A solution of crude 8-bromo-N-(2-chlorophenyl)-4,5-dihydrobenzo[b]thieno[2,3-d]oxepine-2-carbohydrazonamide (150 mg, 0.334 mmol) in acetic acid (0.5 mL) was treated with a solution of sodium nitrite (115 mg, 1.6 mmol) in water (0.5 mL) at 0° C. After 30 min, an additional 50 mg of sodium nitrite was added. After 10 min, 3 mL of 10% aqueous sodium hydroxide was added. The mixture was extracted with ethyl acetate and the organics dried over sodium sulfate and concentrated. The crude residue was purified by flash column chromatography to give 286 as a colorless solid (111 mg). 1H NMR (dmso-d6, 400 MHz) δ 8.00 (m, 1H), 7.98 (m, 1H), 7.85 (m, 1H), 7.56 (m, 1H), 7.46 (m, 1H), 7.26 (m, 2H), 7.13 (m, 1H), 4.27 (t, 2H), 3.11 (t, 2H). MS (ESI) 461.1
