chapter 4 cycloaddition reactions of 0-thioquinones...

CHAPTER 4

CYCLOADDITION REACTIONS OF

0-THIOQUINONES WITH ALKENES AND ALKYNES

4.1 INTRODUCTION

Only scant information has been available on the cycloaddition chemistry of

o-benzoquinones with alkenes and alkynes.'-3 Recent investigations in our

laboratory have clearly established the reactivity of o-benzoquinones with alkenes

and a ~ k ~ n e s . ~

In vlew of the facility with which o-thioquinones underwent cycloaddition

to various conjugated n-systems (see Chapters 2 and 3), it was of interest to

investigate their reactivity towards alkenes and alkynes. It may be mentioned that

there has been only one isolated report on the cycloaddition reactions of

o-thioquinones with aryl alkenes and alkynes.' CMethoxystyrene has been shown

to react with 1-thionaphthoquinone leading to the formation of 1 in 62% yield

(Scheme 1).

Ar = p-anisyl

Scheme 1

It 1s reported in the same paper that I-thionaphthoquinone on treatment with

ethoxyethyne underwent two consecutive [4+2] cycloadditions to afford the

bisadduct 2 (Scheme 2).

L

Scheme 2

4.2 THE PRESENT WORK

It was clear Gom the literature survey that the reactivity profile of

0-thioquinones with alkenes and alkynes has received only limited attention. The

results of our studies on the cycloaddition of o-thioquinones with alkenes and

some acetylenic compounds are presented in this chapter.

The o-thioquinones and, alkenes and a w e s selected for our study are

given respectively in Figures 1 and 2.

Figure 1

Alkenes

Figure 2

4.3 RESULTS AND DISCUSSION

COOMe COPh R

4.3.1 Cycloadditions with Alkenes

Initially we investigated the [4+2] cycloaddition reactions of various

I

substituted o-thioquinones with acenaphthylene. 4-Isopropyl-2-thiobenzoquinone,

generated in srtu from the thiophthalimide 3, on treatment with 4 in chloroform at

70 OC afforded the 1,4-benzoxathiin adduct 5 in 96% yield (Scheme 3).

COOMe COPh R

I I I I

/ \ + -

Me2HC SNPhth \ ' Me2HC \

4 H \ /

I R = n-propyl

3 4 5

i. Pyridine, CHCI,, Sealed tube, 70 OC, 20 h, 96%

Scheme 3

The structure of the product was established on the basis of spectroscopic

data. The IR spectrum of 5 showed ether absorption at 1222 cm-'. In the 'H NMR

spectrum, the (=3)2CH protons resonated as a doublet at 6 1.09 (J = 6.8 Hz). The

( C H 3 ) * B proton was observed as a multiplet centered at 6 2.70. The proton on

C-3 resonated as a doublet at 6 5.22 (J = 7.2 Hz). The signal at 6 6.22

(d, J = 7.2 Hz) can be assigned to C-2 proton. The aromatic protons were visible as

Chapter 4

multiplets centered at 6 7.22. In the I3c NMR spectrum, the signals at 649.66 and

84.66 were assigned to the C-3 and C-2 carbons respectively.

Simllar reactions were observed with other o-thiobenzoquinones also and

the results are summarized in Table 1.

Table 1: Cycloaddition reactions of substituted o-thiobenzoquinones with acenaphthylene

--

Thioquinone precursor product

Me3(: SNPhth

Me0 SNPhth

Me SNPhth

Me3c177;1phth \

CMe3 12

\ Me2HCaoH SNPhth

14

Reaction conditions: Pyridine, CHCI,, Sealed tube, 70 OC, 20 h

1-Thlonaphthoquinone also reacted with 4 in a similar fashion as illustrated

in Scheme 4

SNPhth

+ \

--.-. \ /

4 H \ / /

16 4 17

i. Pyridine, CHCI,, Sealed tube, 70 OC, 20 h, 92%

Scheme 4

The structure of the product was ascertained fiom its spectroscopic data. In

the 'H NMR spectrum, C-3 proton resonated as a doublet at S 5.34 (J = 6.8 H z ) ,

while the C-2 proton appeared as a doublet at 86.39 (J= 6.8 H z ) . In the 13c NMR

spectrum of 17, the characteristic signals at S 49.06 and 84.66 can be assigned to

the C-3 and C-2 carbons respectively.

Subsequent to the above studies, we have carried out the [4+2]

cycloaddition reactions of o-thioquinones with trans-stilbene, 18. 4-Isopropyl-2-

thiobenzoqu~none on treatment with 18 yielded product 19 in 95% yield

(Scheme 5)

I

'. Me2HC SNPhth Ph

3 18 19

i. Pyridine, CHC13, Sealed tube, 70 OC, 24 h, 95%

Scheme 5

The IK spectrum of 19 showed ether absorption at 1239 cm-'. The 'H NMR

spectrum displayed the signals due to methyl protons, (CJ&CH at 6 1.22 (d, J =

6.9 Hz) and the methine proton of the isopropyl group, (CH3l2m was discernible

at 62.81-2.85 as a multiplet. The proton on C-3 resonated as a doublet at 6 4.37

(J = 8.9 H z ) , while the C-2 proton appeared as a doublet at 6 5.00 (J = 8.9 H z ) .

The aromatic protons were visible as multiplets centered at 6 6.99. In the I3c NMR

spectrum, the C-2 and C-3 carbons were observed at 6 82.07 and 49.47

respectively.

The reaction of other o-thiobenzoquinones with trans-stilbene also followed

the same pathway and the results are summarized in Table 2.

Table 2: Cycloaddition reactions of substituted o-thiobenzoquinones with trans-stilbene


Me3C SNPhth Me3C

M e 0 SNPhth M e 0 Ph

Me SNPhth Me

Me3C

SNPhth Ph CMe3 CMe3 12 23 (87%)

Reaction conditions: Pyridine, CHCh, Sealed tube, 70 OC, 24 h

In an analogous manner, reaction of I-thionaphthoquinone with trans-

stilbene afforded 1,4-oxathiin adduct 25 in 83% yield (Scheme 6).

Chapter 4

SNPhth

I

Ph

16 18 25


Scheme 6

As usual the structure of the product was assigned on the basis of

spectroscopic data. In the 'H NMR spectrum, the proton on C-3 resonated as a

doublet at 6 4.34 (J = 8.7 Hz), while the C-2 proton appeared as a doublet at 65.08

(J = 8.7 Hz). In the 13c NMR spectrum, the C-3 and C-2 carbons were visible at

648.96 and 82.08 respectively.

When indene was used in place of trans-stilbene, with 4-isopropyl-2-

thiobenzoqumone, the product 27 was obtained regioselectively in 92% yield. The

reaction is illustrated in Scheme 7.

/ \

\ Me2HC SNPhth Me2HC S 4

3 26 27


Scheme 7

The structure of the adduct was assigned on the basis of spectroscopic data.

In the IR spectrum of 27, the characteristic stretching frequency of C-0 bond was

observed at 1243 cm-I. The 'H NMR spectrum showed a doublet at 6 1.18 (J = 6.9

Hz) correspondmg to (B3)*CH protons. The (CH3)2m proton resonated as a

multiplet in the region 62.76-2.80. The multiplets centered at 63.15 and 3.32 were

assigned to the ~nethylenic protons of the indene ring. The C-3 proton was

observed as a multiplet centered at S 3.97, which is diagnostic for the observed

Chapter 4

regioisomer. The proton on C-2 appeared as a doublet at 65.28 (J = 5.3 Hz). The

aromatic protons were visible as multiplets in the region 6 6.84-7.49. In the 13c NMR spectrum, C-3 carbon resonated at 6 42.83 and the signal at 6 81.54 can be

attributed to C-2 carbon.

In follow-up studies, we examined the generality of the reaction with other

substituted thloquinones and the results are summarized in Table 3.

Table 3: Cycloaddition reactions of substituted o-thiobenzoquinones with indene

Thioquinone precursor

Me3C: SNPhth

M e 0 'SNPhth

product

Reaction conditions: Pyridine, CHCls, Sealed tube, 70 OC, 16 h

In a similar fashion, 1-thionaphthoquinone on heating with indene afforded

the l,4-oxathiin adduct 33 in 92% yield (Scheme 8).

SNPhth

__C

\ 4

16 26 33 i. Pyridine, CHCI3, Sealed tube, 70 OC, 16 h, 92%

Scheme 8

The IR spectrum of 33 showed ether absorption at 1229 cm-' and thioether

absorption at 751 cm-'. The 'H NMR spectrum showed the C-3 proton as a

multiplet centered at 64.07 and the proton on C-2 as a doublet at 6 5.47 (J = 5.0

Hz). In the 'k NMR spec- signals at 642.29 and 81.24 were assigned to the

C-3 and C-2 carbons respectively.

2-Hydroxy-5-isopropylbenzothiophthalimide, 3 on treatment with

1-phenylcyclohexene under sealed tube conditions in presence of pyridine afforded

1,4-benzoxathiin adduct 35 in 17% yield (Scheme 9).

,fJOH+ ph\O i- Me2HC SNPhth Me2HC

3 34 35 i. Pyridine, CHCI3, Sealed tube, 70 OC, 15 h, 17%

Scheme 9

The structure of the adduct 35 was ascertained from its spect~oscopic data.

The IR spectrunl showed ether absorption at 1232 cm-'. In the 'H NMR spectrum,

proton on C-3 appeared as a multiplet centered at 63.36, which is diagnostic for a

product resulting from th~s mode of addition. In the l3c NMR spectrum, C-2 and

C-3 carbons were discernible at 6 77.82 and 42.96 respectively. All other signals

were in accordance with the proposed structure.

Similarly, 4,6-di-tert-butyl-2-hydroxybenzothiophth on reaction

with cyclohexene in presence of pyridine afforded 1,4-benzoxathiin adduct 37 in

33% yield (Scheme lo).

MejC

SNPhth

12 36 37


Scheme 10

The IR spectrum of 37 showed ether absorption at 1303 cm-'. In the 'H

NMR spectrum, the protons on C-2 and C-3 were observed as two separate

multiplets centered at 6 4.37 and 3.11 respectively. In the I3c NMR spectrum, C-2

and C-3 carbons were visible at 672.33 and 39.89 respectively.

Attempted reactions of 4-isopropyl-2-thiobenzoquinone with alkenes such

as I-hexene, a-phellandrene etc. were unsuccessful; the only product isolated was

the dimer o f the thioquinone.

Subsequent to the above investigations, we extended our studies to some

acetylenic compounds and our results are given in the following section.

4.3.2 Cycloadditions with Alkynes

2-Hydroxy-5-isopropylbenzothiophthalimide 3 on treatment with dimethyl

acetylenedicarboxylate (DMAD) and pyridine in chloroform at 70 OC afforded the

1,Cbenzoxathiin monoadduct 39 in 92% yield (Scheme 11).

COOMe COOMe

MeZHC SNPhth COOMe COOMe

3 38 39

i. Pyridine, CHCI 3, Sealed tube, 70 OC, 15 h, 92% Scheme 11

The IK spectrum of 39 showed a strong absorption at 1742 cm-I

characteristic of the ester carbonyl groups. The characteristic stretching frequency

of the C-0 bond was observed at 1297 cm-I. In the 'H NMR spectrum, the

isopropyl protons, ( m ) 2 C H resonated as a doublet at 6 1.17 (J = 6.9 Hz). The

( C H 3 ) a proton appeared as a multiplet centered at 62.78. The -0Me protons of

the ester groups resonated as two separate singlets at 63.80 and 3.85. The aromatic

protons were visible as multiplets between 66.77-6.93. In the I3c NMR spectrum,

the methyl carbons of the isopropyl group appeared at 623.77 whereas the signal

due to the methme carbon, ( C H 3 ) m was observed at 633.37. The -OMe carbons

were visible at 6 52.83. The ester carbonyl groups were discernible at 6 160.98 and

162.66. All other signals were in agreement with the assigned structure.

The reaction was found to be applicable to other substituted

o-thiobenzoquinones and the results are summarized in Table 4.

Table 4: Cycloaddition reactions of substituted o-thiobenzoquinones with dimethyl acetylenedicarboxylate


Me3C SNPh th

M e 0 SNPhth

Me NPhth

'. Me2Hca0H SNPhth 14

COOMe

Me3C COOMe

COOMe

M e 0 a~'cooMe

COOMe

Me COOMe 42 (89%)

Me2Hca;x COOMe

COOMe 43 (73%)

Reaction conditions: Pyridine, CHCIs, Sealed tube, 70 OC, 15 h

Chapter 4

The reaction of 1-thionaphthoquinone with DMAD also followed the same

pathway and it afforded the 1,Coxathiin 44 in 84% yield (Scheme 12).

SNPhth COOMe

&".I s q F ; O M e

1

COOMe 16 38 -& 44

i. Pyridine, CHC13, Sealed tube, 70 OC, 15 h, 84% Scheme 12

The IR spectrum of 44 showed carbonyl absorption at 1755 cm-'. In the 'H

NMR spectrum of 44, the 4 M e protons appeared as two separate singlets at

6 3.86 and 3.90. The 13c NMR spectrum showed the methoxy carbon signal at

6 51.99. The carbonyl carbons resonated at 6 159.92 and 161.66.

Analogous to the reaction of DMAD, dibenzoyl acetylene (DBA) when

treated with 4-isopropyl-2-thiobenzoquinone in chloroform afforded 46 in 80%

yield (Scheme 13).

COPh

Me2HC SNPhth COPh COPh

3 45 46

i. Pyridine, CHCI3, Sealed tube, 70 OC, 15 h, 80%

Scheme 13

The structure of the product was ascertained from its spectroscopic data.

The 1R spectrum of 46 showed a strong absorption at 1674 cm-' indicating the

presence of carbonyl groups. The characteristic stretching frequency of the C-0

bond was observed at 1276 cm-'. The 'H NMR spectrum showed a doublet at 6

I . 15 (J = 6.9 Hz, 6H) assignable to the isopropyl group, (CH3)2CH. The methine

proton of the ~sopropyl g~oup, ( C H 3 ) m resonated as a multiplet between 6 2.75-

2.78. The aromatic protons were visible as a multiplet centered at 6 7.2 1. In the 13c NMR spectrum, the carbonyl groups appeared at 6 185.60 and 188.74. The other

signals were also in agreement with the assigned structure.

Similarly, DBA on reaction with 1-thionaphthoquinone gave the 1,4-

oxathiin adduct 47 in 92% yield (Scheme 14).

COPh SNPhth c o p h

Qy: l l I

COPh

16 45 47


Scheme 14

The IR spectrum of 47 showed a strong absorption at 1681 cm-' indicating

the presence of carbonyl group. In the 'H NMR spectrum, the aromatic protons

were discernible in the region 6 7.19-8.02. Satisfactory HRMS data was also

obtained.

Reaction of 4,6-di-tert-butyl-2-hydroxybenzothiophth with

4-octyne under the usual reaction conditions resulted in the formation of 1,4-

benzoxathiin adduct 49 in 64% yield (Scheme 15).

"

R = n-propyl 1.2 48 49 i. Pyridine, CHC13, Sealed tube, 70 OC, 14 h, 64%

Scheme 15

IR spectrum of 49 showed ether absorption at 1245 cm-'. In the 'H NMR

spectrum, (err-butyl protons and other aliphatic protons resonated as multiplets

centered at 6 1.43. All signals in the I3c NMR spectrum were in agreement with

the assigned structure.

Reactions of 3,5-di-tert-butyl-2-thioquinone with alkynes such as 1-octyne,

methyl propiolate etc. led to intractable mixtures. These reactions were not

persuaded further.

In summary, we have unraveled the reactivity of o-thioquinones towards

various dienophiles leading to novel oxathiin adducts. It is reasonable to assume

that these products can potentially undergo a number of interesting

transformations.

4.4 EXPERIMENTAL

General information about the experiment is given in chapter 2.

Acenapbthylene, indene, 1-phenylcyclohexene and DMAD were purchased fiom

Aldr~ch Co. and were used without purification. trans-Stilbene, cyclohexene and

4-octyne were purchased fiom local sources.

6-(I-Methylethyl)-2,3-dihydro-acenaphthene-[I,4]benzoxathiin (5)

2-Hydroxy-5-isopropylbenzothiophthalimide (100 mg, 0.3 19 mmol),

acenaphthylene (53 mg, 0.350 mmol), pyridine (0.05 mL, 0.638 mmol) and dry

chloroform (2 mL) were taken in a glass tube and sealed under argon atmosphere.

The sealed tube was then heated at 70 OC for 20 hrs. The solvent was removed in

vacuo and the product subjected to chromatography on silica gel column using

petroleum ether as eluent to afford 5 (97 mg, 96%) as a colorless crystalline solid;

recrystallized from dichloromethane-petroleum ether (mp. 125-127 OC).

IR (KBr) v ,,,, 778, 825, 1110, 1222, 1485,2982 cm-'.

'H NMR 6 1.09 (d, J = 6.8 Hz, 6H), 2.67-2.72 (m, lH), 5.22 (4 J = 7.2

Hz, 'lH), 6.22 (4 J = 7.2 Hz, lH), 6.83 (s, 2H), 6.99 (s, IH), 7.37-

'7.66 (m, 6H).

Chapter 4 120

13c NMR 6 23.83, 23.91, 33.31, 49.66, 84.66, 119.63, 120.16, 121.64,

124.00, 124.30, 125.20, 125.71, 127.21, 128.17, 128.28, 130.59,

137.02, 140.05, 142.20, 143.81, 152.76.

HRMS calcd for (:ZIH180S 318.1078, found 318.1072.

6-(1,1-Dimethyletlryl)-2,3-dihydro-acenaphthene-[1,4]benzoxathiin (7)

A solution of 5-tert-butyl-2-hydroxybenzothiophthalimide (100 mg, 0.305

mmol), acenaphthylene (51 mg, 0.336 mmol) and pyridine (0.04 mL, 0.61 mmol)

in dry chloroform (2 mL) was heated according to the usual procedure and the

product when subjected to silica gel column chromatography afforded 7 (83 mg,

82%) as a colorless crystalline solid; recrystallized from dichloromethane-

petroleum ether (mp. 138-140 OC).

IR (KBr) v,,, 784, 1034, 1276, 1499,2942 cm-'.

'H NMR 6 1.23 (s, 9H), 5.26 (d, J = 7.0 Hz, lH), 6.25 (d, J = 7.0 Hz, lH),

6.86 (d, J = 8.2 Hz, lH), 7.04(d, J = 8.2 Hz, lH), 7.18 (s, lH),

7 42-7.72 (m, 6H).

"C NMR 631.64, 34.45, 49.89, 84.83, 119.48, 120.38, 121.87, 124.17,

124.26, 124.92, 125.44, 126.40, 128.41, 128.50, 130.88, 137.24,

140.35, 142.38, 146.34, 152.80.

Anal. Calcd for C22HzoOS: C, 79.47; H, 6.06; S, 9.64. Found: C, 79.38; H, 6.01; S,

51.61.

6-Methoxy-2,3-dihydro-acenaphthene-[1,4]benoxathiin (9)

2-Hydroxy-5-methoxybenzothiophthalimide (100 mg, 0.332 mmol),

acenaphthylene (56 mg, 0.365 mmol), pyridine (0.05 mL, 0.664 mmol) and dry

chloroform (2 m1,) were heated under sealed tube conditions. The reaction mixture

on usual work-up followed by silica gel column chromatography afforded 9 (92

mg, 91%) as a colorless crystalline solid; recrystallized from dichloromethane-

petroleum ether (mp. 139-14 1 OC).

1 ( K ) , 768, 1197, 1259, 1477, 2927, 3052 cm-I.

'H NMR : 63.57 (s, 3H), 5.22 (d, J = 7.3 Hz, lH), 6.26 (d, J = 7.3 Hz, lH),

6.48 (d, J = 2.8 Hz, lH), 6.65 (4 J = 2.8 Hz, lH), 6.75 ( 4 J = 8.7

Hz, IH), 7.40-7.66 (m, 6H).

I3c NMR : 649.73, 55.23, 84.81, 113.35, 114.41, 120.25, 120.54, 121.62,

124.01, 125.18, 125.60, 128.14, 128.31, 130.47, 137.16, 139.89,

142.29, 148.22, 155.17.

Anal. Calcd for C19H1402S: C, 74.48; H, 4.60; S, 10.46. Found: C, 74.42; H, 4.61;

S, 10.31.

6-Methyl-2,3-dihydro-acenaphthene-[1,4]benmxathiin (11)

A solution of 2-hydroxy-5-methylbenzothiophthalimide (100 mg, 0.350

mmol), acenaphthylene (59 mg, 0.385 mmol) and pyridine (0.06 mL, 0.7 mmol) in

dry chloroform (2 mL) was heated under sealed tube conditions. The product when

subjected to column chromatography using silica gel (petroleum ether) afforded 11

(92 mg, 9 1%) as a colorless crystalline solid; recrystallized from dichloromethane-

petroleum ether (mp. 140-142 "C).

IR (KBr) v,,, : 780, 1029, 1265, 1483,2965,3033 cm-I.

'H NMR : 62.15 (s, 3H), 5.22 (d, J = 7.2 Hz, lH), 6.27 (d, J = 7.2 Hz, lH),

6.59 (d, J = 7.5 Hz, lH), 6.71 (s, lH), 6.98 ( 4 J = 7.5 Hz, lH),

7.38-7.68 (m, 6H).

13c NMR : 621.04, 49.77, 84.63, 120.18, 120.75, 121.64, 123.96, 124.20,

125.22, 126.48, 128.15, 128.30, 129.14, 130.49, 137.07, 137.86,

139.93, 142.30, 154.65.


S , 11.01.

5,7-Bis(1, I-dimethylethyl)-2,3-dil~ydro-acenaphthene-[1,4]benzoxathiin (13)

4,6-Di-terf-butyl-2-hydroxybe11zothiophthalimide (100 mg, 0.261 rnmol),

acenaphthylene (44 mg, 0.287 mmol), pyridine (0.04 mL, 0.522 mmol) and dly

chloroform (2 mL) were heated under argon atmosphere. The usual worked-up

followed by silica gel column chromatography using petroleum ether as eluent

afforded 13 (86 mg, 85%) as a colorless crystalline solid; recrystallized from

dichloromethane-petroleum ether (mp. 156-158 OC).

IR (KBr) v,,, : 774, 1041, 1253, 1396,2959,3033 cm-'.

'H NMR : 6 1.18 (s, 9H), 1.40 (s, 9H), 5.20 (4 J = 7.2 Hz, lH), 6.24 ( 4 J =

7.2 Hz, lH), 6.85 (s, lH), 6.97 (s, lH), 7.43-7.67 (m, 6H).

I3c NMR : 6 30.27, 31.14, 34.56, 36.37, 50.82, 85.08, 115.97, 118.24,

120.50, 121.25, 121.71, 123.91, 125.03, 127.98, 130.61, 137.56,

140.19, 141.48, 149.05, 149.80, 155.82.

Anal. Calcd for C26H2*OS: C, 80.36; H, 7.26; S, 8.25. Found: C, 80.27; H, 7.12; S,

8.47.

7-(l-Methylethyr)-2,3-dihydro-acenaphthene-[l,4]benoxathiin (15)

A solution of 2-hydroxy-4-isopropylbemothiophthalimide (100 mg, 0.319

rnrnol), acenaphthylene (53 mg, 0.350 mmol) and pyridine (0.05 mL, 0.638 mmol)

in dry chloroform (2 mL) was heated according to the earlier procedure followed

by silica gel column chromatography to afford 15 (87 mg, 86%) as a colorless

crystalline solid; recrystallized from dichloromethane-petroleum ether

(mp. 115-117 "C).

1R (KBr) v,,, : 778, 818, 1040, 1357, 1425, 1485, 1566, 1600,2962 cm-l.

'H NMR : 6 1.04 (d, J = 6.8 Hz, 6H), 2.65-2.69 (m, lH), 5.17 ( 4 J = 7.1

Hz, lH), 6.17(d, J = 7.1 Hz, lH), 6.63 (dd, J = 1.5 Hz, lH), 6.75

(s, lH), 6.97 ( 4 J = 7.8 Hz, lH), 7.33-7.69 (m, 6H).

I3c NMR : 623.97, 33.88, 50.01, 84.92, 118.25, 120.38, 121.80, 121.85,

124.26, 125.42, 128.38, 128.52, 128.76, 129.34, 130.87, 137.24,

140.29, 142.41, 149.29, 155.20.

HRMS calcd for C21HI80S 3 18.1078, found 3 18.1072.

2 , 3 - ~ i h ~ d r o - a c e n a p h t h e n e - n a p h t h o [ a J - [ 1 , 4 ~ ~ ~ (17)

A solution of 2-hydroqmaphthothiophthalimide (100 mg, 0.311 mmol),

acenaphthylene (52 mg, 0.342 mmol) and pyridine (0.05 mL, 0.622 mmol) in dry

chloroform (2 mL) was heated under the usual conditions and the product was

purified by silica gel column chromatography to afford 17 (93 mg, 92%) as a

colorless c~ystalline solid; recrystallized from dichloromethane-petroleum ether

(mp. 165-167 "C).

IR (KBr) v,,, : 825, 1040,1108, 1222,1378,1499, 1593,3049 cm-I.

'H NMR : 65.34 (d, J= 6.8 Hz, lH), 6.39 (d, J = 6.8 Hz, lH), 7.05 (d, J =

8.6 Hz, lH), 7.20-7.47 (q IOH), 8.05 ( 4 J = 8 . 1 Hz, 1H).

I3c NMR : 649.06, 84.66, 118.82, 119.24, 119.41, 120.67, 122.32, 123.08,

123.50, 124.32, 125.21, 126.36, 127.09, 127.19, 127.38, 129.38,

129.51, 131.64, 136.18, 138.97, 141.07, 152.11.

Anal. Calcd for C22H,.,0S: C, 80.95; H, 4.32; S, 9.82. Found: C, 81.00; H, 4.38; S,

9.47

2,3-trans-Diphenyl-6-(l-methylethyl)-2,3-dihydro-[I,4benzoxhiin (19)

The reaction of 2-hydroxy-5-isopropylbenzothiophthalimide (100 mg, 0.3 19

mmol) with trans-stilbene (63 mg, 0.350 mmol) in presence of pyridine (0.05 mL,

0.638 mmol) in dry chloroform (2 mL) was carried out under the usual conditions

and the product subjected to chromatography on silica gel column (light

petroleum) to afford 19 (105 mg, 95%) as a colorless crystalline solid;

recrystallized fiom dichloromethane-petrolem ether (mp. 135-137 OC).

IR(KBr)v ,,,, : 760,815,1021,1239, 1318, 1490,2969cm-I.

'H NMR 6 1.22 (d, J = 6.9 Hz, 6H), 2.81-2.85 (m, lH), 4.37 ( 4 J = 8.9

Hz, lH),5.00(d,J=8.9Hz, 1H),6.88-7.14(m, 13H).

j3c NMR : 6 24.06, 33.36, 49.47, 82.07, 118.28, 119.32, 123.52, 123.83,

127.08, 127.83, 127.97, 128.35, 128.90, 136.81, 138.29, 142.14,

150.26.

Anal. Calcd for C23Hz2OS: C, 79.74; H, 6.41. Found: C, 79.80; H, 6.38.

2,3-t~~n~-~~phenyl-~-(r,l-dimethylethyr)-2,3-dihydro-[l,4Jben~,xathiin (20)

A solution of 5-tert-butyl-2-hydroxybetlzothiophthalimide (100 mg, 0.305

mmol), trans-stilbene (60 mg, 0.336 mmol) and pyridine (0.04 mL, 0.61 mmol) in

dry chloroform (2 mL) was heated under sealed tube conditions. The product was

worked-up as usual and purified by silica gel column chromatography to afford 20

(88 mg, 80%) as a colorless clystalline solid, it was reclystallized from

dichloromethane-petroleum ether (mp. 147-149 OC).

IR (KBr) v,,, : 81 1, 1020,1256, 1499,2874,2955 cm-'.

'H NMR : 6 1.23 (s, 9H), 4.28 (d, J = 8.8 Hz, lH), 4.92 (d, J= 8.8 Hz, IH),

6.79 (d, J = 8.5 Hz, IH), 6.95-7.05 (m, 12H).

I3C NMR : 631.42, 34.20, 49.53, 82.14, 118.01, 118.93, 122.67, 122.91,

127.11, 127.86, 128.01, 128.38, 128.93, 136.83, 138.31, 144.50,

149.99.

Anal. Calcd for C:Z~H~~OS: C, 79.95; H, 6.70; S, 8.89. Found: C, 79.88; H, 6.61; S,

8.88

2,3-trans-Dipheny1-6-methoxy-2,3-dihydro-1,4benxthiin (21)

2-Hydroxy-5-rnethoxybenzothiophthalimide (100 mg, 0.332 mmol), trans-

stilbene (66 mg, 0.365 mmol), pyridine (0.05 mL, 0.664 mmol) and dry

chloroform (2 mL) were heated in a sealed tube. The usual work-up followed by

silica gel column chromatography afforded 21 (95 mg, 86%) as a colorless

crystalline solid; recrystallized from dichloromethane-petroleum ether

(mp. 148-150 "C).

IR (KBr) v ,,,, : 805, 1029, 1259, 1489,2965 cm-'.

'H NMR : 63.76 (s, 3H), 4.40 (d, J= 8.9 Hz, IH), 4.96 (d, J = 8.9 Hz, IH),

6.57-7.24 (m, 13H).

I3c NMR : 649.63, 55.58, 82.06, 110.24, 118.97, 119.15, 120.49, 127.10,

127.91. 128.02, 128.40, 128.93, 136.76, 138.31, 146.40, 154.20.


S, 9.69.

2,3-trans-Diphenyl-6-methyl-2,3-dihydro-[l,4Jbenxhiin (22)


mmol), trans-stilbene (69 mg, 0.385 mmol) and pyridine (0.06 mL, 0.7 mmol) in

dry chloroform (2 mL) was heated under argon atmosphere. The product when

subjected to work-up followed- by silica gel column chromatography afforded 22

(96 mg, 86%) as a colorless crystalline solid; recrystallized from dichloromethane-

petToleum ether (mp. 95-97 "C).

IR (KBr) v,,, : 799, 1023, 1259, 1446,2965,3039 cm-'.

I H NMR : 62.29 (s, 3H), 4.34 (d, J= 8.2 Hz, lH), 5.01 (d, J= 8.2 Hz, lH),

6.72-7.24 (m, 13H).

13C NMR : 629.64, 49.27, 81.47, 115.96, 118.94, 122.59, 124.44, 126.14,

127.07, 127.90, 128.37, 128.94, 135.35, 136.90, 138.34, 151.95.


s, 10.01. 2,3-trans-Diphenyl-5,7-bis(I,l-dimethylethyl)-2,3-dihydro-[l,4Jbenxathiin (23)

The reaction of 4,6-di-tert-butyl-2-hydroxybenzothiophthalmide (100 mg,

0.261 mmol) with trans-stilbene (52 mg, 0.287 mmol) in presence of pyridine

(0.04 mL, 0.522 mrnol) in dry chloroform (2 mL) was carried out under sealed

tube conditions. The product on purification by silica gel column chromatography

afforded 23 (94 mg, 87%) as a colorless crystalline solid; recrystallized from

dichloromethane-petroleum ether (mp. 2 10-2 12 'C).

1R (KBr) v,,, : 742, 1035, 1297, 1452, 1552,2952 cm-I.

'H NMR : 6 1.30 (s, 9H), 1.51 (s, 9H), 4.26 (4 J= 9.4 Hz, lH), 5.13 (d, J=

9.4 HZ, lH), 6.92 (s, lH), 7.10-7.17 (m, 11H).

Chapter 4 126

13c NMR 6 29.99, 31.28, 34.55, 36.81, 50.72, 82.78, 104.69, 114.19,

116.47, 117.05, 126.99, 127.84, 128.03, 128.42, 128.90, 137.21,

138.89, 146.45, 147.93.

Anal. Calcd for C2sH320S: C, 80.72; H, 7.74. Found: C, 80.68; H, 7.71.

2,3-trans-Dipheny1-7-(1-methylethy1)-2,3-dihdro-[14benmxathiin (24)

2-Hydroxy-4-isopropylbenzothiophthalimide (100 mg, 0.3 19 mmol), trans-

stilbene (63 mg, 0.350 mmol), pyridine (0.05 mL, 0.638 mmol) and dry

chloroform (2 mL) were heated in a sealed tube. The usual procedure followed by


crystalline solid; recrystallized fiom dichloromethane-petroleum ether

(mp. 125-127 'C).

IR (KBr) v ,,,, : 757,879, 1027, 1297, 1418,1485, 1566,2969,3056 cm-I.

'H NMR : 6 1.22 (d, J = 6.8 Hz, 6H), 2.81-2.86 (m, lH), 4.37 (d, J = 8.9

Hz, lH), 5.04 (d, J = 8.9 Hz, lH), 6.81-7.25 (m, 13H).

13c NMR : 624.66, 33.36, 49.47, 82.07, 118.28, 119.32, 123.52, 123.83,

127.08, 127.88, 127.07, 128.35, 128.90, 136.81, 138.29, 142.14,

150.26.

Anal. Calcd for CZ3Hz2OS: C, 79.74; H, 6.41. Found: C, 79.80; H, 6.38.

2,3-trans-Diphenyl-2,3-dihydro-naphtho[aJ-[l,4Jbenmxathiin (25)

A solution of 2-hydroxynaphthothiophthalimide (100 mg, 0.3 11 mmol),

trans-stilbene (62 mg, 0.342 mmol) and pyridine (0.05 mL, 0.622 mmol) in dry

chloroform (2 mL) was heated under the sealed tube conditions. The product when

subjected to usual work-up followed by silica gel column chromatography using

petroleum ether as eluent afforded 25 (91 mg, 83%) as a colorless crystalline solid;

recrystallized from dichloromethane-petroleum ether (mp. 170-172 OC).

IR (KBr) v ,,,,, : 697, 825, 1007, 1229, 1378, 1499, 1607,2968, 3050 cm-I.

'H NMR : 64.34 (d, J = 8.7 Hz, lH), 5.08 (d, J = 8.7 Hz, lH), 7.04-7.83

(m, 16H).

I3c NMR : 648.96, 82.08, 112.89, 119.74, 122.76, 124.23, 125.67, 126.39,

127.26, 128.11, 128.19, 128.26, 128.37, 128.59, 129.09, 129.46,

130.85, 136.98, 138.26, 149.98.

HRMS calcd for C24HleOS 354.1078, found 354.1078.

6-(1-Methylethyr)-2,3-dihydro-indan/b]-[1,4]ben~x~hiin (27)

2-Hydroxy-5-isopropylbenzothiophthalimde (156 mg, 0.5 mmol), indene

(70 mg, 0.6 mmol), pyridine (0.08 mL, 1 mmol) and dry chloroform (2 mL) were

heated under argon atmosphere. The product on usual work-up followed by silica

gel column chromatography using petroleum ether as eluent afforded 27 (130 mg,

92%) as a colorless crystalline solid; recrystallized from dichloromethane-

petroleum ether (mp. 67-69 OC).

IR (KBr) v,,, : 764, 83 1, 1054, 1243, 1492,2962 cm-'.

'H NMR : 6 1.18 (d, J = 6.9 Hz, 6H), 2.76-2.80 (m, lH), 3.14-3.16 (m, lH), 3.28-3.36 (m, lH), 3.96-3.98 (m, lH), 5-28 (4 J = 5.3 Hz, lH),

6.84 (s, 2H), 6.97 (s, IH), 7.20-7.49 (m, 4H).

I3c NMR : S 24.01, 33.38, 39.37, 42.83, 81.54, 118.84, 120.33, 124.15,

124.83, 125.07, 125.45, 127.13, 129.23, 140.51, 141.86, 142.82,

151.01.

HRMS calcd for Cl8Hl80S 282.1078, found 282.1071.

6-(1,l-Dimethylethyl)-Z,3-dihydro-indan[b/-[l,4/benzoxathiin (28)

The reaction of 5-tert-butyl-2-hydroxybenzothiophthalimide (163 mg, 0.5

mrnol), indene (70 mg, 0.6 mmol) and pyridine (0.08 mL, 1 mmol) in dry

chloroform (2 mL) was carried out and the product worked-up according to the

usual procedure. Silica gel column chromatography of the crude product afforded

28 (134 mg, 91%) as a colorless crystalline solid; recrystallized from

dichloromethane-petroleum ether (mp. 68-70 "C).

1R (KBr) v,,,,, : 784, 1061, 11 15, 1236, 1270, 1492,2962 cm-'.

'H NMR : 6 1.20 (s, 9H), 3.09-3.11 (m, lH), 3.24-3.31 (m, lH), 3.92-3.96

(m, lH), 5.24 (d, J = 5.3 Hz, lH), 6.78-7.45 (m, 7H).

I3c NMR 6 31.60, 34.41, 39.56, 43.05, 81.65, 118.73, 119.98, 123.41,

124.34, 125.08, 125.67, 127.37, 129.47, 140.77, 142.09, 145.36,

150.91.

HRMS calcd for C19H200S 296.1234, found 296.1232.

6-Methoxy-2,3-dihydro-indan[b]-[1,4]benzoathiin (29)

2-Hydroxy-5-methoxybenzothiophthalimide (150 mg, 0.5 mmol), indene

(70 mg, 0.6 mmol), pyridine (0.08 mL, 1 mmol) and dry chloroform (2 mL) were

heated under sealed tube conditions. The product when subjected to usual work-up

followed by silica gel column chromatography afforded 29 (86 mg, 80%) as a

colorless viscous liquid.

IR (neat) v ,,,, : 746, 1045, 1214, 1258, 1601,2837, 2956 cm-I.

'H NMR : 6 3.08-3.15 (m, lH), 3.28-3.36 (m, lH), 3.69 (s, 3H), 3.95-3.99

(m, IH), 5.29 (d, J = 5.4 Hz, lH), 6.53-7.48 (m, 7H).

I3c NhlR , 639.51, 42.98, 55.37, 82.01, 111.94, 112.17, 119.70, 122.17,

124.74, 125.46, 127.11, 129.21, 140.22, 141.81, 146.91, 154.62.


6-Metl~yl-2,3-dihydro-indan/b]-/1,4/benmxathiin (30)


mmol), indene (70 mg, 0.6 mmol) and pyridine (0.08 mL, 1 mmol) in dry

chloroform (2 mL) was heated according to the usual procedure and the product

subjected to column chromatography on silica gel (petroleum ether) to afford 30

(1 17 mg, 92%) as a colorless viscous liquid.

IR (neat) v ,,,,, : 796, 1052, 1151, 1251, 1476, 1563, 2912,2962, 3024 cm'.

'H NMR 62.23 (s, 3H), 3.04-3.12 (m, lH), 3.26-3.33 (m, lH), 3.93-3.99

( ~ n , l H), 5.35 (d, J = 5.4 Hz, lH), 6.67-7.48 (m, 7H).

13c NMR : 6 19.67, 39.40, 42.83, 81.16, 116.85, 119.89, 123.39, 124.96,

127.29, 129.37, 136.31, 140.64, 141.92, 153.21.


5,7-Bis(l,l-dimethyleihyr)-Z,3-dihydro-indanbf-[1,4fbenxhiin (31)

4,6-Di-tert-butyl-2-hydroxybemthiophthde (191 mg, 0.5 mmol),

indene (70 mg, 0.6 mmol), pyridine (0.08 mL, 1 mmol) and dry chloroform (2 mL)

were heated under argon atmosphere. The product was purified by silica gel

column chromatography to afford 31 (150 mg, 85%) as a colorless crystalline

solid; recrystallized from dichloromethane-petroleum ether (mp. 78-80 "C).

789, 1058, 1283, 1489, 1557,2968 cm". IR (KBr) V,,X

'H NMR 6 1.26 (s, 9H), 1.49 (s, 9H), 3.04-3.10 (m, lH), 3.34-3.42 (m,

lH), 3.97-4.03 (m, lH), 5.63 (d, J = 6.0 Hz, IH), 6.90-7.58 (m,

6H).

I3c NMR : 630.23, 31.25, 34.64, 36.51, 38.60,44.86, 86.02, 115.22, 117.78,

120.69, 124.49, 125.93, 127.21, 129.11, 140.06, 141.49, 148.56,

149.38, 155.97.


7-(l-Methylethy~-2,3-dihydro-indan[b/-[l,4fbenmxathiin (32)

2-Hydroxy-4-isopropylbenzothiophthalimide (156 mg, 0.5 mmol), indene

(70 mg, 0.6 mmol), pyndine (0.08 mL, 1 mmol) and dry chloroform (2 mL) were

heated according to the earlier procedure. The product when subjected to silica gel

column chromatography afforded 32 (127 mg, 90%) as a colorless viscous liquid.

IR (neat) v ,,,,, : 764, 1013, 1074, 1236, 1485, 1573, 2969, 3050 cm-I.

'H NMR : 6 1.09 (d, J = 6.9 Hz, 6H), 2.68-2.73 (m, lH), 2.99-3.07 (m, lH),

3.18-3.26 (m, lH), 3.82-3.86 (m, IH), 5.21 (4 J = 5.3 Hz, IH),

6.66-7.43 (m, 7H).

13c NMR : 624.02, 33.75, 39.37, 42.85, 81.65, 117.09, 117.46, 120.81,

125.00, 125.54, 127.28, 127.33, 129.37, 140.71, 142.01, 147.46,

153.13.


53-Dihydro-indan[bJ-naphtho/aJ-/1,4]benmx&hiin (33)

A solution of 2-hydroxynaphthothiophthalimide (160 mg, 0.5 mmol),

indene (70 mg, 0.6 mmol) and pyridine (0.08 mL, 1 mmol) in dry chloroform (2

mL) was heated under the usual conditions and the product on purification by


crystalline solid; recrystallized from dichloromethane-petroleum ether (mp. 1 18-

120 OC).

IR(KBr) v ,,,, : 751, 811, 1108, 1229, 1398, 1472, 1613,2960,3042 ern-I. 'H NMR : 63.12-3.19 (m, lH), 3.34-3.42 (m, lH), 4.04-4.10 (m, lH), 5.47

(d, J=5.0Hz, lH), 7.11-7.97(m, 10H).

"C NMR : 639.17, 42.29, 81.24, 113.75, 119.98, 122.64, 124.12, 124.98,

125.25, 125.79, 126.10, 127.15, 128.20, 129.25, 129.76, 131.30,

140.73, 141.61, 150.44.

HRMS calcd for CI9HI40S 290.0765, found 290.0755.

6-(1 -Methylethyl)-2-phenyl-2,3-cy cloh- (35)

2-Hydroxy-5-isopropylbemothiophthalimide (156 mg, 0.5 mmol),

1-phenylcyclohexene (95 mg, 0.6 mmol) and pyridine (0.08 mL, 1 mmol) in dry

chloroform (2 mL) were heated in a sealed tube at 70 OC for 15 h. The reaction

mixture on usual work-up and silica gel column chromatography (petroleum ether)

afforded 35 (27 mg, 17%) as a colorless viscous liquid.

IR (neat) v,,, : 689,739,814,964, 1232, 1438, 1482,2924,2955 cm-I. I H NMR 6 1.13 (d, J = 6.5 Hz, 6H), 1.47-2.20 (m, 8H), 2.67-2.77 (m, lH),

3.33-3.39 (m, lH), 6.67-7.31 (m, 8H).

13 C NMR : 621.36, 23.90, 23.97, 26.53, 31.32, 33.15, 42.96, 77.82, 114.85,

117.89, 123.76, 124.51, 126.84, 128.21, 141.21, 145.72, 147.74.

HRMS calcd for C21Hz40S 324.1547, found 324.1546.

3,7-Bis(l, ~-dim~hylethy~-2,3-~yclohacyl-/1,4]benzoxathiin (3 7)

4,6-Di-~ert-butyl-2-hydroxybenzothiophthde (191 mg, 0.5 m 0 l ) ,

cyclohexene (82 mg, 1 mmol) and pyridine (0.08 mL, 1 mmol) in dry chlorofom

(2 mL) were heated at 70 OC for 15 h. The reaction mixture on usual work-up and

silica gel column chromatography (petroleum ether) afforded 37 (53 mg, 33%) as a

colorless wscous liquid.

IR (neat) v ,,,,, 799, 861, 1010, 1303, 1402, 1459, 1558, 1602,2952 cm-'. 1 H NMR S 1.28 (s, 9H), 1.46 (s, 9H), 1.51-2.16 (m, 8H), 3.09-3.13 (m,

IH), 4.36-4.37 (m, lH), 6.72 (d, J = 1.8 Hz, lH), 6.98 (d, J = 1.7

Hz, IH). 13

C NMR : S20.10, 24.98, 29.65, 30.04, 31.39, 31.72, 34.51, 36.82, 39.89,

72.33, 113.79, 116.82, 146.52, 147.35, 151.84.

HRMS calcd for C20H300S 318.2017, found 3 18.2013.

6-(l-M~hylethyl)-2,3-bis(c~rbomethoxy)-[1,4]ben~ox~h (39)

A solution of 2-hydroxy-5-isopropylbenzothiophthalimide (156 mg, 0.5

m o l ) , dimethyl acetylenedicarboxylate (85 mg, 0.6 mmol) and pyridine (0.08

mL, 1 m o l ) in dry chloroform (2 d) was heated according to the usual

procedure followed by silica gel column chromatography using 5% ethyl acetate in

petroleum ether as eluent to afford 39 (141 mg, 92%) as an yellow viscous liquid.

IR (neat) v,,, . 780, 945, 1185, 1297, 1634, 1742,2962 cm-I.

'H NMR : 61.17(d, J=6.9Hz,6H), 2.76-2.81 (m, lH), 3.80 (s, 3H), 3.85

(s, 3H), 6.77-6.93 (m, 3H).

"C NMR : 6 23.77, 33.37, 52.83, 116.96, 117.41, 124.51, 126.41, 146.22,

146.98, 148.08, 160.98, 162.66.

HRMS calcd for CISHI6o5S 308.0718, found 308.0707.

6-(I, I - D i m e t h y l e t h y 1 ) - 2 , 3 - b i s ( c a r b o ~ (40)

A solution of 5-tert-butyl-2-hyclroxybenzothiophthalimide (163 mg, 0.5

mmol), dimethyl acetylenedicarboxylate (85 mg, 0.6 mmol) and pyridine (0.08

mL, 1 mmol) in dry chloroform (2 mL) was heated under sealed tube conditions

and the product when subjected to silica gel column chromatography using 5%

ethyl acetate in petroleum ether as eluent afforded 40 (135 mg, 84%) as an yellow

viscous liquid.

IR (neat) v ,,,, : 831, 1074, 1209, 1263, 1485, 1634, 1748,2962 cm-'.

'H NMR 6 1.85 (s, 9H), 3.73 (s, 3H), 3.78 (s, 3H), 6.72-7.03 (m, 3H).

13c NMR 631.32, 34.57, 52.97, 115.65, 116.83, 117.26, 123.78, 125.60,

146.35, 148.00, 149.51, 161.09, 162.79.

HRMS calcd for c16H1805S 322.0874, found 322.0868.

6-Methoxy-2,3-bis(carbomethoxy)-[l,4]benoxathiin (41)

A solution of 2-hydroxy-5-methoxybe~~zothiophthalirnide (150 mg, 0.5

nunol), dimethyl acetylenedicarboxylate (85 mg, 0.6 mmol) and pyridine (0.08

mL, 1 mmol) in dry chloroform (2 mL) was heated under the usual conditions and

the product was purified by silica gel column chromatography using 7% ethyl

acetate in petroleum ether as eluent to afford 41 (127 mg, 86%) as an yellow

viscous liquid

IR (neat) v,,, : 796, 1033, 1270, 1489, 1507, 1726,2962 cm-'.

'H NMR : 63.65 (s, 3H), 3.75 (s, 3H), 3.78 (s, 3H), 6.38-6.73 (m, 3H).

I3c NMR 651.73, 51.89, 54.40, 110.78, 112.25, 112.86, 113.54, 116.32,

117.13, 142.54, 156.39, 160.12, 161.61.

HRMS calcd for C13HLZ06S 296.0354, found 296.0341.

6-Merhyl-2,3-bis(carbomethoxy)-[1,4]benzoxathh (42)

A solution of 2-hydroxy-5-methylbe11zothiophthalimide (142 mg, 0.5

mmol), dirnethyl acetylenedicarboxylate (85 mg, 0.6 mmol) and pyridine (0.08

mL, 1 mmol) in dry chloroform (2 mL) was heated under the usual conditions and

the product when subjected to silica gel column chromatography using 5% ethyl

acetate in petroleum ether as eluent afforded 42 (124 mg, 89%) as an yellow

viscous liquid.

IR (neat) v,,, : 789, 1070, 1164, 1278, 1482, 1732, 2956 cm'l.

'H NMR : 62.25 (s, 3H), 3.82 (s, 3H), 3.86 (s, 3H), 6.72-6.82 (m, 3H).

13c NMR : 620.79, 52.84, 115.08, 118.36, 126.30, 126.69, 127.15, 127.60,

139.00, 149.99, 160.96, 162.69.

HRMS calcd for CI3HI205S 280.0405, found 280.0415.

7- (I -Methy le thy l ) -2 ,3 -b i s (carbomethoxy l - i in (43)

2-Hydroxy-4-isopropylbe11~othiophthalimide (156 mg, 0.5 mmol), dimethyl

acetylenedicarboxylate (85 mg, 0.6 mmol) and pyridine (0.08 mL, 1 mmol) in dry

chloroform (2 mL) were heated under argon atmosphere. The product when

subjected to usual work-up and silica gel column chromatography using 5% ethyl

acetate in petroleum ether as eluent afforded 43 (1 12 mg, 73%) as an yellow

viscous liquld.

1R (neat) v ,,,, : 798, 1067, 1189, 1256, 1290, 1438, 1634, 1748, 2969 cm-'.

'H NMR : 6 1.18 (d, J = 6.9 Hz, 6H), 2.78-2.82 (m, lH), 3.81 (s, 3H), 3.86

(s, 3H), 6.77-6.86 (m, 3H).

I3c NMR 623.79, 33.76, 53.06, 111.37, 114.08, 115.92, 124.42, 126.57,

145.94, 150.21, 150.42, 161.16, 162.91.

HRMS calcd for CI5Hl6O5S 308.0718, found 308.0707.

2,3-Bis(carbomethoxy)-naphtho[a]-[1,4]benzoxathiin (44)


dimethyl acetylenedicarboxylate (85 mg, 0.6 mmol) and pyridine (0.08 mL, 1

mmol) in dry chloroform (2 mL) was heated according to the usual procedure. The

product on work-up followed by silica gel column chromatography using 5% ethyl

acetate in petroleum ether as eluent afforded 44 (133 mg, 84%) as an yellow

viscous liqu~d

IR (neat) v,, : 81 1, 1155, 1209, 1276, 1458, 1587, 1647, 1755,2955 cm-I.

'H NMR : 6 3.86 (s, 3H), 3.90 (s, 3H), 7.08-7.77 (m, 6H).

I3c NMR 651.99, 116.45, 121.88, 124.64, 126.23, 127.27, 127.56, 128.54,

128.90, 129.90, 130.68, 145.80, 146.88, 159.92, 161.66.

HRMS calcd for C16H1205S 3 16.3318, found 3 16.3315.

6-(1-Methylethyl)-2,3-bk@enzoyl)-[l,4Jbenzoxathiin (46)

2-Hydroxy-5-isopropylbenzothiophthalimide (78 mg, 0.25 mmol),

dibenzoyl acetylene (70 mg, 0.3 mmol), pyridine (0.04 mL, 0.5 mmol) and dry

chloroform (2 mL) were heated according to the usual procedure. The reaction

mixture on usual work-up followed by silica gel column chromatography using

5% ethyl acetate in petroleum ether as eluent afforded 46 (80 mg, 80%) as an

yellow crystalline solid; recrystallized from dichloromethane-petroleum ether

(mp. 80-82 "C:).

IR (KBr) v,,, 724, 1276, 1485, 1607, 1674,2975 cm-l.

'H NMR 6 1.15 (d, J = 6.9 Hz, 6H), 2.75-2.78 (m, IH), 6.75-7.81 (m,

13H).

I3c NMR 623.48, 33.11, 117.06, 117.66, 124.41, 126.41, 127.86, 128.18,

128.46, 128.57, 129.17, 132.86, 133.07, 133.33, 134.62, 135.15,

135.29, 146.64, 148.47, 148.80, 185.60, 188.74.

Anal. Calcd for CzsHzo03S: C, 74.98; H, 5.04. Found: C, 74.88; H, 5.02.

2,3-Bis(benzoy1)-naphtho[aJ-[1,4/benzoxhiin (47)


dibenzoyl acetylene (70 mg, 0.3 mmol) and pyridine (0.04 mL, 0.5 mmol) in dry

chloroform (2 mL,) was heated under sealed tube conditions. The reaction mixture

on usual work-up followed by silica gel column chromatography afforded 47 (94

mg, 92%) as an yellow crystalline solid; recrystallized from dichloromethane-

petroleum ether (mp. 118-120 "C).

R ( K B ) v 804, 1034, 1276, 1587, 1681,2969, 3063 cm-I.

'H NMR h' 7.19-8.02 (m, 16H).

I3c NMR 6 117.06, 117.66, 123.50, 124.41, 126.41, 127.86, 128.18,

128.46, 128.51, 129.17, 132.82, 132.99, 133.07, 133.23, 134.62,

134.86, 135.15, 135.79, 146.64, 148.47, 148.80, 150.13, 186.60,

187.74.

HRMS calcd for C26H16@S 408.0820, found 408.0815.

5 , 7 - B ~ ( l , l - d i m e t h y l e t h y l ) - 2 , 3 - b i s ~ r o p y l ) (49)

4,6-Di-tert-butyl-2-hydroxybe11zothiophth (191 mg, 0.5 mmol),

4-octyne, (1 10 mg, 1 rnmol) and pyridine (0.08 mL, 1 mmol) in dry chloroform

(1.5 mL) were heated in a sealed tube at 70 OC for 15 h. The reaction mixture on

usual work-up and silica gel column chromatography (petroleum ether) afforded

49 as a colorless viscous liquid (1 10 mg, 64%).

IR(neat)v,,, . 789, 1008, 1120, 1195, 1245, 1295, 1401, 1451, 1551, 1595,

288 1,2956 cm-'. I H NMR 6 0.88-0.96 (m, 6H), 1.25-1.61 (m, 24H), 2.16-2.27 (m, 2H), 6.82

(s, lH), 7.11 (s, 1H). I3

C NMR 6 13.75, 13.91, 20.61, 22.02, 30.10, 31.42, 32.69, 33.40, 34.71,

36.54, 111.10, 112.76, 118.97, 119.73, 146.30, 149.58, 150.53,

154.78.

4.5 REFERENCES

(1) Konovalov, A. I.; Solomonov, B. N.; Chertov, 0. Y. Zh. Org. Khim. (Eng.

Trans.) 1975, 1 1 , 107.

(2) Pyle, J . L.; Shaffer, A. A,; Cantrell, J. S. J. Org. Chem. 1981, 46, 115.

(3) Liao, C. -C.; Lin, H. S.; Lin, J. T. J. Chin. Chem. Soc. 1980,27, 87.

(4) (a) Nair, V.; Maliakal, D.; Treesa, P. M.; Rath, N. P. Synthesis 2000, 850.

(b) 'Thomas, A.; Anilkumar, G.; Nair, V. Tetrahedron 1996,52,2481.

( 5 ) Capozzi, G.; Falciani, C.; Menichetti, S.; Nativi, C. J. Org. Chern. 1997,62,

261 1

chapter 4 cycloaddition reactions of 0-thioquinones...

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