Sulphonate esters trimethylsilyl —

Some functional groups that are sensitive to reaction with strong bases, like alkoxides, undergo reaction under these reaction conditions380,381. Thus 2-chloroethanesulphonyl chloride reacts with alkoxides to give the unsaturated sulphonate ester, as indicated in equation 84. Such side-reactions may be averted by reaction of the sulphonyl chloride, or fluoride, with the trimethylsilyl derivative of the alcohol382, as indicated by equation 85. The derivative may be formed under mild conditions from the alcohol. 

Two other trialkylsilyl trifluoromethanesulphonates, the TBDMS and tri-isopropylsilyl (TIPS) compounds, have been prepared and used in silylation reactions catalysed by 2,6-lutidine " TBDMS triflate allows formation of TBDMS ethers from tertiary and unreactive secondary alcohols, and TIPS triflate reacts effectively with primary and secondary alcohols. Use of the perfluorinated resin sulphonic acid trimethylsilyl ester Nafion-TMS , an immobilized TMS triflate, as a silylating agent for alcohols cf. 5,167) is discussed in a publication on applications of TMS triflate in synthesis. ... 

The perfluorinated resiri sulphonic acid trimethylsilyl ester (66 Nafion-TMS ) has been developed as a new silylating agent for alcohols, phenols, etc7 The substrate and resin are shaken in dichloromethane at room temperature, with triethylamine if necessary, before the resin is simply removed by filtration from the solution of products. The trimethylsilylation of tertiary alcohols with trimethylsilyl chloride-triethylamine has been found to be catalysed by various additives, including DMSO and HMPT. Allylsilanes have been used as new silylating reagents for alcohols in the presence of an acid catalyst [equation (19)] trimethylsilyl and t-butyldimethylsilyl (TBDMS) ethers can be made in this way. 

Bonds to Oxygen.—Compounds of Lower Oxidation State. Mixed sulphur-phosphorus anhydrides result when sulphonic acids and dialkyl hydrogen phosphites react according to equation (17).448 Further work on the preparation of trimethylsilyl esters of phosphorous acids has been carried out by... 

Poly(2-alkyl oxazoline)s having methacrylate or acrylate end groups were prepared by two methods [182]. a) Living polyoxazoline chains, prepared using methyl p-toluene sulphonate as initiator, were end-capped by reaction with metal salts or tetraalkylammonium salts of acrylic or methacrylic acid or a trialky-lammonium salt or trimethylsilyl ester of methacrylic acid (functional termination). b) The living polymers were terminated with water in the presence of Na2C03 to provide hydroxyl-terminated chains. Subsequent acylation with acry-loyl or methacryloyl chloride in the presence of triethylamine led to the formation of the macromonomers. The procedures are outlined in the following Scheme 51. 

Ethers, Esters, and Related Derivatives of Alcohols.—5a-Cholestanyl methyl ether has been cleaved inter alia) and converted into 5a-cholestanol by successive treatment with trimethylsilyl iodide and water.Pyridinium toluene-p-sulphonate has been reported as an efficient and mild catalyst for the conversion of alcohols into their tetrahydropyranyl ethers.Bile acids were efficiently performylated by treatment with 90% HCO2H-HCIO4. Selective base-catalysed... 

Other reactive halides employed include butyl iodide to yield butyl esters with, for example, the silver salts of methane- and ethanesulphonic acids106 or p-nitrobenzyl chloride or bromide, reacting in pyridine solution with sulphonates to yield addition product with pyridine molecules107. Classifiable here also is conversion to trimethylsilyl derivatives with bis (trimethylsilyl) trifluoroacetamide108. 

Other reactions forming sulphonyl halides from sulphonic acid derivatives include sulphonyl chlorides from esters with PC13647, sulphonyl fluorides from anhydrides with fluoride salts627 and sulphonyl chlorides from trimethylsilyl derivatives of sulphonic acids by reaction with dichloromethyl methyl ether648. 

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