Hydroformylation of vinylsilanes with Rh(acac) (CO)(2)/tris(N-pyrrolyl)phosphine catalytic system

Rh(acac)(CO)(2) as catalyst precursor with a small excess of free N-pyrroly lphosphine ([P(NC4H4)]:[Rh] = 3-10) was found to be very active in hydrofor mylation of vinyltrisubstituted silanes at 80 degrees C and 10 atm CO/H-2 = 1. After 2 h the yields of aldehydes were 80 % (n/iso = 8) for vinyltrimet hylsilane, 100 % (only n-isomer) for vinyldimethylphenylsilane and 95% (n/i so = 5.5) for vinyltrimethoxysilane. The rate of hydroformylation of vinylt rimethylsilane is ca. three times higher than that: of other vinylsilanes. 3,3-Dimethyl-1-butene undergoes hydroformylation much slower than vinyltrim ethylsilane probably because of its high steric hindrance and the reaction produces 4,4-dimethylpentanal as the only product. (C) Academie des science s/Elsevier, Paris.