Access to the Cinnoline Scaffold via Rhodium-Catalyzed Intermolecular Cyclization under Mild Conditions

Abstract

Herein, we report Rh(III)-catalyzed, N-amino (hydrazine)-directed C-H functionalization with α-diazo-β-ketoesters for access to the cinnoline scaffold. A diverse set of nondiscriminating conditions obtained for a highly efficient test transformation prompted use of a substrate-replacement technique for an in-depth search of experimental parameter space and pinpointing of the optimized conditions. A successive C-H activation/C-C coupling/intramolecular dehydration mechanistic sequence is proposed. The ability to perform gram-scale synthesis proves the synthetic utility of this simple, yet efficient, method.