Oxidant-Controlled Divergent Syntheses of Pyrazoles and Pyrroles by Copper(I)-Catalyzed Oxidative Coupling of beta-Enamino Esters

Abstract

Copper(I)-catalyzed oxidative annulations of beta-enamino esters with oxidant dependence are disclosed. These reactions offer divergent syntheses of fully substituted pyrazoles and pyrroles from a common enamine substrate through sequential C-C and N-N or C-N bond-forming reactions in the presence of nitriles as reagent or cosolvent. A mechanism involving radical intermediates generated by single-electron transfer (SET) is proposed for both processes.