Trimethylsilyl sulfate

Bis(trimethylsilyl)sulfate 559, which is readily available from TCS 14 and H2SO4 in 76% yield [94], reacts on heating with anisole to form the trimethylsilyl ester of p-methoxybenzenesulfonic acid 1331 in 92% yield [95]. The hexamethyldi-siloxane (HMDSO) 7 and H2O formed are removed during the reaction by azeotropic distillation [95]. On heating of acetyl chloride with 559 the probable intermediate 1332 rearranges to give 1333 in 63% yield. The last reaction can be extended to other acid chlorides [95] (Scheme 8.37). 

Bis-trimethylsilyl sulfate in the presence of silica also promotes formation of dithio-lanes.103... 

Silylation of carboxylic acids.1 This reagent in the presence of sulfuric acid silvlates carboxylic acids in 75-95% isolated yield. The actual reagent may be bis(trimethylsilyl) sulfate, [(CH3).jSi]2SO.,. Several other acids are less effective as catalysts. 

TETRAHYDROPYRANYLATION Bis(trimethylsilyl) sulfate. THIOACETALIZATION Aluminum chloride. THIONATION 2,4-Bis(4-methoxyphenyl)... 

Trimethylsilyl esters. Trimethylsilyl esters are obtained in 65-90% yield by reaction of carboxylic acids with hexamethyldisiloxane in refluxing toluene containing a catalytic amount of sulfuric acid.1 The actual catalyst is probably bis(trimethylsilyl) sulfate, [(CH3)3Si]2S04. Pyridinium trifluoromethanesulfonate also can serve as catalyst. 

Bis(trimethylsilyl)propyne, 126 Bis(trimethylsilyl) sulfate, 44,196 Bis(triphenylphospliine)copper(I) tetra-... 

Acid-catalysed addition of primary, secondary, and tertiary alcohols to 3,4-dihy-dro-2//-pyran in dichloromethane at room temperature is the only general method currently in use for preparing THP ethers and the variations cited below concern the choice of acid. The reaction proceeds by protonation of the enol ether carbon to generate a highly electrophilic oxonium ion which is then attacked by the alcohol. Yields are generally good. Favoured acid catalysts include p-toluenesulfonic acid or camphorsulfonic acid. To protect tertiary allylic alcohols and sensitive functional groups such as epoxides, the milder acid pyridinium p-toluenesulfonate has been employed (Scheme 4.316]. A variety of other acid catalysts have been used such as phosphorus oxychloride, iodotrimethylsilane- and bis(trimethylsilyl)sulfate. but one cannot help but suspect that in all of these cases, the real catalyst is a proton derived from reaction of the putative catalysts with adventitious water. Scheme 4.317 illustrates the use of bis(trimethylsilyl)sulfate in circumstances where other traditional methods failed. - For the protection of tertiary benzylic alcohols, a transition metal catalyst, [Ru(MeCN)2(triphos)](OTf)2 (0.05 mol%) in dichloromethane at room temperature is effective. ... 

This reaction was initially reported by Flood in 1933. It is a synthesis of trialkylsilyl halide involving the treatment of the mixture of di-trialkylsilyl oxide and concentrated sulfuric acid with sodium halide or ammonium halide. The resulting trialkylsilyl halide can be extracted by petroleum ether and then purified via distillation. It was found that when di-trimethylsilyl oxide is mixed with concentrated sulfuric acid, trimethylsilyl sulfate can be isolated as a white crystalline (m.p., Sb-SS C), which forms trimethylsilyl halide when it reacts with ammonium halide. The reaction has been improved by continuous extraction of the reaction mixture with pentane to yield more and purer trialkylsilyl halide and by the addition of ammonium bisulfate to the reaction mixture. ... 

In 1998, Wilson Greatbatch Technologies found that chain sulfates, such as dial-lyl sulfate (45) and benzyl methyl sulfate (46), as well as chain sulfates including silyl groups, such as bis(trimethylsilyl) sulfate (47), can be used as additives in small quantities [76],... 

Isocyanato-trimethyl sUane isocyanate 512 was obtained in high yield (80%) from bis(trimethylsilyl)sulfate 511 and dried urea at 150 °C, the product being distilled [357],... 

An equimolar mixture of hexamelhyldisiloxane and trimethylsilyl chlorosulfonate refluxed several hrs. after the initial exothermic reaction has subsided bis (trimethylsilyl) sulfate (Y 94.5%) and trimethylchlorosilane (Y 93.4%).—Silyl chlorosulfonates are highly reactive compounds and very strong sulfating agents. F. e. s. M. Schmidt and H. Schmidbaur, B. 9A, 2446 (1961). 

The reaction of bis(trimethylsilyl)sulfate with the potassium salts of pseudohalides in A-methylpyrrolidine [194] is an effective method for the preparation of cyano, isocyanato and isothiocyanato trimethylsilanes (Scheme 3.5) ... 

Tetrahydropyranylation of alcohols can be carried out under very mild conditions in the presence of bis(trimethylsilyl) sulfate (0°C, 1 h, 89-100%). No rearrangement is observed even with tertiary allylic alcohols. ... 

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