Diastereo- and Enantioselective Direct Catalytic Aldol Reaction of 2-Hydroxyacetophenones with Aldehydes Promoted by a Heteropolymetallic Complex: Catalytic Asymmetric Synthesis of anti-1,2-Diols

An anti-selective direct catalytic asymmetric aldol reaction of 2-hydroxyacetophenones with aldehydes is described. The reaction is catalyzed by a heteropolymetallic complex to afford anti-alpha,beta-dihydroxy ketones as the major diastereomer with excellent enantioselectivity. The use of 2-hydroxyacetophenones bearing electron-donating groups at the phenyl moiety enabled efficient transformation of the aldol products (alpha,beta-dihydroxy ketones) into the corresponding alpha,beta-dihydroxy ester derivatives via Baeyer-Villiger oxidation. A plausible reaction mechanism is also discussed based on the stereochemistry of the products.