Reagent stereocontrol in the proline‐catalyzed aldol reaction of 2,2‐dimethyl‐1,3‐dioxane‐5‐one 1 with chiral aldehydes has been investigated. Synthetically useful levels of diastereoselectivity could be achieved in reactions with acyclic chiral α‐oxy and α‐amino aldehydes in both matched and mismatched cases. By using this reaction as a key step, two medicinally relevant azasugars, 1‐deoxy‐galactonojirimycin (9) and 2,5‐dideoxy‐2,5‐imino‐d‐altritol (10), were efficiently synthesized.

A catalytic asymmetric synthesis of (+)-aza-galacto-fagomine (AGF) -the most promising compound for the pharmacological chaperone therapy of Krabbe disease -was accomplished in six steps, in 14% overall yield. The synthesis hinges on the combination of organocatalyzed aldolization and reductive hydrazination.