liNTRODUCTION OBJECTIVES AND INVESTIGATIONS …shodhganga.inflibnet.ac.in/bitstream/10603/35164/9/09_chapter3.pdf · 3 synthesis ii-indirect approaches towards thiacalixarene synthesis

3 SYNTHESIS II-INDIRECT APPROACHES TOWARDS THIACALIXARENE SYNTHESIS

ABSTRACT

liNTRODUCTION

2 OBJECTIVES AND INVESTIGATIONS

3 EXPERIMENTAL

3.1 SYNTHESIS AND CHARACTERIZATION

3.1.1 CAux[n]ARENES (CnAs, n=4-8) 2n

3.1.1.1 p-tert-BUTYLCALIX[ 4 )ARENE

3.1.1.2 p-tert-BUTYLCALIX[5)ARENE

3.1.1.3 p-tert-BUTYLCALIX[6]ARENE



3.1.2 2-CHLOROALKYL-ETHERS OF CALJX(n]ARENES 3n

3.1.3 2-CHLOROALKYL-(p-tert-BUTYL)PHENYL ETHER 6

3.1.4 CAux[n]ARENE-(p-tert-BUTYL)PHENYL 1,2-DIETHERS 4n

3.1.5 CALIX(n]ARENE-THIACALIX(n)ARENE PSEUDO DIMERS Sn

3.1.6 HALO-DE-ALKOXYLATION OF Sn

3.1.7 A BRIEF DISCUSSION ON CONFORMATIONAL PREFERENCES OF Sn

4 CONCLUSION

REFERENCES

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57

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81

SYNTHESIS II-INDIRECT APPROACHES TOWARDS THIACALIXARENE SYNTHESIS

Abstract

The trend in supramolecular chemistry till date has been the synthesis of novel receptors

and subsequent exploration of their possible applications. As evident from literature, the

number of publications concerning the synthesis {not derivatization) of thiacalixarenes has

reached a plateau. Present chapter demonstrates a simple and versatile approach for the

synthesis of various thiacalixarene homologs, and hence, we hope, may rejuvenate the

chemistry of this exciting class of supramolecules. The modularity of the strategy permits

its adaptation to produce variety of other supramolecular assemblies like carcerands and a

plethora of other heteracalixarenes.

56

SYNTHESIS II-INDIRECT APPROACHES TOWARDS THIACAUXARENE SYNTHESIS

liNTRODUCTION

Heteracalixarenes (HCnAs, n=4-8 represents number of phenyl units in the macrocycle,

(Figure 3.1), the hetero-atom bridged metacyclophens, have earned significant interest in

the last decade by virtue of their structural similarities with calixarenes 2n (CnAs), but with

much superior complexing abilities.l1·3l The main hurdle in the evolution of

heteracalixarene chemistry is their synthesis, especially, of higher HCnAs, which are not

easily accessible generally.l4l In this chapter, we demonstrate an intuitive strategy to

synthesize various thiacalixarene homologs ln (TCnAs-sulfur bridged heteracalixarenes),

via respective calixarene templates.

Since the first practicable synthesis of TCnAs,l5l

there has been very few successful reports on the

subject.IG-11) Previously (Chapter 2}, we have

investigated microwave assisted reactions,

yielding ls-s in minor yields.l12l No reports for

synthesis of ls-s (especially for ls and l1) in substantial yields are available so far. To

understand the problem on hand in its correct perspective, it would be appropriate to

briefly review the chemistry of thiacalixarene synthesis. As has been reported earlier, the

template effect is not so pronounced in the case of TCnA synthesis, as compared to CnAs.

l1-3,5l In case of CnA synthesis, the number of aromatic units in the product macrocycle

depends largely on the template ion used as base catalyst.l13lln the presence of NaOH, the

predominant product is 24, while, if KOH is used, the product is a mixture of 26 and 2s.

Further, odd member CnAs (2s, 27) are achievable as byproducts in synthetically useful

yields, which is not the case with TCnAs, where such products are generally obtained in

trace amounts. The reason being, stringent thermodynamic requirements for the

cyclization of acyclic oligo-phenolsulfide intermediates whose fate depends upon their

thermodynamic stability, and hence end up as 14-the most thermodynamically stable

product amongst all TCnAs.l5l This was further evident from our recent investigations

(Chapter 2) of thiacalixarene synthesis protocoJ.14•12l Though significant success was

achieved in the synthesis of higher TCnAs (ls-s), the optimized methods required much

more rigorous maintenance of reaction conditions, and thus not viable for large scale

synthesis.

57


2 OBJECTIVES AND INVESTIGATION

One way to prepare higher TCnAs in good yields is to search for better templates {a partly

successful approach).l6-11l However, a more appropriate approach would be, to pre

organize individual phenol units according to required geometry and then add sulfur

bridges between them, thereby removing the possibility of uncontrollable oligomerization

completely. Pre-organizing many phenol units may seem a daunting task at first, which

may not be possible practically except via templation or better true complexation.

However, if the phenol units are restricted to move within certain limits, it may essentially

serve the same purpose. In practice, the restriction was imposed upon the phenol units by

anchoring them covalently on fixed scaffolds, namely, calixarenes, and thus, were brought

into a state of pre-organization.

!~,,:·, ~~rq~:;~%{;

. ~v1~'t;l!WJ:i;f¥l

~,~~t{:~~-~e,~i~~~~sr~~~l1~~~~i5~ It was also required by this strategy tHat; after anchoring the pHenol units to the calixarene

scaffold, the calix should retain/acquire a cone conformation, otherwise, cyclization {via

complete sulfurization) to form a macrocycle would be impossible. Two pathways were

employed to anchor phenol units on a calixarene scaffold {Scheme 3.1). The first approach

was to append an ethylchloride chain on 2n {Route A-by reacting with 1-chloro-2-

bromoethane) and react p-tert-butylphenol with the available chloride of 3n. While

successful in case of 4 and partly for 2s, the approach failed to secure the cone

conformation in case of higher CnAs {26-s) due to small size of appended chain, which was

unable to restrict the flip-flop motion of the calix-framework,113l and hence a mixture of

conformers was obtained, separable only through tedious column chromatography. The

second approach was to utilize template effect of CnAs towards alkali metal ions and

directly attach pre-formatted Ph-0-Et- chains on CnAs {Route B-by reaction with 6). This

approach was greatly successful on a wide range for 24-7, and partly for 2s. Beyond 28, the

cavity size becomes too large and hence, the restriction of the flip-flop motion of the

58


calixarene-framework becomes too tough to accomplish.

Having pre-organized the phenol units, the next step would be to add sulfur bridges

between the appended phenol units. However, the traditional 'elemental su/fur-NaOH

heating' method would not work satisfactorily in this case, reason being, the sulfurization

process involves a keto intermediate,14l which in turn requires a free phenolic -OH, not

available in 4n. Indeed, direct sulfurization of 4n with this approach yielded a very small

amount of completely sulfurized products Sn, along with a diverse consortium of mono

sulfurized to poly sulfurized products, as detected by UPLC-MS analysis of the reaction

mixture after completion of the reaction. Though 5n were detected in the reaction

mixture, it was not possible to isolate them, and hence a better method was required for

sulfurization. An already known sulfurization technique is the one using SCh, which was

coincidently used for the first synthesis of 14 in a step-wise manner.114l In present case,

sulfurization of 4n with SCb gave excellent results in all the cases, and CnA-TCnA pseudo

dimers 5n were obtained in good yields. Compound 54 has already been prepared by

reacting tetra-((2-tosyl}-ethyl}ether of calix[4]arene with thiacalix[4]arene. Conformational

preferences of various 54 derivatives and their comparative study with bis(calix[4]arenes}

has also been reported.l15l The 1HNMR spectra of all variants 54-s showed similar

unrestrained structuresJl&-zo)

The final step to achieve the TCnA derivatives was exhaustive halo-de-alkoxylation121l of 5n

in aqueous ethanol using lil, to cleave the ether linkages between two macrocycles (1n &

2n}, followed by their chromatographic separation or fractional crystallization (based on

differential solubility}. As can be inferred from the data listed in Table 3.1, all TCnA variants

have been achieved in very decent yields, and though being a multi-step synthesis,

satisfactory overall yields promise its application on relatively larger scales. Further, the

CnA templates may be recuperated with high overall% recovery ranging from ca. 60-75%.

Present strategy, viz. pre-organization of individual aromatic units with the help of other

a~~,Wi:t~t~~rj~t~~~~r~g!~\"~~~~{~r~~~~,~t~::~~i~~~l"g:~~,~~E!~~~~~,~::: ·.7c''

similar assembly and subsequent cyclization to produce pseudo dimers, is modular in a

59


sense that it can be applied to synthesize other supramolecular assemblies of calix family

in numerous ways. A complimentary approach has been successfully demonstrated by

Gale et. al.,l22,23) whereby, to manifest calix[4/S]pyrroles, four/five ketone functions

{bridging units) were appended to the calix[4/S]arene scaffold and pyrroles {aromatic

units) were inserted afterwards. For instance, the strategy can be extended {a) to prepare

various heteracalixarenes, with hetero-atom bridges other than sulfur, by employing

different reagents for cyclization of appended phenol units {b) to synthesize TCnA

derivatives with various p-substitutions {for which cyclization is not possible via direct

sulfurization), as long as they are sufficiently activating to permit m-substitution. It may be

noticed that 5 possesses a carcerand type structure, and thus, this approach can be

employed to produce some more exciting carcerands as well.

It may be noticed here that some of the calix[n]arene templates {especially the odd

numbered homologs) are themselves not very easy to prepare {and thus expensive),

therefore it is highly desirable to recover the unreacted/partially reacted templates. In this

regard, two strategies can be employed. That is, either to recover the unreacted fraction at

the end of each step and hydrolyze them appropriately, or collect unreacted fractions of all

steps and proceed with the hydrolysis. Both the strategies were tested and gave equally

satisfactory results, however, from practical view point the latter strategy is beneficial. In

practice, all the residual fractions {including solid residues, washings, mother liquor of

crystallization etc.) were collected and evaporated to dryness under vacuum. The solid/

semi-solid residue obtained was then washed/triturated with hexane and evaporated to

dryness to give solid powder. The powder was washed with warm aq. ethanol {10%, v/v) to

remove inorganic salts. The final residue was then subjected to alkaline hydrolysis with aq.

NaOH/KOH {2M) or halo-de-alkoxy/ation under reflux conditions followed by usual work

up. The purification was carried out by crystallization or column chromatography. For the

sake of obtaining a clear picture of quantitative recovery, the results of recovery {%) of

calix[S]arene for all individual steps {in a complete reaction cycle) have been summarized

in Table 3.2 as a representative example. Overall % recovery of 2s is ca. 70% in this case.

Similarly, the % recovery ranges from ca. 60-75% for different homologs, which is very

good for a four step reaction. % Recoveries are calculated on the basis of initial amount of

2s derivative reacted in each step.

60


3 EXPERIMENTAL

All the reagents used were of AR grade, procured from Sigma-Aldrich. The reagents were

used without further purification. The solvents were dried appropriately wherever

required. Melting points were taken in a single capillary tube using Toshniwal melting point

apparatus and are uncorrected. EA was carried out on Heraeus CarloEbra 1108 elemental

analyzer. NMR spectra were recorded on Bruker DPX-400 AVANCE in CDCh with

tetramethylsilane as internal standard. Liquid chromatography was conducted on Waters

Acquity UPLC system (Milford, MA, USA) with Waters analytical column, type UPLC BEH Cts

reversed phase (lOOmm long and 2.1mm internal diameter with 1.7Sj..lm particle size)

maintained at 40°C, mobile phase composition was methanoi:O.Ol% acetic acid (90:10, v/

v). Waters Oasis HlB solid phase extraction cartridges (30j..lm) were used for extraction.

Mass measurements were done on Waters, ·Quattro Premier XE (Milford, MA, USA),

equipped with electrospray ionization and operating in positive ionization mode.

3.1 SYNTHESIS AND CHARACTERIZATION

3.1.1 CAux[n]ARENES (CnAs, n=4-8) 2n

Calix[n]arenes were prepared by established procedures (Scheme 3.2).124-25)

3.1.1.1 p-tert-BUTYLCALIX[ 4 ]ARENE

lOg (66mmol) of p-tert-butylphenol was mixed with

lOml of 3N NaOH and 9. 7g of 37% formaldehyde

solution. The mixture was heated at 50-SSOC for 4-Sh and

then at 110-120°C for 2h to give a yellow solid. This was

stirred with lOOml of lN HCI for lh to neutralize the P;~~~~ ' /i:f'Jt?:;{b'(~~";,..,; ~o,-.;:;.,~:~)i_

2 ~·· n>

base, and the solid was removed by filtration, washed ~~i~-q~~~:~t4~~~~';

with water, and dried in an oven at 110-120°C for 30min. This material was mixed with 70g

of diphenyl ether and heated to 210-220°( for 2h. The reaction mixture was cooled,

treated with 150ml of ethyl acetate, and filtered to yield 5.47g of a white solid. This

material was treated with 75ml of toluene, heated at reflux for 30min, and filtered hot to

remove insoluble higher oligomers. Upon cooling, the toluene solution deposited crystals

which were recrystallized from toluene to give 2.75g (25%) of p-tert-butylcalix[4]arene.

3.1.1.2 p-tert-BUTYLCALIX[S]ARENE

A mixture of 22.50g (lSOmmol) of p-tert-butylphenol, lS.Og (37.5mmol) of paraformal

dehyde, 4.50g (40mmol) of potassium tert-butoxide, and 300ml of tetraline was stirred

61


mechanically for 6h at 55°( in a 1l three-necked round-bottomed flask equipped with a

Dean-Stark trap. The temperature was then raised to 150°C and maintained for 6h, with

mechanical stirring. The product mixture was cooled to room temperature, and 900ml of

CHCI3 was added. The insoluble polymer that precipitated was removed by filtration after

2h. The CHCh solution was washed sequentially with 300ml of a 5% aqueous NaOH

solution, 300ml of 5% HCI, and 300ml of water and dried (anhydrous Na2S04) for 24h. The

solution was then concentrated under reduced pressure {1mm Hg). The residue was

triturated with 150ml of absolute ethanol at 40°C. The ethanol solution was found to

contain five components by TLC (silica). After the solution was allowed to stand for 48h at

0°C, 4.3g of a solid product precipitated from the ethanol solution. Thin-layer

chromatography revealed that the solid was a mixture of two compounds. Column

chromatography of the crude product, which was soluble in the hot iso-propyl alcohol,

with 100g of silica gel, afforded 2.06g of pure p-tert-butylcalix[5]arene, yield 6.1%.


A slurry of 10.0g (0.066 mol) of p-tert-butylphenol, 4.0g {133mmol) of paraformaldehyde,

and 6ml of 5N RbOH in 100ml of xylene was refluxed in an inert atmosphere with efficient

stirring for 4h in a 500ml flask equipped with a Dean and Stark collector. The cooled

reaction mixture was filtered, and the solid obtained was suspended in 300ml of CHCb,

and shaken with 100ml of 1N HCI. The organic layer was separated, washed with water,

dried over anhydrous Na2S04, and concentrated to 100ml. Addition of methanol caused

the precipitation of a solid, which was removed by filtration to give 7.85g (73%) colorless

product. Recrystallization from CHCI3 produced a white solid with the melting point of

380-381°(.

3.1.1.4 p-tert-BUTYLCALIX(7]ARENE

A 1-l three-necked round-bottomed flask equipped with a mechanical stirrer, condenser,

and Dean-Stark trap was charged with 180g (1.20mol) of p-tert-butylphenol, 72g (2.40mol)

of paraformaldehyde, 600ml of 1,4-dioxane, and 13.50g (240mmol) of KOH dissolved in

6ml of water. The heterogeneous mixture was refluxed under a nitrogen atmosphere for

30h, with efficient mechanical stirring. After the mixture was cooled to room temperature

and 30ml of 8M HCI was added, the solvents were removed under reduced pressure. The

crude product was then triturated successively, with 600ml of water (12h) and 1l of

methanol (6h), dissolved in 1.1l of CHCb, and dried over anhydrous Na2S03, for 24h. After

addition of 450ml of methanol, the solution was allowed to remain at ooc for 24h,

resulting in the crystallization of white solid, removed by filtration. The filtrate was

62


concentrated under reduced pressure to 1.3l and 450ml of methanol then added. Further

crystallization at ooc for 24h furnished an additional white substance, removed by

filtration. The filtrate was concentrated, diluted with methanol, and allowed to crystallize

in the same manner for additional two times. Purification of these combined fractions by

column chromatography (two times) with silica afforded G.llg {3.7%} of p-tert-butylcalix

[7]arene, MP 248-2Src.

3.1.1.5 p-tert-BUTYLCALIX(8]ARENE

A slurry of 27.8g {0.18mol) p-tert-butylphenol, 9.0g {0.30mol) paraformaldehyde, and

0.4ml 10N KOH in 150ml of xylene was refluxed in an inert atmosphere with efficient

stirring for 4h in a SOOml flask equipped with a Dean-Stark water collector. After 30min all

of the solid had gone into solution, and after 1h a white precipitate began to separate. The

reaction mixture was refluxed for 4h, cooled, and filtered. The solid product was washed,

in succession with 100ml portions of toluene, ether, acetone and water and was then

dried and recrystallized from CHCI3 to afford 20.4g (64%) of the p-tert-butylcalix[B]arene as

colorless, glistening needles:MP 411-412°C.

3.1.2 2-CHLOROALKYL-ETHERS OF CALIX(n)ARENES 3n

2n (2Smmol) was suspended in dry acetone

(SOOml) containing anhydrous alkali carbonate

(nx3.75mmol) and 1,2-chlorobromo-ethane

(nxSOmmol). The mixture was heated under

reflux for 6-14h. After cooling, the solid resi

due was filtered and extracted thrice with di

chloromethane. The combined filtrates were evaporated under vacuum to remove. From

the solid residue containing the mixture of conformational isomers, the cone isomer 3n

was separated by fractional crystallization from ethanol-chloroform (4:1, v/v) solution

(Scheme 3.3). Yields are summarized in Table 3.3.

63


34:Colorless prisms (from CHCI3) MP >3oo·c, MS m/z 900 (M+1), 1HNMR (300 MHz, CDCh):6 1.19 (s,

36H,But), 6.41 (s, 8H, Ar-H), 3.24 & 4.66 (d, 8H, ArCH2Ar, j=12.6), 4.35 & 4.18 (t, OCH2CHzCI), 13CNMR (75 MHz, CDCh):6 31.6 (But), 32.6 (ArCHzAr), 43.1 (CHzCI), 75.0 (OCHz), 135.9, 143.1, 160.7 (Ar), EA Calc. for

CszHGs04CI4 (C:69.48, H:7.62), Found (C:69.40, H:7.59).

lHNMR Data for 34

8 7

4.40

1 rl ... \1)

0 0

6

BCNMR Data for 3 ..

r- r-iO\O'IoOM

0 MlOII')O'\U') \1) ~MMNN rl ..................... ..-t

I I y \ I

I I I 170 150 130

4.30 ppm

\1)

U) .., \1) ...

"' rl

4.20

rl rl rl

5 4 ppm

0

U)

r-

1

... "'

3

3.25

2

I

"' rl

0 0

"'

110 90 80 70 60 50 40 30 20 10 ppm

0

0

Current Data Parameters NAME Octll 2006 EXPNO 11 PROCNO

F2 - Acquisition Parameters Oat• 20061013 TiMe 2. 31 IN STRUM spect PROBHD 5 .. PABBO BB-

PULPROG ~q30

TD 32168 SOLVENT CDC13 NS 3200 DS SWH 10330.578 Hz

riDERS 0.366732 Hz

AQ 1. 5900832 RG 179 DW 48.400 DE 6. 00 TE 299.8 K

Dl 1. 00000000 TDO

CHANNEL fl --------NUCl 1H

Pl 10.65 PL1 0.00 dB

SFOl 300.1330875 MHZ

F2 - Processnq Paraaeters sr 32768 SF 300.1300000 MHZ

NOW EM

SSB 0 LB 0. 30 Hz

GB 0 PC 1. 00

Current Data Paraaeters NAME Oct13 2006 EXPNO 23 PROCNO 1

F2 ... Acquisition Para•eters Date 20061013 Time 3.37 IN STRUM

PROBHD PULPROG TD SOLVENT NS DS SWH FIDERS AQ

RG DW DE TE D1 dll DELTA TDO

NUCl P1 PL1 SFOl

spect 5 •• PABBO BB-

19PCJ30 32768 CDC13

3000

29761.904 Hz 0. 8979536 Hz

0. !>969723 210

16.800 6.00

299.8 K 2. 00000000 0. 03000000 1. 89999998

1

CHANNEL fl .............. .. 13C

7. 80 0.00 dB

75.7703643 MHZ

•••••••• CHANNEL f2 --------CPDPRG2 waltzl6 NUC2 1H PCPD2 80.00 PL12 11. so dB PL13 11. so dB

PL2 0.00 dB

SF02 300.1320005 MHZ

F2 - Processng Parameters SI 32168 SF 15.7518790 MHZ

WDW EM SSB 0 LB 1. 00 Hz

GB 0 PC 1. 40

64


3s:MP >300"C, MS m/z 1125 (M+1), 1HNMR (300 MHz, CDCh) 6 1.18 (s, 36H,Bu1), 6.49 (s, 8H, Ar-H), 3.66 &

5.58 (d, 8H, ArCH2Ar, j=12.5), 4.37 & 4.14 (t, OCH2CH2CI), 13CNMR (75 MHz, CDCh) 6 31.1 (Bu1), 32.7 (ArCH2Ar), 43.1 (CH2CI), 74.8 (OCH2), 135.9, 143.3, 159.9 (Ar), EA Calc. for <=GsHssOsCis (C:69.48, H:7.62),

Found (C:69.35, H:7.56).

lHNMR Data for 3s

Current Data ParaMeters NAME Octl3 2006 EXPNO ,.

... ... co PROCNO 1 M ..... ..... ... F2 - Acquisition Para111eters

Date 20061013 -co

~ Jlk_ "' Time 2.57

A _a IN STRUM spect PROBHD 5 mm PABBO 88-

PULPROG zg30 TO 32768

/ SOLVENT CDC13

5.6 4.4 4.1 3.7 NS 3200

ppm OS 4 SWH 10330.578 Hz

FIDERS 0.355582 Hz

AQ 1. 7233946

I I I RG 180

_r ow 48.400

DE 6.00 TE 300.0 K

"' Dl 1. 00000000 ... TOO

"' CHANNEL fl --------... ... NUCl lH M .....

Pl 10.65 co ... "' PLl o.oo dB

"' "' f l ~ 1

SFOl 300.1330875 MKZ

J; !! T' F2 - Processng Parameters 0 ... ..... 51 32768 0 0 "' "' 0 0 SF 300.1300000 MKz

N "' wow EM

SSB 0

LB 0.30 Hz

GB 8 7 6 5 4 3 2 0 PC 1.00

ppm

13CNMR Data for 3s Current Data Paraaeters

"' C""''0\0'\0M NAME Octll 2006 co ......tNr"'-...-tr-41""1

"' MLOIIlO\LO EXPNO 25

"' o::rMP\NN ... MLON...-t....t..-1 PROCNO ..... .... r-4 .-1..-t r-t ... ~MMMMM

I I y \ I I '-.'-.!::::,.,"+-" F2 - Acquisition Para•etera Data 20061013 -Time 3 .sa IN STRUM spect PROBHD 5 •• PABBO BB-

PULPROG ZC}pg30

TD 32768

SOLVENT CDC13 NS 3000 OS 4 SWH 29761.904 Hz

FIDERS 0.9032895 Hz

AQ 0.6134749

RG 209 OW 16.800 DE 6.00 TE 299.9 K

Dl 2. 00000000

dll 0. 03000000 DELTA 1. 89999998

TOO 1

CHANNEL fl --------NOCl 13C Pl 1.80 PLl 0 .oo dB

SFOl 15.1703643 MHZ

CHANNEL f 2 •••••••• CPDPRG2 waltzl6 NUC2 lH PCPD2 80.00 PL12 17. so dB

PL13 11. so dB

PL2 o. 00 dB

SF02 300. 1320005 MHZ


NOW EM SSB 0 LB 1.00 Hz GB 0

170 150 130 110 90 80 70 60 50 40 30 20 10 0 PC 1. 40

ppm

65


3.1.3 2-CHLOROALKYL-(p-tert-BUTYL)PHENYL ETHER 6

p-tert-Butylphenol (100mmol) was suspended

in dry acetone (SOOml) containing a 1.5 fold

excess of anhydrous KzC03 (150mmol) and two

fold excess of 1,2-chlorobromoethane (200

mmol). The mixture was heated under reflux

for 4 h. After cooling, the solid residue was ~~11f~Y?*~~1;: ~~ert~~~~t

filtered and extracted with dichloromethane three times. The combined filtrates were

evaporated under vacuum to remove solvents. The solid residue was crystallized from

CHCI3, Yield 89% (Scheme 3.4).

6:1HNMR (300 MHz, CDCh):6 7.50 (s, 2H, Ar-H), 6.92 (s, 2H, Ar-H, j=7.50), 1.34 (s, 9H, t-Bu), 4.23 (s, 2H,

OCH2), 4.12 (s, 2H, CH2CI, j=7.70), 13CNMR (75 MHz, CDCh):6 31.3, 34.2 (But), 125.4, 114. 7, 142.9, 156.6 (Ar),

75.2 (OCH2), 43.1) (CH2CI) I ESI MS:m/z 214 (M+1), EA Calc. for c12H170CI (C:67.76, H:8.06), Found (C:67.69, H

8.09).

lHNMR Spectrum of 6

6.95 4.25 4.15 ppm

I I }( ....

0 N ~ ., "' ...

f f u I I !! 0 ": 00\

N N N..,

8 7 6 5 4 3 2 ppm

3.1.4 CAux[n]ARENE-(p-tert-BUTYL)PHENYL 1,2-DJETHERS 4n

... ....

...

N

"' 00

1

Current Data Paraaeters NAME Octl2 2006

EXPNO 8

PROCNO 1

F2 - Acquisition Para•eters Date_ 20061012 Ti111e 3. 31 INSTRUM spect PROBHO 5 mm PABBO BB-

PULPROG !:930

TO 32168 SOLVENT CDC13 NS 3200 OS • SKH 10330.578 •• FIDERS 0.369452 .. AQ 1. 6342901 sec RG 183

•• 48.400 usee DE 6. 00 usee TE 300.2 • 01 1. 00000000 sec TOO 1

•••••••• CHANNEL fl •••••••• NUCl lH Pl 10.65 usee PLl 0.00 dB SFOl 300.1330875 MH~

F2 - Processnq Parameters Sl 32768 SF 300.1300000 MHZ WOW EM SSB 0 LB 0.30 Hz GB D

0 PC 1. 00

Route A:A mixture of 3n (2Smmol) and p-tert-butylphenol (nxSOmmol) was suspended in

dry acetone (SOOmL) containing anhydrous alkali carbonate (nx37.Smmol). The mixture

was heated under reflux for 10-24h. After cooling, the solid residue was filtered and

washed with CHzCh (SOmL) three times. The combined filtrates were evaporated under

vacuum to remove solvents. The product was crystallized from chloroform (Scheme 3.5).

66

BCNMR Spectrum of 6

"' a. ..; N

"' ... .... .... I I

I I I I I

170 150

I

...... "'"' "'"' .... .... y

I I

130

01:1&~

Ai¥h .. ~ >: .

. . '

r-r-...... ........ ........ y

I I I

110


Current Data Para•eter.s NAME Oct:l2 2006

N r-fNP'lM(I") EXPNO 13 ...; M"=r'.-tr-f.-t PROCHO 1 r- VMMMM

I I ........~ F2 - Acquisition Parameter., Date 20061002 -Ti•e 4 .11 INSTRUH spect PROBHD 5 •• PABBO BB-

POLPROG zgpCJ30

TD 32168

SOLVENT CDC13

NS 3000

DS SWR 29761.904 Hz

FIDERS 0.9197351 Hz

•o 0.6253191

RG 208 DW 16.800 usee

DE 6. 00 usee

TE 300.1 • Dl 2. 00000000 ... dll 0. 03000000 ... DELTA 1. 8!U99998 ... TOO 1

.................. CHANNEL f1 --------NUCl 13C

P1 1. 80 usee PL1 0. 00 dB

SFOl 75.7703643 MHZ

................ CHANNEL f2 --------CPDPRG2 waltzl6 NUC2 1R

PCPD2 80.00 use<: PL12 17. so dB

PLll 17. so dB

PL2 0.00 dB

SF02 300.1320005 MRz

F2 - Procesang Parameters SI 32768 SF 75.7578790 ""' wow EM

SSB LB 1.00 ••

I I I I I I GB 0

90 80 70 60 50 40 30 20 10 0 PC 1.40

ppm

(SOOml) containing anhydrous alkali carbonate (nx38mmol) and heated under reflux for

10-24h. After cooling, the solid residue was filtered and CH2Ch soluble fraction was

separated by extraction, cone conformer 4n was obtained by crystallization from CHCh.

67


44 :Yield 82%. 1HNMR (300 MHz, CDCJ3):8 7.10, 7.50 (s, 8H, Ar-H), 0.82, 0.85, 1.33 (s, 72H, t-Bu), 6.32, 6.96 (s,

8H, Ar-H), 4.35, 5.43(m, 16H, OCH2CH20, j=7.7), 3.24, 4.66 (d, 16H, ArCH2Ar, j=12.5}, 13CNMR (75 MHz,

CDCJ3):8 30.8, 31.8, 34.1, 36.5 (Bu1), 133.6, 135.8, 144.2, 161.5 (Ar), 72.1, 75.0 (OCH2CH20), 31.9 (ArCH2Ar),

MS:m/z 1353 (M+1), EA Calc. for C92H12oOs (C:81.61, H:8.93), Found (C:81.61, H:8.80).

tHNMR Spectrum of 44

,., ... U")

U") ,.,

... Jl

,......-( ....... ' -r--r--r--"1---r""'•' ..... 'T'I -r--r---r>' .....,..,....., ...,........,..1""""""T 7.7 7.0 5.5 4.7

ppm

J I _r I

8

U")

r-

I 0

"' "' d !"! "''"' ON

7

N ,., "'

CX)

"'

6

U")

l ! "'

t3CNMR Spectrum of 44

...-4...-tqtqti.I')U")lf"'lOC""'MMM \0\0"''"'::'MMMMMMMM

v~~)-7d~

5

"'

U") ,.,

1 l ~ ! 0 "' .....

4 ppm

4. 4 3.3

... N

~ 0

0.-<

U"'IN r-r-

\ I

I

3 2

,., "' CX)

;

N 0

"'

I.C)qoqt<Q'...-4.-1000 MMMMMMMMM

~v~

170 150 130 110 90 80 70 60 50 40 30 20 10 ppm

Current Data ParaMeters NAME Nov02 2006

EXPNO

PROCNO

F2 - Acquisition Parameters Date 20061102 Time 10.37 INSTRUM spect PROBHD 5 mm PABBO BB-

PULPROG

TO

SOLVENT NS

OS

SWH

FI DERS AQ RG ow DE

TE

01 TOO

<l930 32768 CDC13

3200

10330.578 Hz 0.349935 Hz

1. 5293553 180

48.400 usee 6.00 usee

299.9 K 1.00000000

CHANNEL fl ••••••••

NUCl lH Pl 10.65 usee PLl 0.00 dB SFOl 300.1330875 Mflz

F2 - Processng Parameters SI 32768 SF 300.1300000 MHz wow

••• LB GB

EM

0 0. 30 Hz

Q PC 1. 00

0

Current Data Para•eters NAME Nov04 2006 EXPNO

PROCNO

F2 - Acquisition Para•eters Date 20061104 TiJie- 10.31 INSTRUM spect PROBHD 5 IDIA PA880 88-

PULPROG TO

SOLVENT NS

OS

SWH

FIDERS AO RG OM

DE

TE

01 dll DELTA

TOO

NUCl P1 PL1 SFOl

CPDPRG2 NUC2 PCPD2 PL12 PL13 PL2 SF02

zgpg30 32768 CDC13

3000

29761.904 Hz 0.8980452 Hz 0.5954638 sec

210 16.800

6.00 usee 299.9 K

2. 00000000 0.03000000 1.89999998

CHANNEL fl •••••••• 13C

7.80 0. 00 dB

75.7103643 MHZ

CHANNEL f2 --------waltzl6

1H 80.00 11.50 dB 11.50 dB

0.00 dB 300.1320005 MHZ


wow EM SSB 0 LB 1. 00 Hz

GB 0 PC 1. 40

68


45:Yield 78%. 1HNMR (300 MHz, CDCI3):& 7.10, 7.68 (s, 8H, Ar-H), 0.82, 0.87, 1.32 (s, 72H, t-Bu), 6.33, 6.71 (s,

8H, Ar-H), 4.37, 5.33(m, 16H, OCH2CHzO, j=7.7), 3.66, 5.58 (d, 16H, ArCH2Ar, j=12.6), 13CNMR (75 MHz,

CDCh):& 30.5, 31.1, 34.0, 35.9 (Bu1), 133.2, 135.7, 144.3, 159.9 (Ar), 71.9, 75.6 (OCHzCH20), 32.1 (ArCH2Ar),

M5:m/z 1693 (M+1), EA Calc. for CmH1so01o (C:81.61, H:8.93), Found (C:81.52, H:8.79).

1HNMR Spectrum of 4s

....--.',......,....... ~ .........--.-.- ,.._,_r-..',.......-r--<' ~ 7.7 7.1 6.7 5.6 5.3 4.4 3.7

.r .r I I Jl

0)

"' 0 ....

i f

,., ,., "'

0)

,., ,.,

f l !'! 0 0\

ppm

I f

.... ,.,

! 0\

"' "'

r 0

.... ....

N ,.,

N 0\

,., 0

0) 0\

Current Data Paraaetera NAME Nov02 2006

EXPNO PROCNO

F2 - Acquisition Paraaeters Date_ 20061102 'riae 10.56 INSTRVH #pect PROBHD S am PABBO 88-

PULPROG TO SOLVENT HS

OS

SWH

FIDERS AO kG ow DE TE 01 TOO

zg30 32168 CDC13

3200

• 10330.578 Hz

0. 340753 Hz 1.5174056 sec

181 48.400 usee

6.00 uaec 300.1 K

1. 00000000 sec 1

•••••••• CHANNEL f 1 •••••••• NUCl lH. Pl 10.65 usee PLl 0.00 dB SFOl 300.1330815 MHZ

F2 - Processnq Para•eters St 32768 SF 300.1300000 MHZ MDV

sse Le Ge

EM 0

8 7 6 5 4 ppm

3 2 I

1 0 PC

0. 30 Hz 0

1.00

13(NMR Spectrum of 4s

0\ 0\

0\ 0\ U")U") ........ y

C"')Mf"'"r""-t"-\DNNN('I

~<QOU")ll'}lt)LOMMMM

.;roqoMMMP'lMMM"'l ,...,...,...,...,...,...r-tr-tr-t .... y Vr.J.J d, J....l

I I I I I I I I I I I I I I

170 150 130 110

"'"' .., .... .... ....

II

0'1000.-tr-11/li.Oil')

LO.;r.;r...,.Nr-tOOO MMMMMMMMM

~\~

I I I I I I I I I I I I I I I I I I I I I

90 80 70 60 50 40 30 20 10 0 ppm

Current Data Paraaetera NAME Nov04 2006 EXPNO 4 PROCNO

F2 - Acquisition Para•etera Date_ 20061104 Time 10.11 INSTRUH spect PROBHD 5 •na PABBO 88-PULPROG Z«Jpg30 TO 321'68 SOLVENT CDC13 NS 3000 OS 4

s•a 29761.904 Hz FlDERS 0.9177,83 Hz AO 0. 6060S32 sec RG 208 DW 16.800 usee a£ 6.00 usee TE 300.1 K Dl 2. 00000000 sec dll 0.03000000 sec DELTA 1.89999998 .uc TOO 1

•••••••• CHANNEL t.l •••••••• NUC1 l3C Pl 7,80 u•ec PLl 0.00 dB SFOl 75.7703643 MHZ

•••••••• CBAHH.EL 12 •••••••• CPDPRG2 NUC2 PCPD2 PL12 PL13 PL2 SF02

walttl6

1R 80.00 usee 11.50 dB 11.50 dB o.oo dl!l

300.1320005 MHZ

F2 - Processng Parameters SI 32768 SF wow sse LB

G.e PC

75.7518790 MHZ EM

0 1. 00 Hz

0 1.40

69


46:Yield 70%. 1HNMR (300 MHz, CDCh):5 7.10, 7.56 (s, 8H, Ar-H), 0.90, 0.93, 1.33 (s, 72H, t-Bu), 6.37, 6.88 (s,

8H, Ar-H), 4.25, 5.41(m, 16H, OCH2CH20, j=7.7), 4.03, 5.44 (d, 16H, ArCH2Ar, j=12.6), 13CNMR (75 MHz,

CDCh):5 30.9, 31.6, 34.8, 37.0 (But), 134.8, 135.8, 144.8, 161.4 (Ar), 72.0, 77.2 (OCH2CH20), 32.2 (ArCH2Ar),

MS:m/z 2032 (M+1), EA Calc. for C13aH1ao012 (C:81.61, H:8.93), Found (C:81.55, H:8.95).

lHNMR Spectrum of 4&

M .... "' M ... "' "'

"' OA ~~k "' .... 00

__;(A_ XA_ _.; / ' I .. '

7.1 6.9 ppm

..r JJ I J r-..,

"' .... ... "' oa> "' "'

.... ., ~ jf I

I :!:1 "' '! 0 0 0 "' 0

......... M

8 7 6 5

13(NMR Spectrum of 4&

........

170

CDOOCDCOOO\DCDCOOOCD

"Q'~tt)ti)U")I/)OQ'"Q'"Q'OQ' qto;;J"P"'MMMMMMM ...-tt-tr-tr-tr-t"""r-t""".-f..-t y "J.-,) .J J J .1 .J

150 130 110

5.4

!..J

"' "' ... M

! 1 !'3 "'0

........

4 ppm

"'0 r- "' r- r-

1 I

I

,...__

~

"' .... "' 0

"' 0\

3 2 1

OOOQ)C:ON\D0\0\0'\

90 80 70 60 50 40 30 20 10 ppm

0

0

Current Data Parameters NAME Nov02 2006

EXPNO 12

PROCNO 1

F2 - Acquisition Paraaeters Date 20061102 -Til'le 11.31 IN STRUM spect PROBHD 5 mm PABBO 88-

PULPROG zgJO TO 32768 SOLVENT CDC13

NS 3200 OS • SWR 10330.578 .. FIDERS 0.352843 •• AO 1.5234126 RG 179 ow 48.400 DE 6. 00 usee TE 299.8 • 01 1. 00000000 TOO 1

CHANNEL fl ···= ...... N\JCl '" Pl 10.65 PLl 0.00 dB

SFOl 300.1330815 HH•

F2 - Proceasng Parameters 51 32768

SF 300.1300000 HH<

wow EM

SSB 0

LB 0. 30 •• GB 0 PC 1. 00

Current Data Para•eters NAME Nov04 2006 EXPNO 9

PROCNO

F2 - Acquisition Paraaeters Date_ 20061104 Time 11.01 INSTRUH speet PROBHD 5 mm PAB80 88-

PULPROG Z9P930 TO 32168 SOLVENT CDC13 NS 3000 OS • ••• 29761.904 .. F IDERS 0.9123079 .. AQ 0.5863124 RG 20. DW 16.800 usee D£ 6. 00

T£ 300.1 K

Dl 2.00000000 dll 0. 03000000 DELTA 1. 89999998 TOO

CHANNEL fl --------NUCl 13C Pl 1. 80 usee

PLl 0.00 dB SFOl 15-.7103643 MH•

CHANNEL f2 --------CPDPRG2 waltz16 NUC2 lH PCPD2 80.00 usee

PL12 11.50 dB

PL13 11. so dB

PL2 0. 00 dB

SF02 300.132000~ ""' F2 Sl

- Pcocessng Parameters 32768

SF NOW SSB LB GB PC

75.1578790 MHZ.

EM

0 1.00 Hz

0 1. 40

70


47:Yield 59%. lHNMR (300 MHz, CDCh):b 7.15, 7.69 (s, 8H, Ar-H), 0.90, 1.02, 1.32 (s, 72H, t-Bu), 6.43, 6.99 (s,

8H, Ar-H), 4.25, 5.53(m, 16H, OCHzCHzO, j=7.7), 3.78, 5.64 (d, 16H, ArCH2Ar, j=12.5), 13CNMR (75 MHz,

CDCh):b 30.8, 32.0, 34.5, 36.2 (Bu1), 135.1, 135.6, 146.6, 160.7 (Ar), 73.3, 76.1 (OCHzCHzO), 32.3 (ArCHzAr),

MS:m/z 2370 (M+1), EA Calc. for C161H210014 (C:81.61, H:8.93), Found (C:81.49, H:8.81).

1HNMR Spectrum of 47

M U') "' N

N M

["""r--,-_,~............,~~~T--

8.0

"' 0

N

8

1.1

U'>N o .....

"'"" 1

f M ...

Q)

"' M

6

1.0

_jl

M U')

"""' 0"'

N M

ppm

5

13(NMR Spectrum of 47

r-r- \0\0\01.0\D\0.-4.-I.-tr-1

00 \DIDLOLOLOLOLOLOLOLO

"'"' 'lll''lll'MMPlMMMMM .......... ....-lr-lr-f....-l ..... l""fr-lr-1.-t...-4

y y 'l,d J J I J J

110 150 130 110

5.5

/_r

"' N

N

"' M

"' 0

N

4 ppm

..... ..,

.,.., r- ....

\ I

I

90 80 10 ppm

3.8

0

""'' Q) . "'"' r-..... Q) Q)

3 2 1

NLOLOLOMOCOCOCO

\O'IIl''lll'-=:I'"NNOOO Mr")Mt"lMMr")MM

~v~

60 50 40 30 20

0

10 0

Current Data Parameters NAME Nov02 2006

EXPNO PROCHO

18

F2 - Acquisition Parameters Date 20061102 -Time 11.47

IN STRUM spect

PROBHD 5 ... PABBO BB-

PULPROG Z930 TD 32768

SOLVENT CDC13

NS 3200

DS 4 SHH 10330.578 Hz

FIDER.S 0.350982 Hz

•o 1.4499934 RG 178 DH 48.400 usee:

DE 6.00 TE 299.8 • 01 1.00000000 TOO 1

CHANNEL fl --------NUCl 18

Pl 10.65 usee: PL1 0.00 dB

SFOl 300.1330875 MHz

F2 - Processng Paraaeters SI 32768

SF 300.1300000 MHz

WOW EM

SSB 0

LB 0. 30 Hz

GB

PC 1. 00

Curren~ Data Para•eters NAME Nov04 2006 EXPNO 13

PROCNO

F2 - Acquisition Para•eters Date 20061104 Tiae 12.11 IN STRUM spect PROBHD 5 •• PABBO BB-

PULPROG %9P930 TD 32768 SOLVENT CDC13

NS 3000 DS SWH 29761.904 Hz

FIDERS 0.9145464 Rz

AQ 0. 5849659 RG 208

DW 16.800 DE 6.00 usee TE 300.1 K

01 2. 00000000 dll 0.03000000 DELTA 1. 89999998 TOO

............. CHANNEL fl --------NUCl 13C

P1 1.80

PL1 o.oo dB

SFOl 75.7703643 MHz

CHANNEL f2 •••••••• CPDPRG2 valtzl6 NUC2 1H

PCPD2 80.00 PL12 11. so dB

PL13 17. so dB

PL2 0. 00 dB

SF02 300.I32000S MHZ

F2 - Proce.ssng Parameters SI 32768 SF 75.7518790 HHz wow EM

SSB 0 LB 1. 00 Hz

GB 0 PC 1.40

71


4a:Yield 37%. 1HNMR (300 MHz, CDCI3):& 7.18, 7.76 (s, 8H, Ar-H), 0.89, 1.10, 1.32 (s, 72H, t-Bu), 6.51, 7.01 (s,


CDCh):& 30.9, 31.9, 34.4, 36.3 (Bu1), 134.9, 135.8, 146.3, 160.8 (Ar), 73.1, 76.0 (OCH2CH20), 32.4 (ArCH2Ar),

MS:m/z 2709 (M+1), EA Calc. for C184H24o016 (C:81.61, H:8.93), Found (C:81.50, H:8.87).

lHNMR Spectrum of 4a

( ~ .......-------...........,.... 8.0 7.2 7.0

_[ _r[ J _jf ..... "' "' "' "'

"' .... "' .... 0

"' "'"' "' U'IM 0 .-.o "' 0"'

N Nqo .... NM

8 7 6 5

13CNMR Spectrum of 4a

"'"' MMOOOOQ)000\0\0'10\

"'"' \0\DtOLOtOLO...rqo.qo.qo

"'"' .qo.qoMMMMMMMM ........ ........................ r-t.-tl"""fr-4.-t ....

y y 'Jrd J J d ,.J..J

170 150 130 110

5.6 ppm

I _j

"' N

0

N "' "' 0

.... N

4 ppm

o.-.

"'M .... .... \ I

I I

90 80 70 ppm

I' 4.2

3

60

3.8

2

N ....

.... 0'1 r.:J:i I,Q

. "'"' .... .... "'"'

1

P'}~.q'<q'<q'0\0\0'10\

\Dqo'QO.qoNI"""fOOO MMMMMMMMM

~v~

50 40 30 20

0

10 0

current Data Parameters NAME Nov02 2006 EXPNO 23 PROCNO

F2 - Acquisition Paraaeters Date 20061102 Time 12.09 INSTRUM PROBRD

POLPROG

TD SOLVENT NS

DS SWR

FIDERS AQ

RG

DW

DE

TE

01

TDO

Smm spect

PABBO BB-Z930

32768 CDC13

3200

• 10330.578 0.361149

1. 6234983 181

48.400 6.00

300.2 1. 00000000

I

•• ••

K

CHANNEL fl •••••••• NUCl 1H P1 10.65 PLl 0.00 dB SFOl 300.1330875 MRz

F2 - Processng Para•eters Sl 32768 SF 300.1300000 ""' WDW •• SSB 0

LB 0. 30 "' GB

PC 1.00

Current Da~a Paraaeters NAHE Nov04 2006 EXPHO 18 PROCNO

F2 - Acquisition ParaMeters Date 20061104 Ti•e 12.51 INSTRUK spect PROBHD 5 •• PABBO 88-

PULPROG Z9P930 TO 32768 SOLVENT CDC13 NS 3000 OS • s•• 29761.904 .. riDERS 0. 9235188 •• AQ 0.59-15372 RG 210

DN u.aoo DE 6. 00 TE 300.0 • Dl 2. 00000000 dll 0.03000000 DELTA 1. 89999998 TOO I

•••••-•• CHANNEL fl --------NIJCl 13C

PI 1. 80 PLI 0. 00 dB

SFOl 15.7703643 ••• CHANNEL f2 ••••••••

CPDPRG2 waltz16 NUC2 IH

PCPD2 80.00 PL12 17. so •• PL13 17. so dB

PL2 0.00 dB

SF02 300. 1320005 ••• F2 - Processng Paramet.ers Sl 32768 SF 75. 7!:178790 ••• wow EM SSB 0 LB 1.00 •• GB 0 PC 1. 40

72


3.1.5 CALIX(n)ARENE-THIACALIX(n)ARENE PSEUDO DIMERS 5n

Method C:A mixture of 4 (2Smmol), elemental sulfur Ss (SOmmol), and MOH (2Smmol) in

super-dry diphenyl ether (100ml) was stirred for 15min, heated gradually to 160°C over a

period of 1h and kept at this temperature for further 3h. The temperature was again raised

to 230°C over a period of 3h and maintained for further 3h. The resulting reaction mixture

was cooled to ambient temperature and analyzed by UPLC-MS. 1ml of reaction mixture

was sampled after every 30min, loaded on solid phase extraction cartridge and washed

with acetonitrile (1mlx2) to selectively remove decomposition residues. The products

were then eluted with methanol (1mlx3) and SOjlL of the elute was injected for analysis of

product mixture. No isolable quantity of 5 was achieved in any case (Scheme 3.6) .

.

~ g J ~~:~).

.

.

.

.

'

:~:-; ".9

'

#~ <"

... ~··

.. ~ ~:: ) ••• ···.&\VlJf'

0< :1, . 11.: .. \••i' (::.:.~-

.. ,,,.

Method D:To a solution of 4 (10mmol) in dry CH2Ch (100ml) was added SCh (nx40mmol in

CH2Cb) and stirred for 2h at 0°C. The reaction mixture was refluxed for 2h and allowed to

cool to ambient temperature spontaneously. The excess of SChwas destroyed with careful

addition of iced water with continuous stirring. The organic layer was separated and

evaporated to dryness with aid of vacuum. The residue obtained was washed with

acetone, ethanol and chloroform:ethylacetate (1:1, v/v) mixture to obtain respective

products 5n. The products were recrystallized in CH2Cb.

~,~t

\~~:~t! >350•>

:---~.t;;','i4V'

~.I>· 221~

~.~!~ 2581+ 'i~Rr%'i•

>~5Qfi ,-_{.~-~

C:748Q.

~t~i,. ~i~~;

~~i 2~;49:; t:.:~~ j· ·,

73


54:Yield 62%. 1HNMR (300 MHz, CDC!s):& 7.12, 7.66 (s, 8H, Ar-H), 0.82, 0.85, 1.33 (s, 72H, t-Bu), 6.49, 6.94 (s,

8H, Ar-H), 4.35, 5.43(m, 16H, OCHzCHzO, j=7.7), 3.24, 4.66 (d, 16H, ArCH 2Ar, j=12.7), 13CNMR (75 MHz,

CDC!s):l> 30.9, 31.8, 33.5, 34.3 (Bu1), 134.2, 135.4, 144.3, 160.9 (Ar), 72.6, 74.0 (OCH2CH20), 31.9 (ArCH2Ar),

EA Calc. for C92H1120a54 (C:74.96, H:7.66, 5:8.70), Found (C:75.01, H:7.60, 5:8.66).

lHNMR Spectrum of 54

M

"' M ..,. M M

"' ..,.

JA_AA_hRhA ' ' I .

7.7 7.1 5.4 4.3 ppm

f fJ J I ..,.

"' M

"' ..,. ..,.

"' "' "' "' "'

M M 0 "' "' 0 0 0 "' "' 0

8 7 6 5

13CNMR Spectrum of 54

170

"' en 00

"'"' .......... y

o:;ro:;rLOI.OLOLOo:;r~"'t'"'t' o:;r...,MMMMMMMM ......tMMMr-tMMr-lr-lr-1 Y'Ja.d.JddJ.J

150 130 110

II "' "'

M 0

"' M

..,.

"' "' .....

4 ppm

I

M 0

0\0

.,.N

\I

3

"' ..,.

"' 0

"'

2 1

~MMMM...-tOOO MMMMMMMMM

~~

90 80 70 60 50 40 30 20 10 ppm

0

0

Current Data Paraaeters NAME Novll 2006 EXPNO 9 PROCNO

F2 - Acquisition Para•eters Date 20061111 Time 10.44 IN STRUM spect PROBHD 5 mm PABBO BB-PULPROG zq30 TD 32768 SOLVENT CDCll NS 3200 DS SWH 10330.518 Hz

F IDERS 0.351194 Hz

AQ 1. 5151749 RG 180 DW 48.400 DE 6.00 TE 300.0 K

Dl 1. 00000000 TDO

CHANNEL f1 --------NUCl lH Pl 10.65 PLl 0.00 dB

SFOl 300.1330875 MHZ

F2 - Processng Parameters SI 32768 SF 300.1300000 MHz

WDW EM SSB 0 LB 0.30 Hz

GB 0 PC 1.00

Current Data Paraaeters NAME Novll 2006 EXPNO 2 PROCNO

F2 - Acquisition Paraaeters Date_ 20061112 Time 10.17 IN STRUM spect PROBHD 5 mm PABBO 88-PULPROG zgpg30 TD 32768 SOLVENT CDC13 NS 3000 DS SWH 29761.904 Hz

FIOERS 0.9184965 Hz

AQ 0.6134259 ••c RG 208 DW 16.800 DE 6.00 TE 300.0 K Dl 2. 00000000 dll 0.03000000 DELTA 1. 89999998 TDO

CHANNEL f1 --------NUCl 13C Pl 1. so PLl 0.00 dB SFOl 75.7703643 MHz

CHANNEL f2 --------CPDPRG2 walt1:16 NUC2 lH PCPD2 80.00 PL12 17.50 dB PL13 17.50 dB PL2 0. 00 dB SF02 300.1320005 MHz

F2 SI

- Processnq Parameters 32768

SF WDW SSB LB GB PC

75.7578790 HHz EM

0 1. 00 Hz

0 1.40

74


55:Yield 58%. 1HNMR (300 MHz, CDCh):5 7.10, 7.48 (s, 8H, Ar-H), 0.82, 0.87, 1.30 (s, 72H, t-Bu), 6.49, 6.69 (s,


CDCh):5 29.8, 31.1, 35.0, 35.9 (Bu1), 133.6, 135.0, 144.1, 158.7 (Ar), 71.1, 73.6 (OCH2CH20), 31.7 (ArCH2Ar),

EA Calc. for CmH14001oSs (C:74.96, H:7.66, S:8.70), Found (C:74.85, H:7.63, S:8.76).

lHNMR Spectrum of Ss

M M

"'

rM

0 M

00 C>

)A_~~ "' ... .-< "'

___jQ __KA__ _ft / ..,_,... ,...__,.....

7.5 7.1 5.6

II f f m

"' "' 0

M M om 0 0 om

.-<0

8 7 6

13CNMR Spectrum of Ss

170

r- roo 00

"'"' .-< .-<

y

150 130

ppm

_r/ M M

"'

... "' 0 m

5

110

5.3 4.4

I _[ ..... M

"' M m 0

4 ppm

"'.-<

M C> r-r-

1 I

I

~ 3.7

3

... "' m 0

00 m

2

cnooor--nc»coco lt")l/')PJ'lPJ'lr-lr-10\0\0\ MMMMMMNNN

~v~

90 80 70 60 50 40 30 20 10 ppm

0

0

Current Data Parameters NAME Novll 2006 EXPNO 12

PROCNO

F2 - Acquisition Parameters Date 20061111 Time 11.17 IN STRUM spect PROBHD 5 mm PABBO BB-PULPROG zq30 TD 32768 SOLVENT CDC!)

NS 3200 DS SWH 10330.578 Hz

FIDERS 0.351814 Hz

AQ 1.7168524 RG 183 DW 48.400 DE 6.00 TE 300.1 K

D1 1. 00000000 TDO

CHANNEL fl --------NUCl 1H

P1 10.65 PL1 0. 00 dB

SFOl 300.1330&75 MHz

F2 - P.rocessng Para•eters Sl 32768 SF 300.1300000 MHZ

WDW EM

SSB 0 LB 0. 30 Hz

GB 0 PC 1.00

Current. D.at:a Paraaet:ers NAME Novl2 2006 EXPNO 5 PROCNO

F2 - Acquisition Para•eters Date_ 20061112 Time 10.46 IN STRUM PROBHD

PULPROG

TD SOLVENT NS DS ... FIDERS

AO RG

DW DE TE D1 dll DELTA TDO

NUCl P1 PL1

SFOl

CPDPRG2 NUC2 PCPD2 PL12 PL13 PL2 SF02

spect 5 •• PABBO BB-

zqpq30 32768 CDC13

3000

29761.904 Rz

0.8979497 Hz

0.5923531 209

16.800 6.00

300.1 • 2. 00000000 0. 03000000 1.89999998

1

CHANNEL f1 ••••••••

1JC 7. 80 0. 00 dB

75.1703643 MHz

CHANNEL f2 --------wa1tz16

lH 80.00 11.50 dB 11.50 dB

0.00 dB 300.1320005 MHz

F2 - P:cocessng Parameters S1 32168 SF 75.7578790 HHz wow EM SSB 0 LB 1. 00 Hz GB 0 PC 1.40

75


56:Yield 57%. 1HNMR (300 MHz, CDCb):~ 7.10, 7.56 (s, 8H, Ar-H), 0.90, 0.93, 1.31 (s, 72H, t-Bu), 6.47, 6.88 {s,

8H, Ar-H), 4.25, 5.41{m, 16H, OCH2CH20, j=7.7), 4.03, 5.44 (d, 16H, ArCHzAr, j=12.6), 13CNMR (75 MHz,

CDCb):~ 30.5, 31.6, 33.7, 35.0 (Bu1), 134.4, 135.9, 143.6, 161.1 (Ar), 73.0, 78.2 (OCH2CH20), 31.9 (ArCH2Ar),

EA Calc. for C13sHt6s012S6 (C:74.96, H:7.66, 5:8.70), Found (C:74.91, H:7.59, 5:8.68).

IHNMR Spectrum of 56

8

7.1

_[ _[ J J

N 0

co co

o"'

M"' "' 0"' "'

.-<0 0

7 6

t3CNMR Spectrum of 56

I I I 170 150 130

J .... ~

"'

.... 0

M

5.4 ppm

5

I 110

4.3

If "' N

"' ... "'0

I

4 ppm

90

4.2

N 0

M r- r-

1 I

I

I 80 70

3

ppm

4.0

2

I 60 50 40

.... M

~

"' co

30

M 0

"'

1 0

20 10 0

current Data Paraaeters NAME Novll 2006 EXPNO PROCNO

15

F2 - Acquisition Parameters Date 20061111 TiMe 12.45 !NSTRUM PROBHD POLPROG

TD SOLVENT NS DS SWH

FIDERS

•o RG DW DE TE D1 TDO

NUCl

P1

PL1

spect S mm PABBO BB-

ZC)30

32768 CDC13

3200

10330.578 Hz

0.360142 Hz 1.5381499

178 48.400

6. 00 300.2 K

1. 00000000 1

CHANNEL fl •••••s•• 18

10.65 u:sec 0. 00 dB

SFOl 300.1330875 MHz

F2 - Processng Parameters SI 32768 SF 300.1300000 MHz

WDN EM

SSB 0

LB 0.30 Hz

GB PC 1. 00

Current Data Para•eters NAME Nov12 2006 EXPNO PROCNO

F2 - Acquisition Paraaetera Date 20061112 -Tl•e 11.21 IN STRUM spect PROBHD s mm PABBO BB-

PULPROG zgpg30 TD 32768 SOLVENT CDC13 NS 3000 DS SOH 29161.904 Hz

FIDERS 0.9073924 Hz

AO 0.5990628 RG 209 DW 16.800 DE 6.00 TE 300.0 K

D1 2.00000000 .. c dll 0.03000000 soc DELTA 1.89999998 TDO 1

CHANNEL f1 ................ NUCl 13C P1 1. 80 usee PL1 0.00 dB

SFOl 75.1703643 MHz

CHANNEL f2 --------CPDPRG2 walt2:16 NUC2 1H PCPD2 80.00 usee PL12 11. !10 dB PL13 11. so dB

PL2 0.00 dB SF02 300.1320005 MHZ

F2 - Pcocessng Parameters SI 32768 SF 15. 7!»78190 MHZ WDW EM SSB 0 LB 1. 00 Hz GB 0 PC 1.40

76


S1:Yield 54%. 1HNMR (300 MHz, CDCh):8 7.18, 7.68 (s, 8H, Ar-H), 0.90, 1.02, 1.32 (s, 72H, t-Bu), 6.51, 6.97 {s,

8H, Ar-H), 4.25, 5.53{m, 16H, OCH2CH20, j=7.7), .3.78, 5.64 (d, 16H, ArCH2Ar, j=12.4}, 13CNMR (75 MHz,

CDCh):8 30.9, 32.0, 35.2, 36.6 (Bu1}, 135.0, 135.9, 147.5, 160.8 (Ar), 74.4, 76.1 (OCH2CH20), 33.0 (ArCH2Ar),

EA Calc. for C161H19601~1 (C:74.96, H:7.66, S:8.70), Found (C:74.90, H:7.61, S:8.73}.

1HNMR Spectrum of 57

.., "' "' N

"' N ...

JL _A_ __al _l_ JL ---,----.-.' I ~ I

7.7 7.2 5.7 5.6

I If J Jf ,.... .... ... "' "' "'

00 ..;

"' "' "'

~~ ~ ~ ,....

~ "' r-o "' ....... 0 00 0\ 00\

N N N NM

8 7 6

13CNMR Spectrum of 57

00 00

00

"'"' ........ y

lf)lf'I0\0\0\0'10000

f'f"""I.OI.ll&Oillll")lf'III'II.O -.:r"'I'MPlMMP')MMM ...-l.....t.....t...-1-tr-fr-f.-tr-t.-1

Y'~.J.J•J.J

I 5.5

ppm

5

I 170

I 150

I 130 110

. . I .... I 4.3 4.2 3.8 3.7 (

I _[ "' N

.... 00

1 ,....

1 T I .... ( N "' 0\.-<0

"' 0 •00 ,.... ... N "'"'"' -r

4 3 2 1 ppm

"'"" \7

II I I I

90 80 70 60 50 40 30 20 10 ppm

0

I 0

Cun:ent Data Para•eters N!o-ME Novll 2006 EXPNO 20 PROCNO 1

F2 - Acquisition Para•eters Date 20061111 -Tiae 1.28 INSTRUM apeet PROBHD 5 •m PABBO 88-

PULPROG zq30 TD 32768 SOLVENT CDC13 NS 3200 DS 4 SWH 10330.578 Hz

FI DERS 0.359879 Hz AQ 1. 454182 RG 180 DW 48.400 DE 6. 00 TE 299.8 • 01 1. 00000000 TOO 1

CHANNEL fl --------NUCl 1H Pl 10.65 PL1 0 .oo dB

SFOl 300.1330875 MRz

F2 - Proceasnq Par•meters SI 32768 SF 300. 1300000 MHz

wow EM SSB 0 LB 0.30 Hz

GB 0 PC 1.00

Current Data Para•eters NAME Nov12 2006 EXPNO PROCNO

12

F2 - Acquisition Para•eter• Date 20061112 -Ti•e 12.07 IN STRUM spect PROBHD 5 •• PABlO BB-PULPROG &9P930 TD 32768 SOLVENT CDCl) NS 3000 DS SWH 29761.904 Rz FIDERS 0.9142965 Hz AQ 0.5915273 RG 210 DW 16.800 DE 6. 00 usee TE 299.9 • Dl 2. 00000000 dii 0. 03000000 DELTA 1. 89999998 TOO

CHANNEL f1 --------NUCl 13C Pl 1.80 PLI 0.00 dB SFOl 75.7703643 MHZ

CHANNEL .. --------CPDPilG2 walt&16 tlUC2 IR PCPD2 80.00 uaec PL12 11.50 dB PLll 17.50 dB PL2 0.00 dB SF02 300.1320005 MHZ

F2 - P.rocessng; Parameter• SI 32768 SF 75.7578790 MHZ WON EM SSB 0 LB 1. 00 Hz GB 0 PC 1.40

77


Sa:Yield 32%. 1HNMR (300 MHz, CDCh):l> 7.18, 7.76 (s, 8H, Ar-H), 0.89, 1.10, 1.32 (s, 72H, t-Bu), 6.50, 7.01 (s,


CDCh):l> 30.8, 31.9, 35.2, 36.5 (Bu1), 134.8, 135.7, 147.4, 158.9 (Ar), 74.6, 77.0 (OCH2CH20), 33.0 (ArCH2Ar),

EA Calc. for C184Hm016Ss (C:74.96, H:7.66, S:8.70), Found (C:74.89, H:7.60, S:8.67).

1HNMR Spectrum of Sa

8

I

"' 0

JJ .... 0

0\0 00

NN

7

J 0

"'

"' "' ....

7.1

6

Jf "' "' "'

"' .... 00\

N..,

5.6 ppm

5

13CNMR Spectrum of Sa

170

"'"' Q) Q)

"' "' ........ y

l"""r"'-IJ')lt11J")lt)<o;f'~"''f'<o;f'

'OIP<o:t'MMMMMMMM ............... .-f .......................... .....

y~.JJJL.J

I 150 130 110

5.5

I _[ "' N

N

"' .... "' 0

N

4 ppm

0\0

,... .... ,...,... \1

I

..--.-.---4.2 3. 8

3

00\

.... "' "' Q) . "'"' ,... .... Q) Q)

2 1

l()NNNOO'\CX>C:OCXI

I.Dl()U")l()M ..... OOO MMMMMMMf"''M

~\~

I I I I I I 90 80 70 60 50 40 30 20 10

ppm

0

0

current Data Para•et.er:s NAME Novll 2006 EXPNO 24 PROCNO

F2 - Acquisition Para••tera Date 20061111 -Tirne 1. 49 INSTP.UM spec:t PROBHD 5 •m PABBO 88-

PULPROG zglO TD 32768 SOLVENT CDCll NS 3200 DS • SWR 10130.578 Hz FIDERS 0.340611 Hz AQ 1. 5134257 ... RG 181

DW 48.400 usee D£ '· 00

usee

T£ 300.2 • D1 1. 00000000 ... TDO

CHANNEL f1 --------NUCl 18

P1 10.65 usee PLl o.oo dB

SFOl 300.1330175 MR•

F2 - Proc•11snq Parameters 51 32768 SF 300.1300000 MH•

WDW EM SSB 0 LB 0. 30 Hz GB 0 PC 1.00

Current. Data Para•etera NAME Nov12 2006 EXPNO l8

PROCNO

F2 - Acquisition Para•eters Date 20061112 -Time 12.55 INSTRUH spect PROBHD 5 •• PABBO 88-PULPROG &qpC)30 TD 32768 SOLVENT CDC13

NS 3000 DS • SWB 29161.904 .. FIDERS 0.9014S59 .. AQ 0.5814326 ... RG 208 DW 16.800 usee DE 6.00 us•c TE 300.1 • 01 2. 00000000 ... dll 0. 03000000 ... DELTA 1. 89999998 ... TDO

CHANNEL t1 --------HUCI 13C PI 1. 80 usee PL1 o. 00 dB SFOl 75.7703Ei43 MHZ

•••••••• CHANNEL l2 •••••••• CPDPRG2 wdtzl6 NUC2 PCPD2 PL12 PL13 PL2 SF02

F2 -51 SF WOW

SSB LB GB PC

1R 80.00 17.50 17.50 o. 00

300.132000S

ProeessnC) Parameters 32168

75.7578190 EM

l. 00 0

1. 40

dB dB dB M ..

MH&

••

78


3.1.6 HALO-DE-ALKOXVLATION OF 5n

:~~:::::nal::h:~::. :::::,::o:~u::o:~:~~:: ~. '.f .. £.:, .. :~.:.".··· ".".~.·'.' and added with nxSOml Lil solution {4M in 50% aq. . -1 ,_, :· )i

~-~·~·.· ~), ~- .... ·,}~;,,

alcohol, v/v). The reaction mixture was brought to ~"''~)~;: al

::.":1::::::::~::::::::~~ :ti::i:~~::: :::~~ ~.~.-.·.~.!' .•... :.,i~l The reaction mixture was acidified with lOOml 1M L'i· ·. HCI and the products were recovered by filtration, · ·~:v

~!i~:~;~0~~~~:~~~~!,:~~~·· followed by drying to yield solid residue. The residue

was dissolved in SOml chloroform, filtered and chromatographed on silica gel {200mesh,

lOOmm length, 15mm diameter column) using hexane:chloroform {1:1-2, v/v) mobile

phase {Scheme 3.7).

Characterization data of all calixarene derivatives 24-8 have already been published,124•25l

where as characterization data of 14-s derivatives have already been recorded in previous

chapter and hence not repeated here.

3.1.7 A BRIEF DISCUSSION ON CONFORMATIONAL PREFERENCES OF 5n

The structure of pseudo dimers {calix-thiacalix tubes) 5n was confirmed by 1H & BCNMR,

and ESI-mass spectral data. The 1HNMR spectra of all 5n homologs were well resolved. For

instance, in case of 56, the 1HNMR spectrum contains four singlets in the aromatic region

{6.47, 6.88, 7.10, 7.56), two pairs of multiplets of ethylene -QCHzCHzD- protons {4.25,

4.82, 5.05, 5.41), two doublets from bridging methylene group -ArCH2Ar- protons {4.03 &

5.44), and also a set of singlets from tert-butyl groups {0.90, 0.93}. 13CNMR spectra contain

eight sets of closely spaced aromatic signals {two in each set) in aromatic region, four

signals of -OCHzCHzO- carbons, and four signals from p-tert-butyl substituents of the upper

rim. The results of 1H & BCNMR measurements are in very good agreement with existing

literature, especially with the results of extensive study of structural preferences {of calix-,

thiacalix-, and hybrid calix-thiacalix tubes, i.e. symmetric and asymmetric/pseudo dimers)

carried out by Kovalev et a/.1151 throug 1HNMR spectroscopy {tube 54 has already been

reported by Kovalev eta/.)

Now let us examine the NMR Spectra. The double set of all NMR signals, especially in the

aromatic region, indicates that both calix frameworks {calix and thiacalix) of pseudo dimers

56 contain two types of aromatic rings, suggesting Czv symmetry. Further, it is known that

79


C6A and TC6A possess near C2v symmetry in their crystal structure with a single

conformation, but when solvated, they exhibit two different conformers (flattened/

pinched cone - C2v and cone CGv) at lower temperature (as is evident from their NMR

spectra). At higher temperature, in solution, they undergo rapid pinched cone - cone -

pinched cone inter conversion, effectively giving averaged signals. A similar pattern of

apparent asymmetry in present compounds (pseudo dimers) can be envisaged due to

conformational properties of constituent calixarene fragments themselves, which form the

tube (pseudo dimer). A more comprehensive discussion on the conformational

preferences of calix[4]arene-thiacalix[4]arene tubes (and other symmetric tubes) can be

availed by referring to the work of Kovalev et a/.115) where as the work of Beer et a/.116-20)

may be of particular interest for study of conformational analysis of bis(calix[4]arene)

tubes and their various derivatives (accomplished with the aid of NMR spectroscopy as

well as X-ray diffraction analysis). The latter have also studied the metal complexation and

accompanying structural changes for the bis-calix tubes.

5 CONCLUSION

In the present chapter, we have demonstrated a simple and versatile approach for the

synthesis of various thiacalixarene homologs. The modularity of the strategy permits its

adaptation to produce variety of other supramolecular assemblies like carcerands and a

plethora of other heteracalixarenes. Further, the carcerand like intermediates (pseudo

dimers) achieved in this fashion have dimensions of nano scale, and are excellent

examples of supramolecular nano-tubes, which may be further explored in future course

to fulfill variety of purposes already described in nano-sciences.

80

------------------------------------ ---- -


REFERENCES

1. Z. Asfari, V. Bohmer, J. Harrowfield, J. Vicens, in Calixarenes 2001, Kluwer

Academic, Dordrecht, 2001.

2. N. Morohashi, F. Narumi, N. lki, T. Hattori, S. Miyano, Chern. Rev. 2006, 106, 5291.

3. P. Lhotak, Eur. J. Org. Chern. 2004, 1675.

4. M. Patel, V. Patel, P. Shrivastav, Tetrahedron Lett. 2008, 64, 3087.

5. H. Kumagai, M. Hasegawa, S. Miyanari, Y. Sugawa, Y. Sato, T. Hori, S. Ueda, H.

Kamiyama, S. Miyano, Tetrahedron Lett. 1997, 38, 3971.

6. N. Kon, N. lki, and S. Miyano, Tetrahedron Lett. 2002, 43, 2231.

7. N. lki, C. Kabuto, T. Fukushima, H. Kumagai, H. Takeya, S. Miyanari, T. Miyashi and S.

Miyano, Tetrahedron 2000, 56, 1437.

8. S. Shokova, V. Tafeenko, V. Kovalev, Tetrahedron Lett. 2002, 43, 5153.

9. P. Lhotak, T. Smejkal, I. Stibor, J. Havlicek, M. Tkadlecova, H. Petnckova, Tetrahedron

Lett.2003,44,8093.

10. Y. Kondo, K. Endo, N. lki, S. Miyano, F. Hamada, J. Incl. Phenom. Macrocycl. Chern.

2005, 52, 45.

11. Y. Kondo, F. Hamada, J. Incl. Phenom. Macrocycl. Chern. 2007, 58, 123.

12. M. Patel and P. Shrivastav, J. Incl. Phenom. Macrocycl. Chern. 2009, 63, 379.

13. J. Lang, J. Vagherova, J. Czernec, P. Lhotak, Supremo/. Chern. 2006, 18, 371.

14. T. Sone, Y. Ohba, K. Moriya, H. Kumada, K. Ito, Tetrahedron 1997, 53, 10689.

15. E. Khomich, M. Kashapov, I Vatsuro, E. Shokova, B. Kovalev, Russ. J. Org. Chern.

2007, 43, 192.

16. P. Schmitt, P. Beer, G. Michael, P. Sheen, Angew. Chern., Int. Ed. 1997, 36, 1840.

17. S. Matthews, P. Schmitt, V. Felix, M. Drew, P. Beer, J. Am. Chern. Soc. 2002, 124,

1341.

18. S. Matthews, V. Felix, M. Drew, P. Beer, Org. Biomol. Chern. 2003, 1, 1232.

19. P. Webber, P. Beer, G. Chen, V. Felix, M. Drew, J. Am. Chern. Soc. 2003,125, 5774.

20. S. Matthews, N. Rees, V. Felix, M. Drew, P. Beer, lnorg. Chern. 2003,42,729.

21. J. March, in March's Advanced Organic Chemistry, ed. M. Smith, John Wiley & Sons

Inc., New York, 5th edn. 2001, 519.

22. P. Gale, J. Sessler, V. Lynch, P. Sansom, Tetrahedron Lett. 1996, 37, 7881.

81

-------------------------- -~-- -- -


23. P. Gale, J. Genge, V. Kral, M. McKervey, J. Sessler, A. Walker, Tetrahedron Lett. 1997,

38,8443.

24. C. D. Gutsche, in Calixarenes, Monographs in_ Supramolecular Chemistry, J. F.

Stoddart, Ed., The Royal Society of Chemistry, Cambridge and london, 1989.

25. C. D. Gutsche, in Calixarenes Revisited, Monographs in Supramolecular Chemistry,

Cambridge, 1998.

82

Documents

liNTRODUCTION OBJECTIVES AND INVESTIGATIONS …shodhganga.inflibnet.ac.in/bitstream/10603/35164/9/09_chapter3.pdf · 3 synthesis ii-indirect approaches towards thiacalixarene synthesis