Silver® trifluoromethanesulfonate

Form Supplied in white sohd widely available. 

Preparative Method can be prepared from the barium salt via treatment with dil H2SO4 followed by neutralization with Ag2C03.5 

Handling, Storage, and Precautions hght sensitive irritant. Use in a fume hood. 

Oxonium (Iminium) Reactions. Oxygen- and nitrogen- containing molecules bearing an a-nucleofuge such as a halide or sulfur are converted by AgOTf to highly electrophilic onium (eq 1) or iminium (eq 2) species. The intermediacy of a planar cation is substantiated by the formation of the same diastereomer from either substrate isomer in some cyclization reactions (eq 1). 

Friedel-Crafts (and Other Aromatic Functionalization) Reactions. When treated with AgOTf, alkyl, acyl (eq 4), and sulfonyl halides are converted to extremely electrophilic triflate species that react rapidly with even deactivated aromatic rings in the absence of catalysis. Benzylic chloroformates participate similarly (eq 5). Aromatic rings are also efficiently vinylated and iodinated via AgOTf-promoted processes. 

---

PhenyI-3,3-dichIoro-l-azetine (222) forms a 2 1 complex with silver tetrafluoroborate and 1 1 complexes with silver trifluoromethanesulfonate and with boron trifluoride. The dibromo analogue of (222) affords a similar 2 1 complex with silver tetrafluoroborate (79CB3914). 

A mixture consisting of the step 1 product (4.7 mmol), 4-(2-pyridyl) benzaldehyde (9.3 mmol), and 500 ml of toluene was stirred at ambient temperature for several hours and then treated with silver trifluoromethanesulfonate (9.3 mmol). The mixture refluxed for 3 hours and was then cooled to ambient temperature and filtered through Celite and then concentrated. The residue was purified by silica gel column chromatography using chloroform/ethyl acetate, 19 1, respectively, and then recrystallized in CH2CI2/methanol and 0.95 g of product isolated. 

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. 

T. Ziegler, P. Kovac, and C. P. J. Glaudemans, Transesterification during glycosylation promoted by silver trifluoromethanesulfonate, Liebigs Ann. Chem. p. 613 (1990) and references cited therein. 

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... 

Caution. Silver trifluoromethanesulfonate is an irritant. Propanenitrile, thioethers, and all organic solvents used are toxic. Contact with the liquids and vapors should be avoided. Appropriate precautions must be taken, and an efficient hood must be used. 

The advances that have led to the almost routine synthesis of tri- and tetrasaccha-rides began in the early 1970s and included a new approach to a-glycosides, the halide-ion catalyzed glycosylation [4], and the introduction of improved heavy metal catalysts such as silver trifluoromethanesulfonate (triflate) [5]. Numerous other technical and conceptual advances punctuated the intervening period and reference to these developments are to be found in the cited literature of several reviews [6—9]. 

Silver trifluoromethanesulfonate, methylsilyl trifluoromethanesulfonate, dime-thylmethylthiosulfonium-trifluoromethane sulfonate (DMTST), and boron trifluoride diethyl etherate were obtained from Sigma-Aldrich. 

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 cyclohexadiene complex 29 has been further elaborated to afford either the cydo-hexenone 34 or the cyclohexene 36 in moderate yields (Scheme 1) [21]. The addition of HOTf to 29 generates the oxonium species 33, which can be hydrolyzed and treated with cerium(IV) ammonium nitrate (CAN) to release the cyclohexanone 34 in 43 % yield from 29. Alternatively, hydride reduction of 33 followed by treatment with acid eliminates methanol to generate the r 3-allyl complex 35. This species can be trapped by the conjugate base of dimethyl malonate to afford a cyclohexene complex. Oxidative decomplexation of this species using silver trifluoromethanesulfonate liberates the cyclohexene 36 in 57 % overall yield (based on 29). 

The silver perchlorate solution may be substituted by 8.5 mL of 0.4 M silver trifluoromethanesulfonate (Fluka) in toluene. 

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. 

Meijer, A, Ellervik, U, Study of interhalogens/silver trifluoromethanesulfonate as promoter systems for high-yielding sialylations, J. Org. Chem., 67, 7407-7412, 2002. 

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. 

Morishima, N, Koto, S, Zen, S, Dehydrative a-glucosylation using a mixture of p-nitrobenzene-sulfonyl chloride, silver trifluoromethanesulfonate, 7/,Al-dimethylacetamide, and triethylamine,... 

---