Palladium-catalyzed coupling of vinyl triflates with organostannanes. Synthetic and mechanistic studies

The palladium-catalyzed coupling reaction of vinyl triflates with acetylenic, vinyl, allyl, and alkyl tin reagents in the presence of lithium chloride or another suitable salt takes place in high yields under mild reaction conditions; however, benzyl and phenyl tin reagents give poor yield of coupled product. The utilization of a tin or silicon hydride reagent in place of the organotin partner yields the alkene by reductive cleavage of the triflate group. The palladium-catalyzed reaction of vinyl triflates with hexamethylditin gives vinyl stannanes in high yields. Regioselectively formed vinyl triflates can be used to produce 1,3-dienes as the regioisomeric coupled products.