Reaction of .LAMBDA.3-Vinyliodanes. Generation and Alkylidene-Transfer of Monocarbonyl Iodonium Ylides.

Abstract

This review summarizes the generation and characterization of monocarbonyl iodonium ylides and their alkylidene-transfer reactions to aldehydes and activated imines. Exposure of Z- (2-acetoxy-l-alkenyl) -λ3-iodanes, prepared stereoselectively by sodium acetate-catalyzed Michael addition of acetic acid to 1-alkynyl-λ3-iodanes, to EtOLi in THE at 78 °C results in ester exchange to generate the labile monocarbonyl iodonium ylides with the liberation of ethyl acetate. The monocarbonyl iodonium ylide acts as an alkylidene-transfer agent to carbonyl compounds to give α, β-epoxy ketones with E-isomers as a major product. Reaction with activated imines affords 2-acylaziridines in good yields. The stereochemical outcome of this aziridination depends on both the activating groups of the imines and the reaction solvents. Measurement of the relative rates of these alkylidene-transfer reactions indicates that the monocarbonyl iodonium ylide is moderately nucleophilic in nature. Wittig olefination of aldehydes with Z- (2-acetoxy-l-alkenyl) -λ3-iodanes, which involves transylidation between monocarbonyl iodonium and phosphonium ylides, is also discussed.