Dual Au/Ag Catalyzed Regiospecific Intramolecular Hydroacyloxylation and Hydroalkoxylation of Unactivated Geminal-Substituted Olefins.

Abstract

A mild, regiospecific Gold-Silver bimetallic catalytic system has been devised for the intramolecular hydroacyloxylation and hydroetherification of alkenoic acids and alcohols. This method exhibits precise specificity for the geminal substituted olefinic center and facilitates the synthesis of substituted phthalide and hydroisocoumarin derivatives. This method has been effectively applied for late-state functionalization to produce bioactive natural products such as rumphellaone A, mycophenolate, and (-)-ambrox. The successful gram-scale synthesis of the anticonvulsant, hypnotic drug (±)-ethyl phenyl butyro lactone (EPBL), (±)-Boivinianin A and the ability to synthesize challenging spiro and bicyclic lactone underscores the synthetic potential of this methodology. Mechanistic insights into gold-silver catalyzed lactonization of olefins have also been discussed.