Asymmetric Aldol Reaction Using New Bispidine Catalysts

Significance

New organocatalysts, derived from the covalent attachment of the bispidine framework with different α-amino acids, are shown to be very effective in the direct aldol reaction between acetone and functionalized ketones. The substrate scope includes α-keto esters, α-keto phosphonates and α,α-dialkoxy ketones. The best results were achieved with catalyst 1 and formic acid as cocatalyst in a 1:1 ratio. With catalyst loadings ranging from 5 to 30 mol% the desired aldol products were obtained in moderate to high yields and excellent enantioselectivities (er = 91:9 to 99:1).