FORMATION OF CYCLOPETANE DERIVATIVES ASSISTED USING A PALLADIUM HYDRIDE SPECIES - SYNTHESIS AND MECHANISM

In the presence of a palladium(0) complex and potassium t-butoxide, the acetylenic compounds 2 bearing in delta a nucleophilic functionality are smoothly transformed with excellent yields, either into 2,2-difunctionalized methylene cyclopentanes or into monofunctionalized 2-methylcyclopentenes. Each of these compounds can be specifically obtained depending on the choice of the experimental conditions. A set of diverse reactions involving mainly potassium hydride as the base showed clearly that HPdOtBu is not the active catalytic species which is mainly a sigma-ethynylpalladium hydride formed by the metal insertion in the acetylenic carbon hydrogen bond.