Highly Selective Catalytic Cross-Aldol Reactions of Chloral with Aliphatic Aldehydes

An efficient synthetic method for (beta)-trichloromethyl-(beta)-hydroxy aldehydes is described. Using piperidine or l-prolinamide as the catalyst, direct cross-aldol reactions of chloral with aliphatic aldehydes occur smoothly at room temperature. The cross-aldol condensation products are isolated in high yields (up to 95%), and a moderate to high enantioselectivity (up to 88% ee) is observed in the case of l-prolinamide.