Asymmetric Hydrogenation oftert-Alkyl Ketones

摘要: A combined system of RuCl2(tolbinap)(pica) and an alkaline or organic phosphazene base catalyzes asymmetric hydrogenation sterically congested tert-alkyl ketones (TolBINAP = 2,2'-bis(di-4-tolylphosphino)-1,1'-binaphthyl, PICA alpha-picolylamine). Hydrogenation with RuH(eta1-BH4)(tolbinap)(pica) does not require any strong base. Alcoholic solvents strongly affect the catalytic efficiency. The reaction proceeds smoothly in ethanol under 1-20 atm H2 at room temperature a substrate to catalyst molar ratio up 100 000. Various aliphatic, aromatic, heteroaromatic, olefinic are convertible corresponding chiral carbinols high enantiomeric purity. Olefinic heteroaromatic functions left intact. Certain cyclic also usable. mode enantioface selection is consistent predictable.