Intramolecular vs. intermolecular induction in the diastereoselective catalytic reduction of 17-oxo-steroids

Article abstract of DOI:10.1016/0957-4166(96)00211-X

The asymmetric reduction of enantiomerically pure steroid ketones was carried out by using oxazaborolidine catalysts with a variety of achiral or chiral ligands. The efficiency of chiral ligands (1,2-amino alcohols) as well as the effect of the stereogenic centers in the substrate on the catalytic asymmetric reduction were studied. It was found that the diastereoselectivity is mainly controlled by the absolute configuration of the chiral ligand. The reduction gave either the 17α- or 17β-alcohol with high diastereomeric purity. This catalytic reduction represents a very practical solution to the problem of controlling C(17)-stereochemistry in synthesis of steroid compounds.