Efficient Palladium-Catalyzed Aerobic Arylative Carbocyclization of Enallenynes

Abstract

Herein, we communicate a selective and efficient protocol for oxidative arylating carbocyclization of enallenynes using O2 as the oxidant. The key to success for this aerobic transformation is the application of a specific electron transfer mediator (ETM), a bifunctional catalyst consisting of a metal-macrocycle and quinone moieties. This catalyst significantly facilitates the reoxidation of Pd0 to PdII under atmospheric pressure of O2. Diverse functionalized enallenynes react with aryl boronic acids to afford the corresponding cyclic tetraenes in moderate to good yields.