Enantioselective Processes. Reaction of Optically Active Amines with Photochemically Generated Ketenes

Article abstract of DOI:10.1021/jo00200a038

The diastereoselectivity of the reaction of d- and l-ephedrine with ketenes photochemically generated from 6-(2-oxopropyl)-2,4,6-trimethyl-2,4-cyclohexadien-1-one (1a), 6-(2-oxopropyl)-2,6-dimethyl-2,4-cyclohexadien-1-one (1b), and 6-acetoxy-2,4,6-trimethyl-2,4-cyclohexadien-1-one (3a) is described.Configurational assignments at C(2) in the major products 5a and 6 resulting from irradiation of 1a in the presence of d-ephedrine and l-ephedrine, respectively, were made by chemical degradation and correlation studies with (S)-(+)-3-hydroxy-2-methylpropanoic acid (7a).