Synthesis and Characterization of 2-Carboxyethyltriphenyl Phosphonium Tribromide and its Application as Catalyst in Silylation of Alcohols and Thiols under Solvent Free Condition (original) (raw)
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Chinese Journal of Catalysis, 2008
Many primary, secondary, tertiary alcohols, and phenolic hydroxyl groups were effectively converted to their corresponding trimethylsilyl ethers using hexamethyldisilazane in the presence of catalytic amounts of tribromoisocyanuric acid and DABCO-bromine under mild conditions at room temperature with short reaction times in good to excellent yields. Excellent chemoselective silylation of hydroxyl groups in the presence of other functional groups were also observed.
Synthesis, 2005
Various types of carbonyl compounds are efficiently converted to their 1,3-dioxanes and pentaerythritol diacetals by the use of either 1,3-bistrimethylsiloxy propane (A) or 1,3-bistrimethylsilanyloxy-2,2-bistrimethylsilanyloxymethyl propane (D) and a catalytic amount of N-bromosuccinimide (3-10 mol%) under essentially neutral aprotic condition, respectively. A variety of functionalities such as both aliphatic and phenolic-OTBDMS,-OMe,-OBz, furan ring, double bonds and more significantly phenolic-OTHP survived under the present reaction condition. The efficient conversion of two a-tertiary ketones to their cyclic acetals was also achieved using the present protocol.
Chemistry (Weinheim an der Bergstrasse, Germany), 2015
The electrophilic phosphonium salt, [(C6 F5 )3 PF][B(C6 F5 )4 ], catalyses the efficient hydrosilylation of ketones, imines and nitriles at room temperature. In the presence of this catalyst, adding one equivalent of hydrosilane to a nitrile yields a silylimine product, whereas adding a second equivalent produces the corresponding disilylamine. [(C6 F5 )3 PCl][B(C6 F5 )4 ] and [(C6 F5 )3 PBr][B(C6 F5 )4 ] are also synthesised and tested as catalysts. Competition experiments demonstrate that the reaction exhibits selectivity for the following functional groups in order of preference: ketone>nitrile>imine>olefin. Computational studies reveal the reaction mechanism to involve initial activation of the SiH bond by its interaction with the phosphonium centre. The activated complex then acts cooperatively on the unsaturated substrate.
Inorganica Chimica Acta, 2016
The treatment of tri(p-tolyl)phosphine with 1,2-bis(bromomethyl)benzene results in (2-bromomethylbenzyl)tri(p-tolyl)phosphonium bromide. The resulted phosphonium salt reacts with palladium acetate (II) in a molar ratio of 1.5:1, respectively, to give [(CH 3 C 6 H 4) 3 PCH 2 C 6 H 4 CH 2 OC(O)CH 3 ] 2 [Pd 2 Br 6 ], bis[(2methylacetatobenzyl)tri(p-tolyl)phosphonium]hexabromodipalladate(II), as a dark brown powder. Characterization of the obtained compound was performed by elemental analysis (CHN), IR, 1 H, 31 P, 13 C NMR and X-ray crystallography techniques. This compound was found to be an efficient catalyst for the amination of aryl halides using aqueous ammonia to produce primary amines and for Stille cross-coupling reaction to produce biphenyl and its derivatives as well. Describe catalyst showed satisfactory results and could be recovered and reused without significant loss of its catalytic activity in both reactions.
2011
1,1'-(Ethane-1,2-diyl)dipyridinium bistribromide (EDPBT) was used as a chemoselective and effective organocatalyst for the silylation of hydroxyl groups as well as desilylation of trimethylsilyl ethers under mild conditions at room temperature with good to excellent yields.
Synthesis, 2006
A variety of substrates containing hydroxy groups have been protected as their corresponding trimethylsilyl ethers using 1,1,1,3,3,3-hexamethyldisilazane in the presence of indium tribromide. The catalyst indium tribromide activates the 1,1,1,3,3,3-hexamethyldisilazane and accelerates the reaction under mild reaction conditions at room temperature.