Acyl chlorides silanes

Less reactive silyl metal species such as lithium bis(triphenylsilyl) cuprate react with a variety of acyl chlorides to give the corresponding acyl silanes in moderate to good yields75. Dilithium bis(trimethylsilyl) cyanocuprate is particularly effective for the preparation of sterically hindered acyl silanes (Scheme 8), and appears to provide a good general... 

Picard has reported more direct approaches to acyl silanes and to their silyl enol ethers by reductive silylation of substituted benzoates and of w./i-dihalo-a, /Tunsaturated acyl chlorides, respectively, using a similar reagent mixture of trimethylchlorosilane, magnesium and IIMPA96. 

The selenophene ring may be acylated by acyl chlorides under Friedel-Crafts conditions7 63 by acid anhydrides in the presence of 85% phosphoric acid64 and by organic silicoanhydrides (tetraacyloxy-silanes) in the presence of stannic chloride.65-67 When acylated by silicoanhydrides of dibasic organic acids (succinic, adipic, azelaic, or... 

In an extension of the high temperature reaction of hypervalent silanes with carboxylic acids to produce aldehydes (see Section 1.11.2), it was found that acyl chlorides reacted at room temperature with... 

Control in the selection of ring substituents is an important element of oxazole synthesis. This is a feature of a new route that employs 0-trimethylsilyl acyltrimethylsilane cyanohydrins (148), which are obtained from aldehydes or acyl silanes <92JOC333l>. These intermediates, which provide the C-5 substituent and four of the five ring atoms, are reacted sequentially with organolithium reagents (C-4 substituent) and acyl chlorides or anhydrides (C-2 substituent) to furnish, -bis(trimethylsilyl) enamines (149), which cyclize under thermal conditions or upon treatment with trimethylsilyl trilluoromethanesulfonate (Scheme 68). The range of oxazoles accessible by this method includes those with alkyl, alkenyl, phenyl, and functionalized substituents at C-2, alkyl, alkenyl, and phenyl substituents at C-4, and alkyl and phenyl substituents at C-5. The rare 4-(, -dialkylamino)oxazoles (150) may also be prepared. 

Surface oxides on graphite undergo the reactions typical of carboxylic acids, phenols and alcohols. Methylation with diazomethane or dimethylsulfate, silanization of—OH groups by reaction with halosilanes, formation of acyl chlorides by reaction with thionyl chloride, further reactions of these acyl chlorides, neutralization of acidic surface groups with different bases, ion exchange and more special reactions are used to characterize surface oxides on carbon and to modify their properties for technical applications . 

Mochalin et al modified their procedure for linking octadecylamine to NDs via amide bonds [53] to link ethylenediamine to the surface of purified carboxylated NDs and to produce covalently bonded ND-epoxy composites [54,55]. Alkyl chains or polymers can be grafted onto NDs via the reaction of esterification or silanization [25,56-60]. Zhang et al. employed an approach for grafting polyimides from ND surface via acyl chloride functionalization. This technique provided a superior dispersion... 

The low ionic character of the aluminium-silicon bond has been cleverly utilized to develop a very mild, general and effective synthesis of acyl silanes, successful for aliphatic, aromatic, heteroaromatic, a-aUcoxy, a-amino and even a-chiral and a-cyclopropyl acyl sUanes. Acyl chlorides are treated with lithium tetrakis(trimethylsilyl)aluminium or lithium methyl tris(trimethylsilyl) aluminium in the presence of copper(I) cyanide as catalyst to give the acyl silanes in excellent yields after work-up. Later improvements include the use of 2-pyridinethiolesters in place of acyl halides, allowing preparation of acyl silanes in just a few minutes in very high yields indeed (Scheme 9) °, and the use of bis(dimethylphenylsilyl) copper lithium and a dimethylphenylsilyl zinc cuprate species as nucleophiles. 

Synthetic routes to acyl(methyldiphenyl)silanes have mainly been based on methodology developed by Brook and Corey. According to Brook s synthesis of aryl silyl ketones, benzyl-magnesium chloride or bromide, for example, were silylated with methyldiphenylchlorosilane to afford benzylmethyldiphenylsi-lane (28) that, on dibromination of the benzyl methylene group and subsequent hydrolysis, gave the benzoylsilane (29) (eq 17). ... 

Acyl chlorides are converted by tris(trimethylsilyl)silane to the corresponding hydrocarbons. Tertiary and secondary acid chlorides react at 80 °C, while the reduction of primary derivatives requires higher temperatures. The radical deoxygenation of hydroxyl groups is carried out by conversion of the alcohol to a thionocarbonate, which can be reduced by tris(trimethylsilyl) silane (eq 1). This very mild method is especially useful in natural product synthesis. It has been utilized for the deoxygenation of lanosterol (eq 2) and the dideoxygenation of 1,6-anhydro-D-glucose (eq 3). ... 

This product is then treated with acryloyl chloride. The initial step in this case probably involves the acylation of nitrogen on the enamine conjugate addition then completes the formation of the lactam ring (23-5). Treatment of that product with triethyl silane then reduces the ring unsaturation and cleaves the benzylic nitrogen bond on the auxiliary to yield (23-6) as the optically pure tmns isomer. Displacement of bromine with the mercapto benzthiazole (23-7) completes the synthesis of izonsteride (23-8) [25]. 

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