The Noyori-type (1S,2S)- and (1R,2R)-N-(para-tosyl)-1,2-diphenylethylene-1,2-diamine ligands complexed with ruthenium have been found to be effective catalysts for the regiospecific transfer hydrogenation of 3-methoxy- and 3-benzyloxy-(Z)16-hydroxymethylidene-13α-estra-1,3,5(10)-trien-17-ones to 3-methoxy- and 3-benzyloxy-16-hydroxymethyl-13α-estra-1,3,5(10)-trien-17-one diastereomers. The ratio of the diastereomers depends on the catalyst used. Further reduction of the isolated products with NaBH4 in the presence of cerium(III) chloride (Luche reduction conditions) yielded the corresponding diols. In contrast to the previous preparation methods, this two-step simple hydrogenation/reduction protocol afforded all four possible isomers in almost equal amounts.
- Asymmetric catalysis
- Transfer hydrogenation
ASJC Scopus subject areas
- Physical and Theoretical Chemistry