Regioselective Formal Hydroamination of Styrenes with 1‑Phenyl‑1H‑tetrazole-5-thiol

1-Phenyl-1H-tetrazole-5-thiol 1 (PT-thiol) is employed in a unique Markovnikov-selective formal hydroamination of styrenyl compounds in the presence of catalytic amounts of Ga­(OTf)₃. This gives rise to the formation of tetrazolothione moieties in an atom-economical manner. Mechanistically, we have determined that this transformation may occur by kinetically favored hydrothiolation, followed by rearrangement to the observed hydroamination products.