An efficient organo-catalytic, highly syn-stereoselective method for aldol additions between enolizable aldehydes and hydroxyacetone as well as dihydroxyacetone is disclosed. Reactions proceed in the presence of tertiary amines at room temperature. The aldol adducts can be obtained in good to high yields and with high degrees of syn-diastereoselectivity. This new aldol reaction provides an operationally simple protocol for the stereocontrolled synthesis of carbohydrates