Abstract An efficient method for the preparation of 4β-and 6α-hydroxylated bile acids has been developed. It involved a highly stereoselective acetoxylation at the 4β and 6α positions of 3-and 7-oxo bile acids, respectively, with lead tetraacetate in the presence of boron trifluoride etherate in acetic acid. Reduction of the resulting α-acetoxy ketones with sodium borohydride or tert-butylamine borane complex, and alkaline hydrolysis, provided the ...