Alcohols trifluoromethanesulfonate

Trichloroacetonitrile reacts with glycosidic hydroxy groups of protected sugars to form glycosyl trichloroacetimidates (R. R. Schmidt, 1980, 1984,1985,1986 B. Wegmann, 1988). The imidate is substituted by alcohols in the presence of trimethylsilyl trifluoromethanesulfonate... 

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. 

DiaLkyl peroxides may be prepared by reaction of alcohols or alkyl trifluoromethanesulfonates with organomineral peroxides of siUcon, tin, and germanium (44,108), where Q = Sn and Ge ... 

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). 

Opening by trimethylsilyl trifluoromethanesulfonate yields an adduct (54) from which trifluoromethanesulfonic acid can be eliminated to give an allylic alcohol (Scheme 47) (79JA2738) [cf. base-promoted isomerization to allylic alcohols (Section 5.05.3.2.2)]. 

This method is especially useful for the conversion of ketones to ketals, since the direct reaction of a ketone with an alcohol often gives poor results. In another method, the substrate is treated with an alkoxysilane ROSiMe3 in the presence of trimethylsilyl trifluoromethanesulfonate. ... 

CHROMIUM TRIOXIDE-PYRIDINE COMPLEX, preparation in situ, 55, 84 Chrysene, 58,15, 16 fzans-Cinnamaldehyde, 57, 85 Cinnamaldehyde dimethylacetal, 57, 84 Cinnamyl alcohol, 56,105 58, 9 2-Cinnamylthio-2-thiazoline, 56, 82 Citric acid, 58,43 Citronellal, 58, 107, 112 Cleavage of methyl ethers with iodotri-methylsilane, 59, 35 Cobalt(II) acetylacetonate, 57, 13 Conjugate addition of aryl aldehydes, 59, 53 Copper (I) bromide, 58, 52, 54, 56 59,123 COPPER CATALYZED ARYLATION OF /3-DlCARBONYL COMPOUNDS, 58, 52 Copper (I) chloride, 57, 34 Copper (II) chloride, 56, 10 Copper(I) iodide, 55, 105, 123, 124 Copper(I) oxide, 59, 206 Copper(ll) oxide, 56, 10 Copper salts of carboxylic acids, 59, 127 Copper(l) thiophenoxide, 55, 123 59, 210 Copper(l) trifluoromethanesulfonate, 59, 202... 

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. 

Additions of the Reformatsky-type reagents to aldehydes can also proceed in ionic solvents (Scheme 108).287 Three ionic liquids have been tested 8-ethyl-l,8-diazbicyclo[5,4,0]-7-undecenium trifluoromethanesulfonate ([EtDBU][OTf]), [bmim][BF4], and [bmim][PF6]. The reactions in the first solvent provided higher yields of alcohols 194 (up to 93%), although results obtained for two other ionic liquids were also comparable with those reported for conventional solvents. 

Acids that are used in addition to trifluoroacetic acid include trifluoroacetic acid with added sulfuric acid203 or boron trifluoride etherate,210,211 perfluorobu-tyric acid,212 hydrogen chloride/aluminum chloride,136,146,213 perchloric acid in chloroform,214 p-loluenesull onic acid alone134 or with aluminum bromide or aluminum chloride,192 concentrated sulfuric acid in two-phase systems with dichloromethane, alcohol, or ether solvents,209,215 trifluoromethanesulfonic acid,216 chlorodifluoroacetic acid,134 and the monohydrate of boron trifluoride... 

The formylmethyl complex 21 also serves as a source of free acetaldehyde, and one equivalent of trifluoromethanesulfonic acid in CH2CI2 releases it from 21 within one hour at room temperature. Acetaldehyde was identified by its 2,4-dinitrophenylhydrazone (isolated in 42% yield), and was determined directly (48%) by quantitative analysis of its IR v 1716 cm"l absorption. The protonation of 21 presumably generates a n2-vinyl alcohol compound 19 (R=H) [IR observable v 1983 cm" ], which then dissociates acetaldehyde. We have overall converted selectively two carbonyls on CpFe(CO)3+ (1) to acetaldehyde. 

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 ... 

Besides the l-(but-3-enyl)allyl alcohols discussed above, 2- and 3-(pent-4-enyl)allyl alcohols also undergo clean photobicyclization in the presence of copper trifluoromethanesulfonate as catalyst. However, no intramolecular photocycloaddition product could be isolated from irradiation of a homologous 2-(hex-5-enyl)allyl alcohol.8... 

If one of the C —C double bonds of the 1,6-diene is incorporated in or attached to a ring (e.g., cycloalkene, methylenecycloalkane) tricyclic compounds containing a bicyclo[3.2.0]heptane subunit are obtained as products. Thus, photobicyclization of monocyclic diallyl ethers or homoallyl vinyl ethers afford oxatricycloalkanes.6 Similarly, allylic alcohols containing an additional cycloalkenyl ring are converted to oxatricycloalkanes by irradiation in the presence of copper(I) trifluoromethanesulfonate as catalyst.9... 

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. 

Although tris(dialkylamino)sulfonium difluorotrimethylsilicates are not sufficiently reactive to fluorinate alcohols, they are able to convert trifluoromethanesulfonates to their corresponding fluorides under mild conditions. The mild conditions required to form the ester and to perform the fluorination step, has resulted in TASF (1) and related reagents finding wide application in the syntheses of fluorinated carbohydrates (see Table 10).5"76-78 It is of interest that this process is a modern development of the first reaction ever used to synthesize an organic fluoride in 1835 (see Introduction 1.2.). 

The nucleophilic displacement efficacy of tetraethylammonium fluoride has been efficiently exploited in the preparation of 10 from the alcohol 9 via its trifluoromethanesulfonate derivative.195... 

---