Solvent-modulated Pd/C-catalyzed deprotection of silyl ethers and chemoselective hydrogenation
摘要:
Recently we have reported undesirable and frequent deprotection of the TBDMS protective group of a variety of hydroxyl functions occurred under neutral and mild hydrogenation conditions using 10% Pd/C in MeOH. The deprotection of silyl ethers is susceptible to significant solvent effect. TBDMS and TES protecting groups were selectively cleaved in the presence of acid-sensitive functional groups such as TIPS ether, TBDPS ether and dimethyl acetal under hydrogenation condition using 10% Pd/C in MeOH. In contrast, chemoselective hydrogenation of reducible functional groups such as acetylene, olefin and benzyl ether, proceeds in the presence of TBDMS or TES ethers in AcOEt or MeCN. (C) 2004 Elsevier Ltd. All rights reserved.
Ruthenium catalyzed selective hydrosilylation of aldehydes
作者:Basujit Chatterjee、Chidambaram Gunanathan
DOI:10.1039/c3cc47593j
日期:——
A chemoselective hydrosilylation method for aldehydes is developed using a ruthenium catalyst [(Ru(p-cymene)Cl2)2] and triethylsilane; a mono hydride bridged dinuclear complex [(η6-p-cymene)RuCl}2(μ-H-μ-Cl)] and a Ru(IV) mononuclear dihydride complex [(η6-p-cymene)Ru(H)2(SiEt3)2] are identified as potential intermediates in the reaction and the proposed catalytic cycle involves a 1,3-hydride migration.
A remarkable solvent effect toward the Pd/C-catalyzed cleavage of silyl ethersElectronic supplementary information (ESI) available: characterization data and references and supplementary Tables 4 and 5. See http://www.rsc.org/suppdata/cc/b2/b211313a/
[reaction: see text] A gold(I) complex of Xantphos AuCl(xantphos) catalyzes the dehydrogenativesilylation of alcohols with high chemoselectivity and solvent tolerance. It is selective for the silylation of hydroxyl groups in the presence of alkenes, alkynes, alkyl halides (RCl, RBr), ketones, aldehydes, conjugated enones, esters, and carbamates.
Versatile Dehydrogenative Alcohol Silylation Catalyzed by Cu(I)−Phosphine Complex
作者:Hajime Ito、Akiko Watanabe、Masaya Sawamura
DOI:10.1021/ol050559+
日期:2005.4.1
[reaction: see text] Cu(I) complexes of xanthane-based diphosphines were versatile catalysts for dehydrogenative alcohol silylation, exhibiting high activity and broad substrate scope. Highlyselectivesilylation of 1-decanol over 2-decanol is possible even with a silylating reagent of small steric demand such as HSiMe(2)Ph or HSiEt(3).
Efficient deoxygenative silylation of C(sp3)–O bonds with hydrosilanes by supported Au catalysts is described. Goldnanoparticlessupported on TiO2 enabled various hydrosilanes to be used as sources of silyl groups in C–Si cross-coupling reactions. A variety of alkyl acetates and propargyl carbonates participated in the Au-catalyzed reactions to furnish the corresponding alkyl and allenylsilanes in
描述了负载型 Au 催化剂对 C(sp 3 )–O 键与氢硅烷的有效脱氧硅烷化。负载在 TiO 2上的金纳米粒子使各种氢硅烷能够在 C-Si 交叉偶联反应中用作甲硅烷基的来源。各种乙酸烷基酯和碳酸炔丙酯参与了金催化的反应,以高产率提供相应的烷基和烯丙基硅烷。此外,Au/TiO 2对环醚的开环甲硅烷基化也有效。详细的机理研究证实标题反应涉及甲硅烷基和烷基自由基中间体的形成,而 Au 纳米颗粒作为单电子转移催化剂与金属氧化物表面的路易斯酸位点的合作是氢硅烷异常反应性的原因特定的 C(sp 3 )–Si 键形成。