反应详情

To the Compound 1b (1.0 mmol) in Chloroform (10 ml) was added titanium tetrachloride (1.1 mmol) under nitrogen at ambient temperature. After 3 hours, the solvent was removed in vacuo and the residue flash chromatographed on silica gel eluted with hexane:diethyl ether (1:2) to afford the desired product. The β-isomer was a white solid (Rf =0.4, m.p. 104.5°-105.5° C.). The α-isomer was a white solid (Rf =0.3, m.p. 160°-161.5° C.).

1. customthe solvent was removed in vacuo
2. customthe residue flash chromatographed on silica gel
3. washeluted with hexane:diethyl ether (1:2)