Ruthenium-catalyzed hydrosilylation of terminal alkynes:: stereodivergent synthesis of (E)- and (Z)-alkenylsilanes

Stereodivergent hydrosilylation of terminal alkynes (RCequivalent toCH; R = Ph, p-tolyl, Cy, n-hexyl) with hydrosilanes (HSiMe2Ar; Arequivalent toPh, 3.5-(CF3)(2)C6H3, 4-CFC3H4, 4-MeOC6H4) has been examined using ruthenium catalysts. (E)-selective reactions giving (E)-RCH=CHSiMe2Ar proceed in over 99% selectivity in the presence of a catalytic amount of RuHCl(CO)(PPh3)(3). On the other hand, (Z)-selective reactions are successfully conducted in 91-99% selectivity by using Ru(SiMe2Ph)Cl(CO)(PPr'(3))(2) as the catalyst. All reactions readily proceed at room temperature in high yields. (E)- and (Z)-styrylsilanes having a SiMe2[C6H3-3,5-(CF3)(2)] group serve as good cross-coupling reagents with p-iodotoluene in the presence of tetrabutylammonium. fluoride and [Pd(eta(3)-al-lyl)Cl](2) catalyst. (C) 2002 Elsevier Science B.V. All rights reserved.