Vitamin Catalysis: Direct, Photocatalytic Synthesis of Benzocoumarins via (−)-Riboflavin-Mediated Electron Transfer

An operationally simple protocol is disclosed to facilitate entry to benzo-3,4-coumarins directly from biaryl carboxylic acids without the need for substrate prefunctionalization. Complementary to classic lactonization strategies, this disconnection relies on the oxidation competence of photoactivated (−)-riboflavin (vitamin B₂) to generate the heterocyclic core via photoinduced single electron transfer. Collectively, the inexpensive nature of the catalyst, ease of execution, and absence of external metal additives are a convincing endorsement for the incorporation of simple vitamins in contemporary catalysis

One-Pot Acid-Catalyzed Ring-Opening/Cyclization/Oxidation of Aziridines with <i>N</i>‑Tosylhydrazones: Access to 1,2,4-Triazines

A new, three-step, telescoped reaction sequence for the regioselective conversion of <i>N</i>-tosyl hydrazones and aziridines to 3,6-disubstituted and 3,5,6-trisubstituted 1,2,4-triazines is described. The process involves an efficient nucleophilic ring opening of the aziridine, giving access to a wide range of aminohydrazones, isolated with excellent yields. A “one-pot” procedure, combining the ring opening with a cyclization and an oxidation step, allows the preparation of diversified triazines in good yields