Catalytic Enantioselective\nAldol Reactions of Pyruvates\nas Nucleophiles with Chlorinated and Fluorinated Aldehydes and Ketones

Reactions of pyruvates as nucleophiles\nunder catalytic conditions\nare difficult to control without the use of enzymes as catalysts.\nHere, enantioselective aldol reactions of pyruvates with chlorinated\nand fluorinated aldehydes and ketones under organocatalytic conditions,\nin which pyruvates act as nucleophiles, are reported. Based on analyses\nof self-aldol reactions of pyruvates in the presence of model catalysts,\ncatalysts of the desired cross aldol reactions were developed. Using\nthe primary amine-derived catalyst, the desired aldol products, i.e.,\nγ-chlorinated alkyl or γ-fluorinated alkyl group-substituted\nγ-hydroxy α-ketoesters, were obtained in good to high\nyields with high enantioselectivities.