Concise synthetic strategy toward cyclic α,α-disubstituted α-amino acids bearing a δ-nitrogen atom: chiral 1-substituted 4-aminopiperidine-4-carboxylic acids

A concise synthetic strategy toward cyclic α,α-disubstituted α-amino acids, 1-substituted 4-aminopiperidine-4-carboxylic acids have been developed. The synthetic route is a reductive amination of dimethyl bis(dioxolanemethyl)malonate with various amines, followed by Curtius rearrangement. This synthetic route is capable of synthesizing 4-aminopiperidine-4-carboxylic acids bearing a bulky substituent and optically active ones bearing a pendent chiral substituent, by the change of condensed amines.