Development of highly enantioselective oxazaborolidinone catalysts for the reactions of acyclic α,β-unsaturated ketones

Chiral Lewis acid catalysis for ketones is one of the active areas in enantioselective reactions to expand the scope of substrates previously limited to aldehydes and bidentate carbonyl compounds. In this account, we describe the development of new oxazaboroliditione (OXB) catalysts derived from allo-threonine for asymmetric Mukaiyama-Michael and Diels-Alder reactions of acyclic alpha,beta-unsaturated ketones. The scope of these reactions is outlined with particular emphasis on the origin of the enantioselective activation by the oxazaborolidinone catalysts.