Formal highly enantioselective organocatalytic addition of fluoromethyl anion to α,β-unsaturated aldehydes

The first organocatalytic enantioselective fluoro(bis-phenlsulfonyl) methylation of α-β-unsaturated aldehydes in high yields and enantioselective fluoro(bis-phenylsulfonyl) methylation of α-β- unsaturated aldehydes in high yields and enantioselectivity was investigated. Compounds 3 a, 3 b, and 3 c were reduced with sodium borohydride to afford the corresponding alcohols 4, and then treated with Mg in methanol for the removal of sulfonyl groups. It was decided to prepare more derivatives such as esters or amines in order to expand the utility of the reaction. Compound 3d was easily oxidized by known procedures to acid 7d in quantitative yield, after treatment with dicyclohexylcarbodiimide (DCC) and (-)-menthol this acid afforded ester 8d in moderate yield. A slight increase of enantioselectivities without appreciable loss of conversion at 4°C was found.