Protonation of oxygen in the side chain of the Me3SiO group (followed by the elimination of Me3SiOH) and protonation of the thiophene ring in 2-chloro(or bromo)-5-(1′-Me3SiO-1′-trifluoromethyl-alkyl)thiophenes in Brønsted superacids (CF3SO3H, FSO3H) gave rise to short-lived and reactive trifluoroalkyl carbocations of the thiophene series. These cations were studied by low-temperature NMR spectroscopy in the superacids, which shed light on their reactivity and reaction mechanisms. The cations may react with (hetero)aromatic π-nucleophiles in various directions, depending on their structures as well as the reaction temperature and time. These transformations resulted in the formation of novel fluoro-organics of the thiophene family, namely, products of arylation of both the thiophene system and its side chain, hydrodehalogenation of halothiophenes, or electrophilic "dimerization".
Scopus subject areas
- Organic Chemistry