ORGANIC SPECTROSCOPY INTERNATIONAL: 1,1-Dimethyl-3,8-dihydro-1H-indeno[1,2-c]thiophen-3-one

1,1-Dimethyl-3,8-dihydro-1H-indeno[1,2-c]thiophen-3-one
3,6-Di(2-pyridyl)stetrazine (0.45g; 1.9 mmol) was added slowly to a stirred solution of the hydrocarbon 33 (0.30g; 1.6 mmol) and thiophosgene (0.125 ml; 1.6 mmol) in a 1:1 mixture of ethanol and chloroform (10 ml) and the resulting mixture stirred for 15 minutes. The solvent was removed and the residue partitioned between ether and water. The ethereal phase was washed with hydrochloric acid (3 x 20 ml; 0.5M) and water (2 x 10 ml), dried, and the solvent removed to yield the crude product. Purification by rapid preparative thinlayer chromatography (silica, chloroform/light petroleum 2:1) yielded a pale brown coloured oil which crystallized from ethanol. Recrystallization from ethanol afforded the product as clear, pale brown crystals (0.18g; 52%), m.p. 66-67 ^oC.
uv, visible spectrum: lmax 238, 243 (inf), 263 (inf), 300 (inf), nm; e 12650, 12080, 5120, 1490.
infra red spectrum: umax 1695 (s), 1315 (w), 1305 (m), 1270 (m), 1240 (m), 1200 (w), 1185 (w), 1145 (m), 1120 (m), 1080 (w), 1065 (m), 1015 (w), 870 (w), 855 (w), 835 (s), 780 (m), 760 (m), 720 (s), 690 (m) cm^-1.
P.m.r. spectrum (CDCl₃): d 1.82 (6H, s, methyl protons), 3.54 (2H, s, benzylic protons), 7.20-7.60 (3H, m, Hb), 7.70-7.90 (1H, m, Ha),
13C-[¹H] nmr spectrum (CDCl₃): d 29.12 (C9 & C10), 33.70 (C8), 55.90 (C1), 121.04 (C5), 124.91 (C6), 126.25 (C4), 127.12 (C7), 136.05 (C3b), 143.16 (C3a), 145.89 (C7a), 181.25 (C8a), 191.33 (C3).
Mass spectrum: m/e 217 (10%), 216 (M⁺, 61), 215(5), 201(15), 189(6), 188(29), 187(20), 183(9), 173(14), 171(6), 158(8), 157(26), 156(14), 155(33), 153(8), 152(7), 142(22), 141(18), 139(14), 130(6), 129(38), 128(19) 127(10), 116(7), 115(38), 114(20), 113(8), 102(7), 89(9), 88(7), 87(9), 86(8), 85(5), 79(9), 77(12), 76(10), 75(10), 74(10), 70(5), 69(5), 65(8), 64(10), 653(27), 62(13), 61(8), 59(100), 51(21), 50(11), 45(14), 41(12), 39(30), all other peaks less than 5%.
Analysis: Found: C, 71.9; H, 5.8, S, 14.9. C13H12OS requires C, 72.2; H, 5.6; S, 14.8%.