Trifluoromethyl sulfate

Covalent fluorosulfates are often used as starting materials for trifluoromethyl sulfate derivatives. Complete degradation of S03F moieties by HS03CF3 is the... 

The moderate thermal stability of the xenon fluorosulfates suggested that trifluoromethyl sulfates and even the methyl sulfates might be preparable. Although reactions to produce these compounds did proceed, under control, at temperatures of —20° or lower, the solid products usually detonated at or below room temperatures. The interaction of XeFa with a slight molar excess of HOSO2CF3 in HF has yielded a solid product which is indicated by vibrational spectroscopic evidence to be CFsSOaXeF. 

A slightly more complex reaction allows the solvolytic conversion of fluoro-sulfates into trifluoromethyl sulfates (5) however, here the HSO3F initially formed reacts further with HSO3CF3, present in an excess, to produce a range of volatile materials that do not interfere in the isolation of the binary or ternary trifluoromethyl sulfates. Solvolysis of RnSnCl4 n, R = CH3 and n = 2,3, or 4, in strong acids is the preferred synthetic route to dime yltin(IV) salts. 

B) Preparation of S-Trifluoromethyl-2,4-Disulfamylaniline—The 5-trifluoromethylaniline-2,4-disulfonyl chloride obtained in step (A) is taken up in ether and the ether solution dried with magnesium sulfate. The ether is removed from the solution by distillation, the residue is cooled to 0°C, and 60 ml of ice-cooled, concentrated ammonia water is added while stirring. The solution is then heated for one hour on a steam bath and evaporated... 

The only stable 1,3,2-dioxathietanes known are fluorinated sulfate derivatives formed by addition of sulfur trioxide to bis(trifluoromethyl)ketene. These structures are fairly well characterized from spectral data and from reactions with nucleophiles. Hexafluoroisopropy-lidene-l,3,2-dioxathietane 2,2-dioxide acts as a sulfur trioxide transfer agent to alkenes and is in equilibrium with a dimeric form as indicated by 19F NMR (Scheme 138) (71KGS1645, 72KGS306, 73KGS178, 132l). 

Trifluoro-5-trifluoromethyl-l,3,2-dioxathiolane 2,2-dioxide (96) was obtained among other products by reaction of perfluoropropene oxide with sulfur trioxide at 150°C (73IZV2725). Perfluorobutadiene reacted with sulfur trioxide to give the cyclic sulfate (31)... 

As in Explanation 27, sulfur of sulfur trioxide becomes attached to the more electronegative (electrophilic) carbon of the double bond of perflu-oroisobutylene. The electron density of the central carbon is increased by back-donation of electrons of the difluoromethylene group, and by electron withdrawal of the two trifluoromethyl groups. The intermediate four-membered cyclic sulfate rearranges to 2,2-bis(trifluoromethyl)-l-fluoroethenyl fluorosulfate 46. ... 

Click chemistry also found applications in peptides and peptidomimetics. Alkyne-azide cycloaddition between two peptide strands provided an efficient convergent synthesis of triazole ring-based P-tum mimics <07CC3069>. The synthesis of a-substituted prolines has been accomplished by microwave-assisted Huisgen 1,3-dipolar cycloaddition between azides and orthogonally protected a-propynyl proline in the presence of Cu(I) sulfate <07SL2882>. The synthesis of new trifluoromethyl peptidomimetics with a triazole moiety has been reported <07TL8360>. 

Bis-trifluoromethylmethylene)-1,2,4-thiadioxetane 1,1-dioxide (hexafluoro-isobutenylidene sulfate) (499) is a stable, colorless liquid obtained by treatment of bis(trifluoromethyl) ketene, 3,3,3-trifluoro-2-trifluoromethylpropanoic acid, or the anhydride of the latter with sulfur trioxide. It is said, on the basis of F nmr data, to be in equilibrium with a cyclic, eight-membered dimer (/Teq = 0.1321iter/mole at 34.5°C), analogous to the structure of the above-mentioned methylene sulfate . Hydrolysis of 499 gives 3,3,3-trifluoro-2-trifluoromethyl-propanoic acid. The cyclic sulfate is a powerful donor of sulfur trioxide, as exemplified by its reactions with fluoride, bromide, and iodide ions (but not chloride ions), triethylamine, dioxane, sulfolane, and alkenes (See... 

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