Asymmetric synthesis of anti-1,2-amino alcohols via the Borono-Mannich reaction: a formal synthesis of (-)-swainsonine

Chiral α-hydroxy-aldehydes generated in situ by the ADH reaction of vinyl sulfones undergo a borono-Mannich reaction with β-styrenyl boronic acid and primary amines to give anti-1,2-amino alcohols in high enantiomeric purities (ee 83-95%). This new method allows much more rapid access to these valuable chiral building blocks that has been used in a short formal synthesis (10 synthetic steps from 4-penten-1-ol) of (-)-swainsonine.