Intramolecular Umpolung Synthesis of Exocyclic β‑Amino Alcohols through Decarboxylative Amination

An intramolecular
aminative Umpolung cyclization strategy has been
developed by using α,α-diphenylglycine (2) as the amination and Umpolung reagent. Aldehydes (1) bearing an additional carbonyl group underwent condensation with
α,α-diphenylglycine to form an imine, decarboxylation
to generate a delocalized 2-azaallylanion, and subsequent intramolecular
Umpolung cyclization to produce a variety of exocyclic β-amino
alcohols (6) in 60–93% yields with up to >20:1
trans/cis selectivity under mild conditions.