Practical, Modular, and General Synthesis of 3-Coumaranones through Gold-Catalyzed Intermolecular Alkyne Oxidation Strategy

A gold-catalyzed intermolecular alkyne oxidation for the preparation of 3-coumaranones has been developed. Using 8-isopropylquinoline N-oxides as oxidants, the reactions of o-ethynylanisoles afford versatile 3-coumaranones in moderate to good isolated yields. The synthetic utility of this chemistry is also indicated by the synthesis of the natural product sulfuretin.