“…A mixture of ethyl 2-oxo-2 H -chromene-3-carboxylate ( 1 , 2.18 g, 10 mmol) and hydrazine hydrate, (99%, 1.3 g, 25 mmol) in absolute ethanol (50 mL) was heated under reflux for 2 h. The precipitate formed was filtered off, washed with ethanol and dried. Recrystallization from ethanol gave yellow crystalsof salicyaldehyde azine ( 3 ) [ 38 , 39 ] (1.15 g, 48%); m.p. 205–206 °C (204.3 °C) [ 39 ]; IR ν 3350–2830 (OH), 1633 (C=N) cm −1 ; 1 H-NMR δ 6.84–7.72 (m, 8H, ArH), 8.86 (s, 2H, –CH=), 10.90 (s, D 2 O exch., 2H, OH); 13 C-NMR δ 117.9, 118.7, 121.4, 132.0, 132.5, 159.2, 162.0; MS m/z : 240.5 (M + ).…”