Trifluoromethoxy fluorides

An example of cleavage ol the sulfur-oxygen bond in trifluoromethane-sulfonic ester has been reported Tnfluororaethyl triflate reacts with neutral or anionic nucleophiles with elimination of carbonyl difluoride and formation of trifluoromethanesulfonyl fluoride [57] (equation 32) The mechanism of this reaction involves elimination of fluoride ion, which is a chain carrier in the substitution of fluorine for the trifluoromethoxy group... 

In the low-temperature fluorination of benzofuran (39, Y = O) and 1-acetylindole (39. Y = NAc), addition reactions are observed as well as vicinal fluoro trifluoromethoxy adducts 40A and 40B, vicinal difluoridcs 41 are formed.63 Trichloromethiazide is converted into the 5-fluoro derivative 42 in tetrahydrofuran/hydrogen fluoride at 0 C (in dichloromethanc/acetone 42 is accompanied by two nonfluorinated products).64... 

Propanoyl Fluoride TetraUuoro-3-trifluoromethoxy- ElOa, 313 (Alkanol + HF e9)... 

Poly[tetrafluoroethene-co-trifluoro(trifluoromethoxy)ethene] also decomposes at lower temperatures than perfluorinated macromolecules, and the major products of pyrolysis include hydrogen fluoride [65], tetrafluoroethene, hexafluoroethane and perfluoro(methyl vinyl) ether [64]. 

The only other relevant benzo derivatives apart from (349) are obtained by pyrolysis of ben-zenesulfonate salts. Lithium o-(trifluoromethylthio)benzenesulfonate (350) on heating at 360 °C in vacuo loses lithium fluoride and cyclizes to 3,3-difluoro-2-oxa-l,4-dithia-naphthalene 1,1-dioxide (351) in 70% yield (Equation (49)). Pyrolysis of the o-trifluoromethoxy analogue (352) at 260°C is less efficient, giving the 1,3,4-dioxathiane (353) in 17% yield <72ZOR1023>. 

Other addition/elimination sequence was utilized for monofluorination of benzofuran and its derivatives. Thus, the reaction of benzofuran 11 with trifluoromethyl hypofluorite (CF3OF) furnished 2-fluoro-3-trifluoromethoxy-2,3-dihydrobenzofurans 16 (43 % cis- and 15 % franx-isomer) and dx-difluoroderivative 17 (19 %). Treatment of the derivative 17 with ethanohc potassium hydroxide produced 3-fluorobenzofuran 18 in 61 % yield [20], 3-Fluorobenzofuran 18 was also synthesized from the compound 19 using silver fluoride as fluorinating and dehydrohalogenating reagent at the second step [21],... 

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