Hydrosilylation of unsaturated compounds with 5-dimethylsilylfurfural diethyl acetal

Hydrosilylation of terminal acetylenes, HC≡CR (R = CMe₃,n-C₇H₁₅, SiMe₃, Ph, COOEt, CH₂N(CH₂)₄, and CH₂N(CH₂)₅) with 5-dimethylsilylfurfural diethyl acetal (1) gives a mixture of products of bothtrans-β- and α-addition. When R = CMe₃ or SiMe₃, the reaction proceeds regio- and stereospecifically to give only thetrans-β-derivatives. The formation of β-adducts is favored by pronounced electron-donating substituents and steric hindrance at the C_α atom. Terminal alkenes, H₂C=CHR (R = CH₂CN, CH₂N(CH₂)₄, CH₂N(CH₂)₅, SiMe₃, SiMe(α-furyl)₂, SiMe₂(α-furyl), SiMe₂(α-thienyl), and SiMe₂(5-chloro-2-thienyl)), react with silane1 to give only the products of β-addition; the reaction of1 with H₂C=CHCH₂NHC₆H₁₃-n affords a mixture of β- and α-adducts in a ratio of 1.8∶1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1784–1788, October, 1993.