Stereoselectivity in the Triose Aldol Condensation and the Aldol Condensation Between Glyceraldehyde and Glycolaldehyde

Hydroxides of various alkali and alkaline earth metals have been investigated as catalysts in the triose aldol condensation and the aldol condensation between glyceraldehyde and glycolaldehyde. The proportions of diastereomers are very similar in the different product mixtures. Mechanistic models, previously suggested for other aldol condensations, have been considered for the reaction, and the observed diastereoselectivity is in accordance with a pericyclic transition state formed from a cis-enediolate-attack on the aldehyde.