New hydrosilylation reaction of arylacetylene accompanied by C-H bond activation catalyzed by a xantsil ruthenium complex

Abstract

A new type of catalytic hydrosilylation of arylalkynes was induced by a 16-electron ruthenium bis(silyl) phosphine complex, resulting in ortho-silylation of the aryl group as well as a hydrogenation of the alkyne CC bond to give an (E)-form of alkene selectively. On the other hand, the same reaction using a related bis(silyl) complex having an η6-toluene ligand instead of the phosphine ligand as a catalyst led to a normal hydrosilylation reaction to afford silylalkene.

Hyperbranched Polymers Formed through Irreversible Step Polymerization of AB2‐Type Monomer in a Continuous Flow Stirred‐Tank Reactor (CSTR)

“…Note that a quite similar situation was observed in free-radical polymerization that involves chain transfer to polymer, conducted in a CSTR [22,26] and in emulsion polymerization [27][28][29] during Interval 2 in which the polymer concentration is kept constant. For these cases, the MWD follows the power law, and the MWD formed at a large operation time is essentially unchanged even when P w cannot reach the steady state, except for the high molecular weight tail.…”

“…As correctly pointed out by Friis et al, [38] a variablevolume reactor with constant composition is equivalent to a constant-volume reactor with constant composition (CSTR) at a long operation time limit, [26][27][28][29] i.e., a steadystate CSTR is equivalent to a semibatch operation with a constant composition at large operation time. Therefore, a CSTR operation with x A → 1 corresponds to the slow monomer addition process with [A] → 0.…”

Catalysis using transition metal complexes featuring main group metal and metalloid compounds as supporting ligands

“…The xantsil–Ru complex 77 catalyzed an unusual hydrosilylation reaction of arylacetylenes with silane, in which ortho -C–H silylation of the aryl moiety occurs accompanied by trans -hydrogenation of the C–C triple bond to give trans -( o -silylaryl)alkenes (Scheme 35). 77 It is proposed that one of the silyl ligands fluxionally dissociates from Ru after oxidative addition of a C–H bond and reforms after the formation of the product during the reaction. Slight modification of the substituents on the phosphorus ligand switched the reaction pathway to tandem hydrosilylation/C–H silylation of alkynes to give bis(silylated) stilbene derivatives.…”

Synthesis of Ruthenium Complexes with a Nonspectator Si,O,P-Chelate Ligand: Interconversion between a Hydrido(η2-silane) Complex and a Silyl Complex Leading to Catalytic Alkene Hydrogenation

“…We have previously reported the synthesis and reactions of metal complexes bearing a bis­(silyl) chelate ligand, xantsil, in which two silyl ligand moieties are connected by a xanthene backbone . Along the same lines, we aimed at developing an unsymmetrical chelate ligand with silicon- and phosphorus-coordinating moieties on this backbone.…”