A Short, Convenient Synthesis of Enantiomerically Pure N-Protected 2-Azanorbornane­-3-carboxaldehydes and Related Amino Alcohols

ABSTRACT The aza-Diels-Alder reaction between cyclopentadiene and the bis(1-phenylethyl)imine of glyoxal provides a short route to the two enantiomerically pure exo-diastereomers of N-(1-phenylethyl)-2-azanorbornane-3-carboxaldehyde. Addition of 1-naphthylmagnesium bromide to these aldehydes followed by reductive removal of the 1-phenylethyl group affords the corresponding amino alcohols with high diastereoselectivity. In the Pt-catalyzed hydrogenation of ethyl pyruvate, 64% ee was obtained when using these amino alcohols as modifiers.