Thermal Synthesis of 3‐Bromothieno[3,2‐c]pyridin‐4‐(5H)‐one: A Telescoped Procedure with Tributylamine

3-Bromothieno[3,2-c]pyridine-4-(5H)-one (1) was prepared from (2E)-3-(4-bromo-2-thienyl)-2-propenoic acid (3) by the Eloy-Deryckere thermal benzo/heteropyridinone synthesis. A telescoped procedure was developed, which reduces some of the risk associated with the classic procedure. Use of tributylamine as an additive in this process was shown to facilitate E/Z-isomerization of the intermediate vinyl isocyanate and lower the temperature necessary for the overall thermal process.