Tandem Hydrosilylation/<i>o</i>-C–H Silylation of Arylalkynes Catalyzed by Ruthenium Bis(silyl) Aminophosphine Complexes

Abstract

An unprecedented reaction via consecutive trans-selective hydrosilylation and o-C–H silylation of arylalkynes with hydrosilanes was developed by use of ruthenium complex catalysts Ru{κ3(Si,O,Si)-xantsil}(CO)(PR3) (R = NC4H8 (1-Pyrr), NC5H10 (1-Pip); xantsil = (9,9-dimethylxanthene-4,5-diyl)bis(dimethylsilyl)). This reaction proceeded with gentle heating at 40–60 °C and afforded novel 2,α-bis-silylated (Z)-stilbene or (Z)-styrene derivatives 2 together with an equimolar amount of (E)-/(Z)-arylalkenes as byproducts. The selectivity of the formation of 2 reached a maximum by employing catalyst 1-Pyrr ligated by the less bulky triaminophosphine P(NC4H8)3 and hydrosilane HSiMe(OSiMe3)2 having moderately bulky and electron withdrawing substituents.