Synthesis of racemic δ,δ-dimethylproline derivatives

Abstract

A versatile methodology for the preparation of racemic δ,δ- dimethylproline derivatives has been developed. Methyl N-Boc-δ,δ- dimethylprolinate was synthesized from a β-amino acid in six steps and 55 % overall yield. The route is amenable to the preparation of a broad range of δ,δ-disubstituted prolines by starting with the adequate β-amino acids. In addition, one of the intermediate compounds in the synthetic route has been used for the preparation of a δ,δ- dimethylproline derivative that is substituted at the β-position with a phenyl group. This has been achieved by coupling phenylboronic acid with a regioselectively generated vinyl triflate followed by a stereoselective hydrogenation. δ,δ-Dimethylproline derivatives have been efficiently synthesized by employing a β-amino acid as the starting material. The methodology is amenable to the preparation of other δ,δ- disubstituted prolines. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.