Triethylsilyl triflate

Glycosyl trichloroacetimidate donors in the presence of selenoglycoside acceptors can be used with triethylsilyl triflate as promoter. 

Scheme 5.7 (a) Mechanism of the w-pentenyl glycoside-based glycosylation method. Electrophiles commonly employed include iodonium di-sym-collidine perchlorate (IDCP) and A-iodosuccinimide/triethylsilyl triflate (NIS/Et3SiOTf) (b) Mechanism for the activation of NIS by EtsSiOTf.55... 

Despite these restrictions, the acceptor-bound succinoyl MPEG28 was found to permit glycosylations with glycosyl trichloroacetimidates promoted by boron trifluoride, triflic anhydride, and trimethylsilyl or triethylsilyl triflates, with glycosyl halogenates promoted by silver triflate, and with thioglycosides promoted by the iodonium ion. It is compatible with long-term ester protection, with allylic,... 

Treatment of 109 with triethylsilyl triflate and acetic anhydride gave the acetate 110 [62], convertible into the bromide 111 and thence the thioglyco-side 112. Of these three glycosyl donors, only the thioglycoside 112 was useful... 

Three of the most common procedures for the formation TES ethers have been selected for their large scale preparative value. Triethylsilyl ethers are prepared by the reaction of the alcohol with chlorotriethylsilane in the presence of a catalytic amount of imidazole [Scheme 4.23]30 or DMAP31 Triethylsilyl triflate in the presence of pyridine [Scheme 4.24]32 or 2,6-lutidine [Scheme 4.25]23 can be... 

Triethylsilyl triflate. This has become a popular reagent for the preparation of TES ethers. Commonly used bases are pyridine and 2,6-lutidine. The most frequently used solvent is CH2CI2, but others such as CH3CN have also been used. 

OH, 4-SH, and 4-SeH groups of glucopyranoside acceptors 383-385, inthe presence of triethylsilyl triflate as catalyst. The notable a-selectivity is attributed to the greater stability of the a anomers. 5 -Thiomaltoside, 4,5 -ditluomaltosidc, and... 

This segment was also obtained from anhydrodeacyltautomycin 5, formed by degradation of tautomycin 1, as shown in Scheme 13 (14). When we treated 1 with triethylsilyl triflate and 2,6-lutidine at 3°C, the silyl enol ether 74 was obtained. Considering this finding, we decided to mask the C2 carbonyl as an olefin before the retro-aldol reaction to prevent C3 epimerization. 

Trimethylsilylation has been accomplished with a large number of reagents most of which are commercially available. The cheapest (chlorotrimethylsilane) and the most reactive (trimethylsilyl triflate) rapidly silylate hydroxyl groups in the presence of a suitable base such as pyridine, triethylamine, i-Pr2NEt, imidazole, or DBU but an aqueous workup is required to ensure complete removal of the resultant amine hydrochloride or triflate whence hydrolysis of the nascent TMS ether may occur. In some cases the insoluble salt may be removed by filtration without aqueous workup. A wide range of solvents can be used for the reaction such as dichloromethane, acetonitrile, THF, or DMF. Care must be taken with trimethylsilyl triflate (TMSOTf) since it will convert aldehydes and ketones to the corresponding enol silanes and it will open epoxides in a reaction that has preparative significance [Scheme 4.6]. Similar transformations can be accomplished with tert-butyldimelhylsilyl triflate (TBSOTf) or triethylsilyl triflate (TESOTf). ... 

The system TMSOTf/2,6-lutidine has been proved to be highly effective for the deprotection of cyclic and acyclic acetals from aldehydes (eq 99) on the other hand, high chemoselectivity has been achieved when using triethylsilyl triflate/2,6-lutidine, which can deprotect acetals in the presence of ketals. ... 

Ketals are converted to allyl vinyl ethers after Wittig olefination [14]. Wittig reactions permit the incorporation of various substituents into the allyhc terminal of the ether. Enol ethers have been conveniently prepared by cleavage of acetals with various Lewis acids. Cleavage of the ketals with the Lewis acid, for example, triethylsilyl triflate, in the presence of diisopropylethylamine in refluxing 1,2-di-chloroethane afforded the enol ethers (Eq. 3.1.9). The resulting enol ethers were then heated to effect the Claisen rearrangement without isolation. 

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