Completely selective synthesis of (E)-β-(triethylsilyl) styrenes by Fe₃(CO)₁₂-catalyzed reaction of styrenes with triethylsilane

Using Fe₃(CO)₁₂ as the catalyst, the reaction of styrenes (C₆H₅CHCH₂, p-CH₃C₆H₄CHCH2, p- ClC₆H₄CHCH₂, and p-CH₃OC₆H₄CHCH₂) with triethyisilane gave (E)-β-(triethylsilyl)styrenes (2a, (E)-C₆H₅CHCHSiEt₃; 2b, (E)-p-CH₃C₆H₄CHCHSiEt₃; 2c, (E)-p-ClC ₆H₄CHCHSiEt₃; 2d, (E)-p-CH₃OC₆H₄CHCHSiEt₃) in 66-89% yields with complete selectivity. Similarly, Fe₂(CO)₉ also catalyzed dehydrogenative silylation again, with complete selectivity but in low yields. The reaction of styrene with treithylsilane, catalysed by OS₃(CO)₁₂, gave a mixture of the corresponding vinylsilane (dehydrogenative silylation product) and alkylsilane (hydrosilylation product).