General procedure for the synthesis of 2-chloro-6-formylbenzonitrile (III-B) from the compound (CAS: 77532-80-0): to a solution of IV-B (18.0 g, 58.2 mmol) in acetonitrile (60 mL) was added an aqueous solution of silver nitrate (AgNO3, 39.5 g, 23.3 mmol) (32 mL). The resulting yellow suspension was refluxed for 20 min. The solids were removed by filtration and washed with dichloromethane (150 mL). The combined filtrates were washed with water (25 mL), dried over sodium sulfate (Na2SO4) and subsequently concentrated under vacuum. The crude product was purified by rapid chromatography on silica gel (eluent: hexane/ethyl acetate, 2/1) to afford pure III-B, 8.67 g (90% yield).1H-NMR (300 MHz, CDCl3): δ 7.72 (t, J = 7.9 Hz, 1H), 7.79 (dd, J = 1.2, 7.9 Hz, 1H), 7.94 (dd, J = 1.2, 7.9 Hz, 1H), 10.31 (s, 1H) ppm. 13C-NMR (75.4 MHz, CDCl3): δ 112.9 (C), 114.4 (C), 127.5 (CH), 133.8 (CH), 134.9 (CH), 138.5 (C), 139.0 (C), 187.6 (CH) ppm. IR (HATR): 3069, 2865, 2221, 1697, 1584, 1566, 1443, 1395, 1291, 1224, 1195, 1182, 1155, 922, 798, 781, 726, 675 cm-1. EI-MS m/z (% relative intensity): 167 (5); 165 (15), 139 (33), 137 (100), 110 (24), 101 (44), 84 (13), 75 (79), 61 (23), 50 (45). Melting point: 140°C.
