Dehydrogenative coupling between hydrosilanes and alkynes catalyzed by alkoxides, alkylmetals, and metalamides

The selective dehydrogenative coupling reaction between phenylsilane and ethynylbenzene occurred in the presence of some homogeneous base catalysts such as alkoxides, alkyl compounds, and the amides of alkali metals or barium. The order of the catalytic activities was Ba(OR)(2) > LiN(SiMe3)(2) similar to n-BuLi > LiOEt. Barium alkoxide showed the highest activity and selectivity for the reaction, and gave the polymer poly [(phenylsilylene)ethynylene-1,3-phenyleneethynylene] in the reaction of phenylsilane with m-diethynylbenzene. The correlation between the catalytic activities and the catalyst basicities was discussed, and a reaction mechanism involving both the metal acetylide and the metal hydride was proposed. (C) 1999 Academic Press.