Trifluoromethyl silane

Lithium silylamides react smoothly with tiifluoronitrosomethane to give diazenes Traces ot water initiate the decomposition of the latter with liberation of a trifluoromethyl carbanion, which is trapped by carbonyl compounds [775] (equation 116) Desilylation of trialkyl(trifluoromethyl)silanes by fluoride ion produces also a trifluoromethyl carbanion, which adds to carbonyl carbon atoms [136, 137] (equations 117 and 118)... 

Trifluoromethyl thioethers are produced in a fluoride-catalysed one-pot reaction of alkyl or aryl thiocyanates with trifluoromethyl silanes [37]. The reaction is initiated by fluoride ion displacement of the trifluoromethyl anion from the silane the thioether is formed from the thiocyanate by displacement by the trifluoromethyl anion of the cyanide ion, which then perpetuates the reaction. Trifluoromethyl selenoethers are obtained by an analogous route. In a similar manner, disulphides can be converted into trifluoromethyl thio- or selenoethers [38],... 

Recently, Olah and co-workers reported a new route to tributyl(trifluoro-methyl)tin via in situ formation and capture of the trifluoromethyl anion by trialkyltin oxide [106]. Reaction of trimethyl(trifluoromethyl)silane with tribu-tyltin oxide in the presence of catalytic TBAF in THF afforded the corresponding tributyl(trifluoromethyl)tin in good yield (Scheme 38). This reaction system was first reported by Warner and Buchwald [107]. 

Triethyl(trifluoromethyl)silaneandtributyl(trifluoromethyl)silane(64% bp53-58 C/0.5 Torr) can be synthesized by the reaction of bromotrifluoromethane with chlorotrielhylsilane and... 

The method has been further improved." Trimethyl(perfluoroalkyl)silanes RpTMS (Rp = c, -C, perfluoroaliphatic groups) are prepared by reaction of perfluoroalkyl halides RpX (X = Br, I) with chlorotrimethylsilane in the presence of tris(dialkylamino)phosphanes in acetonitrile. For example, chlorotrimethylsilane was treated with bromotrifluoromethane and tris(diethylamino)phosphane in acetonitrile at — 40"C for 1 hour to give trimethyl(trifluo-romethyl)silane in 90% yield. Bis(dimethylamino)(trifluoromethyl)silane is available from the reaction of chlorobis(dimethylamino)silane with the system bromotrifluoromethane/tris-(diethylamino)phosphane, while trichloro(trifluoromethyl)silane is prepared by nucleophilic trifluoromethylation of tetrachlorosilane with bromotrifluorornethane/tris(diethylamino)phos-phane. " ... 

Grobe and Hegge demonstrated that aluminum powder in fV-methylpyrrolidinone (NMP) can also be used for the reduction of bromotrifluoromethane in the presence ofchlorotrimethyl-silane to produce trimethyl(trifluoromethyl)silane, a method more convenient than the modified Ruppert procedure. The C Br bond of bromochlorodifluoromethane is selectively reduced by aluminum powder in. V-methylpyrrolidinone in the presence of ehlorotrimethylsilane giving (chlorodifluoromethyl)trimethylsilane in 80% isolated yield. The process appears to involve a two-electron reduction of the C Br bond of bromochlorodifluoromethane followed by trapping of the resulting CFjCU" anion by chlorotrimethylsilane. Aluminum powder, corresponding to a net consumption of two electrons per mole of bromochlorodifluoromethane. is needed for the reduction. 

Many new syntheses have been developed using triethyl(trifluoromethyl)silane and other per-fluoroalkylsilanes. ... 

Dichlorofluoromethyl)trimethylsilane and trimethyl(trifluoromethyl)silane react (under the conditions of nucleophilic catalysis by fluoride ions) with compounds containing halogen atoms at C = N or N = groups, e.g. formation of 6 and 7. Such halogen atoms can be easily substituted by dichlorofluoromcthyl or trifluoromethyl groups. 

In many cases, the preparation of poly- and perfluorinated tertiary and secondary alcohols by reacting trimethyl(trifluoromethyl)silane with fluorinated ketones or aldehydes provides a simple, inexpensive, high-yield route to these materials.When trimethyl(trifluoromethyl)-silane is reacted in a 1 1 mole ratio with perfluorobenzaldchyde. followed by hydrolysis, the corresponding tertiary alcohol 14 is obtained in 60 -70% yield with trimethyl(penta-fluoroethyl)silanc the corresponding product is obtained in 85% yield. 

Trimethyl(trifluoromethyl)silanc reacts with the derivatives of four- and six valent sulfur-containing mobile halogen atoms to form the trifluoroniethyl deri vatives. Trifluoromethylation with trimethyl(trifluoromethyl)silane has also been used in the preparation of a trifluoro-methylatcd sugar derivative. 

Trifluoromethylated phenols and anilines have been made by reaction of ortho- and pani-quinoncs with trialkyl(trifluoromethyl)silanes, under base catalysis with subsequent reduction or reductive amination of the reaction products. 

Various organic compounds containing carbonyl groups in different chemical environments have been subjected to trifluoromethylation with trimethyl(trifluoromethyl)silane. ... 

Interestingly, when large excesses of both trimethyl(trifluoromethyl)silane and potassium fluoride are reacted with oxalyl fluoride (3 or 4 1). a new oligomer (CF3)3C0[C(CF3)20] -C(0)Cp3 (n = 2-4) is obtained these symmetrical branched-chain polyethers are difficult to... 

Acid halides, such as benzoyl chloride, also react with trimethyl(trifluoromethyl)silane to give a mixture of products 20 and 21. The reaction requires the presence of more than one molar equivalent of tetrabutylammonium fluoride. ... 

Lactones have also been reacted with trimethyl(trifluoromethyl)silane under fluoride catalysis in tetrahydrofuran however, only the silylated hemiketals could be isolated cleanly in the case of five- and six-membered ring lactones (in 70 and 75% yield, respectively). In the case of the seven-membered ring lactone, a mixture of products resulted. 

Trimelhyl(trifluoromethyl)silane reacts with a-oxo esters in the presence of potassium fluoride to give the corresponding a-alcohols (Table 2). ... 

Cyclic anhydrides react well with trimethyl(trifluoromethyl)silane however, a stoichiometric amount of tctrabutylammonium fluoride is required. - For example, succinic anhydride undergoes efficient addition of trimethyl(trifluoromethyl)silane to initially form an adduct, which upon hydrolysis aflbrds the trifluoromethyl-substiluted 0x0 carboxylic acid 27. Simple amides, such as benzamide and acetamide, do not react with trimetliyl(trifluoromethyl)silane even when a molar quantity of tetrabutylainmonium fluoride is used. Furthermore, lactams, such as caprolactam, do not react with trimethyl(trifluoromethyl)silane under similar conditions. An activated amide carbonyl, such as that in A -methylsuccinimide. however, reacts smoothly to afford an interesting adduct, which upon acid hydrolysis affords the hcmiaminal 28. 

Hexyl trifluoroacetate reacts w ith trimethyl(trifluoromethyl)silane in the presence of a molar equivalent of tetrabutylammonium fluoride to give the silylated hemiketal 29 in. 3.5% yield. Much of the trimethyl(trifluoromcthyl)silanc is converted into the undesired trifluoromethane due to rapid quenching of the incipient trifluoromethide species by the protic impurities in the reaction mixture. "... 

No reaction between triiiiethyl(trifluoromethyl)silane and sulfur dioxide occurs in the absence of an anionic initiator when one molar equivalent of tetrabutylammonium fluoride is used, clean foriiiiition of tetrabutylammonium trilluoromethancsullinatc is observed." Although oxidation to the corresponding sulfonate occurred readily upon treatment with 30% hydrogen peroxide, attempts to liberate the free acid from the salt proved unsuccessful. When sodium trimcthylsilanolate was used as the initiator, however, the reaction sequence was successful. The Overall yield of trifluoromethancsulfonic acid (31) was about 30%. 

Trimethyl(trifluoromethyl)silane can be converted into tributyl(trifluoromethyl)tin (40) in quantitative yield by treatment with bis(tributyltin) oxide in tetrahydrofuran under fluoride ion initiation. Tributyl(trifluoromethyl)tin readily trifluoromethylates disilyl sulfides at room temperature giving the corresponding trifluoromethylated di- and trialkylsilancs 41 in high yields. This method provides a new approach for the preparation of silicon-based trifluoro-methylating reagents via transtrifluoromethylation of compounds containing Si — S bonds. 

The reaction of trimethyl(perfluorophenyl)silanc with carbonyl centers occurs under mild reaction conditions, similar to those used for trimethyl(trifluoromethyl)silane. Acetyl fluoride in acetonitrile in the presence of catalytic amounts of potassium fluoride gives l-fluoro-l-(penta-fluoropheny )ethyl acetate (12) in 65% yield. When the bifunctional acid fluoride perfluoro-glutaryl difluoride reacts with trimethyl(perfluorophcnyl)silane in acetonitrile in the presence of potassium fluoride, the perfluorinated diketone perfluoro(l,5-diphenylpcntane-l,5-dione)... 

A final introductory note a powerful strategy has emerged which allows one to employ trimethylsilyl-substituted perfluorocarbons under conditions of nucleophilic activation as carb-anion equivalents. The most important member of this class is the commercially available trimethyl(trifluoromethyl)silane (TMSCF3) reagent, which was first utilized by Prakash. These processes are covered in Section 2.1.1.1. 

Perfluoroalkylcopper reagents are the most studied perfluoroalkyl organometallic reagents due to their unique combination of thermal stability and chemical reactivity. They are readily prepared by copper metal insertion reactions with perfluoroalkyl halides in a coordinating solvent (e.g., formation of decarboxylation reactions of perfluoroalkanoic acid salts and copper(I) halide (e.g., formation of 2 ), or metathesis reactions (e.g., formation of 4 via 3 ). (Trifluoro-methyl)copper (4) has also been recently accessed by decomposition of methyl 2,2-difluoro-2-(fluorosulfonyl)acetate (5) or methyl perfluoro [2-(fluorosulfonyl)ethoxy]acetate (6) in the presence of copper(I) iodide and by reaction of trimethyl(trifluoromethyl)silane (7) with fluoride and copper(I) iodide. ... 

A general method for the preparation of trifluoromethyl sulfides involves the utilization of trimethyl(trifluoromethyl)silane ("Ruppert s Reagent") in a reaction with disulfides 32. ... 

Phosphane 9 is a useful intermediate which can be converted easily into trifluoromethyl anion equivalents, e. g. trimclhyl(trifluoromethyl)silane. Similarly, 1,2-bis(dichlorophosphi-iio)cthanc (10) and bromotrifluoromclhane react in the presence of 8 to form l,2-bis[bis(tri-fluoromethyl)phosphino]ethane (11). ... 

The efficient preparation of trimethyl(trifluoromethyl)silane via the electroreduction of bromotrifluoromethane in dimethylformamide in the presence of chlorotrimethylsilane using a sacrificial aluminum anode and nickel foam cathode (area 20 cm2) containing tetrabutylam-... 

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