HYDROSILYLATION OF UNSATURATED-COMPOUNDS WITH 5-DIMETHYLSILYLFURFURALDIETHYL ACETAL

Hydrosilylation of terminal acetylenes, HC=CR (R = CMe3, n-C7H15, SiMe 3, Ph, COOEt, CH2N(CH2)4, and CH2N(CH2)5) with 5-dimethylsilylfurfural diethyl acetal (1) gives a mixture of products of both trans-beta- an d alpha-addition. When R = CMe3 or SiMe3, the reaction proceeds regio- and stereospecifically to give only the trans-beta-derivatives. The f ormation of beta-adducts is favored by pronounced electron-donating su bstituents and steric hindrance at the Ca atom. Terminal alkenes, H2C= CHR (R = CH2CN, CH2N(CH2)4, CH2N(CH2)5, SiMe3, SiMe(alpha-furyl)2, SiM e2(alpha-furyl), SiMe2(alpha-thienyl), and SiMe2(5-chloro-2-thienyl)), react with silane 1 to give only the products of beta-addition; the r eaction of 1 with H2C=CHCH2NHC6H13-n affords a mixture of beta- and al pha-adducts in a ratio of 1.8:1.