Trimethylsilyl ethanol

Form Supplied in colorless liquid 99% purity widely available. 

Preparative Methods three methods of preparation have been reported (a) from the treatment of ethyl bromoacetate with zinc followed by the reaction with chlorotrimethylsUane and subsequent reduction of the resultant ethyl trimethylsUylacetate with lithium aluminum hydride or borane-tetrahydrofuran (eq 1) (b) from the hydroboration/oxidation or oxymercu-ration/ demercuration of vinyltrimethylsUane (eq 2) and (c) most conveniently, by the reaction of the Grignard reagent formed from (chloromethyl)trimethylsilane with paraformaldehyde (eq 3).  

A variety of methods are available for the protection of carboxylic acids as 2-(trimethylsilyl)ethyl esters. 2-(Trimethylsilyl) ethyl esters are stable to conditions used in peptide synthesis. Deprotection of the ester is readily accomplished by treatment with tetra-n-butylammonium fluoride (TBAF). Hemisuccinates have been prepared indirectly under nonacidic conditions by monoprotection of succinic anhydride as 2-(trimethylsilyl)ethyl esters followed by esterification (eq 4) and then selective deprotection of the resultant diester (eq 5).  

A list of General Abbreviations appears on the front Endpapers 

Transesterification of methyl esters to 2-(trimethylsilyl)ethyl esters under mild and neutral conditions takes place in the presence of titanium tetraisopropoxide (eqs 6-8). Deprotection of the 2-(trimethylsilyl)ethyl ester in the presence of an O-TBDMS protected secondary hydroxyl group has been achieved (eq Q). An alternative method for the transesterification uses l,8-diazabicyclo[5.4.0]undec-7-ene/lithium bromide and 2-(trimethylsilyl) ethanol.  

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Early attempts to generate the 1-phenyl-l-(trimethyl ilyl)ethyl cation 1 by ionization of the 1-phenyl-l-(trimethylsilyl)ethanol 2 with FS03H in S02C1F at -78 °C were unsuccessful. Only the cumyl cation 3 was observed instead (77). 

Early attempts to generate ot-aryl-(3-silyl substituted carbocations by ionization of 1,1-diphenyl-2-(trimethylsilyl)ethanol 10 usipg FS03H in S02C1F even at very low temperature of -140 °C were unsuccessful (77). Only 1,1-diphenylethyl cation 11 and trimethylsilyl fluorosulfate, fhe products of P-silyl cleavage were observed. 

Example 29 iV,Ar-diisopropyl-bis[(trimethylsilyl)ethyl]phosphoroamidite have been prepared from commercial available dichloro(diisopropy-lamino)phosphine and 2-(trimethylsilyl)-ethanol [60] in 65% yield after purification by chromatography. Chao et al. have used this phosphitylating reagent in a way which is compatible with the Fmoc/tcrt-butyl strategy for the synthesis of phosphotyrosine containing peptides [61]. 

Scheldt and co-workers have also illustrated the oxidation of activated alcohols to esters [132], Oxidations of alcohols such as 260 provide the electrophile (acyl donor) for a nucleophilic alcohol 261. Esters 262 are derived from propargylic, allylic, aromatic, and hetero-aromatic substrates (Table 20). The nucleophilic alcohol scope includes MeOH, n-BuOH, f-BuOH, 2,2,2-trichloroethanol, 2-methoxyethanol, and 2-(trimethylsilyl) ethanol. 

Bei einer anderen Verfahrensweise wird die Carbonsaure mittels Phosphorsaure-azid-di-phenylester in ihr Azid fibergefuhrt3, die Umlagerung zum Isocyanat durch Erhitzcn be-wirkt, das nicht isolierte Isocyanat mit 2-Trimethylsilyl-ethanol in den Carbamidsaure-(2-trimethylsilyl-ethylester) iibergefuhrt, dieser isoliert und zum Amin gespalten4 ... 

Trimethylsilyl ethanol [2916-68-9] M 118.3, b 53-55 /llmm, 75 /41mm, 95 /100mm, 0.8254, np 1.4220. It the NMR spectrum is not clean then dissolve in Et2O, wash with aqueous NH4CI solution, dry (Na2SO4), evaporate and distil. The 3,4-dinitrobenzoyl deriv has m 66 (from EtOH). [NMR JACS 79 974 7957 Z Naturforsch 14b 137 7959],... 

Hi. pSilyl-substituted tertiary benzyl cations. Earlier attempts to prepare the 1,1-diphenyl-2-trimethylsilylethyl cation 345 by ionization of l,l-diphenyl-2-trimethylsilyl-ethanol in FS03H/S02C1F at both -78 °C and -140 °C failed and led only to the formation of 1,1-diphenylethyl cation 298 along with trimethylsilyl fluorosulphate113. 

A mixture consisting of the Step 2 product (200mg), l,3-bis(diphenylphosphino) propane (8.7 mg), and Pd(OAc)2 (4.7 mg) was placed under a carbon monoxide atmosphere, then treated with 0.2 ml 2-(trimethylsilyl)ethanol, 0.12 ml triethylamine, and 0.9 ml DMSO. The mixture was stirred 3 hours at 70°C and was then extracted with CH2C12. It was washed with 1M HC1, then purified by flash chromatography using EtOAc/petroleum ether, 5 95 to 10 90, and the product isolated in 91% yield, mp = 205°C. 

Diazo compounds have also been used as precursors in the preparation of pyrazoles and indazoles. The copper-promoted cycloaddition reaction of lithium acetylides 18 with diazocarbonyl compounds 19 provided a direct and efficient approach to the synthesis of pyrazoles 20 <07AG(I)3242>. A facile, efficient, and general method for the synthesis of 1-arylated indazoles 22 and A-unsubstituted indazoles 23 by the 1,3-dipolar cycloaddition of benzynes, generated from 21, with diazomethane derivatives has been reported <07AG(I)3323>. Reaction of diazo(trimethylsilyl)methylmagnesium bromide with aldehydes or ketones gave 2-diazo-2-(trimethylsilyl)ethanols, which were applied to the synthesis of di- and trisubstituted pyrazoles via [3+2] cycloaddition reaction with ethyl propiolate or dimethyl acetylenedicarboxylate <07S3371>. 

To a cooled soln of Ph3P (3.72 g, 14 mmol) and DEAD (2.3 mL, 14 mmol) in THE (25 mL) in a flame-dried round-bottomed flask, was added Z-Tyr-ONbz (14 mmol), followed by 2-(trimethylsilyl)ethanol (2.14 mL, 14 mmol). Soon after the addition was complete, the evolution of Nj was noted. The ice bath was removed and the soln was stirred for 10 min. The solvent was removed, the resulting syrup was dissolved in MeOH (1L), and the soln was allowed to stand at rt for at least 2d. The MeOH was then removed and the residue was subjected to flash chromatography (10-cm column, CH2Cl2/Et20 98 2), which gave an oil yield 2.65 g (35%). 

The use of 2-(trimethylsilyl)ethanol allows the very mild and selective conversion of the initially formed urethanes into the cyclopropylamines with tetrabutylammonium fluoride, e.g. the synthesis of 2,2-dimethyl-3-(2-methylprop-l -enyl)cyclopropylamine (13) from /ra i-chrysanthemic acid (11). ... 

A new sulphamoylation agent, N-carbo(trimethylsilyloxy)sulphamoyl chloride (286), prepared by the reaction of (trimethylsilyl)ethanol with chlorosulphonyl isocyanate followed by the elimination of ethylene, has been reported297 (equation 89). This reagent has been used successfully in the preparation of 3-amino-4-A/-alkyl-5-aryloxy-l,2,4,6-thiatriazine-1,1-dioxide (288) (equation 90) by reaction of 286 with N-cyano-N-alkyl pseudoureas (287). The 2-N-alkyl isomer of 288 has also been synthesized. 

For the sake of increased stability and improved storage, somewhat less reactive alternatives have been prepared from the labile chloroformate. For example, 2-(trimethylsilyl)ethyl -succinimidyl carbonate has been used to prepare Teoc-protected amino acids in water or dioxane using sodium hydrogen carbonate or triethylamine as the base. - 2-(Trimethylsilyl)ethyl 4-nitrophenyl carbo-nate2 246 g commercially available reagent (mp 34-36 C) that reacts with amino acids in a mixture of aqueous sodium hydroxide and rert-butyl alcohol or dioxane. Simple amines can be acylated with triethylamine under anhydrous conditions [Scheme 8.105]. Teoc derivatives can also be prepared by an exchange reaction using an aryl carbamate derivative and 2-(trimethylsilyl)ethanol as shown in Scheme 8.106. ... 

Pentaphenyl-L-acylazideferrocene (1.48 g, 2.3 mmol) was dissolved in 15 mL toluene the solution was heated to 105°C, and 0.67 mL of 2-(trimethylsilyl)ethanol (4.7 mmol) was added in a single portion. The red solution obtained was stirred at this temperature for 3 h, by which time the color had changed to dark orange. The mixture was cooled to room temperature, 50 mL 1 M NaOH was added, and the solution was stirred for... 

Koenigs-Knorr reaction of methyl 4,7,8,9-tetra-0-acetyl-2-chloro-P-Neu5Ac with 2-(trimethylsilyl)ethanol [12b]. 

That the trimethylsilyl group actively participates at the p position was demonstrated as shown in 8cheme 10.65. 80, when the l,l-dideutero-2-trimethylsilyl ethanol [(Ol3)38iOl2C H20H] shown in the scheme was treated with phosphorus... 

Accordingly, deprotection of the TBS in 174 and transesterification of the salicylic acid acetonide with 2-(trimethylsilyl)ethanol gave deactivated monomeric salicylate ester 175. Ester 175 was stable to strong base, whereas 174 (Scheme 6.31) was decomposing under basic conditions therefore, 175 acted as pronucleophile for acylation with 174 to afford 176 as dimeric ester. Protection of dimeric ester 176 followed by desilylation provided the seco-acid, which on macrolactonization using the modified Mukaiyama salt and deprotection furnished 44-membered C2-symmetrical marinomycin A 177. 

Diazo-2-(trimethylsilyl)ethanols can be almost quantitatively obtained from carbonyl compounds by the reaction with diazo-(trimethylsilyl)methylmagnesium bromide (TMSC(MgBr)N2)... 

Analogously, 2-diazo-2-(trimethylsilyl)ethanols react with benzynes from o-(trimethylsilyl)aryltriflates to furnish 3-substituted indazoles, [3 + 2] cycloadducts (eq 14). ... 

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