Palladium Catalyzed Reaction of Silacyclobutanes with Acetylenes

Whereas the reaction of 1,1-dimethyl-1-silacyclobutane (1a) with dimethyl acetylenedicarboxylate in the presence of Pd catalyst provides dimethyl 1,1-dimethyl-1-sila-2-cyclohexene-2,3-dicarboxylate almost exclusively, the reaction of 1a with phenylacetylene affords allyldimethylstyrylsilane as a major product. The reaction of silacyclobutane with phenylallene provided three isomeric products.