Triflates trimethylsilyl

After the readily available Friedel-Crafts catalyst, tin(IV) chloride, had been established as a catalyst for nucleoside synthesis, several other new catalysts, such as trimethylsilyl triflate (trimethylsilyl trifluoromethanesulfonate TMSOTf), etc., which are less acidic as Lewis acids... 

CT3795 EINECS 248-5664 Methanesulfonio acid, trifluoro-, trimethylsilyl ester Trifluoromethanesulfonic acid trimethylsilyl ester Trimethylsilyl triflate Trimethylsilyl trifluoromethanesulfonate ... 

Acetal-P, P-diglucosides In the presence of trimethylsilyl triflate, trimethylsilyl-2,3,4,6-tetra-0-acetyl- 3-D-glucopyranoside (1) reacts with aldehydes at -78° to form acetal-/3, -diglucosides 2 in 30-85% yield. At higher temperatures, mixtures of acetal-a,/3-, and a,a-diglucosides are obtained. The yields arc dependent on the reactivity and steric bulk of the aldehyde. Ketones do not undergo this reaction. 

Trimethyls lyl triflate. See Trimethylsilyl trifluoromethane sulfonate Trimethylsilyl trifluoromethane sulfonate CAS 27607-77-8 EINECS/ELINCS 248-565-4 Synonyms Trifluoromethanesulfonic acid trimethylsilyl ester Trimethylsilyl triflate Trimethylsilyl trifluoromethyl sulfonate Classification Silane Empirical C4HgF303SSi Formula CF3S03Si(CH3)3... 

Conjugate Addition of Alkynylzinc Bromides. Alkynylz-inc bromides undergo conjugate addition with a, 8-unsaturated ketones in the presence of ferf-butyldimethylsilyl trifluo-romethanesulfonate or TIPS triflate (trimethylsilyl trifluo-romethanesulfonate is also effective) in ether-THF at —40 °C to give the corresponding 1,4-adducts (54-96% yields). A representative example is illustrated in eq 7. 

Ac, acetyl BSA, MO-hw-trimethylsilyl-acetamide Bz, benzoyl DMF, dimethylformamide Ibu, isobutyryl THF, tetrahydro-furan TMS-triflate, trimethylsilyl trifluoromethanesulfonate Tol toluoyl Pal, palmitoyl. 

Direct 3-silylation of A -substituted indoles has been ellected by reaction of the indoles with trimethylsilyl triflate in the presence of triethylamine[12]. The trimethylsilyl group has also been introduced via 3-lithio-l-(phenylsulfonyl)-indole[13]. 

Trimethylsilyl triflate—silver perchlorate (1 1) also cataly2es the highly stereoselective glycosylation of P-naphthol to provide predominantiy the P-anomer. 

Trimethylsilyl trifluoromethanesulfonate (trimethylsilyl triflate) is the most synthetically useful representative of the family of trialkylsilyl perfluoroalkane-sulfonates (for a review, see reference 101) This reagent is commercially available or can be prepared easily by the reaction of chlorotrimethylsilane and triflic acid [101] It has wide application in organic synthesis as an excellent silylating reagent... 

Compound 40 has not yet been synthesized. However, there is a large body of synthetic data for nucleophilic substitution reactions with derivatives of 41 [synthesized from aliphatic and aromatic aldehydes, pyridine, and trimethylsilyl triflate (92S577)]. All of these experimental results reveal that the exclusive preference of pathway b is the most important feature of 41 (and also presumably of 40). 

The reaction processes shown in Scheme 8 not only accomplish the construction of an oxepane system but also furnish a valuable keto function. The realization that this function could, in an appropriate setting, be used to achieve the annulation of the second oxepane ring led to the development of a new strategy for the synthesis of cyclic ethers the reductive cyclization of hydroxy ketones (see Schemes 9 and 10).23 The development of this strategy was inspired by the elegant work of Olah 24 the scenario depicted in Scheme 9 captures its key features. It was anticipated that activation of the Lewis-basic keto function in 43 with a Lewis acid, perhaps trimethylsilyl triflate, would induce nucleophilic attack by the proximal hydroxyl group to give an intermediate of the type 44. 

The diastereomeric ratio of the trimethylsilyl triflate catalyzed amidoalkylation of a number of silyl enol ethers at — 40 CC appears to be dependent on the substituents in the substrate87. At — 40 °C the diastereomeric ratio is shown to be kinetically controlled. On allowing the reaction mixture to warm to 20 "C slow epimerization, increasing the amount of the minor isomer, is observed. In the case of the naphthalene derivative, sodium methoxide catalyzed epimerization of the kinetic mixture [(antijsyn) 88 12] produces the thermodynamic mixture [(antijsyn) 9 91]. 

This can also be done at room temperamre by treatment with trimethylsilyl triflate and a tertiary amine or with MesSil in the presence of hexamethyldisilazane. Enol ethers can be pyrolyzed to alkenes and aldehydes in a manner similar to that of 17-3 ... 

The related planar pyrrole analog 118 has also been prepared (2) from either ethyl or benzyl pyrrole-2-carboxylate 116. Direct alkylation with diethyl phosphonomethyl triflate (70) and base produced the N-phosphonomethylpyrrole 2-carboxylate 117, which was deprotected with trimethylsilyl bromide and saponified to the corresponding phosphonic acid 118. 

Trimethylsilyl triflate has also been used as an initiator. High yields of PCL were obtained in 1,2-dichloroethane at 50°C and Myy values up to 50.000 were attained after 192 hr (135). 

The use of the enolsilyl ether of 1-menthone [16, 19, 21-23] and of some free triflic acid favors the formation of the thermodynamically controlled products as with free 2,2 -dihydroxydiphenyl [22] and only subsequently added HMDS 2 [22]. On reacting silylated alcohols and carbonyl compounds with pure trimethylsilyl triflate 20 under strictly anhydrous conditions no conversion to acetals is observed [24]. Apparently, only addition of minor amounts of humidity to hydrolyze TMSOTf 20 to the much stronger free triflic acid and hexamethyldisiloxane 7 or addition of traces of free triflic acid [18-21, 24, 26] or HCIO4 [25] leads to formation of acetals. 

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