A short stereoselective synthesis of disubstituted cyclic amino acids

A new synthetic route to enantiomerically pure disubstituted derivatives of cyclic amino acids is reported. Key step of this synthesis is an oxidative cleavage of azabicycloalkene precursors that are synthesized in enantiomerically pure form via aza-Diels–Alder reaction. A range of different disubstituted pipecolic acid derivatives has been synthesized and their structure has been evaluated by X-ray analysis.