Silver trifluoromethanesulfonate, reactions

Vinyltrimethylstannanes react with xenon difluoride in dichloromethane at room temperature in the presence of equimolar (or a 50 Vo excess) of silver trifluoromethanesulfonate and a catalytical (0.1 equiv) quantity of 2,6-di-/e/7-butyl-4-methylpyridine to form the corresponding vinyl fluorides in high to moderate yields.54 57 The substitution reaction is tolerant to various functional groups, such as ketones, esters, carbamates, ketals, ethers, phenol rings and tertiary alcohols. As byproducts corresponding alkenes have been detected due to pro-tiodestannylation. 

In relation to carbohydrate chemistry, the Koenigs-Knorr synthesis of glycosides involves the treatment of glycosyl halides with an alcohol or phenol in the presence of a heavy metal salt.267 Karrer268 discovered that reaction of silver salts of hydros acids could also be used and use of these reagents has been extended more recently. Numerous variations and improvements on the original method have now been reported, and silver oxide, silver carbonate or silver trifluoromethanesulfonate have since become the accepted standard reagents.267... 

It has also been shown that treatment of primary bis(alkylmagnesium halides) with silver trifluoromethanesulfonate effects ring closure under mild conditions for a range of substrates, thus highlighting the generality of this reaction for producing small carbocycles (Table 1.3). 

The oligomerization and cooligomerization of conjugated dienes are representative reactions that proceed via transition-metal Jt-allyl intermediates. When (CsMesjRuCljt/ -butadiene) in dichloromethane was treated with an acetone solution of an equimolar amount of silver trifluoromethanesulfonate (AgOTf) in the presence of excess butadiene at ambient temperature, after which the mixture was allowed to react with carbon monoxide (1 atm), a cationic 1,5-cyclooctadiene carbonyl complex, [(C5Me5)Ru(CO)( -l,5-C8Hi2)]OTf, was isolated in 95% yield (Eq. 

Douglas, S P, Whitfield, D M, Krepinsky, J J, Silver trifluoromethanesulfonate(triflate) activation of trichloroacetimidates in glycosylation reactions, J. Carbohydr. Chem., 12, 131-136, 1993. 

To a solution of silver trifluoromethanesulfonate (7.71 g, 30 mmol) in dry dichloromethane (100 mL) at —40°C in the dark is added dropwise a solution of 9-fluorenylmethoxycarbony 1 serine benzyl ester 11 (8.45 g, 20 nunol), 2,3,4-tri-O-benzoyl-a-D-xylopyranosyl bromide 12 (11.14 g, 21.2 nunol) and tetramethyl urea (3.65 g, 31.4 nunol) in dichloromethane (100 mL). After 18 h of stirring at room temperature, the precipitate is filtered off and washed with dichloromethane (200 mL). The organic solution is washed with water (200 mL), 1% KHCO3 solution (twice 200 mL) and water, dried with Na SO, and concentrated in vacuo. The crude product is recrystallized from ethyl acetate-n-hexane. (If the reaction was not complete, chromatography on silica gel 60 in toluene/ethanol 9 1 is recommended). Yield 15 g (87%) mp 136°C, [a], —27.8° (c 1.3, CHCI3), 0.64 (toluene/ethanol 26 1). 

Conductivity measurements have revealed that DMF and carboxylic acid chlorides form salt-like adducts (22) in an equilibrium reaction (equation 12). Such adducts can be prepared either from DMF and acid halides (chlorides and bromides) or from chloromethyleneiminium salts and salts of carboxylic acids. Acyloxyiminium salts (23) can be prepared in the pure state by reacting acid amides with carboxylic acid chlorides in the presence of silver trifluoromethanesulfonate (equation 13). Salts of type (24 equation 14) are regarded as being intermediates in the synthesis of ketones from carboxylic acids and Grignard reagents in the presence of a-chloroenamines as well as in the preparation of acyl halides (F, Cl, Br, I) by action of a-haloenamines on carboxylic acids. ... 

Palladium complexes (43) and (44) have been obtained from the reaction of [Pd(r -C3H5)C1]2 with (41b) and (42b), respectively, in presence of AgBp4. Complexes (47a,b) and (48a,b) have been prepared in a similar way starting from the P-phenyl-substituted 1,2 phosphoranediimines (45) or (46) in presence of either silver tetrafluoroborate or silver trifluoromethanesulfonate. All complexes exhibit a good stability, which is in line with the capability of the 1,2-phosphoranediimides to stabilize Pd° centres in catalytic processes. It has been shown that (45) induces the highest enantioselectivity in a Pd-catalysed... 

These reagents are prepared by reaction of alkanesulfonyl bromides with silver trifluoromethanesulfonate. They are stable at room temperature when R is a primary alkyl group. When R = CH(CH3)2, the anhydride decomposes on attempted vacuum distillation. 

Seibel et al. [36] reported, for the first time, the use of microwave heating in the glycosylation of amino acids. They performed glycosyl transfer reactions of perace-tylated monosaccharides (glucose and galactose) and disaccharides (maltose and lactose) with N-9-fluorenylmethoxycarbonyl-L-serine benzyl ester in the presence of iron trichloride with short reaction times (4 min, compared with 5-10 h by conventional heating) and with improved yields (52-61% compared with 10-31% by conventional heating). It is worthy of note that in these reactions heavy metal compounds, for example silver trifluoromethanesulfonate, mercury dibromide and di-cyanide, or boron trifluoride-diethyl etherate, can be replaced by the environmentally safe promoter iron trichloride. 

Treatment of [Cp Ru(Ti -C4H6)(X)] (X = Cl, Br) with excess buta-l,3-dicne in the presence of silver trifluoromethanesulfonate (AgOTf) followed by carbon monoxide afforded OS the cycloocta-1,5-diene complex [Cp Ru(Ti -COD)(CO)]+[(OTf)], by means of a (4 + 4] cycloaddition reaction. Similar dimerisation, both stoichiometric and catalytic, was observed with other conjugated dienes. 

Roundhill, Joslin and Mague treated the ruthenium(II) complex, [RuCl(PPh3) P(OPh)3KTi5-Cp)], with silver trifluoromethanesulfonate and piperidine in THF. The reaction occurred over 30 minutes and yielded the cyclometallated product shown in Scheme 6.7 ... 

SESCI in Synthesis. The SES group has been used successfully in the synthesis of glycosides (eq 5). Reaction of (6) with SES-sulfonamide and lodonium Di-sym-collidine Perchlorate provides the iodo sulfonamide (7) in 82% yield. Treatment of (7) with (benzyloxy)tributylstannane in the presence of Silver ) Trifluoromethanesulfonate provides the p-benzyl glycoside (8). Fluoride treatment of (8) removes both the silyl ether and the SES group, giving the amino alcohol (9). 

In this procedure, the chiral alcohol is converted to the corresponding tetra-0-benzoyl-)8-glucoside by reaction with commercial 2,3,4,6-tetra-O-benzoyl-a-D-glucopyranosyl bromide in the presence of silver trifluoromethanesulfonate and 1,1,3,3-tetramethyl-urea. The NMR spectrum of the product is then compared with that of the free alcohol. The observed differences between the two spectra are caused by the anisotropic effect of the benzoyl groups and the... 

Alkyl esters of trifluoromethanesulfonic acid, commonly called triflates, have been prepared from the silver salt and an alkyl iodide, or by reaction of the anhydride with an alcohol (18,20,21). Triflates of the 1,1-dihydroperfluoroalkanols, CF2S020CH2R can be prepared by the reaction of perfluoromethanesulfonyl fluoride with the dihydroalcohol in the presence of triethylamine (22,23). Triflates are important intermediates in synthetic chemistry. They are among the best leaving groups known, so they are commonly employed in anionic displacement reactions. 

Glycosidation Allyl chloroformate, 9 Boron trifluoride etherate, 43 Silver(I) tetrafluoroborate, 273 Silver (I) trifluoromethanesulfonate, 274 Thallium zeolites, 296 Tin(II) trifluoromethanesulfonate, 301 Trichloroacetonitrile, 321 Grignard reactions and reactions of... 

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