Syntheses by a new procedure of the known 3α,6α,7β- and 3α,6β,7β-trihydroxy-5α-cholanoic acids, and of the once-reported analog 3α,6α,7β,12α-, as well as the new 3α,6β,7β,12α-tetrahydroxy-5α-cholanoic acids, are described. Key intermediates of the syntheses are the 6-oxo-7β-ols of the respective 5α-cholanoic acids (and their methyl esters) prepared by allomerization at C-5 of appropriate 6-bromo-7-oxo derivatives of the corresponding 5β-acids. Successful reduction of the 6,7-ketols to the desired products depended on the proper choice of reagents, either Zn(BH4)2 or Li/NH3/MeOH. (Steroids 58:148-152, 1993).
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