Platinum complex-catalyzed hydrosilylation and isomerization of methylenecyclopropane derivatives. Effect of structures of the substrate and catalyst.
PtI(2)(PPh(3))(2) catalyzes hydrosilylation of 2,2-diphenyl-1-methylenecyclopropane with HSiEt(3), HSiPh(3), HSiEt(2)Ph, HSiPhCl(2), and HSiCl(3) under solvent-free conditions at 140 degrees C to produce the silyl compounds with a (2,2-diphenylcyclopropyl)methyl substituent in moderate to high yields without ring-opening of the substrate. PtI(2)(PPh(3))(2) is converted by the reaction into PtH(I)(PPh(3))(2), which also catalyzes the hydrosilylation of the methylenecyclopropanes. The reaction of 2-phenyl-1-methylenecyclopropane, 2-methyl-2-phenyl-1-methylenecyclopropane, 2,2-diphenethyl-1-methylenecyclopropane, and alkylidenecyclopropanes with HSiEt(3) catalyzed by PtI(2)(PPh(3))(2) causes addition of hydrosilane to the substrate accompanied by ring-opening. 2,2-Diphenyl-1-methylenecyclopropane undergoes ring-opening isomerization in the presence of HSi(OEt)Me(2) and Pt(PEt(3))(3) catalyst to give 1,1-diphenyl-1,3-butadiene. The pathways for the hydrosilylation and the isomerization are discussed.