Reactions of the Readily Accessible Electrophile, Trifluoroacetyl Triflate: A Very Reactive Agent for Trifluoroacetylations at Oxygen, Nitrogen, Carbon, or Halogen Centers

Article abstract of DOI:10.1021/jo00228a002

Trifluoroacetyl triflate (TFAT) is readily prepared in 82percent yield by the dehydration (phosphorus pentoxide) of a 2:1 mixture of trifluoroacetic acid and trifluoromethanesulfonic (triflic) acid.Reactions of this highly electrophilic trifluoroacetylating reagent with alcohols, ketones, ethers, amines, and pyridines give esters, enol esters, ether cleavage, amides, and acylpyridinium ions, respectively.Reactions with ionic or easily ionizable alkyl halides give the very volatile trifluoroacetyl halides and the ionic triflate.Triphenylmethyl chloride, for example, is quantitatively converted to triphenylcarbenium triflate in a very convenient synthetic procedure.Trifluoroacetyl triflate is used in the synthesis of the first member of a new class of pyrylium salts, 2,6-dimethoxypyrylium triflate.