K<sub>2</sub>S<sub>2</sub>O<sub>8</sub>‑Mediated\nDenitrogenative Formal Transformylation of Amines with Formylhydrazine\nin Water

A new approach for direct formylation of various amines\nhas been\ndisclosed using a novel formylating agent, formylhydrazine, to afford <i>N</i>-formylamines in significant yields with application in\nthe gram-scale synthesis of chlorothiazide. This transformylation\n(transfer of a formyl group from hydrazine to amines) occurs via denitrogenation\nin the presence of K<sub>2</sub>S<sub>2</sub>O<sub>8</sub> as the\nexclusive reagent with water as the solvent. Two reaction pathways\ninvolving extremely underexplored formyl or hemiaminal radicals have\nbeen postulated, which require further investigation.