Catalytic,Enantioselective [4 + 2]-Cycloadditions of Ketene Enolates and o-Quinones: Efficient Entry to Chiral,alpha-Oxygenated Carboxylic Acid Derivatives

摘要

The use of chiral,catalytically derived zwitterionic "ketene" enolates has brought forth powerful methodology for the synthesis of a diverse variety of optically enriched products.Chiral ketene enolate intermediates are well-known for undergoing highly enantio-selective [2 + 2]-cycloadditions with both aldehydes and imines to produce beta-lactones and beta-lactams,respectively.