Indian Journal of Chemistry Vol. 39B, August 2000, pp. 603 - 609

Synthesis of new heterocycles by using thiocarbohydrazide and thiosemicarbazides

Madhukar S Chande*, M o hd Aslarn Pankhi & Shireesh B Ambhaikar t

Department of Chemistry, The Institute of Science, IS, M. Cama Road, Mumbai 400032, India

Received 28 July 1997; accepted (revised ) 20 August 1999

3-Amino-2-alkyllarylimino-S-carbethoxy-thiazolidin-4-ones 2, 2-hydrazi no-6-carbethoxy-4H,6H-I,3.4-thiadiazin-S­one 5 , 2-hydrazino-7-substituted, S,7-di substituted-4H-pyrazolo[S.4-e]- 1,3.4- thi adiazincs and 12 and 2- hydrazi no-7-phenyl -4H-isoxazolo[S.4-e]-1 .3,4-thiadiazine 12e have been synthesised . The compounds have been characterised by chemical reactions, alternate syntheses and spectral data.

In continuation of our work' ,2 on the synthesi s of an­ticarcinogenic and antimicrobial compounds, we now report the interaction of diethyl bromomal onate (OBM) with 4(H)-bromopyrazol-S-ones Ha-d, isox­azol-5-one He thiocarbohydrazide 4 and thiosemi­carbazides 1. The survey of literature indicated that the chemistry of thi ocarbohydrazides has not been explored much 3.5.

The reaction of OBM with 4-aryl-substituted thio­semicarbazides 1 in ethanol in the presence of pyri­dine afforded 3-ami no-2-alky I/ary I imino-5-carbe­thoxythiazolidin-4-ones 2 . The free amjno group at position-3 was converted into Schiff bases 3 (Scheme I Table I).

OBM also reacted with thiocarbohydrazide 4 under simjlar conditions affording 2-hydrazino-6-carbethoxy-4H,6H-I ,3 ,4-thiadiazin-5-one 5 ; IR (KBr): 3433, 33 13 (-N Hl asymm and sym str. ), 32 10 and 2978 (-NH str.), 1739 (carbethoxy carbonyl), 1594 cm" (>C=N) ; 'HNMR (OMSO-d6) at 300MHz

showed signals at 8 1.2 (t, 3H, J = 8.2Hz, -CH3), 4 .2 (q, 2H, 1 = 8.2Hz, -CH1 ), S.2 (s , I H, exocyc lic -NH), S.4 (!), 2H, -NH1)' 7.2 (s , IH , ring -NH) and 12.7 (s, I H,enolic -OH); "c NMR (OMSO-d6) : 14.3 (-CH.1), 47.547 (-CH2), 62 .90 1 (-CH) , 155.020 (C=N taut. ), 164.914( >C=N ring), 16S.926 (>C=O) and 166.656 ppm (carbeth oxy carbonyl carbon ).

Compound 5 on reaction with a ldehydes afforded the corresponding Schiff bases '6 which were also obtained d irec tl y from the reac ti on of OBM with 1-

t Prescnt add ress: Novarti s India Ltd , Thane.

alkylidene/arylidene thiocarbohydrazides7.8 7 (cf.

Scheme II). Their spectral data are gi ven in Table II .

Thiad iaz ine 5 with an excess of hyd razine hydrate (80%) afforded 2-hydrazino-pyrazolo [3,4-e] -1 ,3,4 -thiadiazine - 7- one 8 ; IR (KBr): 34 16, 3 197 , 292S, 1640 and 1591 cm" ; 'H NMR (OMSO-d6): 8 4 .S (s, I H, exocyc\ic -NH), 5 .3(s, 2H, -NH2), 7 .2 (s, I H, ring -NH) , 8.85 (s, I H, ring -NH at posi ti on 5) and 10.2 (s, I H, -NHCO); ' :lC NMR (OMSO-d6): 119.496 (>C=C<), IS5.037 (exocyclic C=N taut. ), 163.246 (>C=N), 164 .876 [C(OH)=N] and 16S.298 ppm (C=O) .

Presence of the exocyc lic hydrazino group in 5 was further confirmed by the reacti on of 5 with ace­tylacetone and acetoacetic ester in OMF. With ace­tylacetone it afforded 6-carbethoxy-4H,6H-2 (3',5'­dimethyl-pyrazol-l '-yl) -1 ,3,4 -thi ad iazi n-5-one 9 ; 'H NMR (OMSO-d6) : 8 1.2 (t, 3H, 1=8.1 Hz, -CH, of

COOCH2CH.1), 2.S (s, 6H, 2xCH, of pyrazole ring), 4.2 (q , 2H, 1=8.1 Hz of COOCH1CH.1 ), S.IS (s, I H, -CH of pyrazole ring), 7.0S (s, I H,ring -NH) , 7.3 (s, I H,-C HCOOEt) and 11 .8 (s, I H , C(OH)= ). Simi­larly , with acetoacetic ester, it afforded 6-carbethoxy-4H, 6H-2-(3 '-methyl-4'H-S'-oxopyrazol-I'-yl)-1 ,3,4-thi ad iazin-5-one 10 ; 'H NMR : 8 1.2 (t, 3H, 1=8. 1 Hz, CH.1 of COOCH2CH3), 2.2(s, 3H, C H3 of pyrazoli­none ring), 3.9 (s, 2H, -CH1CO) , 4 .2 (g, 2H. 1=8. 1 Hz, -CH1 of COOCH2GH 3), 7.0 (s, I H, ring -NH) and 7.2 (s, I H, -CH COOC2H5) .

2-H ydraz ino-5-substituted-4H-pyrazolo [S ,4-e]-1,3,4 -thiadiazines 12a-d were prepared by the reac­ti on of 4 with 4-bromo-4H-3-substitutedl!,3 disub-

604 INDIAN J CHEM, SEC B, AUGUST 2000

s BXr C<X>C

2HS

'OOC2H S

+

I RNH-C-NH-NH

2

( DBM )

Base

1 EtOH

where R • H, -Q.Hs, p - C'H:J - 4H • . p - CHaO- 4Il4 .

1 R'CHO

R'HC= N 0

RN~OOC2H5 3

Scheme I

s

• H N-NH-C-N H-NH .. 2 2

s I

DBM

R-HC~-NH-C-N-INH2" OBM

6,7 R

7

stituted - pyrazol-5-ones 11 in the presence of pyri­dine by a one-step synthesis (d. Scheme III).

Compounds 12 with aldehydes afforded the corre­sponding Schiff bases 13 (cf. Table IV). The struc­ture of 13 was established by an alternate unambigu­ous synthesis by reacting l-alkylidene/arylidene thi­carbohydrazide 7 with 11. Further confirmation was achieved through superimposable IR, undepressed mmp and co-TLC with those obtained from 12.

Experimental Section General . All solvents and reagents were of reagent

grade. Melting points were determinedl in open capil­laries and are uncorrected. IR spectra were recorded on a Perkin-Elmer 257 spectrometer in KEr discs. IH NMR and 13C NMR spectra were recorded on a Var­ian VXR 300s (300 MHz) instrument using DMSO-d6

as solvent (chemical shifts in 8, ppm) using TMS as internal standard (coupling constant in Hz) . All com­pounds analysed satisfactorily for C,H,N and S.

Thiocarbohydrazide4 and DBM9 were prepared by known methods. 4-Aryl substituted thiosemicarbazide was prepared by the method of Konher. 3-Substituted-4-bromo-pyrazolin-5-ones were prepared by Vogels procedure 10. 4-Bromo-3-phenyl-4H­isoxazol-5-one was prepared by the method of Pos-

II ner .

5-Carbethoxy-3-amino-2-phenylimino-thiazolidin-4-one 2 : A representative procedure. Phenyl thio-

EtCH

EtOH base

SchemeD

•

RCHol EIQi t..

6

).

CHANDE et al. : SYNTHESIS OF NEW HETEROCYCLES

H

(80%), R.T. A ·I NH N,..NyH

Hpt'4 S I o

5 8

DMF

5

CH.COCH2COOB ~o L-______________________ -+. ~S~H

S I

H2N-H~C-NH-NH2

5

H S

DMF

11

I I I R-C =N-HN-C-NH- NH

2 + 11

7

~ COOEt HSC 0

10

__ E_tO_H ___ ~ Rt::(yNHNH2

N I N b_e .~ N/

EtOH •

base

I

H

12

.... 1 ~~HO H

R I ,

~yNH-I=C-R

~A~ I

H

R' • Ci&, o-HQ..Q.&, o-OaI:J-Ci&, fuduxyl CIJ:J, CH~.

l1a - 13& ; X· D, R • CIJ:J.

lIb - 13b ; X· D, R· ~

llc - 13c ; X· If-Ph, R· CIJ:J.

lid - 13d ; X· If-Ph, R • ~.

lie - 13e ; X· 0 , R • ~.

Scheme III

605

606 INDIAN J CHEM, SEC B, AUGUST 2000

Table I-2-AlkyVarylimino-3-amino-5-carbethoxy-thiazolidin-4-ones 2 and their Schiff bases 3

Compd

2a

2b

2c

2d

3a

3b

3c

3d

3e

H

mp

°C

254-56

125

81-83

95-97

240

232

195

223

204

semi carbazide l a (0.05 mole, 8.35 g) and pyridine (0.05 mole, 3.95 g) were taken in ethanol (70 mL). Diethyl bromomalonate (0.05 mole, 11 .95 g) was then added and the reaction mixture refluxed for 10 min ., and poured onto crushed ice to give 2b which was crystallized from ethanol , mp 125°C, yield 80%.Compounds 2a-d were prepared similarly and are listed in Table I .,

Schiff bases 3 : A general procedure. A mixture of 2 (0.0 I mole), aldehyde (0.0 I mole) and anhyd. so­dium acetate (0.0 I mole, 0.8 g) was taken in absolute ethanol (20 mL) and reflu xed for 3 hr. The precipitate obtained was fil tered and recrystallized from ethanol. Other compounds prepared are listed in Table I with their spectral data.

Yield (%)

85

80

75

80

80

80

65

70

72.3

IH NMR, I3C NMR (0, ppm )

IH NMR: 0 1.3 (t, 3H; -CH3) , 4.2 (q, 2H, -CH2), 5.1 (s, 2H, -NH2), 5.2 (s , 1 H, -CH), 7.76 (m, 5H, Ar-H). I3C NMR (DMSO-d6) : 0 14.1 (-CH3) , 46.7 (-CH), 62.5 (-CH2 ), 121 - 130 (arom. car­bons) , 148.0 (-C=N), 164.6 (carbethoxy car­bonyl carbon), 167.2 (CON-NH2).

IH NMR : 0 1.3 ( t, 3H , -CH3) , 4 .0 (q,2H, -CH2), 5 .2 (s, IH, -CH of -CH-COOEt) 7.0 - 7.6 ( m, IOH, Ar-H), 7.9 (s, IH, CH=N) I3C NMR : 014.5 (-CH3) , 58 (-CH2), 122 - 137 (1 2 aromatic carbons), 139 and 146.8 (two >C=C< at 4 & 5), 151.5 (C=NR), 160 (RCH=N-N-), 164.1 (carbethoxy carbonyl carbon).

6-Carbethoxy-2-hydrazino-( 4H, 6H)-113,4-thiadia­zin-5-one 5 . A mi xture of 4 ( 1.06 g, 0.01 mole), DBM (2.39 g, 0.01 mole) and pyridine (0.8 mL, 0.01 mole) in ethanol (20 mL) was refluxed for 4 hr,

cooled, poured onto ice, filtered and recrystallized from DMF-water to give 5, yield 55 %, mp 184°C.

2-N'-Benzalhydrazino-6-carbethoxy-4H,6H-l, 3, 4-thiadiazin-5-one 6: A represenltative procedure. A mixture of thiadiazine 5 (2.18 g., 0.01 mole), benzal­dehyde ( 1.06 g, 0.01 TlJole) and fused sodium acetate (0.82 g, 0.01 mole) in ethanol (25 mL) was refluxed for 3hr and poured over crushed ice. The product isolated was characterised as 6a.

Likewise compound 3b-f were prepared and re-

CHANDE et aJ.: SYNTHESIS OF NEW HpTEROCYCLES 607

Table ll-Characteristic data of 6 - carbethoxy - 2 - N' - alkylidenelarylidene hydrazino-4H,6H - 1,3 4 - thiadiazin - 5- ones 6

Compd*

6.

6b 6c

6d

6e

6r

R

o-HO- C6 H4 P-CH30-C6H4

Furfuryl

Mol. fonnula

C13HI4N404S C13HI6N404S

*C,H,N,S analyses were found to be satisfactory.

Yield (%)

71.8

68.3 71.4

67.5

60.3

60.1

crystallized from glacial acetic acid. Their physical and spectral data are listed in Table II.

An alternate synthesis of 6: A general procedure. A mixture of 1-alkylidene/arylidene thicarbohy­drazide 7 (0.01 mole) and DBM (2.39 g, 0.01 mole) in pyridine (1 mL) and ethanol (20 mL) was refluxed for 3 hr and poured into ice-cold water to afford 6. It was recrystallized from acetic acid.

2-Hydrazino-4H, 5H, 6H-pyrazolo-[3,4-e]-1, 3, 4-thiadiazin-7-one 8 . A mixture of thiadiazine 5 (2.18 g, 0.01 mole) and hydrazine hydrate (80%) (in excess ) was left standing at room temperature (28-30DC) for 24 hr. The seperated product was filtered, washed several times with ice-cold water and recrystallized from ethanol, mp 230De, yield 59.13 %.

6-Carbethoxy-2-(3', 5' -dimethylpyrazol-1' -yl)-4H,

mp °C

137

220 186

139

265

168

Spectral data

IH NMR ; 0 1.2 (t, 3H, ) = 8.1 Hz, CH3 of carbethoxy group), 4.2 (q, 2H, ) = 8.1 Hz, CH2

of carbethoxy group ), 5.2 (5, I H, exocyclic -NH ), 7.5 - 7.7 (5, IH, -NHCO ) and 9.15 (s, I H, CH=N).

IHNMR : 0 1.3 ( t,) = 8.1 Hz, -CH3 of car­bethoxy group), 3.9 (5, 3H, -OCH3), 4.3 (q, 2H,J = 8.1 Hz, -CH2 of carbethoxy group ), 4.75 ( 5, I H, exocyclic -NH), 7.0 (d,2H.J=8Hz, Ar-H), 7.2 (s, IH, -CH at C-6), 7.9 (d, 2H,)= 8.0Hz, Ar-H), 8.0 (s,IH,cyclic -NH) and 9.1 (s,IH,CH=N). 13CNMR : 0 14.036( -CH3 carbon), 47.467 (-CH2 carbon), 55.56 (-OCH3), 63.41 (-CH carbon),114.46(-CH=N), 125.34-130.87 (aro­matic carbon), 156.537 and 163.232 (two >C=N carbons),I64.149 (cyclic CONH car­bon), and 165.881 ppm (carbeth-oxy carbonyl carbon).

6H-1,3,4-thiadiazin-5-one 9. A mixture of 5 (2.18 g, 0.01 mole) and acetyl acetone (1 g, 0.01 mole) in DMF was refluxed for 3 hr and then poured over crushed i~e. The crude product isolated was recrys­tallised from DMF, mp 235DC (chars), yield 58%.

6-Carbethoxy-2-(3' -methyl-4' H -5-oxo-pyrazol-1' - yl)-4H,6H-1,3,4-thiodiazin-5-one 10. A mixture of 5 (2.18 g, 0.01 mole) and ethyl acetoacetate (1.3 g, O.Olmole) in DMF afforded the title compound, mp 245DC (chars), yield 57.60 %.

Synthesis of 2-hydrazino-7-methyl-4H-pyra­zolo[5,4-e ]-1,3,4-thiadiazine 12a . A mixture of 4 (1.06 g, 0.01 mole), 4-bromo-3-methyl-4H-pyrazol-5-one 11a (1.77 g, 0.01 mole) and pyridine (0.8 mL, 0.01 mole) in ethanol (25 mL) was refluxed for 3-4 hr. The solvent was evaporated and the product ob­tained was identified as 12a. Similarly, 12b-e were

608 INDIAN J CHEM, SEC B, AUGUST 2000

Table llI-Physical and characteristic data of 2-hydrazino-7-methyl-4H-pyrazolo[5,4-e]-I,3,4-thiadiazine 12a, 2-hYdrazino-7-phenYI-4H-pyrazolo[5,4-e]-I,3,4-thiadiazine 12b, 2 - hydrazino - 5-phenyl-7-methyl-4H-pyrazolo[5,4-e]-I ,3,4-thiadiazine 12e, 2-hydrazino-5,7 _ diphenyl - 4H - pyrazolo[5,4-e] - 1,3,4 - thiadaizine 12d and hydrazino-7-phenyl-4H-isooxazolo[5,4-e]- 1,3,4 -thiadiazine 12e.

Compd X R2 mp Yield I HNMR, 13CNMR ( /), ppm} °C (%)

12a NH CH3 228 65 IHNMR : /)2.2 (s, 3H, CH3), 2.25 (s, I H, exo-cylic -NH), 5.25 (s, 2H, -NH2), 5.15 (s, IH , ring NB at position 4) and 7.2 (s,1 H, ring -NH at position 5 ). 13CNMR : ~ 10 ( -CH3), 96 (>C=C<), 146 and 154 ppm are due to two C=N carbons.

12b NH C6HS 227 70 IHNMR: /)2.08 (s, IH, exocyclk -NH), 5.35 (5, 2H, - NH2), 5.85 (5 , I H, ring NH at posi-tion 4), 7.2 - 7.75 ( m, 6H, aromatic 5H + ring -NH at position 5). 13 CNMR : /) 125.82 (>C=C<), 128.19 -130.048 (aromatic carbons), 145.91 and I 54. (two C=N carbons)

12c N-Ph CH3 > 270 60 IHNMR : /)2.15 (s, 3H, -CH3), 2.10 (s,1H, exocyclic -NH ), 5.27 ( s, 2H, -Nl-h), 5.65 (s, I H, ring -NH ), 7.2 - 7.8 (m, 5H, Ar-H ).

12d N-Ph C6HS 115 74 IHNMR: /) 2.3( s,IH, exocyclic -NH }, 5.25 (s,1 H, ring -NH at position 4 ), 6.0 ( s,2M,

-NH2), 7.2 -7.9 (m, lOB, Ar- H). 13CNMR : /) 126 ( >C==C<), 129 c 134 (aro-matic carbon), 141 - 145 (two C==N carbons).

12e 0 C6Hs 179 67 IHNMR : /)2.35 (t, J == 9.5 Hz, I H, ex.ocyclic - NH-N), 5.2 ( d, J == 9.5 Hz, 2H, -N-NH2) and

7.2 - 7.95 ( m,6H, aromatic 5H + one ring-NH). 13CNMR : .124 and 126 ( C=C carbons), 127 -132 ( aromatic carbons) and 159 and 164 (two C==N carbons ).

Table I v-Pnyslcal and spectral data of Schiff bases 13

Compd* X R R' Yield mp (%) °C

Baa NH CH3 C6Hs 70 219 13ab NH CH3 o-HO - C6H4 72 165

13aet NH CH3 P-CH30-C6H4 76 206 13ad NH CH3 furfuryl 71 >280 13ae NH CH3 CH2CH3 68 215 13ba:j: NH C6HS C6HS 72 246

13bb NH C6Hs o-HO - C6H4 74 202

13bc NH C6HS P-CH30-C6H4 78 199

13bd NH C6HS furfuryl 71 > 270

13be NH C6Hs CH3 64 217

13bC NH C6HS CH2 CH3 66 195

13ca§ N-C6HS CH3 C6Hs 74 > 270

13eb N-C6Hs CH3 o-HO - C6H4 75 > 280

13ee N-C6HS CH3 P-CH30-C6H4 77 203

Contd

;.

CHAN DE el al.: SYNTHESIS OF NEW HETEROCYCLES 609

Table IV-Physical and spectral data of Schiff bases 13

Compd* X R R' Yield mp (%) °C

13cd N-C~H5 CH3 furfuryl 69 186 13da·· N-C~H5 C~H5 C~H5 75 172

13db N-C~H5 C~H5 o-HO-C~H4 72 168

13dctt N-C~H5 C~H5 P-CH30-C~H4 77 128 l3dd N-C~H5 C~H5 CH3 68 169

l3de N-C~H5 C~H5 CH2 CH) 68 143

l3eau 0 C~H5 C~H5 70 130

13eb 0 C~H5 o-HO-C~H4 75 155 l3ecH 0 C~H5 P-CH 30-C~H4 74 141

l3ed 0 C~H5 CH2CH) 64 184

.l3ee 0 C~H5 CH) 62 191

* C, H,N ,S analyses were found to be sati sfactory (± 0.1 % of theoretical values) t I HNMR : 82.2 (s, I H, exocycl ic -NH ), 2.3 ( s, 3H, CH3), 3.8 ( s,3 H, -OCH), 5.95 (s, I H, ring -NH at position 4 ), 7.0 ( s, I H, ring -N H at position 5), 7.05 (d, 2H, 1=6.8 Hz, Ar-H), 7.7 ( d, 2H, 1 = 6.8 Hz, Ar-H ), 8.3 (5, I H, CH=N). i3CN MR : 8 16 ( -CH) carbon), 56 ppm (-OCH3 carbon), 115 (CH=N carbon), 56 ppm ( -OCH) carbon), 115 ( CH=N carbon), 127 ppm (>C=C<), 128 - 13 1 ( aromatic carbons), 147 and 149 ppm ( two C=N carbons). + IHNMR : 82.25 (5, I H, exocyclic -N H ), 5.8 ( 5, 1 H, ring -NH at position 4 ), 7. 1 -7.9 (m, II H, one ring -NH + 5 Ar-H) and 8.3 (5, 1 H, CH=N ). i3CNMR : 8 114 (CH=N carbon ), 126 (>C=C<), 127 - 131 ( aromatic carbons), 143 and 146 ( two C=N carbons). § IHNMR : 82.25 (s, 3H, CH,), 2.35 (5, I H, exocyclic -NH ), 6.0 (5 , I H, ring -NH at position-4 ), 7.2 -7 .9 (m, 10H, Ar-H), 8.3 (5, 1 H, CH=N). ** lHNMR : 82. 3 (5, I H, exocyclic -NH ), 5.25 (s, I H, ring -NH at position-4), 7.2 - 7.9 (m, 15H, Ar-H ) & 8.25 (s, I H, CH=N). tt IHNMR : 82.3 (5, IH , exocyclic -NH ), 3.9 (5 , 3H, -OCH), 5.25 (5, IH, ring -NH at position 4) , 7.2 - 7.9 (m, 14H, Ar-H ), 8.3 (5, IH , CH=N ). 13CNMR : 857 (-OCH3 carbon), 115 (CH=N carbon ), 11 9 ( >C=C<), 122 - 138 ( aromatic carbon), 150 and 153 ( two C=N carbons). ++ IHNMR : 82.0 (5, I H, exocyclic -N H ), 7.3 - 7.95 (m, II H, aromatic 10H + ring -NH ) and 8.2'(5, I H, CH=N). §§ IHNMR : 82.3 (5, I H, exocyclic -NH ), 3.8 (5, 3H, -OCH), 7.1 -7.9 (m, I OH, aromatic 9H containing two doublets + ring -NH ) and 8.3 (5, I H, CH=N).

prepared, their physical and spectral data are listed in Table III.

Formation of Schiff bases 13 : A general proce­dure. A mixture of thiadiazine 12 (0.01 mole) and alkyl/aryl aldehyde (0.0 I mole) in ethanol (25 mL) containing few drops of piperidine was refluxed for 3 hr. The contents were poured onto crushed ice when 13 was obtained in good yield. Its characteristic data are listed in Table IV.

General procedure for an alternate route of Schiff bases 13. A mixture of I-alkylidene/arylidene thio­carbohydrazide 7 (0.0 1 mole), 11 (0.01 mole) and pyridine (0.01 mole) in ethanol (20 mL) was refluxed for 4 hr, and poured into ice-cold water, when com­pounds 13 were obtained. These were recrystallized from glacial acetic acid .

Acknowledgement The authors thank Head of the Chemistry Depart­

ment and Director, The Institute of Science, Mumbai for providing facilities and Head, RSIC, ITT, Mumbai

for spectral studies . A supporting grant from Dupont International , Delaware (USA) is gratefully acknowl­edged. One of the authors (M.AP.) thanks the Uni­versity of Mumbai for the award of Sir Currimbhoy Ebrahim and Bai Khanoobai Noormohamed lairazb­hoy Peerbhoy Scholarship.

References I Chande M S & Jagtap R S, Indian 1 Chern, 34 B, 1995,923 . 2 Chande M S, Jatthar K S, Pannikkar K R, Pannikar B &

Anto J, Indian 1 Chern, 34 B, 1995,654. 3 Kurzer F & Wilkinson, Chern Rev, 70, 1970, II I . 4 Audrieth L F, Scott E S & Kippur P S, 1 Org Chern , 19,

1954 , 733. 5 Freedlander B I & Furst A, Pmc Soc Exptl Biol Med , 81,

1952,638. 6 Buu-Hoi N P, Loc T B & Xuong N D, Bull Soc Chim,

France, 1955 , 694. 7 Stolle R & Gaertner E, 1 Prakt Chern , 132, 1931, 209. 8 SandstormJ ,ActaChemScand, 14 , 1960 , 1037, 1039. 9 Plamer C S, McWherter P W, Collective Organic Synthesis,

Vol. I ( John Wiley & Sons Inc, New York ), 1941 , P 240. 10 Vogel A I, The Text Book oj Practical Organic Chemistry,

4'h Edn (ELBS/Longmann Harlow), p 584, 88 1. I I Posner T, Ber dt Chern Ges, 39, 1906, 352 1.