A mixture of 3-{[4-(difluoromethoxy)phenyl]ethynyl}benzaldehyde (3.69 g, 13.57 mmol), 4-methylbenzenesulfonohydrazide (2.9 g, 15.6 mmol) and EtOH (11 mL) was refluxed for 30 minutes. cooled to room temperature, poured into water and extracted with ethyl ether. The organic extracts were combined dried over MgSO4 and concentrated in vacuo. The resultant residue was purified on silica gel (Biotage) using hexanes/EtOAc (2/1) as the eluting solvents to give N′-[(1E)-(3-{[4-(difluoromethoxy)phenyl]ethynyl}phenyl)methylene]-4-methylbenzenesulfonohydrazide as a tan solid (5.4 g, 90% yield), MS m/e (M+H)+ 441; 1H NMR (400 MHz, DMSO-d6) 2.32 (s, 3H), 7.2 (d, J=8.66 Hz, 2H), 7.3-7.6 (m, 8H), 7.72 (d, J=8.3 Hz, 2H), 7.88 (s, 1H), 11.54 (s, 1H).
