New routes to conformationally restricted peptide building blocks: A convenient preparation of bicyclic piperazinone derivatives

A facile route for the synthesis of peptide building blocks that constrain the peptide backbone with a 1,4-diazabicyclo[4.3.0]nonane ring skeleton is reported. The synthesis employed an anodic amide oxidation based approach for generating a functionalized proline derivative, and then utilized the derivative as a general substrate for rapidly assembling the bicyclic ring system.