Asymmetric synthesis of 2,3-methanoleucine stereoisomers from common intermediates

2,3-Methanoamino acids are useful probes for studying the bioactive conformation of peptides and for investigating the effect of local conformational constraints on the activity of peptidomimetics. We synthesized all four stereoisomers of Cbz-protected 2, 3-methanoleucine for incorporation into peptidomimetic inhibitors of calpain. While the synthesis of 2,3-methanoamino acids has been previously reported, our procedure offers a versatile route in which the pair of diastereomers of each geometric isomer was synthesized from a common intermediate.