Synthesis of (R)- and (S)-4-hydroxyisophorone by ruthenium-catalyzed asymmetric transfer hydrogenation of ketoisophorone

The first synthesis of (R)- and (S)-4-hydroxyisophorone by catalytic transf er hydrogenation of keto-isophorone is reported. Ruthenium catalysts contai ning commercially available chiral amino alcohols afforded 4-hydroxyisophor one in up to 97% selectivity and 97% ee. (R)- or (S)-4-Hydroxyisophorones w ith >99% ee were isolated by crystallization. The catalyst precursors [RuCl 2((S,R)-ADPE)(eta(6)-p-cymene)] ((S,R)-ADPE = (1S,2R)-amino-1,2-diphenyleth anol-N) and (R-Ru)-[RuCl((s,R)-ADPE(-1))(eta(6)-p-cymene)] (ADPE(-1) = amin o-1,2-diphenylethanolato-N,O) were isolated for the first time and the X-ra y crystal structure of the latter determined. (C) 2000 Elsevier Science Ltd . All rights reserved.