N- and C-Attacks of phenylnitrenium ions generated from phenyl azides in the presence of trifluoroacetic acid and/or trifluoromethanesulphonic acid

Abstract

Phenylnitrenium ions were generated from phenyl azides in the presence of trifluoroacetic acid (TFA) and/or trifluoromethanesulphonic acid (TFSA). Unsubstituted phenylnitrenium ions and those with an electron-withdrawing group such as NO₂ or CN undergo aromatic N-substitution, whereas those with an electron-donating group such as Me, OMe, CH₂Ph, or Ph undergo C-substitution, hydrogen abstraction, and tar formation. The special character of TFA and TFSA as compared with other acids is discussed.