E–H (E = R<sub>3</sub>Si or H) bond activation by B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and heteroarenes; competitive dehydrosilylation, hydrosilylation and hydrogenation
作者:Liam D. Curless、Ewan R. Clark、Jay J. Dunsford、Michael J. Ingleson
DOI:10.1039/c3cc47372d
日期:——
Addition of R3Si–H–B(C6F5)3 to heteroarenes leads to surprisingly complex and substrate dependent mixtures due to competing dehydrosilylation, hydrosilylation and hydrogenation.
A pincer Ru(II) catalyst for the highly efficient undirected silylation of O- and S-heteroarenes with (TMSO)(2)MeSiH and Et3SiH is described, producing heteroarylsilanes with exclusive C2-regioselectivity, good functional group tolerance, and high turnover numbers (up to 1960). The synthetic utility of the silylated products is demonstrated by Pd-catalyzed Hiyama-Denmark cross-coupling under mild conditions. One-pot, two-step silylation and coupling procedures have been also developed.
Intermolecular C–H Silylation of Arenes and Heteroarenes with HSiEt<sub>3</sub>under Operationally Diverse Conditions: Neat/Stoichiometric and Acceptor/Acceptorless
作者:Kang-sang Lee、Dimitris Katsoulis、Jongwook Choi
DOI:10.1021/acscatal.5b02806
日期:2016.3.4
Efficient protocols for Rh-catalyzed intermolecular C-H silylation of unactivated arenes and heteroarenes are disclosed. The silylations are catalyzed by a Rh-complex (2 mol %) derived in situ from commercially available Rh(nbd)(2)BF4 and (S,S)-i-Pr-BPE (L3) with Et3SiH in the presence of hydrogen acceptor under either neat (excess of arene) or stoichiometric conditions. The regioselectivity is determined mainly by the steric bulk of the substituents and by the electronic effect as an ancillary factor. In addition, our preliminary result shows that the current protocol catalyzes the silylation of arenes in the absence of hydrogen acceptors.