1398
K. C. Majumdar, S. Alam and S. Muhuri
Vol 44
General procedure for the synthesis of Compounds 9a-e.
Compound 8a (0.52 g, 1.5 mmol) was refluxed in chlorobenzene
(10 ml) for 2 h. Then the reaction mixture was subjected to
column chromatography over silica gel (60-120 mesh). Elution
of the column with petroleum ether followed by petroleum
ether-ethylacetate (9:1) gave compound 9a as viscous liquid in
82% yield. Compounds 9b-e were similarly synthesized from
8b-e in 77-82% yields.
5-Acetyl-4-(2'-methylphenyloxymethyl)-2,5-dihydrothio-
pyrano[3,2-b]indole (9a). Yield: 82%, viscous liquid; ir (neat):
1455 (C-H bending), 1704 (C=O), 2919, 3050 (C-H stretching)
cm-1; 1H nmr (400 MHz, CDCl3): ꢀ 2.07 (s, 3H, ArCH3), 2.64 (s,
3H, -COCH3), 3.40 (d, 2H, J = 6.2 Hz, -SCH2), 4.87 (s, 2H,
-OCH2), 5.89 (t, 1H, J = 6.2 Hz, =CH), 6.72-7.78 (m, 8H, ArH);
ms: m/z 349 (M+). Anal. Calcd. for C21H19NO2S: C, 72.21; H,
5.44; N, 4.01. Found: C, 72.12; H, 5.57; N, 4.08.
4-(2',3'-Dimethylphenyloxymethylene)-2,3,5-trihydrothio-
pyrano[3,2-b]indole (2e). Yield: 79%, viscous liquid; ir (neat):
1468 (C-H bending), 2921, 3056 (C-H stretching), 3405 (N-H)
cm-1; 1H nmr (400 MHz, CDCl3): ꢀ 2.31 (s, 3H, ArCH3), 2.33 (s,
3H, ArCH3), 2.84-2.87 (m, 2H, -SCH2CH2), 3.09-3.12 (m, 2H,
-SCH2), 6.35 (s, 1H, =CH), 6.95-7.49 (m, 7H, ArH), 9.28 (brs,
1H, NH); ms: m/z 321 (M+). Anal. Calcd. for C20H19NOS: C,
74.77; H, 5.92; N, 4.36. Found: C, 74.57; H, 5.85; N, 4.30.
General procedure for the preparation of Compounds
8a-e. Bu4NHSO4 (10 mg, 0.01 eqiv.) and NaOH (0.2 g, powder)
were added to the dichloromethane solution (10 ml) of 1a (0.61
g, 2 mmol) at 0°C, then a solution of acetyl chloride (0.24 g, 1.5
eqiv.) in dry dichloromethane (5 ml) was added to it drop wise
and stirred for 1 h. The reaction mixture was washed with cold
saturated Na2CO3 solution (2x15 ml), water (2x15 ml), brine (15
ml) and dried (Na2SO4) and then evaporated. Finally the crude
reaction mixture was purified by column chromatography.
Elution of the column with petroleum ether-ethyl acetate (9:1)
on silica gel (60-120 mesh) afforded compound 8a. Compounds
8b-e were obtained by the same procedure from compounds
1b-e in 80-85% yields.
1-Acetyl-3-{4'-(2-methylphenyloxy)but-2'-ynylthio}indole
(8a). Yield: 80%, viscous liquid; ir (neat): 1370, 1440 (C-H
bending), 1712 (C=O), 2925 (C-H stretching) cm-1; 1H nmr (400
MHz, CDCl3): ꢀ 2.19 (s, 3H, ArCH3), 2.49 (s, 3H, -COCH3),
3.54 (s, 2H, -SCH2), 4.64 (s, 2H, -OCH2), 6.79-7.37 (m, 6H,
ArH), 7.53 (s, 1H, =CH), 7.67-8.42 (m, 2H, ArH); ms: m/z 349
(M+). Anal. Calcd. for C21H19NO2S: C, 72.21; H, 5.44; N, 4.01.
Found: C, 72.44; H, 5.53; N, 3.89.
1-Acetyl-3-{4'-(4-methoxyphenyloxy)but-2'-ynylthio}indole
(8b). Yield: 85%, viscous liquid; ir (neat): 1375, 1446 (C-H
bending), 1713 (C=O), 2920 (C-H stretching) cm-1; 1H nmr (300
MHz, CDCl3): ꢀ 2.54 (s, 3H, -COCH3), 3.53 (s, 2H, -SCH2), 3.57
(s, 3H, -OCH3), 4.56 (s, 2H, -OCH2), 6.74-7.31 (m, 6H, ArH),
7.58 (s, 1H, =CH), 7.68-8.43 (m, 2H, ArH); ms: m/z 365 (M+).
Anal. Calcd. for C21H19NO3S: C, 69.04; H, 5.20; N, 3.84. Found:
C, 69.22; H, 5.12; N, 3.93.
1-Acetyl-3-{4'-(4-methylphenyloxy)but-2'-ynylthio}indole
(8c). Yield: 82%, viscous liquid; ir (neat): 1375, 1450 (C-H
bending), 1708 (C=O), 2922 (C-H stretching) cm-1; 1H nmr (400
MHz, CDCl3): ꢀ 2.26 (s, 3H, ArCH3), 2.50 (s, 3H, -COCH3),
3.52 (s, 2H, -SCH2), 4.59 (s, 2H, -OCH2), 6.75-7.41 (m, 6H,
ArH), 7.54 (s, 1H, =CH), 7.66-8.44 (m, 2H, ArH); ms: m/z 349
(M+). Anal. Calcd. for C21H19NO2S: C, 72.21; H, 5.44; N, 4.01.
Found: C, 72.25; H, 5.54; N, 4.12.
1-Acetyl-3-{4'-(2,4-dimethylphenyloxy)but-2'-ynylthio}in-
dole (8d). Yield: 85%, viscous liquid; ir (neat): 1375, 1448 (C-H
bending), 1712 (C=O), 2922 (C-H stretching) cm-1; 1H nmr (400
MHz, CDCl3): ꢀ 2.15 (s, 3H, ArCH3), 2.23 (s, 3H, ArCH3), 2.48
(s, 3H, -COCH3), 3.53 (s, 2H, -SCH2), 4.60 (s, 2H, -OCH2),
6.68-7.41 (m, 5H, ArH), 7.53 (s, 1H, =CH), 7.67-8.44 (m, 2H,
ArH); ms: m/z 363 (M+). Anal. Calcd. for C22H21NO2S: C, 72.73;
H, 5.78; N, 3.86. Found: C, 72.54; H, 5.71; N, 3.92.
1-Acetyl-3-{4'-(2,3-dimethylphenyloxy)but-2'-ynylthio}in-
dole (8e). Yield: 84%, viscous liquid; ir (neat): 1374, 1446 (C-H
bending), 1713 (C=O), 2919 (C-H stretching) cm-1; 1H nmr (400
MHz, CDCl3): ꢀ 2.10 (s, 3H, ArCH3), 2.24 (s, 3H, ArCH3), 2.48
(s, 3H, -COCH3), 3.53 (s, 2H, -SCH2), 4.62 (s, 2H, -OCH2),
6.68-7.41 (m, 5H, ArH), 7.53 (s, 1H, =CH), 7.67-8.44 (m, 2H,
ArH); ms: m/z 363 (M+). Anal. Calcd. for C22H21NO2S: C, 72.73;
H, 5.78; N, 3.86. Found: C, 72.85; H, 5.88; N, 3.81.
5-Acetyl-4-(4'-methoxyphenyloxymethyl)-2,5-dihydrothio-
pyrano[3,2-b]indole (9b). Yield: 82%, viscous liquid; ir (neat):
1448 (C-H bending), 1703 (C=O), 2922, 3028 (C-H stretching)
1
cm-1; H nmr (300 MHz, CDCl3): ꢀ 2.60 (s, 3H, -COCH3), 3.31
(d, 2H, J = 6 Hz, -SCH2), 3.65 (s, 3H, -OCH3), 4.73 (s, 2H,
-OCH2), 5.78 (t, 1H, J = 6 Hz, =CH), 6.67-7.70 (m, 8H, ArH);
ms: m/z 365 (M+). Anal. Calcd. for C21H19NO3S: C, 69.04; H,
5.20; N, 3.84. Found: C, 69.18; H, 5.34; N, 3.75.
5-Acetyl-4-(4'-methylphenyloxymethyl)-2,5-dihydrothio-
pyrano[3,2-b]indole (9c). Yield: 81%, viscous liquid; ir (neat):
1446 (C-H bending), 1704 (C=O), 2921, 3028 (C-H stretching)
cm-1; 1H nmr (400 MHz, CDCl3): ꢀ 2.30 (s, 3H, ArCH3), 2.66 (s,
3H, -COCH3), 3.38 (d, 2H, J = 6 Hz, -SCH2), 4.81 (s, 2H,
-OCH2), 5.85 (t, 1H, J = 6 Hz, =CH), 6.68-7.76 (m, 8H, ArH);
ms: m/z 349 (M+). Anal. Calcd. for C21H19NO2S: C, 72.21; H,
5.44; N, 4.01. Found: C, 72.35; H, 5.43; N, 3.92.
5-Acetyl-4-(2',4'-dimethylphenyloxymethyl)-2,5-dihydro-
thiopyrano[3,2-b]indole (9d). Yield: 79%, viscous liquid; ir
(neat): 1456 (C-H bending), 1695 (C=O), 2916, 3020 (C-H
stretching) cm-1; 1H nmr (400 MHz, CDCl3): ꢀ 2.01 (s, 3H,
ArCH3), 2.21 (s, 3H, ArCH3), 2.64 (s, 3H, -COCH3), 3.39 (d,
2H, J = 6.2 Hz, -SCH2), 4.82 (s, 2H, -OCH2), 5.88 (t, 1H, J = 6.2
Hz, =CH), 6.68-7.78 (m, 7H, ArH); ms: m/z 363 (M+). Anal.
Calcd. for C22H21NO2S: C, 72.73; H, 5.78; N, 3.86. Found: C,
72.56; H, 5.95; N, 3.90.
5-Acetyl-4-(2',3'-dimethylphenyloxymethyl)-2,5-dihydro-
thiopyrano[3,2-b]indole (9e). Yield: 77%, viscous liquid; ir
(neat): 1455 (C-H bending), 1701 (C=O), 2918 (C-H stretching)
1
cm-1; H nmr (400 MHz, CDCl3): ꢀH 1.97 (s, 3H, ArCH3), 2.19
(s, 3H, ArCH3), 2.64 (s, 3H, -COCH3), 3.40 (d, 2H, J = 6.2 Hz,
-SCH2), 4.83 (s, 2H, -OCH2), 5.89 (t, 1H, J = 6.2 Hz, =CH),
6.72-7.77 (m, 7H, ArH); ms: m/z 363 (M+). Anal. Calcd. for
C22H21NO2S: C, 72.73; H, 5.78; N, 3.86. Found: C, 72.78; H,
5.90; N, 3.92.
Acknowledgements. We thank the CSIR (New Delhi) for
financial assistance. Two of us S. A. and S. M. are grateful to
UGC and CSIR (New Delhi) respectively for their Senior
Research fellowship. We also thank DST (New Delhi) for
providing us UV-VIS and FT-IR under FIST programm and the
University of Kalyani for laboratory facilities.
REFERENCES
[1] (a) Claisen, L. Ber. Btsch. Chem. Ges 1912, 45, 3157. (b)
Castro, A. M. M. Chem. Rev. 2004, 104, 2939.