the presence of a double bond andallows selective transformation of the non-co-ordinated olefinic bond.lo3Removal of the protecting metal is simple. Thus vinylacetylenes when treatedwith strong acids usually form the products of hydration of the triple bond,and the ene-yne-ol (140) reacts with fluoroboric-acetic acid at 25OC for24 h to form an intractable mixture. Its complex (141) reacted at OC for15 min to give 91 % of (142) on work-up, which implies a metal-stabilizedcarbonium ion intermediate. Oxidative degradation with Fe(NO,), gener-ates the acetylene (143) in excellent yield.

On treatment with hydrobromic-acetic acids the diol (144) gives the di-bromotetraene (145).The corresponding methoxylated analogue (146), how-ever, yields the benzofuranyl acetylene (147) after chromatography overalumina. Allene (148) was shown to be an intermediate in this reaction andwas converted into (147) by a1umina.l"lo l B . R. O'Connor and F. N. Jones, J . O r g . C h e m ., 1970,35,2002.lo2M . Jautelat and K. Ley, Synthesis, 1970, 593.lo3K . M . Nichols and R. Pettit, Tetrahedron Letters, 1971, 3475.lo4 S. Kobayashi, M . Shinya, and H . Taniguchi, Tetrahedron L ette rs, 1971, 71.


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34 Aliphatic, Alicyclic, and Saturated Heterocyclic ChemistryH0. 0 1 1

(CO),Co- :co(co),(141)

(144)R' = RZ = ?(146) R1 = Me, R! = OMcJ

BrPh2C=C=!'C=G=CPhp

Br(145)

L\

Me


35/78

Acetylenes, Allenes, and Olefins 35A study of the metallation of 1-phenylpropyne (149) has shown that the

dianion produced is different from that prepared from 3-phenylpropyne andP h C H ~ C ~ C I I-d.-PhCECCH3 BLLi P h C s C C I I PhCHC=C


36/78

36 AlQhatic, Alicyclic, and Saturated Heterocyclic Chemistry2 Allenes

Synthesis.-A usually reliable method of preparing allenes is by the in-sertion of cyclopropylidene carbenes (carbenoids). However, treatment oftetrasubs ituted gem-dibromocyclopropanes with met hyl-lithium gives bi-cyclobutanes with allenes as minor products.l1 The dibromocyclopropane(155) yields only the bicyclobutane (156) and no allene is detectable, whereasthe isomeric dibromocyclopropane (1 57) yields, in addition to the bicyclo-butane (158), appreciable amounts of allene (159). This is attributed to alengthening of the C-2-C-3 bond in an unsymmetrical transition state withpositive charge better accommodated on a carbon bearing two phenyl groups.

The acetylene (1 60 ), derived from phenyldibromocyclopropane(161) withexcess methyl-lithium, is now believed to be the product of the reaction ofmethyl bromide with the dianion of the allene generated in situ. ll l Theacetylene (160) appears to be the kinetically formed product on neutralizationbut may be converted into the allene (162) by shaking with powderedpotassium hydroxide in hexane.

lV1CB i 'Brf1611 (162)

Decomposition of the N-nitroso-oxazolidone(163) with base in a solutionof ethoxyacetylene gives the allene diethylacetal (164) ; the carbene inter-mediate in the suggested mechanism is supported by previous work.l12

An attempt was made to prepare diphenyldiazoallene (165) by base de-composition of the dinitrosourethane (166). The major product was the110 W. R . Moore and J. B. Hill, Tetrahedron Letters , 1970,4553 .ll 1 E . V. Dehmlow and G. C . Ezimora, Tetrahedron Letters, 1971, 5 6 3 ; E.V. Dehmlow11 2 M . S . Newman and C. D . Beard, J . Org . C h e m . , 1970, 3 5 , 2412; M . S . Newman andand G. C . Ezimora, ibid., p. 1599.A. 0. M . Okorodudu, ibid., 1969, 34, 1220.


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Acetylenes, Allenes, and OleJins 37

'NO(163) 1IMe2C=C\ +CI-I=COE t

diazopropanone (167), believed to be derived

,CH(OEt),--+ Mc,C=C=C

'11(16 4

from an oxadiazole and con-firming that at least the first steps of the anticipated reaction had occurred.l13The presence of at least a small quantity of the evidently unstable (165) asone of the reaction products was indicated by the trapping of the derivedcarbene, giving the adduct (168) with tetramethylethylene.

N;

By analogy with the preparation of ketens from acid chlorides, the 7-chlorovinylaldehydes (169)-vinylogous acid chlorides-were treated withtriethylamine and yielded the allenic aldehydes (1 70).11d

R2 0 R2 0I /, I / /R'CH,C=C-C + EtSN + 'CH=C=C-C'H'\ HI

(169) (1 70)c1

1 1 3 D. J. Northington and W. M . Jones, Tetrahedroii Letters, 1971, 317.1 1 4 E. Schelhorn, H . Frischleder, and S . H a u p t ma n n , Tetrahedron Let ters , 1970, 4315 .


38/78

38 Aliphatic, Alicyclic, and Saturated Heterocyclic ChemistryAllenes of the type (171) have been prepared by cycloaddition of ynamines

with carbon dioxide.l15 The reaction with diethylaminopropyne is completein one hour at -60 "C and the only contaminant is a small quantity of theaminocyclobutenone (1 72).

1,l Dialkyl-3-iodoallenes are efficiently prepared from 1,l dialkylprop-2-yn-1-01s [ e g . (173) - 174)] using a two-phases ystem, the product being ex-tract ed into petroleum.16HI-CUI-NH~IMe,C-C=CH . Me,C=C=CHICu powderI

(173) (174)OH

Dibrominated diarylallenes (1 75) are readily derivatized via the carbenoidformed with butyl-lithium. The acid (176) appears to be formed in the work-up from the bromide (177), which seems to be readily so l ~ o l y s e d . ~ ~ ~

/Co2HBr Li/ BuLi / co,\Ar2C==C=C + r2C=C=C + r,C==C==C BrBrBr

(175) (177)CICOzMeJCO,Me OHIAr,C-C=CCO,HAr,C==C===C,\Br

Other allene syntheses employing acetylenic starting materials include thepreparation of b-allenic esters (1 78) via an intramolecular Claisen rearrange-ment;ll* the rearrangement of acetylenic esters of sulphinic acid (179) to116 J. Ficini and J. Pouliquen, J . Amer. Chem. SOC., 971, 93, 3295.116 P . M . Greaves, M . Kalli, P. D. Landor, and S . R . Landor, J . Chem. SOC. C ) , 1971,11' G. Kobrich and E. Wagner, An gew. Chem. Internat. Edn., 1970,9, 524.11 * J . K . Crandall and G. L . Tindell, Chem. Comm., 1970, 1411.

667; see also J. Gore and M.-L. Roumestant, Tetrahedron Letters, 1971, 1027.


39/78

Acetylenes, Allenes, and OlefinsR2

39I HfRL-C~C--C-OH + R4CH2C(OEt)3II,R'CeC-CR2R3

R3 '0/R4CH2-C(OEt),

\/\

(178)

C=C===CR2R3R'CH

CO2Et35-60 %0

ArS IArS02C=C=CHR2F A 30 O C ,

allenyl sulphones (1 SO) involves a similar cyclic rearrangement. When opti-cally active acetylene is used, the absolute configuration of the product, de-duced from the polarizability sequence of substituents on the allene, is inagreement with a cyclic mechanism. Rearrangement of the correspondingsulphenate ester to sulphoxide (180; SO instead of SO,) is much faster butappears to follow a similar pathway.ll9

The potentially useful allenic amines (181) are prepared from ap-un-saturated ketones by the route shown.12*Propargyl chlorides are converted in good yields via a hydroboration

procedure into terminal allenes (182).1211 ZCyclononadiene has been partially resolved by crystallization of a

diastereoisomeric mixture of its platinum complexes (183). Optically purersamples of both enantiomers were prepared from optically active trans-cyclo-octenes via the dibromocarbene adduct?,,Cycloaddition Reactions.-The theoretical predictions of Woodward andHoffmann to the effect that [2 + 21 cycloadditions of alIenes (and ketens)llg G . Smith and C. J. M. Stirling, J . Chem. SOC.C),1971, 1530.12 0 J.-P. Dulcere, M. Santelli, and M . Bertrand, Cornpt. rend., 1970, 271, C, 585.lZ1 G. Zweifel, A. Horng, and J. T. Snow, J . A m er . Chem. SOC.,1970, 92, 1427.l z 2 A . C. Cope, W. R . Moore, R. D. Bach, and H . J. S. Winkler, J . Am er . Chem. SOC.,1970,92, 1243.


40/78

40 Aliphatic, Alicyclic, and Saturated Heterocyclic ChemistryR 2 R 3 R1 R2 R 3

0I R4 OH R4I / HC=CLi-NH3 I 1 /R--G-C=C HeC-C-C=C

IR ReI 1HC=C-C=C-CR3R *ICI

[( )-CBH14(PtC12)Am*] Am* = optically active a-methylbenzylamine(183) or p-nitro-a-methylbenzylamine.

may be concerted have led to a detailed investigation of the dimerimtion ofallenes. Dimerization of equimolar mixtures of tetradeuterioallene and alleneleads to a statistical distribution of [2Ho],[2Ha],and [2H8]dimeric products(1 ,Zdimethylenecyclobutanes). When 1, l-dideuterioallene s dimerized undersimilar conditions, an intramolecular kinetic isotope effect of k H / k D=1.14 f .02 is observed with an excess of deuterium located in the vinylpositions (184). These results are reconciled by postulating the presence of

H2CurHz H2wCDz D 2 C . C D ;HzC=C=CDz 4 D2

(4 (b) (d(184)


41/78

Acetylenes, Allenes, and Olefins 41more than one energy barrier in the mechanistic pathway, with the rate-determining step not identical to the product-determining step.123Dimeriza-tion of optically active 2,3-pentadiene gives sixstereoisomeric 1,2-diethyIidene-3,4-dimethylcyclobutanes 185), which were isolated and identified by their220 MHz spectra. The results did not distinguish between a concerted cyclo-addition and a biradical mechanism.124

Ph P h Ms MsMeHCM eXIMe l:ypu:"

(185) (186) (187)X-Ray structure determinations of the major dimer from 3-chIoro-1,l-

diphenylallene and the symmetrical dimer from 3-chloro-1 mesityl-alleneshows them to have structures (186) and (187), re~pective1y.l~~

The stereochemistry of the dimerization products of l-adamantyl-3-chloroallene has been assigned.126Although the dimerization of opticallyactive cyclononadiene gives results which strongly support a [,2, + n2a]con-certed cy~l oa dd it io n, ~~ ~he possibility that an intermediate biradical is pro-duced and reacts stereospecificallymust also be considered.Cycloaddition of 1,l-dimethylallene with tetrafluoroethylene is believedto be a non-synchronous process.128 The biradical (188) was suggested asan intermediate in formation of the 1 :1 adducts isolated [(189a) and (189b)],rotation of the CH, group out of the ally1 plane occurring more easily thanthat of the heavier hyperconjugated CMe, group and accounting for the3.6:l ratio of (189a) : 189b).

Mey)' *.'F ,.as 189b)(189a)F F(188)It appears that the 1,2-addition of an electron-deficient olefin to an alleneresembles the analogous 1,2-additionof olefins to 1,3-dienes, accepted to be atwo-step mechanism.129Benzyne reacts with allenes to give benzocyclobutenes;lZ3 W. R. Dolbier and S.-H. Dai, J. Amer. Chem. SOC., 970, 92, 1774.lz4 J. J. Gajewski and W. A. Black, Tetrahedron Le tters, 1970, 899.lZ 5 S . R. Byrn, E. Maverick, 0. J. Muscio, K. N. Trueblood, and T. L. Jacobs, J. Ame r .lZ 6 T. L. Jacobs and 0. J. Muscio, Tetrahedron Le tters, 1970, 4829.lZ7 W. R. Moore, R. D. Bach, and T. M . Ozretich,J. Amer. Chem. SOC., 969, 91, 5918.lz8 D. R. Taylor, M. R. Warburton, and D. B. Wright , J. Chem. Sac. ( C ) , 1971, 385;lZe P. D. Bartlett, Quart . Rev. , 1970, 24, 473.

Cliem. SOC., 971, 93, 6680.

D. R. Taylor and D. B. Wright, ibid., p. 391.4


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42 Aliphatic, Alicyclic, and Saturated Heterocyclic Chemistry1,3-dienes and acetylenes, products of an ene reaction, are also obtained(Scheme 9). Benzocyclobutene formation is favoured where the allene is

'C-C=C!-CH I/ I IPh

Scheme 9substituted with electron-rich groups.130 Phenylallene undergoes a new type ofdimerization on heating to give the naphthalene (190), for which a self DieIs-Alder adduct is the postulated intermediate.131

PhCH=C=CH2 AqcHmI:H2H Ph Ph(190)

Tetramethoxyallene and tetracyanoethylene combine to yield an equi-librium mixture of the cyclobutane (191) and the stabilized ring-openeddipolar species (192).132At -95 O C he signals due to both (191) and (192) arerecognizable in the n.m.r. spectrum. A similar situation is observed in theadduct from benzenesulphonyl isocyanate and tetrathi~alkylallenes,~~~heequilibrium between (193) and (194) being established.

OMe

RS

Earlier work in cycloadditions with allene suggested that intramolecularisotope effectswith values of k , /k , > 1 .OO derive from non-concerted, prob-ably biradical processes and that when k , / k , < 1 OO a concerted mechanismlSo H. H. Wasserman and L . S. Keller, Chem. Comm., 970, 1483.lS1 J. E. Baldwin and L. E. Walker, J . Org. Chem. , 1971, 36, 1440.132 R . W. Hoffmann and W. Schgfer, Angew. Chem . Internat. Edn., 1970, 9, 733.133 R . Gompper and D. Lack, Ange w. Chem . Internat. Edn., 1971, 10, 70 .


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Acety lenes, Allenes, and Olefins 43is likely. The isotope effect k, /k, = 0.93 was considered diagnostic of aconcerted reaction between tetracyanoethylene oxide and dideuterioallene(Scheme A similar conclusion was reached in a study of tetracyano-ethylene oxide addition to deuteriated styrenes.135

H

Scheme 10 DIntramolecular nitrone-allene cycloaddition has been used to prepare theAddition of azomethine oxides to allenes does not lead to the anticipatedbicyclic isoxazolidine (1 95).136

1,3-dipolar addition product (196) but to the 3-pyrrolidinonesIIac==C=CJ3\

(CH2)2 + MeNHOH A//o=c\Me

-\HzC=C=C-0\ + FH"*J -r=%eMe

-0+ /H2C=C=CR2 + ArCH-N

'R = H'or MeR

IP h

[197)?37

- rdRRP h(196) (197)13* W . R. Dolbier and S . H . Dai, Tetrahedron Letters, 1970, 4645.135 W . F. Bayne and E. I . Snyder, Tetrahedron Letters , 1970, 2263.136 N. A. Lebel and E. Banucci, J . Amer . Chem. SOC., 970 ,92 , 5278.13' M . C. Aversa, G. Cum, an d N. Uccella, Chem. Comm., 1971, 156.


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44 Aliphatic, Alicyclic, and Saturated Heterocyclic ChemistryThe rearrangement is formulated as passing through a heterolytic cleavageofthe N-0 bond, but a radical mechanism seems more likely.

The cycloaddition of alkenylidenecyclopropanes (198) with the triazoline(199) involves participation of the strained o-bond of the cyclopropane. Aconcerted reaction is believed to be involved since single isomers of (ZOO)and (201) are obtained which are the least thermodynamically ~ t a b 1 e . l ~ ~

(198) R = H o r Me (199)

(200) (201)Allenic esters react predictably with benzonitrile oxide to give isoxazoles(202), but spiro-isoxazolines (203) result when aromatization of the inter-

mediate is diffi~u1t.l~~EtOaCCHMe

Addition

EtOnC, M e

P h+ I

(203)React ion~.~~~~-Aetailed s t ~ d y l * ~f the free-radical chlorination

of penta-Z,3-diene with t-butyl hypochlorite shows that substitution productsare obtained by both allylic and allenic hydrogen-abstraction; addition13 * D. J. Pasto and A. Chen, J . Amer. Chem. SOC., 971, 93, 2562.139 P. Battioni, L. Vo-Quang, J.-C. Raymond, and Y. Vo-Quang, Compr. rend., 1970,lSea M. C . Caserio, SeIectiue Or g. Transform., 1970, 1, 239.140 L. R. Byrd and M . C. Caserio, J . Amer. Chem. SOC., 970, 92, 5422.

271, C, 1468.


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Acetylenes, Allenes, and OleJiris 45products are also obtained. None of the products isolated using opticallyactive penta-2,3-diene are optically active. Free-radical addition of hydrogenbromide to allenes yields olefinic products almost exclusively by addition of abromine atom to the central carbon of the allenic systern.l4l Addition ofhypochlorous acid to allenic hydrocarbons, an electrophilic attack, leads, inall cases, to the placement of the chlorine on the central carbon atom and theOH group on the more substituted of the allenyl ~ a r b 0 n s . l ~ ~lectrophilichydrochlorination of phenylallenes is believed to proceed through a transitionstate more closely related to the localized allylic cation (204) than to thedelocalized cation (205).143

Optically active penta-2,3-diene reacts with iodine, iodine bromide, oriodine chloride in methanol to give optically active tuans-3-iodo-4-methoxypent-2-ene (206). The optical purity of the product was found to vary with thenature of the iodinating agent in the order IC I > IBr > I,. Iodine produced inthe reaction is responsible for the racemization, which is explained below(Scheme 1 l).144

OMeIMe H M e C----Me,/ 1,-MeOHc=c=c ____,\ MeH

IIMe C - M ec=c .

H /

H/ 1

IIM e C---HMe (racemization)I- \ / \- /c=c\N 2 H 1

Scheme 11Oxymercuration studies on optically active penta-2,3-diene using mercuric

acetate in methanol suggest that formation of the unsymmetrical mercurinium141 R. Y . Tien and P. 1. Abell, J . Org. Chem. , 1970, 3 5 , 956.142 J.-P. Bianchini and M. Cocordano, Tetrahedron, 1970, 26, 3401.143 T. Okuyama, K . Izawa, and T. Fueno, Tetrahedron Letters, 1970, 3295.144 M. C. Findlay, W. L. Waters, and M . C. Caserio, J . Org. Chem. , 1971, 3 6 , 275.


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46 Aliphatic, Alicyclic, and Saturated Heterocyclic Chemistryion is the rate-determining step in the formation of the chiral products (207).However, on using mercuric chloride the open ion (208) is apparentlyformed, leading to racemic pr 0 d ~ c t s . l ~ ~

Me Me Hg(OAd\ / ;c=c i\ / '\, iMe\/C=C=C' + Hg(OAc), + MeOH --+H H C---Me\ H

lMeOHMe Hg( O WJ\ // \ /'

IC-C Me

H CAHOMe

(207) (+&-isomer)HgCIIc

I 1(208)

Reduction of organomercurials formed from cyclic allenes (10-14-membered rings) with sodium borohydride yields an increasing ratio oftrans: cis monosubstituted olefins as the ring size is increased.146The stereo-chemistry and mechanism of the reduction of cyclic allenes using di-irnidel4'and sodium in liquid ammonia148have been investigated. A stereospecificre-duction with sodium in liquid ammonia of the intermediate cyclopropylallene(209) has been used to synthesize trans-chrysanthemic acid (21O)?49

Dehydrohalogenation of 1-halogenocyclohexenes with potassium t-butoxide in t-butanol-DMSO has been studied using the deuteriated substrate(211). Two competitive pathways seem to be operating to give cyclohexa-l,2-diene and cyclohexyne (Scheme 12)>50The proposal of Wittig in 1966 thatthe C,, hydrocarbon (212), also produced in the abovereaction, was derived bydimerization of cyclohexa-1 2-diene has been vindicated. When thedeuteriatedsubstrate (21 1) is used the dimer (212) has no protium at vinylic positions.151145 W. S . Linn, W. L. Waters, and M. C. Caserio, J . Amer. Chem. SOC., 970, 92, 4018;14 6 R . Vaidyanathaswamy, D . Devaprabhakara, and V. V. Rao, Tetrahedron Letters,147 G. Nagendrappa and D. Devaprabhakara, Tetrahedron Letters , 1970,4243.148 R. Vaidyanathaswamy, G . C. Joshi, and D. Devaprabhakara, Tetrahedron Letters,14 8 R . W. Mills, R . D. H . Murray, and R. A. Raphael, Chem. Comm., 1971, 5 5 5 .150 A. T. Bottini, F. P. Corson, R. Fitzgerald, and K . A . Frost, Tetrahedron Letters , 1970,15 1 A. T. Bottini, F. P. Corson, R . Fitzgerald, and K . A. Frost, Tetrahedron Letters , 1970,

----c4;bc/

see also R. D. Bach, J . Amer. Chem. SOC., 969,98, 1771.1971,915.1971,2075.

4753.4757.


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Acetylenes, Allenes, and OIejns 47

CHzOH Na-NI13,

M e y C Me ie 1209)M eM e\ /

Other Reactions of Al1enes.-Allylic halides undergo solvolysis at ratesgreater than those of their saturated analogues owing to charge delocalizationthrough the mystem. The vinyl cation,152t may be anticipated, could be

(211)hX = C1, Rr, or I

ButOIl, D& I-OBut

D DMDBUtD@ButD DScheme 12

similarly stabilized by such a neighbouring double bond. This is demon-~ t ra t ed l~~n solvolysesof the allenic chlorides (213), which proceed readily inc1

X(213) X = H or OMe

15* M . Hanack, Accounts Chem. R es . , 1970,3,209.lS3 M . D. Shiavelli, S. H . Hixon, and H . W. Moran, J . Am er . Cliem.SOC., 970, 92, 1082;M . D. Shiavelli, S . H . Hixon, H . W. Moran, and C. J. Boswell, ibid., 1971, 93, 6989.


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48 Aliphatic, Alicyclic, and Saturated Heterocyclic Chemistryaqueous acetone at 25"C at rates far in excess of those of the correspondingaryl vinyl halides.154 Allenyl bromide itself solvolyses in aqueous ethanolat a rate 4 x lo3slower than propargyl bromide.155 This is attributable to alower ground-state energy in allenyl bromide as a result of the stronger sp2hybridized carbon-halogen bond relative to the sp3bond in propargyl bromideas well as to differences in transition-state geometries.

Homoallenic participation has been measured using (214), which is believedto solvolyse through the same intermediate ion (Scheme 13) as the isomerictosylate (215)156on the basis of virtually identical product yields. The tosyl-ate (214) solvolyses approximately 40 times as fast as its saturated analogue

L"H2C=C=C Y O T s -Me(214) /

productsh eScheme 13

2-methyl-l-pentyltosylate. Similarly, the bishomoallenic tosylate (216)solvolyses at a rate which suggests that participation is occurring, and thecyclopentene derivatives (217) and (218) are among the pr0d~cts.l~~his

---+ (217)3.

result suggests that intramolecular participation by an allenyl group issuperior to that of a similarly located eth~1ene. l~~15* Z . Rappoport and A. Gal, J . Amer. Chem. SOC., 969,91, 5246.lS 5 C. V. Lee, R. J . Hargrove, T. E. Dueber, and P . J. Stang, Tetrahedron Letters , 1971,156 R . S . Macomber, J . Am er. Chem. SOC., 970, 92, 7101.15' B . Ragonnet, M . Santelli, and M. Bertrand, Tetrahedron Letter s, 1971, 955.15* P. D. Bartlett, W. D. Closson, an d T. J . Cogdell, J . Am er. Chem. Soc., 1965,87,1308.

2519.


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Acetylenes, Allenes, and Olefins 49The allenic dianion (219) is obtained from the acetylene (220) by treatment

with two moles of b~tyl-1ithiurn.l~~lkylation can be carried out successivelyusing two different reagents to yield the tetrasubstituted allenes (221); hydrol-ysis of the monoalkylated products yields ap-unsaturated aldehydes (222).

BuLi - -PhC=C-CH,OMe + hC=C=COMe2 moles(220) (219)

PhCLCHCHO Ph OMe\ /c=c==cAdsorption of M e k C D on zinc oxide gives rise to an OH band at3515 cm-l in the i.r. spectrum and no band at 2598 cm-l (OD) is observed,

suggesting that the following process is occurring:C H , W D + ZnO + H2-CkCDIZn-0-H

The spectrum is identicalto that of adsorbed allene, implyingthat theadsorbedspecies is the propargyl anion. In agreement with this conclusion is the iso-merization of allene to methylacetylene when the former is circulated overthe activated zinc oxide employed.160Epoxidation of vinylallenes (223) leads to cyclopentenones (224) orallenylepoxides (225) in amounts which depend upon the substitutionpattern of (223).161

/ B \223) R3c=c=cH

R1 K3(224)

/ c.(225)ls g Y. Leroux and R . Mantione, Tetrahedron Letters, 1971, 591; Y . Leroux and R .160 C. C. Chang and R. J. Kokes, J . Amer. Chem. SOC., 970,92, 7517.161 J. Grimaldi and M . Bertrand, Bull. SOC. him. France, 1971, 957.

Mantione, J . Orgaiiometallic Chern., 1971, 30, 295.


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50 Aliphatic, Alicyclic, and Saturated Heterocyclic ChemistryIsomerization of the acetylenic dimethylsulphonium bromide (226) occursreadily in ethanol to yield the allene (227). Addition of p-ketoester, p-diketone, or /I-ketosulphone gives the corresponding furans (228) in high

yield.162Thermolysis of the allenic diamide (229) yielded the a-pyrone (230), wherethe keten (231) was a presumed intermediate formed by a reverse ene

rea~t i0n . l~~

The absolute configuration of ( -)-cyclonona-l,2-diene has been estab-lished as (S) by an 0.r.d.s.d. correlationle4 and by the extended chemicalcorrelation shown (Scheme 14).165 The absolute configuration of the (+)-isomer of (232) was established by X-ray diffraction.Investigations into 13Cn.m.r. spectra of allenes have shown that the centralallenic carbon (C-/?) has an extremely low chemical shift. This technique isuseful for studying charge distribution in allenes, and for a given alkyl sub-stituent there is a fair linear relationship between the number of substituentsand d(C-@5).166 mong studies of the long-range spin-spin coupling over five162 J. W. Batty, P. D . Howes, and C. J. M . Stirling, Chem. Comm., 1971, 534.l m J. Ficini, J. Pouliquen, and J.-P. Paulme, Tetrahedron Letters , 1971, 2483.164 W . R . Moore, H. W. Anderson, S . D . Clark,and T. M . Ozretich,J . Amer. Chem.SOC.,1971,93,4932.R . D. Bach, U. Mazur, R. N. Brumrnel, and L.-H. Lin, J . Amer. Chem. SOC.,1971,93, 7120.188 R . Steur, J. P. C . M . van Dongen, M. J. A. de Bie, W. Drenth, J. W. de Haan, andL. J. M. van de Ven, Tetrahedron Letter s, 1971, 3307.


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H".QAc Q.HiMM e Q .,HNa-NH3

H - - - R - ( - )A g hOMeR - ( + ) MeOH

BrScheme 14

bonds in the 'H n.m.r. of allenes is an attempt to relate the value of 6J tothe dihedral angle 4 between the two planes involved (233).16'

(1R ,8R)-( )-(232)

(233) COMcI

(235) (234)An X-ray elucidation of thep-bromobenzoate shows (234) to be the struc-ture of the allenic ketone formed by photo-oxidation and manganese dioxideoxidation of (235). It is concluded that the naturally occurring allenic ketonelo ' M . Santelli, Chem. Comm., 1971, 938.


52/78

52 Aliphatic, Alicyclic, and Saturated Heterocyclic Chemistryisolated from the large flightless grasshopper differs from (234) in configura-tion at the allenic carbon and supports the view that the latter is derived byin vivo degradation of the carotenoid neoxanthin.168

The propargyl-allenyl free radical (236) has been studied by e.s.r. by re-action of methylacetylene and allene with photochemically generated t -butoxyl radicals. 1,l-Dimethylallene reacts by abstraction of either an allenyl

CH,C=CH 4-+ CH,=C=CH(236)

or a methyl hydrogen to give (237) and (238), distinguishable by their e.s.r.spectra. -c

The radical (238) may be considered in two valence tautomeric forms [(239)and (240)] which differ by a 90 rotation about the C-3-C-4 axis. E.s.r.and calculations favour (240), containing the unpaired electron in a delocal-ized orbital (shaded), over (239) with the electron in a localized 0rbi ta1. l~~

(239)3 Olefins

Reviews on olefins which have appeared during the past two years include theaddition-elimination reactions of palladium compounds with olefins 170elimination reactions leading to olefins;171*172he stereochemistryof the Wittigreaction;173 stereoselective and stereospecific olefin synthesis 174J75 steric168 T. E. DeVille, J. Hora, M . B . Hursthouse, T. P. Toube, and B. C . L . Weedon, Chem.169 J. K. Kochi and P . J. Krusic, J . Amer . Chem. SOC., 970, 92 , 4110.170 R . F. Heck, Fortschr. C hem . Forsch., 1971, 16 , 221.17 1 J. Sicher, Pure A p p l . C h e m . , 1971, 2 5 , 6 5 5 .172 A . J. Parker, Chem. Technol., 1971, 297.173 M . Schlosser, Topics Stereochem., 1970, 5 , 1.175 J. D. Faulkner, Synthesis, 1971, 175.

C o m m . , 1970, 1231.

J. Reucroft and P . G. Sammes, Quart . Reu. , 1971, 2 5 , 135.


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Acetylenes, Allenes, and Olefins 5 3selectivity in addition of carbenes to 01efir-1~;~~~ddition of halogen azides,lY7pseudo-halogen~,l~~r sulphenyl halides179 o olefins;and prototropic iso-merization of olefins with functional groups.lsO n addition, a book has alsoappeared.lS1Synthesis.-Much effort has been expended recently in devising new methodsfor stereospecific syntheses of substituted ~ l e f i n ~ ~ ~ ~ , ~ ~ ~nd, in particular, theirapplication to the synthesis of biologically important terpenoids. Studies ofC,, and CIS Cecropia juvenile hormone necessitated a stereospecific synthesisof the heptenol (241), which was preparedlS2as shown. Conversion of the

(241)phosphonium salt derived from (241) into the trisubstituted olefin (242) usesanother stereospecific reaction, the addition of formaldehyde to the b-oxidoylide (243). Olefin (242) is converted in several steps into (&)XI,

em P P h 3 '

(244)

CHzOTHP A.

' f 'HO (243) THP = tetrahydropyranyl&&zo

f O T H P

(242)17 6 R. A . Moss, Selective O r g . Transform., 1970, 1, 3 5 .177 A. Hassner, Accounts Chem. Res. , 1971, 4, 9.17 8 D. Swern, Amer. Chem. SO C.Div. Petrol. C hem., 1970, 15, E39.18 0 L. A . Yanovskaya and K h. Shakhidayatov, Russ. Chem. Re v., 1970,39, 859.lS 1 'The Chemistry of Alkenes', ed. J. Zabicky, Interscience, London, 1970.

D. R. Hogg, Me ch. Reactions Sulfur Compounds, 1970, 5, 87.E. J. Corey, H . Yamamoto, D. K . Herron, and K . Achiwa, J . Amer . Chem. Soc. ,1970,92,6635.


54/78

54 Aliphatic, Alicyclic, and Saturated Heterocyclic Chemistry(244; R = Me) or (&)-CIS (244; R = Et) juvenile hormone.ls3 The$-oxidoylides may also be converted to chloro-olefins by ha10genation.l~~

Reaction of lithium dialkylcopper complexes with acyclic allylic acetatesproceeds by two predictable pathways depending on the nature of X , Y ,and Z (Scheme 15).lS5Thus the allylic acetate (245), on treatment with

X, Y, = H or alkylScheme 15

lithium dimethylcuprate, st ereoselect vely gave (246), which contains thejuvenile hormone skeleton.

++Co2Ef QAc OAc(245)

(247) I i(248)The dienol derivative (247), when heated, rearranges stereospecificallyby a 1,5-sigmatropic hydrogen shift to (248), from which the aldehyde is

obtained on hydrolysis>s6A synthesis which is applicableto highly hindered olefins is the conversionof (249) to (250) with extrusion of X and Y.la7Thus (251) is converted into thelE3E. J. Corey and H . Yamamoto, J . Am er . Chem. SOC., 970, 92, 6636.lS4M . Schlosser and K . F. Christmann, Synthesis, 1969, 38; E. J. Corey, J. I . Shulman,lR5. J. Anderson, C. A . Hendrick, and J. B . Siddall,J . Amer . Chem. SOC., 9 7 0 ,9 2 ,7 3 5 .lS e E. J. Corey and D. K. Herron, Tetrahedron Letters , 1971, 1641.D. H . R. Barton and B. J. Willis, Chem. Comm., 970, 1225; D. H . R . Barton, E. H .Smith, and B. J. Willis, ibid., p. 1226.

and H . Yamamoto, Tetrahedron Letters , 1970, 447.


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Acety lenes, Allenes , and Olefins 5 5highly hindered (252) in 80% yield on heating in the presence of tris(diethy1-amino)phosphine. Similarly (253), prepared from cyclohexanone, hydrazine,

{253)0I I

RCI 10A

(34)(25s)

and H2S, followed by lead tetra-acetate oxidation, gave bi(cyclohexy1idene)(77%).18 Cyclohexylidene derivatives (254) are also obtained by reaction oflithium cyclohexylphosphonic acid bis(dimethy1amide) (255) with aldehydes.The reaction with ketones is not successful.188

Hindered olefins are obtained by the sequence shown in Scheme 16. TheR R3 R R3 R1 R3\- \ / Na2S \ /

DMF / \C(NO2), + CN02+ C-C -+ C=C/ R4(( R=42 NO2 NO,(256)

Scheme 16required vicinal dinitro-compounds (256) are prepared by reaction of a-dinitro-compounds with a nitroparaffin salt, and treatment with Na,S givesolefins in excellent yields.lg9Treatment of the epoxides (257) with lithium diphenylphosphide givesstereospecific ring-opening and quaternization of the crude product yieldsthe betaines (258). The latter generally fragment under the conditions oflB8. B. Jones and P. W.Marr, Canad. J . Chem., 1971, 49, 1300.lB9. Kornblum, S. D. Boyd, H . W . Pinnick, and R.G . Smith, J . Am er. Chern. Soc.,1971, 93, 4316.


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56 Albhatic, Alicyclic, and Saturated Heterocyclic Chemistry

. . ..(257) (2%)

quaternization and olefins are formed with a stereochemistry inverted relativeto the starting olefin from which the epoxide was derived. Thus cis-octeneoxide may be converted to trans-octene in 95% yield.lgOA synthesis analogous to the Wittig reaction but using silicon compoundsgives olefins in yields >50% (Scheme 17).lg1

Me,SiCH2Cl I___, Me,SiCH,MgBr-, R ~ R ~ C = Oi i , H,O AR1R2CCH2SiMe,- 1R2C=CH2Na SaltIOHScheme 17

Conversion of epoxides into the corresponding alkenes may be achievedwith magnesium amalgam and magnesium bromidelg2 or using a Zn-Cucouple,lg3 methods which may have advantages over that using the CrTr-ethylenediamine complex194 in certain cases.Aliphatic 1,l-dichloro-olefins have been obtained in good yields by treatingaldehydes with tris(dimethy1amino)phosphine and carbon tetrachloride inTHF at low temper at~re s.1~~Mild reagents for dehydration of alcohols include the methyl(carboxy-su1phamoyl)triethylammonium hydroxide inner salt (258a). The trialkyl-ammonium salts (259), formed from secondary or tertiary alcohols, ionize,despite the charge associated with the leaving group, to provide tight ionpairs which undergo fast stereospecific proton transfer, giving olefins in highyield. The stereospecific conversion of (260) to (261a) and (262) to (261b)

MeO,CNSO,NEt, + -C-C-OH _j_ -C-C-0SO2NCO2Me4- I I I I -I IHIH (259)J258a)\ / +/ \C=C + H N E t , 6S0 , N H C 02M elg0E. Vedejs and P. L. Fuchs, J . A m e r . C h e m . SOC., 971, 93, 4070.lol T.-H. Chan, E. Chang, and E. Vinokur, Tetrahedron Letters , 1970, 1137.lg a F. Bertini, P. Grasselli, G . Zubiani, and G. Cainelli, Chem. Com m. , 1970, 144.lo3S . M . Kapchan and M. Maruyama, J . U r g . C h e m. , 1971,36, 1187.lo4J. K . Kochi, D. M. Singleton, and L. J. Andrews, Tetrahedron, 1968, 24, 3503.lo6 G. Lavielle, J.-C. Combret, and J. Villieras, B d . Soc. chim . France, 1971, 2047.


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Acetylenes, Allenes, and Olefins 57M eO CN 0:!

Ph Ri1pj, R2(261a) K = D260) R1 = H , R2= D(262) R =: D , RZ = (261b) R = H

indicates that proton (deuteron) transfer takes place faster than rotationalinterconversion of the ion pairs.lg6

Another dehydrating reagent applicable to secondary and tertiary alcohols,which are otherwise prone to undergo carbonium ion rearrangements, is thestable crystallinc sulphurane (263). An intermediate alkoxysulphonium ion(264) is a postulated intermediate, followed by rapid abstraction of p-proton.For secondary alcohols the mechanism has considerable E , character, asshown by a preference for trans diaxial elimination, whereas in tertiaryalcohols the mechanism is nearer El, with a carbonium ion intermediate.lg7

Me,COH + Ph2S(OR~), Ph,S-OCMe, + RFOHI(263) ORF(264)J

RF = -&PhICF,P h 2 S 0 + Me,C=CH2 + RpOH

Homologation of olefins by four carbon atonis is achieved by reaction ofthe derived borane (265) with buta-1,3-diene monoxide in the presence ofcatalytic amounts of oxygen.lS8Trialkylboranes are also converted into the4,4-dialkyl-cis-but-2-ene-l,4-diols266) in good yields by addition to or-lithiofuran and oxidation of the intermediate boroxarocyclohexenes (267)with hydrogen peroxide.lgg

0 2R,B + CH2=CHCH-CH, + CH2CH=CHCH20H + EtZBOH(265) 0 (89% trans)

G. M . Burgess, H . R . Penton, and E. A . Taylor, J . A m e r. Chem.SOC., 970,92, 5224.lQ7 J. C. Martin and R. J . Arhart, J . Am er . Chem. SOC. ,1971, 93, 4327.lQ 8 A. Suzuki, N. Miyaura, M . Itoh, H . C. Brown, G. W. Holland, and Ei. Negishi,l g9 A . Suzuki, N. Miyaura, and M. Itoh, Tetrahedron, 1971, 27, 2775.J . Amer . Chem. SOC., 971, 93, 2792.

5


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58 Aliphatic, Alicyclic, and Saturated Heterocyclic ChemistryTransformation of vicinal dicarboxylic acids or anhydrides into olefins is a

valuable synthetic transformation. An additional method uses varioustransition metals, exemplified by conversion of (268) into (269) in 53% yield.Even better yields are obtained with thioanhydrides, but mixtures are ob-tained when abstractable B-hydrogens are present.200The transformation of

1,2-diols nto alkenes is likewise useful synthetically. A new method requiresheating the diol, e .g . (270), with NN-dimethylformamide dimethylacetaland treatment of the dioxolan (271) with acetic anhydride. Although thereaction appears to be stereospecific, the alkene may undergo acid-catalysedisomerization.201

Dehydration of 1,l-di-t-butylethanol with thionyl chloride-pyridine gives(272) with little rearrangement, whereas the major products from the moresubstituted alcohols are the rearranged olfins [e.g. (273) -+ (274)l. This isrationalized on the basis of the most stable intermediate carbonium ionconformations (275) and (276), formed by ionization of the chlorosulphite.In the first case the preferred conformation (275) favours elimination of theproton which is coplanar with the unoccupied orbital of the electron-deficientcarbon, whereas in (276) the lack of such an available proton results inmethyl shift from one of the t-butyl groups.202

Among particular olefins recently synthesized is tetra-acetylethylene (277),potentially useful for heterocyclic synthesis.203B . M . Trost and F. Chen, Tetrahedron Le tters, 1971, 2603.1970, 5223.201 F. W . Eastwood, K . J. Harrington, J. S . Josan, and J. L. Pura, Tetrahedron Le tters,

202 J. S . Lomas, D. S . Sagatys, and J. E. Dubois, Tetrahedron Letters, 1971, 599.203 G. Adembri, F. DeSio, R . Nesi, and M . Scotton, J . Chem.SOC. C ) , 1970, 1536.


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Acetylenes, Allenes, and OleJins

But - B u ~ ) ~ C = C H ~(272)H H(275)

59

CH2But Me%+ ButH H + I5But --+. Me2C-C-CH2ButOClZ( B U * ) ~ C C H ~ B L ~yridine+ B U ~IOH(273) (276) JA survey of the methods for synthesizing tetrathioethylenes includes thenew method of pyrolysis of orthothio-oxalates, e . g . (278).204

TI TII I I2(CH,CO),CH-CH(COCHJ, + CH,CO)2C-C(COCH3)2(CHSC0)2C=C(COCH&

(277)

A synthesis of acyclic 1,5-dienes is exemplified by the route shown inScheme 18. In all cases cleavage of the more substituted of thetwoequivalentlyorientated p,y-cyclohexane ring bonds occurred in the boronate decomposi-tion (279).205A further route to these synthetically valuable 1,Sdienes is*04 D. L. Coffen, J. Q. Chambers, D. R. Williams, P . E . Garrett, and N. D. Canfield,2 0 5 J . A. Marshall and J . H . Babler, TefruhedronLetters, 1970, 3861.J . Amer . Chem. SOC., 971, 93, 2258.


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60 Aliphatic, Alicyclic, and Saturated Heterocyclic ChemistryOM e O M e 0

i. LiAIH4ii. MsCl1OMS OMScEtJJJ(ji;,:yHFt)$iCOHhScheme 18

Et

HO(279)

I(282)

illustrated in the conversion of trans,trans-farnesol (280) into all-trans-squalene (282).206and studied.207206 E. H . Axelrod, G. M . Milne, and E. E. van Tamelen, J . Amer . Chem.SOC., 970,92,2139.20 7 N. Ono, Bull. Chem. SOC. apan, 1971, 44, 1369; R . D. Bach and D. Andrzejewski,J . Amer. Chem. SOC., 971,93, 71 18; D. H. Hunter and D. J. Shearing, ibid.,p. 2348;D. J. Lloyd, D. M . Muir, and A. J . Parker, Tetrahedron Letters, 1971, 3015.

Elimination pathways as routes to olefins have also been


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Acetylenes, Allenes, and Olefins 61Cycloaddition Reactions.-Steric selectivity in the addition of carbenes toolefins has been reviewed.176 The relative reactivity of olefins in the homo-geneousreaction with zinccarbenoid generated from diethylzinc and methylenedi-iodide shows the order tetramethylethylene > trimethylethylene > cyclo-hexene > hept-l-ene, in agreement with the electrophilic character of thecarbenoid. Steric effects appear to be less important, in contrast to the closelyrelated Simmons-Smith reaction where tetramethylethylene has a very lowreactivity. The Hamrnett p-value for addition to substituted styrenes (corre-lation with 0)has the value - 1.61.208 n addition of the phenylcarbenoid ofzinc to olefins, a larger syn selectivity is observed than with the phenylcar-benoid of lithium; electron-donating substituents on the phenyl group andether solvents appear to enhance the selectivity (Scheme 19).209Thc origin of

s y 1 mtiratio 17 1 in ether

Scheme 19this syn selectivity is not clear: it does not appear to be the result of Londondispersion forces since addit ion of fluorocarbenoid with olefins gives syn-fluorocyclopropane (283) stereoselectively in spite of its smaller polariza-bility.210

Hb b- Br2FCH 4- BuLi -+ (283)A rationalization of the &:trans ratios of olefins produced in carbenicdecomposition of diazo-compounds R1CN2CH2R2s based on competingelectrostatic and steric effects in the intermediate singlet carbene.211 Hetero-atom-containing substituents in the 3-position of cyclohexene can direct theaddition of electrophilic species from a cis direction and rates of addition aresometimes accelerated.212The addition of dichlorocarbene to (284), however,*0 8 J. Nishimura, J. Furukawa, N. Kawabata, and M. Kitayama, Tetrahedron, 1971, 27,20* J. Nishimura, J. Furukawa, N. Kawabata, and H . Koyama, Bull. Chern.SOC.apan,210 M. Schlosser and G. Heinz, Chem. Ber . , 1971, 104, 1934.211 Y. amamoto and I . Moritani, Tetrahedron, 1970, 26, 1235.21a C. D. Poulter, E. C. Friedrich, and S . Winstein, J . Amer . Chem. SOC.,1969, 91, 6892.

1799.1971,44, 1127.


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6 2 Aliphatic, Alicyclic, and Saturated Heterocyclic Chem istryproceeds stereoselectively to give the cyclopropane (285) via apparent transattack.213Similarly, the dichlorocarbene addition product of olefin (286) hasbeen shown by an X-ray determination to have structure (287).214

Cope rearrangement of hexa-1 ,5-dienes generally proceeds by a concertedmechanism with concurrent rupture of the 3,4-bond and formation of the1,6-bond. The intervention of a biradical mechanism in certain cases is alsoknown.215 Diene (288) was synthesized to investigate the possible incursion

NCC&f

(289)of a third type of mechanism : he formation and recombination of an ion pair(289).216The rate of isomerization was followed by observation of the ctp-unsaturated dinitrile absorption band at 240nm as a function of solventpolarity. There was an increase in rate of only 17 in changing from cyclo-hexane to ethanol-water, in agreement with secondary deuterium isotopeeffects217 n suggesting that the mechanism is concerted.

Thermolysis of lY5-dien-3-ols290) leads either to Cope rearrangement (a)or to 1,Shydrogen shift reaction products (b). These pathways are bothobserved in rearrangement of 1,2-divinylcycIoalkane-l2-diols; he formerleads to ring enlargement by four carbon atoms [(291) --f (292)].218213 M. A. Tobias and B . E . Johnston, Tetrahedron Letters, 1970, 2703.214 G. R. Clark, B . Fraser-Reid, and G . J. Palenik, Chem. Comm., 1970, 1641.215 G. S . Hammond and C . D . Deboer, J . Amer. Chem. SO C.,1964,86,899.216 D. G. Wigfield and S. Feiner, Cunud. J . Chem., 1970,48, 855 .*17 K . Hum ski, T. Strelkov, S . Borcic, and D . E . Sunko, Cunad.J . Chem., 1970, 48, 8 5 5 .218 P. Leriverend and J.-M. Conia, Bull. SOC. him. France, 1970, 1040; C. Brown andJ.-M . Conia, ibid., p. 1050; P. Leriverend and J.-M. Conia, ibid., p. 1060.


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Keten-olefin [2 + 21 cycloadditions have received considerable attentionre~entIy.2~~he isomer with the larger keten substituent (L) in the endoposition (293) is found in addition of keten to cyclopentadiene. This ispredicted from the orthogonal keten-olefin transition state [2, 3- 2,] ofWoodward and Hoffman, This model also accounts for the reduced reactivitytowards ketens of trans-butene compared with cis-butene.220Methylbromo-and methylchloro-keten undergo cycloaddition with a wide variety of olefinswith only small variation in the endu:exo ratio, i.e. the ratio of (295): (294)

(293) (294) (295)varies only from 5.0 to 4.5 between dihydropyran, cyclo-octene, 1,3-cyclo-octadiene, and cyclohexene. Thus the reaction is controlled by the size of thelarger substituent in the keten molecule.219Norbornene and norbornadieneare reported to be poor ketenophiles although they show high dipolarophilicactivity, and addition of dichloroketen to dicyclopentadiene gives only(296) or (297).221

The concerted suprafacial thermal addition of two olefins is a symmetry-forbidden process and thermal 1 ,Zcycloadditions of simple olefins have beenal D W. T. Brady and R . Roe, J . Amer . Chem.SOC., 971,93, 1662, andrefs. 1-8 therein.p2 0 N. S . Isaacs and P. F. Stanbury, Chem. Comm., 1970, 1061.L. Ghosez, R . Montaigue, A. Roussel, H . Vanlierde, and P. Mollet, Terrukedron, 1971,27, 615.


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64 Aliphatic, Alicyclic, and Saturated Heterocyclic Chemistry

I(1(296) (997)

shown to involve biradical intermediates. The major dimeric product (298),isolated from thermolysis of (299), suggests that the predominant portion ofthe reaction occurs in a stereochemical sense compatible with orbital sym-metry theory [2 + ,,2,].222 However, the isolation of two other dimers

(299)

differingonly in stereochemistry at the ring junctions,and thelackof variationwith temperature in the ratios of these dimers obtained, favours a stepwisemechanism with a biradical intermediate.

JA

//---kPh0(302)

292 A. Padwa, W . Koehn, J. Masaracchia, C. L . Osborn, and D. J. Trecker, J . Amer . Chem.SOC., 971,93 , 3633.


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Acetylenes, Allenes, and Olefins 652-Methylbicyclo 2,1 O]pent-2-ene (300) rearranges thermally to l-methyl-

cyclopentadiene (301), showing the process as one ascribable to a [,2, + ,2,]concerted cycloreaction involving C-1-C-2 and C-4-C-5 bonds andnot a biradical two-step process. The cyclopentadiene (301) was trapped as itwas formed (43"C)as its N-phenylmaleimide adduct (302), a process whichcompletes favourably with the 1,5-hydrogen shift in the diene itself. It ispointed out that this result undermines the usual either/or concertedjnon-concerted question of mechanism in that an unusual or suppressed concertedmechanism may be brought to the fore when the more obvious concertedmechanism is prohibited.223

Under the influence of a nickel catalyst, methylenecyclopropane (303)reacts with methyl acrylate to give the methylenecyclopentane (304) in 82%yield, formally by a [,2 + ,2] cycl~addition.~~~he symmetrical intermedi-ate (305) may be excluded since (306) and (307) are obtained from (308)and (309), respectively. A symmetrical intermediate would give the sameadduct or mixture of adducts.

H,C + v zC HaI \\

C 0 2 M e Nil,(305): CFI:!' qR1f12=CHC02;\lc R'Re' IK" (304) R' = R? = H(307) R' = H. R' = Mex(303) R1 = R2 = I(308) R1= M e, R2 = 11 /(309) R1 = H , KZ = Me (306) R1 M e. R2 = HDiels-Alder addition of 2-chloroacrylonitriIe and dienes gives the expectedadducts, e.g. (310), which may be converted via azide, isocyanate, and hy-drolysis to the ketone (311) in good yield. This constitutes a method for

1,4-additionof the methylenecarbonyl unit (--CH,CO-) to dienes.22sAmong the many 1,3-dipolar additions of olefins recently reported are the

intramolecular nitrone-olefin cycloadditions,22s .g . (312) (313), and thecycloaddition with olefinic dipolarophiles of carbonyl ylides (3 14)227 ndazomethine ylides (315)F2* obtained by conrotatory ring-opening of thecorresponding three-membered rings Attempted cycloaddition of the olefin(316) with benzenesulphonyl isothiocyanate gave the dipolar product (317),whose structure was supported by addition to diphenylketen, giving (3 18)F2'22322422 5

22 6227

228

229

J. E. Baldwin and A . H . Andrist, Chem. Com

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Aliphatic Chemistry Part 1