Synthesis and Characterization of 2‐Thiophenemethanamine‐ ² <i>H</i> ₅ Hydrochloride

Synthesis of the key building block, 2-thiophenemethanamine-²H₅ hydrochloride, was achieved using mild conditions and purification methods in three steps from commercially available thiophene-²H₄, with an overall yield of 61.6% and an overall isotopic enrichment of 87.6%. 2-thiophenemethanamine-²H₅ hydrochloride has the potential to be a useful intermediate in the synthesis of isotopically labelled compounds of pharmaceutical interest.