Synthetic studies of vitamin D3 analogues from bile acids. Part 2. Syntheses of cholesta-1,4-dien- and -1,4,6-trien-3-ones having a 24-and/or 25-hydroxylated side chain from lithocholic acid

Abstract

Syntheses of 3α-hydroxy-5β-cholestanes having a 25-, 24R-, or 24S-hydroxy group [(13), (6a and b)] or a 24,25-dihydroxy group [(14)] from lithocholic acid (1) are described. These hydroxylated cholestanes were converted to the 1,4-dien-3-ones (15), (10a and b), and (16), and then to the 1,4,6-trien-3-ones (18), (11a and b), and (19) by normal dehydrogenation procedures without affecting the side chains.