Aldol type reaction of unprotected sugars in methanol

Article abstract of DOI:10.1016/0040-4039(94)02377-N

Although aldol condensation of 1,3-dihydroxyacetone with formaldehyde in methanol catalyzed by CaCl₂/KOH gave glycero-tetrulose, the reaction catalyzed by Ca(OH)₂ preferentially gave 1,3-dihydroxyacetone dimer. The result was explained by the formation of a chelated enolate. This sequence was successfully applied to the stereoselective synthesis of threo-3-pentulose.