Organocatalyzed Annulation Cascade toward Asymmetric Functionalization of Dibenzoxazepines and Dibenzothiazepines with Vicinal Tertiary Stereogenic Centers

摘要

An efficient organocatalyzed annulation cascade has been established for the stereoselective functionalization of dibenzoxazepine and dibenzothiazepine scaffolds. The protocol used ready-stock proline as a catalyst and a variety biologically important oxa/thiazepine based polycyclic frameworks featuring congested chiral vicinal tertiary centers were obtained in high yields and excellent diastereoselectivities (>20:1 dr) and enantioselectivities (>96:4 er). Synthetic utility was showcased through the gram-scale reaction and diverse derivatization sequences.