On the protonation and deuteration of N , N ‐disubstituted 2‐aminothiophenes, 2‐aminothiazoles, and some 3‐amino substituted analogues

In contrast to their carbocyclic aniline analogues, N , N ‐diarylsubtituted 2‐aminothiophenes are not protonated at their N ‐atoms but at the 5‐position or, to a smaller extent, at the 3‐position of the thiophene nucleus giving rise to cationic species of the Wheland type. However, 5‐formyl and 5‐acetyl‐substituted 2‐( N , N ‐diarylamino)thiophenes are protonated at the corresponding carbonyl moieties. This finding not only enables insight into the mechanism of electrophilic substitution of N , N ‐disubstituted 2‐aminothiophenes but also allows to prepare deurated 2‐aminothiophenes by treatment their non‐deuterated parent compounds with CF 3 COOD.