Chlorotrimethylsilane, reaction with

Chlorothionitrene complex, osmium, 37 262 Chloro(trifluoromethyl) peroxide, 16 144 Chlorotrimethylsilane, reaction with hexafluoro-acetone, 30 225... 

Under the most favourable reaction conditions when methyl chloride is used the crude product from the reaction tube will be composed of about 73.5% dimethyldichlorosilane, 9% trichloromethysilane and 6% chlorotrimethylsilane together with small amounts of other silanes, silicon tetrachloride and high boiling residues. 

One of the more common methods of alcohol protection is by reaction with a chlorotrialkylsilane, CI-S1R3, to yield a trialkylsilyl ether, R -O-SilTj. Chlorotrimethylsilane is often used, and the reaction is carried out in the presence of a base, such as tciethylamine, to help form the alkoxide anion from the alcohol and to remove the HC1 by-product from the reaction. 

The ionic P-P bond polarization renders P-phosphino-NHPs highly active reactants for various metathesis and addition reactions at exceedingly mild conditions. Metathesis is observed in reactions with alcohols, chloroalkanes, and complex transition metal halides (Schemes 11 and 12) [39, 73], Of particular interest are the reactions with chlorotrimethylstannane which yield equilibria that are driven by a subtle balance of P-X bond strengths to yield either diphosphines or P-chloro-NHPs as preferred product (Scheme 11). Chlorotrimethylsilane does not react with... 

Introduction of trimethylsilyl substituents attached directly to the ot-carbon atom of a-(benzotriazol-l-yl)alkyl thioethers provide new opportunities. Thus, treatment of lithiated monosubstituted a-(benzotriazol-l-yl)alkyl thioethers with chlorotrimethylsilane produces a-(trimethylsilyl)alkyl thioethers 837. In reactions with hexamethyl-disilathiane and cobalt dichloride, thioethers 837 are converted to thioacylsilanes 838 that can be trapped in a Diels-Alder reaction with 2,3-dimethylbutadiene to form 2-alkyl-4,5-dimethyl-2-trimethylsilyl-3,6-dihydro-27/-thiopyrans 839 (Scheme 133) <2000JOC9206>. 

A route involving trapping the enolate as a silyl enol ether, subsequent transme-tallation to the corresponding lithium enolate and alkylation turned out to be more efficient (Scheme 18.41) [123]. Thus, treatment of 120 with the cuprate 124 and chlorotrimethylsilane furnished the silyl enol ether 125, which was then converted into the desired enprostil derivative 127 with 68% yield over both steps by reaction with methyllithium and the allenic triflate 126. 

The first formed enolate products from hydrodimerization of esters are trapped by reaction with added chlorotrimethylsilane. By starting with allyl esters, this hy-... 

As an example, carbon tetrachloride (436) gave tetrakis(trimethylsilyl)methane by reaction with chlorotrimethylsilane in 80% isolated yield. 

The formation of doubly lithiated bis(lithiomethyl)acetylene (107) is accompanied by the formation of 2,3-dilithio-l,3-butadiene (108), when starting from bis(trimethylstanno-methyl)acetylene (106). As reported by Reich and coworkers, the molar ratio X of the two compounds depends on the applied temperature protocol (ratio determined by trapping reactions with chlorotrimethylsilane) (Scheme 37). 

Enantioselective deprotonation can also be successfully extended to 4,4-disubstituted cyclohexanones. 4-Methyl-4-phenylcyclohexanone (3) gives, upon reaction with various chiral lithium amides in THF under internal quenching with chlorotrimethylsilane, the silyl enol ether 4 having a quaternary stereogenic carbon atom. Not surprisingly, enantioselectivities are lower than in the case of 4-tm-butylcyclohexanone. Oxidation of 4 with palladium acetate furnishes the a./i-unsaturated ketone 5 whose ee value can be determined by HPLC using the chiral column Chiralcel OJ (Diacel Chemical Industries, Ltd.)59c... 

The anion 7 is quite nucleophilic and undergoes exclusive C-alkylation upon reaction with electrophiles including chlorotrimethylsilane °. These reactivity patterns have led to the suggestion that enolates of iron-acyl complexes may be considered to behave similarly to the organic dianion 910- u. 

The first reference to 2-trimethylsilyloxy-l,3-butadiene (1) was a report2 of its reaction with tetracyanoethylene by Cazeau and Frainnet without mention of any experimental details. Later, Conia3 reported its synthesis in 50% yield with only a reference made to the usual House procedure4 for silyl enol ethers. The diene 1 has also been prepared using lithium diisopropylamide as base and chlorotrimethylsilane in tetrahydrofuran-ether (1 1) in yields up to 65%, but on a smaller scale.s... 

Due to the extremely low nucleophilicity of the imino group, 187,188 acylation of thiazolidine-4-carboxylic acid (11) is not a trivial procedure. In fact, N-protected Thz derivatives can be prepared by standard procedures, but strong acylating conditions are required. The related N-Boc derivative is obtained only by prolonged reaction times with Boc-N3 U2,189 or with Boc20. 113 For preparation of the N-Z derivative, silylation of Thz with, for example, chlorotrimethylsilane is recommended prior to the reaction benzyl chloroformate. 200 Due to the stability of thiazolidine-4-carboxylic acid to acids its methyl ester is obtained by HC1 catalyzed reaction with methanol, 190 whereas the amide is formed by reacting Thz N-carboxyanhydride with ammonia.1 89 Derivatives of thiazolidine-4-carboxylic acid are listed in Table 8. 

Allylsilanes.1 Allyl trimethylsilyl ethers are converted into allylsilanes by reaction with chlorotrimethylsilane (5 equiv.) and lithium sand in THF. 

Since trimethylsilylarenes can be prepared by metallation of the arene followed by treatment with chlorotrimethylsilane, this provides an alternative route into a range of difficult substitution patterns. For example, the ortho/para directing effects of the methoxy groups in 1,3-dimethoxybenzene 75 direct the electrophile to the 4-position. However, lithiation of 1,3-dimethoxybenzene takes place at the 2-position. Reaction with chlorotrimethylsilane then gives the 2-trimethylsilyl compound 76, which undergoes ipso substitution with the electrophile to give the 1,2,3-trisubstituted product 77 (equation 39)101,102. 

The reaction of 1-chlorosiloles with alkali metals leads to unstable species that react with methyl iodide, ethyl bromide or chlorotrimethylsilane in the manner expected for the 1-silacyclopentadienide anion. Interestingly, X-ray quality crystals were isolated from the reaction with Li in THF and the molecular structure was shown to be that of a [2 + 2] head-to-tail dimer, which is formed by the 1,5-rearrangement of the anion in the silole ring185 (equation 70). 

ClSi(CH3)3 is essential use of NH4C1 quench results in large amounts of a tertiary alcohol. This route to ketones is apparently limited to methyl ketones, since reactions with butyl- or phenyllithium promoted with chlorotrimethylsilane give significant amounts of a tertiary alcohol and starting material. 

Fiirstner reported the first McMurry-type reactions working with 5-10 mol% of titanium trichloride and stoichiometric amounts of zinc powder in the presence of chlorotrimethylsilane. The amount of TiCl3 could be reduced to 2 mol% when (ClMe2SiCH2)2 was used as a reagent [125, 131]. At the same time, Burton and coworkers reported atom transfer radical additions of perfluoroalkyl iodides 39 to alkenes 40 catalyzed by 20 mol% of a low-valent titanium compound generated from TiCLt and zinc powder affording 41 in 10-85% yield (Fig. 13). A tandem radical addition/5-exo cyclization/iodine transfer reaction with diallyl ether proceeded in 66% yield [132]. 

Besides simple enones and enals, less reactive Michael acceptors like /3,/3-disubstituted enones, as well as a,/3-unsaturated esters, thioesters, and nitriles, can also be transformed into the 1,4-addition products by this procedure.44,44a,46,46a The conjugate addition of a-aminoalkylcuprates to allenic or acetylenic Michael acceptors has been utilized extensively in the synthesis of heterocyclic products.46-49 For instance, addition of the cuprate, formed from cyclic carbamate 53 by deprotonation and transmetallation, to alkyl-substituted allenic esters proceeded with high stereoselectivity to afford the adducts 54 with good yield (Scheme 12).46,46a 47 Treatment with phenol and chlorotrimethylsilane effected a smooth Boc deprotection and lactam formation. In contrast, the corresponding reaction with acetylenic esters46,46a or ketones48 invariably produced an E Z-mixture of addition products 56. This poor stereoselectivity could be circumvented by the use of (E)- or (Z)-3-iodo-2-enoates instead of acetylenic esters,49 but turned out to be irrelevant for the subsequent deprotection/cyclization to the pyrroles 57 since this step took place with concomitant E/Z-isomerization. 

The reaction of 4-benzyloxy-3-methoxybenzaldehyde (41) with /V-propionyl oxazolidinone (23S) in the presence of chlorotrimethylsilane along with a catalytic amount of MgCl2 provided the aldol adduct 42 in modest yield with a high... 

Added nucleophile for abbreviations of nucleophile names, see Table IV. b Followed by reaction with chlorodimethylphenylsilane. r Followed by reaction with oxalic acid. d Followed by reaction with chlorotrimethylsilane. 

It was found that methyl vinyl ketone could be converted into 2-trimethylsilyl-1,3-butadiene by reaction with chlorotrimethylsilane (TMSC1) in the presence of triethylamie (TEA) and lithium bromide in tetrahydrofuran solution [33]. 

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