Trimethylchlorosilane, effect

Trimethylsilyl iodide [16029-98-4] (TMSI) is an effective reagent for cleaving esters and ethers. The reaction of hexamethyldisilane [1450-14-2] with iodine gives quantitative conversion to TMSI. A simple mixture of trimethylchlorosilane and sodium iodide can be used in a similar way to cleave esters and ethers (8), giving silylated acids or alcohols that can be Hberated by reaction with water. 

Example 10 trimethylchlorosilane TMCS has been found an effective activator in the typical synthesis of dinucleotides in solution and its utility is comparable with that of tetrazole [34]. An example of this activation is the reaction of thymidine with tris(dimethylamino)phosphine. 

Example 33 trimethylchlorosilane (TMCS) has been found to be a highly effective activator in typical couplings leading to dinucleotides and similar biophosphates, and is comparable with tetrazole and imidazolium salts [34]. The optimal amount of this activator is below the stoichiometric ratio. 

Some researchers have tried to stabilize the MCM wall by a complete hydrofobization of the surface, replacing every silanol group with a trimethy Isi ly 1 group, using e.g. trimethylchlorosilane of hexamethyldisilazane [9], Although this treatment is very effective in se, it yields a surface that is completely unreactive towards subsequent grafting of transition metals. We therefore present a silylation procedure with dimethyldichlorosilane (DMDCS), which allows - upon hydrolysis - a recreation of surface silanols. 

The use of lithium tetramethylpiperidide (LiTMP) as the base, followed by a quench with trimethylchlorosilane, has been shown to effectively silylate iV,iV-d i meth y I amides. With two equivalents of base the reaction occurs on the same methyl group, probably because the first trimethylsilyl group favors the formation of and stabilizes the anion on the same carbon atom.136 137 The process has been extended to thiobenzamide136 and aliphatic amides.137... 

In view of the limited stability of the "carbenoid" LiCsCCb Cl, functionalization reactions have to be carried out a temperatures that are as low as possible Silylations of metallated acetylenes are usually rather slow in E12O at temperatures below -20 C. A small amount of HMPT appears to cause a considerable enhancement of the rates of silvlation with trimethylchlorosilane. It is not known whether this effect is only due to the typical properties of HMPT as a dipolar aprorir solvent (also shown in alkylation with alkyl halides) or whether it is a result of active participation of this solvent in the reaction as depicted in the following equations ... 

Reduction of an aryl halide at a cadmium-modified nickel cathode in DMF containing TBABF4 leads to a formylation reaction between aryl carbanions and the solvent [186]. Two papers [187,188] have appeared in which reduction of aryl halides gives an aryl carbanion, which, by acting as a base to deprotonate a suitable nitrile, can cause coupling of the nitrile with esters, aldehydes, and ketones. Electrochemical trimethylsilylation of aryl halides can be effected at a stainless-steel or carbon-cloth cathode in THF-HMPA containing TEABF4 and trimethylchlorosilane [189]. 

H. Yoneyama, Y. Murao, and H. Tamura, Effect of attachment of trimethylchlorosilane and polymer adsorption on stability of silicon photoelectrodes in aqueous solutions, I. Electroanal. Chem. 108, 87, 1980. 

Bis(trimethylsilyl)acetamide (1). Mol. wt. 203.44, b.p. 71-73735 mm. Prepared in 80% yield by reaction of acetamide with trimethylchlorosilane with triethylamine as catalyst, the reagent effects trimethylsilyUuion of amides, ureas, amino acids, phenols, carboxylic acids, enols. ... 

The effect of trimethylchlorosilane on the conjugate addition of organocuprates has been investigated with a,/ -unsaturated esters and amides7 in addition to the already discussed a,/ -unsaturated aldehydes and enones. 

The catalytic performance of highly siliceous ZSM-5 was greatly improved when methanol was co-fed with oxime. Thus it was further claimed that in the presence of methanol the neutral silanol was not the active site for producing s-caprolactam because they were methylated by methanol [56]. The beneficial effect of trimethylchlorosilane treatment was ascribed to reduction of amorphous sila-nols and to enhancement of hydrophobicity. The latter could facilitate the smooth desorption of the oxime [19]. 

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