Steroids and Walden inversion. Part LXX. Re-examination of the substitution reactions of 5α-cholestan-6α-ol

Abstract

High-pressure liquid chromatography, combined with i.r. spectroscopy and mass spectrometry, shows that treatment of 5α-cholestan-6α-ol with phosphorus pentachloride gives not only 6α- but also 6β-chloro-5α-cholestane (5 : 1), with a little cholest-5-ene and its derivative 5,6β-dichloro-5α-cholestane. The formation of both the epimeric 6-chlorides was confirmed by use of g.l.c. and of a computerised g.l.c.–mass spectral system. Treatment of 5α-cholestan-6α-ol with thionyl chloride gives only the 6α-chloride, with cholest-5-ene, its derivative 5-chloro-5α-cholestane, and traces of three unidentified products.