Bile acids. LXXIX: Synthesis and reduction of 1,4-dien-3-ones of various bile acids

Abstract 1,4-Dien-3-ones of various bile acids (IIa-d), their methyl esters (IIe-h), and their formylated derivatives (IIi-k) were synthesized and their reduction investigated by both catalytic and chemical methods as an alternative route to the synthesis of allo bile acids. Lithium-ammonia reduction proved to be the better method for the reduction of these 1,4-dien-3-ones producing the 3-keto- and 3β-hydroxy-allo bile acids (Vb-d) and (VIb-d) in 66–72% yields.