Coupling of beta-cyanocarbene-chromium complexes with 2-alkynylbenzoyl derivatives: A [5+5]-cycloaddition approach to phenanthridines

摘要

The coupling of beta-cyanocarbene complexes and 2-alkynylbenzoyl derivatives has been examined. The reaction afforded phenanthridine derivatives in a complex tandem process involving carbene-alkyne coupling, isobenzofuran formation, intramolecular Diels-Alder reaction using a nitrite dienopbile, and deoxygenation. The chemistry could not be reproduced in non-chromium-based systems.