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Palladium/Copper-Catalyzed Aerobic Intermolecular Cyclization of Enediyne Compounds and Alkynes: Interrupting Cycloaromatization for (4 + 2) Cross-Benzannulation

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posted on 06.08.2014, 00:00 by Fei Ling, Zexiang Li, Chenguang Zheng, Xiang Liu, Cheng Ma
A tandem coupling–ketooxygenation reaction of readily accessible enediyne–carboxylic compounds with inner alkynes has been developed that utilizes the PdCl2/CuBr2 catalytic system under an O2 atmosphere and assembles a class of isoindolinones and o-acylbenzoic acids. The two oxygen atoms are regioselectively incorporated into enediyne units at the 1- and 6-positions from atmospheric molecular oxygen and H2O, respectively, during the present process. This study uncovered a formal [4C + 2C] benzannulation–diketonization of enediynes and alkynes via a coupling and decoupling strategy.