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Conversion of Thiiranes to b-Chlorothioacetates
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EXPERIMENTAL
Infra red spectra were recorded on a Perkin Elmer IR-157 G and a
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Perkin Elmer 781 spectrometer. H and 13C NMR spectra were recorded
on a Bruker Avance DPX-250.
General procedure for preparation of b-chlorothioacetates. To a solu-
tion of thiirane (l mmol) in CH2Cl2 (2 mL), acetyl chloride (1.2–2 mmol)
was added followed by the addition of anhydrous CoCl2 (0.05 mmol,
6.5 mg). The reaction mixture was stirred at room temperature for
0.1–4 h and monitored with GC or TLC analysis. After completion of
the reaction, diethyl ether (35 mL) was added. The organic layer was
separated and washed with water (20 mL) and dried over anhydrous
Na2SO4. Evaporation of the solvent followed by chromatography on a
short column of silica-gel using petroleum ether/ethyl acetate (8:2)
afforded the pure b-chlorothioacetates in 77–94% yield. The ratio of
each isomerwas determined by both GC and NMR analysis.
Thioacetate acid S-(2-chloro-2-phenyl-ethyl) ester (3a). IR (neat)
ꢀ 3095, 3060, 2850, 1705, 1505, 1469, 1369, 1250, 1150. 1H NMR
(CDCl3) ꢁ: 7.2–7.4 (5H, m), 4.9 (IH, t), 3.5 (2H, dd), 2.2 (3H, s).
13C NMR (CDCl3) ꢁ: 194.8, 140.4, 129.2, 128.6, 127.6, 62.3, 38.4, 30.9.
MS (70 eV): (M, 1.7%), (M þ 2, 0.6%), (M-Cl, 3.7%), (M-HCl, 0.8%),
(M-C2H2OS, 8.7%), (M-C2H3OS, 5.1%), (M-C2H4OS, 26.8%), (M-
C2H5OSCl, 10%), (M-C2H4OCl, 13.3%).
Thioacetate acid S-(2-chloro-cyclohexyl-ethyl) ester (3b). Colorless
oil. IR (neat) ꢀ 2925, 2870, 1700, 1450, 1360, 1270, 1238, 1225, 1215,
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1130, 1010. H NMR (CDCl3) ꢁ: 3.95 (1H, m), 3.7 (IH, m), 2.3 (3H, s),
2.15–2.34 (2H, m), 1.75–1.82 (2H, m), 1.41–1.55 (4H, m). 13C NMR
(CDCl3) ꢁ: 194.4, 61.6, 48.95, 34.9, 31.5, 31.1, 24.7, 23.6. MS (70 eV);
(M, 2.8%), (M þ 2, 1%), (M-Cl, 1.2%), (M-HCl, 3.4%), (M-C2H4O5,
12.3%), (M-C2H3OCl, 2.3%), (M-C3H4OSCl, 2.3%), (M-C3H5OSCl,
29.6%), (M-C3H6OSCl, 14.6%).
Thioacetate acid S-(2-chloro-hexyl) ester (3d). Colorless oil. IR (neat)
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ꢀ 2970, 2945, 2890, 2875, 1750, 1710, 1475, 1362, 1240, 1140. H NMR
(CDCl3) ꢁ: 3.7 (2H, m), 3.25 (IH, m), 2.3 (3H, s), 1.8–1.3 (6H, m), 0.9
(3H, t). 13C NMR (CDCl3) ꢁ: 195.4, 61.8, 48.1, 37.2, 30.9, 29.1, 22.7, 14.3.
MS (70 eV): (M, 0.1%), (M-HCl, 0.1%), (M-C2H3OS, 0.3%),
(M-C2H4OS, 0.3%), (M-C2H4OSCl, 0.9%).
Thioacetate acid S-(1-allyloxymethyl-2-chloro-ethyl) ester (2c).
Colorless oil. IR (neat) ꢀ 3090, 2995, 2885, 1700, 1435, 1360, 1240,
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1130. H NMR (CDCl3) ꢁ: 5.87 (1H, m), 5.21 (2H, dd), 4 (3H, m), 3.75
(2H), 3.6 (2H, m), 2.3 (3H). 13C NMR (CDCl3) ꢁ: 194.5, 134.6, 117.8,
72.6, 68.4, 45.4, 44.4, 30.9. MS (70 eV): (M, 1%), (M þ 2, 0.4%), (M-HCl,