A ruthenium complex bearing a bis(silyl)xanthene chelate ligand xantsil, i.e. Ru[κ 3 (Si,O,Si)-xantsil](CO)(PCyp 3 ) (1a, Cyp = cyclopentyl), was found to catalyze both double and single hydroboration reactions of nitriles with pinacolborane (HBpin) and 9-borabicyclo[3.3.1]nonane (9-BBN) to give bis(boryl)amines 2 and N-borylimines 3, respectively, in mostly >99% yields. By combination of these reactions with subsequent palladium-catalyzed deborylative C−N coupling reactions of 2 and 3 with a 1:1 mixture of bromoarenes and KO t Bu, one-pot synthetic routes to tertiary N,N-diarylamines 4 and Narylaldimines 5 from nitriles were developed.

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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{κ 3 (Si,O,Si)-xantsil}-(CO)(PR 3 ) (R = NC 4 H 8 (1-Pyrr), NC 5 H 10 (1-Pip); xantsil = (9,9dimethylxanthene-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(NC 4 H 8 ) 3 and hydrosilane HSiMe(OSiMe 3 ) 2 having moderately bulky and electron withdrawing substituents.

Ruthenium complexes bearing a xanthene-based bis­(silyl) chelate ligand, “xantsil” ((9,9-dimethylxanthene-4,5-diyl)­bis­(dimethylsilyl)), Ru­{κ3(Si,O,Si)-xantsil}­(CO)­(PR3) (1-Cy: R = Cy (cyclohexyl), 1-Cyp: R = Cyp (cyclopentyl)), were found to catalyze the reactions of internal arylalkynes with tertiary silanes (1–1.3 equiv) at a moderate temperature (room temperature to 70 °C) to give (E)-alkenes having an ortho-silylated aryl group, i.e., (E)-R1C­(H)C­(H)­(C6H3-o-SiR3 3-p-R2). These catalytic reactions involve a unique ortho-selective C–H silylation of an aryl group in arylalkynes accompanied by hydrogenation of their C–C triple bonds (ortho-C–H silylation/hydrogenation). Importantly, in these reactions, the alkynyl moiety of arylalkynes serves as both a directing group and a hydrogen acceptor. The substrate scope of this ortho-C–H silylation/hydrogenation was explored by use of eight combinations of arylalkynes and tertiary silanes. In cases using bulky substrates, the catalytic performance of 1-Cyp with a relatively less bulky phosphine ligand (PCyp3) was shown to be superior to that of the PCy3 analogue 1-Cy.

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