Unsaturated Derivatives of Trifluoromethanesulfonamide

Abstract

Unsaturated derivatives of trifluoromethanesulfonamide (CF3SO2NH2, triflamide, TfNH2) of general formula TfNRR′ where R and/or R′ contain C=C or C≡C bonds, are of particular interest in triflate chemistry because they open the way for further functionalization and provide access to new adducts and cycloadducts. Two approaches to these compounds have been developed in our group. One is treatment of triflic anhydride (or fluoride) with unsaturated amines, or alkylation of triflamide with unsaturated alkyl halides. The second approach consists of oxidative triflamidation of dienes, with one C=C bond remaining intact. Another class of unsaturated triflamide derivatives is that of N‐alkylidenetriflamides (TfN=R). At the time our comprehensive review on triflamides and related compounds covering the literature up to 2012 was published, very little information on unsaturated triflamides was available. Since then, research in this area has expanded. In this review we demonstrate new examples of unusual reactivity of unsaturated triflamides, such as unprecedented splitting of α,ω‐bis(triflamidomethyl)diacetylene, diverse courses of oxidative triflamidation and arenesulfonamidation of dienes, different routes of cycloaddition of fluorinated and non‐fluorinated N‐sulfinylsulfonamides to carbodiimides, isomerization, etc. The high NH‐acidity, the strong electron‐acceptor ability and good nucleofugality of the triflyl and triflamido groups, and the presence of multiple bonds in the unsaturated triflamides all make them both interesting objects for investigations of hydrogen bonding and self‐organization processes, as well as valuable synthons in organic chemistry.