Stereoselective Synthesis of β-Lactones and Aldehyde Olefination with Ketene

Significance

The authors report herein an interesting method for E-stereoselective aldehyde olefination, based on the reaction of an aldehyde with a ketene. The reaction is catalyzed by a new salen-quinine mixed catalyst and, depending on the used metal, gives in high yields either an alkene or a β-lactone with almost 100% enantioselectivity, even with the low catalyst loading. This is one of the first reports concerning the new promising type of chiral catalysts, bearing both a Lewis-acidic and a Lewis-basic function.