Esters trifluoromethanesulfonate

Methylacridinium-9-carboxylic ester trifluoromethanesulfonate (100 mg) was dissolved in dichloromethane (100 mL). To this solution perchloric acid (20 drops) and zinc powder (6 g) were added. The mixture was placed in an ultrasonic bath for 3 h and filtered. The solution was washed with water (1 x) and hydrochloric acid (2X, 0.1 M), dried over MgS04, and concentrated. 

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

Synonyms Methanesulfonic acid, trifluoro-, methyl ester Trifluoromethanesulfonic acid, methyl ester Empirical C2H3F3O3S Properties Colorless to brn. liq. sol. in 95% ethanol insol. in water reacts exothermically with DMSO m.w. 164.10 sp.gr. 1.450 (20/4 C) b.p. 94-99 C flash pt. 38 C ref. index 1.3244 (20 C) Toxicology Toxic by inh., ing., skin contact corrosive causes burns extremely destructive to tissues of eyes, skin, mucous membranes, upper respiratory tract risk of irreversible effects inh. may cause spasm, inflamm./edema of larynx/bronchi, chem. pneumonitis, pulmonary edema may cause burning... 

The alkaloid dubamine contains a single bond between the two heteroarene units. This lond was formed in 79% yield by the generally valuable palladium-catalyzed eoupling of an ryltrimethylstannane with an aryl triflate (see section 1.6). The requisite stannane was pre-ared from l,3-benzodioxol-5-yl triflate and hexamethyldistannane with the same palladium atalyst, the triflate ester was obtained from 2(1 f/)-quinolinone and trifluoromethanesulfonic jihydride (A.M. Echavarren, 1987). An earlier attempt to perform this aryl coupling by dassical means gave a yield of only 1 %. 

Trifluoromethanesulfonic acid is miscible in all proportions with water and is soluble in many polar organic solvents such as dimethylformamide, dimethyl sulfoxide, and acetonitrile. In addition, it is soluble in alcohols, ketones, ethers, and esters, but these generally are not suitably inert solvents. The acid reacts with ethyl ether to give a colorless, Hquid oxonium complex, which on further heating gives the ethyl ester and ethylene. Reaction with ethanol gives the ester, but in addition dehydration and ether formation occurs. 

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. 

Esters of / fZ-amyl alcohol can be obtained by acylation of 2-methyl-2-butene in the presence of trifluoromethanesulfonic acid (44). The esters produced, in high yields, from reaction of amyl alcohols with carboxyHc anhydrides, are used as intermediates for preparation of pyryflum salts (45,46) and alkaloids (47). Tria2oles prepared by acylation of 3-methyl-1-butanol are useful as herbicides (48). 

Decomposition of the diazoacetic ester (548) to the keto carbene (549) is promoted by copper(II) trifluoromethanesulfonate. In the presence of nitriles, 1,3-dipolar addition to the nitrile occurred giving the oxazole (550) (75JOM(88)ll5) (see also Section 4.03.8.1). 

Ethyl trifluoromethanesulfonate [425-75-2] M 178.1, b 115 /atm, 118-120 /atm, d 1.378, Hp 1.336. The ester reacts slowly with H2O and aqueous alkali. If its IR has no OH bands (-3000 cm" ) then purify by redistillation. If OH bands are present then dilute with dry Et20 and shake (carefully) with aqueous NaHC03 until effervescence ceases, then wash with H2O and dry (MgSOa), filter, evaporate and distil the residue under slight vacuum then at atmospheric pressure in a N2 atmosphere. IT IS A POWERFUL ALKYLATING AGENT, AND THE FUMES ARE VERY TOXIC - CARRY ALL OPERATIONS IN AN EFFICIENT FUME CUPBOARD. [Gramstad and Hazeldine J Chem Soc 173 7956 Howells and McCown Chem Rev 77 69 1977.]... 

Various sources of fluoride ion have been investigated, of which highly nucleophilic tetraalkylammonium fluorides ate the most effective Thuf, fluoro alkyl halides and N (fluoroalkyl)amines are efficiently synthesized by treatment of the corresponding trifluoromethanesulfonic esters with tetrabutylammonium fluoride trihydrate in aprotic solvents [5fl] (equation 34) The displacement reactions proceed quantitatively at room temperature within seconds, but tail with hydrogen fluoride-pyridine and give reasonable yields only with hydrogen fluo ride-alkylamine reagents... 

Another triflate ester that recently has found growing application in organic synthesis is commercially available trimethylsilylmethyl trifluoromethanesul fonate. This powerful alkylating reagent can be used for the synthesis of various methylides by an alkylation-desilylation sequence A representative example is the generation and subsequent trapping by 1,3-dipolar cycloaddition of indolium methanides from the corresponding indole derivatives and trimethylsilylmethyl trifluoromethanesulfonate [108] (equation 54)... 

Boron azaenolates, generated from achiral 2-ethyl-4,5-dihydro-4,4-dimethyloxazolc (10) and chiral diisopinocamphcylboryl trifluoromethanesulfonate [14, derived from (+)-a-pinene], selectively provide the //////-adducts (>90%) in 77 85% ee. These are converted to the corresponding methyl esters 16 in 22 -36% overall yield20,21. 

As an alternative to lithium enolates. silyl enolates or ketene acetals may be used in a complementary route to pentanedioates. The reaction requires Lewis acid catalysis, for example aluminum trifluoromethanesulfonate (modest diastereoselectivity with unsaturated esters)72 74 antimony(V) chloride/tin(II) trifluoromethanesulfonate (predominant formation of anti-adducts with the more reactive a,/5-unsaturated thioesters)75 montmorillonite clay (modest to good yields but poor diastereoselectivity with unsaturated esters)76 or high pressure77. 

C[iH4F,iN20gS2 157875-58-6) see Imiquimod trifluoromethanesulfonic acid triethylsilyl ester (C7Hi5F303SSi 79271-56-0) see Tacrolimus trifluoromethanesulfonic anhydride (C2F(,05S2 358-23-6) see Imiquimod Zanamivir... 

Trifluoromethanesulfonates of alkyl and allylic alcohols can be prepared by reaction with trifluoromethanesulfonic anhydride in halogenated solvents in the presence of pyridine.3 Since the preparation of sulfonate esters does not disturb the C—O bond, problems of rearrangement or racemization do not arise in the ester formation step. However, sensitive sulfonate esters, such as allylic systems, may be subject to reversible ionization reactions, so appropriate precautions must be taken to ensure structural and stereochemical integrity. Tertiary alkyl sulfonates are neither as easily prepared nor as stable as those from primary and secondary alcohols. Under the standard preparative conditions, tertiary alcohols are likely to be converted to the corresponding alkene. 

See entry ALLYL TRIFLUOROMETHANESULFONATES See other SULFUR ESTERS... 

Methoxy-4 -nitrobiphenyl 1,1 -Biphenyl, 4-methoxy-4 -nitro- (9) (2143-90-0) 4-Nitrophenyl trifluoromethanesulfonate Methanesulfonic acid, trifluoro-, p-nitrophenyl ester (8) Methanesulfonic add, trifluoro-, 4-nitrophenyl ester (9) (17763-80-3)... 

Bromoanlsole Anisole, o-bromo- (8) Benzene, 1-bromo-2-methoxy- (9) (578-57-4) Methyl trifluoromethanesulfonate Methanesulfonic add, trifluoro-, methyl ester (8,9) (333-27-7)... 

Photoproduct of Dl in solid state. Major photoproduct from Dl in the solid state was isolated by silica gel column chromatography and analyzed by IR and NMR spectroscopy (Figures 2 and 3). NMR spectrum shows that a photoproduct of Dl has the absorption band of the N, N-dimethylamino group (2.86 ppm) and the symmetric absorption band of aromatic protons (6.57-7. 10 ppm). The strong IR absorption of the sulfonyl group (12.10 and 1420 cm-1) can be seen in Figure 3. From NMR and TR spectra, the main photoproduct of the Dl was identified as trifluoromethanesulfonic acid 4-N, N-dimethylaminophenyl ester. 

Vinyl trifluoromethanesulfonates (triflates) are a new class of compounds, unknown before 1969, that have been used most extensively in solvolytic studies to generate vinyl cations.2,3,812 Three methods have been used to prepare these sulfonic esters. The first, involving the preparation and decomposition of acyltriazines,4 requires several steps to prepare the acyltriazines and is limited to the preparation of fully substituted vinyl triflates. The second method involves the electrophilic addition of trifluoromethanesulfonic acid to acetylenes5,8,15 and, consequently, is not applicable to the preparation of trisubstituted vinyl triflates and certain cyclic vinyl triflates. However, this second procedure is relatively simple and often gives purer products in higher yield than the subsequently discussed reaction with ketones. Table I lists vinyl triflates that have been prepared by this procedure. ... 

The third procedure illustrated by this preparation involves the reaotion of ketones with trifluoromethanesulfonic anhydride in a solvent such as pentane, methylene chloride, or carbon tetrachloride and in the presence of a base such as pyridine, lutidine, or anhydrous sodium carbonate.7-11,15 This procedure, which presumably involves either acid-catalyzed or base-catalyzed enolization of the ketone followed by acylation of the enol with the acid anhydride, has also been used to prepare other vinyl sulfonate esters such as tosylates12 or methanesulfonates.13... 

Thus, the best compromises for Boc and Fmoc chemistries seem to be cyclohexyl and 2,4-dimethylpent-3-yl (Dmpn), which is of intermediate stability, and the removal of which by trifluoromethanesulfonic acid with the aid of thioanisole (see Section 6.22) leads to minimal imide formation (see Section 6.13). Points to note are that acidolysis of esters by hydrogen fluoride can lead to fission at the oxy-car-bonyl bond instead of the alkyl-oxy bond, thus generating acylium ions that can react with nucleophiles (see Sections 6.16 and 6.22), and that benzyl esters may undergo transesterification if left in methanol. The side reactions of cyclization (see Section 6.16) and acylation of anisole (see Section 6.22) caused by acylium ion formation do not occur at the side chain of aspartic acid.47-51... 

Asymmetric introduction of azide to the a-position of a carbonyl has been achieved by several methods. These include amine to azide conversion by diazo transfer,2 chiral enolate azidation,3 and displacement of optically active trifluoromethanesulfonates,4 p-nitrobenzenesulfonates,5 or halides.6 Alkyl 2-azidopropionates have been prepared in optically active form by diazo transfer,2 p-nitrobenzenesulfonate displacement,5 and the Mitsunobu displacement using zinc azide.7 The method presented here is the simplest of the displacement methods since alcohol activation and displacement steps occur in the same operation. In cases where the a-hydroxy esters are available, this would be the simplest method to introduce azide. 

Trifluoromethanesulfonate esters ( triflates ) of allyl alcohol and its derivatives are very reactive and undiluted samples must be stored in vented containers at — 78° C. A chilled sample of allyl triflate in a sealed ampoule exploded on being allowed to warm to ambient temperature. The esters react violently with aprotic solvents such as DMF or DMSO. Individually indexed compounds are ... 

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