Selective Photocyclization of Glycine in Dipeptides

摘要

Recently we showed that the substituted glycine 1 undergoes a stereoselective photocycfeation and yields proline derivative 3. Biradical 2 is the intermediate that cyclizes via conformer 4. In this conformation the steric repulsion between the phenylgroup and the attached chiral auxiliary 5 is minimized (Ts = p-toluenesulfonyl).