One-Pot Synthesis of CF3-Substituted Vinyl Trifluoromethanesulfonamides from Imines and Trifluoromethanesulfonic Anhydride

Recent Applications of Trifluoromethanesulfonic Anhydride in Organic Synthesis

Trifluoromethanesulfonic anhydride has been widely used in synthetic organic chemistry, not only for the conversion of various oxygen-containing compounds to the triflates, but also for the electrophilic activation and further conversion of amides, sulfoxides, and phosphorus oxides. In recent years, the utilization of Tf₂ O as an activator for nitrogen-containing heterocycles, nitriles and nitro groups has become a promising tool for the development of new valuable methods with considerable success. In addition, Tf₂ O has been used as an efficient radical trifluoromethylation and trifluoromethylthiolation reagent due to the contained SO₂ CF₃ fragment, and significant progress has been made in this area. This review summarizes the recent progress in the applications of Tf₂ O in the above two aspects, and aims to illustrate the role and potential application of this reagent in organic synthesis.

Homolytic N-S Bond Cleavage in Vinyl Triflimides Enabled by Triplet-Triplet Energy Transfer

Vinyl triflimides are a new compound class with unknown reactivity. A computational analysis identified homolytic cleavage of the N-Tf bond induced by triplet-triplet energy transfer (EnT) as a highly interesting reaction type that might be accessible. A combination of experimental and mechanistic work verified this hypothesis and proved the generated radicals to be amenable to radical-radical coupling. Thereby, vinyl triflimides were transformed into a range of α-quaternary, β-trifluoromethylated amines in a 1,2-difunctionalization reaction with no need for external CF₃ reagents.

Triflamides and Triflimides: Synthesis and Applications

Among the variety of sulfonamides, triflamides (CF₃SO₂NHR, TfNHR) occupy a special position in organic chemistry. Triflamides are widely used as reagents, efficient catalysts or additives in numerous reactions. The reasons for the widespread use of these compounds are their high NH-acidity, lipophilicity, catalytic activity and specific chemical properties. Their strong electron-withdrawing properties and low nucleophilicity, combined with their high NH-acidity, makes it possible to use triflamides in a vast variety of organic reactions. This review is devoted to the synthesis and use of N-trifluoromethanesulfonyl derivatives in organic chemistry, medicine, biochemistry, catalysis and agriculture. Part of the work is a review of areas and examples of the use of bis(trifluoromethanesulfonyl)imide (triflimide, (CF₃SO₂)₂NH, Tf₂NH). Being one of the strongest NH-acids, triflimide, and especially its salts, are widely used as catalysts in cycloaddition reactions, Friedel–Crafts reactions, condensation reactions, heterocyclization and many others. Triflamides act as a source of nitrogen in C-amination (sulfonamidation) reactions, the products of which are useful building blocks in organic synthesis, catalysts and ligands in metal complex catalysis, and have found applications in medicine. The addition reactions of triflamide in the presence of oxidizing agents to alkenes and dienes are considered separately.

Recent Advances in Radical Reactions of Vinyl Triflates and Their Derivatives

Vinyl triflates are valuable precursors for vinyl cations and vinyl carbenes and serve as electrophiles in transition-metal-catalyzed cross-coupling reactions. However, the scope of radical reactions involving vinyl triflates has been very limited until recently. In this short review, we summarize the recent development on two categories of radical reactions involving vinyl triflates, i.e., radical trifluoromethylations and radical non-trifluoromethylations of vinyl triflates.

1 I ntroduction to Vinyl Triflates

2 Earlier Work on Radical Reactions of Vinyl Triflates

3 Radical Trifluoromethylations of Vinyl Triflates and Their Derivatives

4 Radical Non-Trifluoromethylation of Vinyl Triflates

5 Conclusions and Outlook