Bis trimethylsilyl cuprate

Lithium bis(trimethylsilyl)cuprate, 29, 52 Lithium diaikylamides, 100 Lithium l-(dimethylamino)naphthalenide (LDMAN), 68, 69. 77 Lithium dimethylcopper, 131 Lithium hexamethyldisilazide, 73. 78 Lithium t-octyl-t-butylamide, 100 2.6-Lutidine, 93.94... 

Lithium bis(trimethylsilyl)cuprate.xl This cuprate, prepared from (CH3),SiLi and CuCN, converts acyl chlorides into acylsilanes in moderate to high yield. 

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... 

V,7V-Diethylcarbamoyl trimethylsilane has been prepared by the reaction of bis(trimethylsilyl) sulphide with bis(A,A-diethylcarbamoyl) mercury (Scheme 30)16. Silylation of the carbamoyl cuprate reagent derived from a lithium amide, by addition of copper(I) cyanide and subsequent exposure to carbon monoxide (1 atm), is also effective75,110. Poor to moderate yields of carbamoyl silanes may be isolated by treatment of lithium silylamides with carbon monoxide and methyl iodide, in a reaction sequence involving a nitrogen to carbon silyl shift in an intramolecular silylation (Scheme 31)111. 

Electrophilic amination of organolithium compounds with methyllithium-methoxamine or amination of higher order cuprates by N,0-bis(trimethylsilyl)hydroxyiamine. Also amination of aryllithium by vinyl azides.3... 

Differences in stereochemical approach of organocopper and cuprates are found in the addition on -y-bis(trimethylsilyl)amino-a-alkynoic esters, amides, and the alkynyl 2-Alkynoic esters are converted into tetrasubstituted a, -unsaturated esters by the addition-trapping technique. ... 

Lithium bis(trimethylsilyl)amide, 542 Lithium r-butoxide, 115, 116, 118 Lithium r-butylmercaptide, 343, 344 Lithium a-carboethoxyvinyl(l -hexenyl)-cuprate, 329-330... 

Scheme 13 shows additional examples of constructions of four-carbon chains functionalized appropriately for condensation to pyrroles. Af,Af-bis(trimethylsilyl)propargyl amines can be converted to ketones or esters by lithiation and acylation. These compounds then undergo cuprate addition. The resulting allenyl silyl ethers cyclize to pyrroles on treatment with acid <93T4603). 

Coupling Reactions to Dienes and Enynes. The silyl bromide (1) participates readily in copper or transition metal-mediated coupling reactions to produce 1,3-butadienes, which are very useful s)mthetic intermediates. For example, 2,3-bis[(trimethylsilyl)methyl]-1,3-butadiene (8), derived from the oxidative dimerization of cuprate (2) (M = Cu) is useful for rapid construction of multicyclic systems via tandem Diels-Alder reactions, as depicted in eq 15 The diene 2-dimethylaminomethyl-3-... 

Preparative Methods prepared by adding 0.5 equiv of dry copper(I) cyanide to dimethylphenylsilyllithium in THF (eq 1), which in turn is generated from chlorodimethylphenyl-silane and lithium metal. Analogous bis(trimethylsilyl)cyano-cuprates are prepared in a similar manner. 

CONJUGATE ADDITIONS Bis(methylthio)(trimethylsilyl)methyllithium. Diethylalum-inum cyanide. Di(a-methoxyvinyl)copperlithium. Ethyl diethoxyacetate. Ethyl methylsulfinylacetate. Lithium a-carboethoxy vinyl(l-hexynyl)cuprate. Potassium fluoride. Quinine, chinchonine. Titanium tetrachloride. Trimethylaluminum. Tris-(phenylthio)methyllithium. 

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. 

Silyl-cupration. Stoichiometric reaction of 3-trimethylsilyl-1 -propyne with a silyl-cuprate reagent gives, after quenching with a proton source at —78 °C, a bis-silylatedpropene (eq 39). ... 

Diene Synthesis. a -(Trimethylsilyl)vinyllithium dimerizes in the presence of copper(I) iodide. This reaction was first observed as a side product during the formation of organo-cuprates, then developed for the synthesis of 2,3-bis(trimethyl-silyl)buta-1,3-diene (eq 9). 

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