The Generation of Allyllithium Reagents by Lithium-Tetrahydrofuran Reduction of Allylic Mesitoates. a New Procedure for Selective Allylic Cross Coupling and Allylcarbinol Synthesis

A variety of allylic mesitoates undergo alkyl-oxygen fission upon reduction by lithium metal in tetrahydrofuran at 0°. The allylic organolithium thus generated is sufficiently stable to undergo reactions with electrophilic species present in situ. In situ reaction with allylic bromides produces fair to excellent yields of 1,5-dienes in a cross-coupling reaction that is considerably more selective than Wurtz-type procedures, in regard to crossed nature and retention of double bond position and geometry. In situ reaction with aldehydes and ketones gives moderate to good yields of allylic carbinols, and has been used to synthesize a component of the Ips confusus pheromone. Both reactions are convenient and possess certain advantages over other currently available methods.