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Group reaction with silanes

Using the metalloradical reactivity of the Rh(II)OEP (OEP = 2,3,7,8,12,13,17,18-octaethylphorphynato) dimer, the preparation of silyl rhodium complexes was achieved by the hydrogen elimination reaction with silanes I R SiH (R = R = Et, Ph R = Me, R = Ph, OEt). The Rh—Si bond length of 2.32(1) A, found when R = Et, is comparable to those in other Rh(III) complexes (Table 11). The crystal packing indicates that all the ethyl groups on the porphyrin periphery are directed toward the silyl group. Consequently, the aromatic part of one complex molecule is in contact with the aromatic part of the next molecule and the aliphatic part is in contact with the aliphatic part of the next molecule204. [Pg.2104]

Synthetic application of group-10 complexes in catalytic and stoichiometric reactions with silanes has produced a large number of interesting compounds which have been recently reviewed elsewhere231,250-253. [Pg.2117]

The poly(methyl methacrylate)s prepared in this experiment, as well as polymers formed in model reactions with silanes that contain bulky substituents (such as phenyldimethyl and diphenylmethyl groups), have predominantly syndiotactic structures identical to polymers prepared by the conventional group-transfer process. This result supports a two-step dissociative mechanism for a group-transfer process, because steric hindrance from bulky silyl groups should increase the proportion of isotactic triads in the hypothetical associative concerted propagation step. [Pg.297]

Functionally substituted benzylic, allylic, and vinylic compounds containing alkoxides, esters, ethers, nitriles, or amides can be reacted with halosilanes under Barbier conditions using HMPT to yield C- and O-silylated products, 1,2- or 1,4-addition products, as well as reductive dimers. Radical and anionic intermediates are postulated, based on SET reactions from the metal, and multiple silated species can be obtained. The use of the TMSCl-Mg-HMPT system has been extensively investigated by Galas group [85] at the University of Bordeaux, and their work has greatly advanced the science of the Barbier reaction with silanes. [Pg.420]

Two aspects of allyl anion chemistry are combined in the synthesis of bicyclic lactams by Gramain and Remuson.36 Treatment of the unsaturated alcohol 123 with BuLi initially forms the lithium alkoxide 124 and then the allyl lithium 125, possibly better represented as 125a. The proton is removed only from the methyl group rather then the internal CH2 group. Reaction with Me3SiCl and careful acidic workup gives the allyl silane 126. [Pg.181]

The surface of silica particles has many exposed silanol —OH groups which are known to imdergo facile reaction with silanes contained —Si(OR), —Si(Cl), and —Si(H) units, and with acyl or sul-fonyl acid chloride functional groups [31,32]. Thus, preparation of the desired derivatized silica particles was easily accomplished by refluxing sihca in a nonhydroxyhc solvent with excess ti receptor reagents such as 3,5- or 2,4-dinitrobenzoyl or dinitrobenzenesulfonyl chloride. This... [Pg.823]

Morken and coworkers [39b] developed the first asymmetric reductive aldol reaction with silanes as reductants in combination with a chiral rhodium catalyst. a,P-Unsaturated esters were reacted with several aldehydes to provide the corresponding aldol products 79 in good yields and enantio- and diastereoselectivities (Scheme 8.23). Both aliphatic and aromatic aldehydes could be converted into aldol products 79 under these conditions. Furthermore, the group reported an iridium-catalyzed asymmetric version that tolerated various protected hydroxyaldehydes [39aj. On the basis of this precedence, a highly enantio- and diastereoselective... [Pg.287]

The starch polymer consists of two important functional groups -OH group, which undergoes substitution reaction, and C-O-C bond, which undergoes breakage of chain. The hydroxyl group is nucleophilic and is modified for various properties. For example, reaction with silane improves its dispersion in... [Pg.634]

The Houk group reported a theoretieal study of the Ni-catalyzed alkyne-aldehyde reductive coupling reactions with silane as reducting agent. They showed that the selectivity of the [5+2] cycloaddition is controlled by the anisotropic steric environment of the NHC ligands. [Pg.424]

Titanocene derivatives catalyze reductive cyclization of an alkene with a hetero-atom-containing functional group and the cleavage of the titanium-oxygen bond in these metallacycles was promoted by reaction with silanes, with concomitant formation of Ti-H and Si-O bonds via a <7-bond metathesis process (Scheme 12.45) [65],... [Pg.525]

The organofunctional group (R) in the coupling agent causes the reaction with the polymer. This could be a copolymerization and/or the formation of an interpenetrating network. This curing reaction of a silane-treated substrate enhances the wetting by the resin (Table 9). [Pg.798]

The polymerization reaction of silanes with Cp2ZrMe2 as catalyst has also been investigated by several research groups. Some evidence for a reaction mechanism proceeding through silylene complexes as intermediates has been given... [Pg.31]

A similar elimination in which the tin is attacked by fluoride anions (cf. the reaction of silanes with F ) has been used179 to synthesize terminal methylene compounds as in equation (75). An analogous reaction sequence using a trimethylsilyl group in place of the trialkyltin group has been published by Hsiao and Shechter180 as part of a synthesis of substituted 1,3-butadienes. [Pg.955]


See other pages where Group reaction with silanes is mentioned: [Pg.41]    [Pg.41]    [Pg.1825]    [Pg.54]    [Pg.129]    [Pg.306]    [Pg.540]    [Pg.49]    [Pg.835]    [Pg.895]    [Pg.373]    [Pg.181]    [Pg.414]    [Pg.31]    [Pg.1825]    [Pg.204]    [Pg.425]    [Pg.68]    [Pg.440]    [Pg.287]    [Pg.410]    [Pg.418]    [Pg.428]    [Pg.691]    [Pg.753]    [Pg.825]    [Pg.603]    [Pg.118]    [Pg.535]    [Pg.220]    [Pg.846]   
See also in sourсe #XX -- [ Pg.66 ]




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Reactions with silanes

Silane, reaction

Silanes reactions

Silanization reaction

With silane

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