Reaction Steps
1,2-Cyclohexanedione (1.52 g, 13.93 mmol) was added to a suspension of 1.56 g (13.93 mmol) of 3,4-diaminopyridine in 50 ml of ethanol. The reaction mixture was subsequently heated at an oil bath temperature of 70° C. for 5 hours, then cooled to room temperature and the solvent was then distilled off on a rotary evaporator. The product obtained was purified by flash chromatography using ethyl acetate as eluent. This gave 1.84 g (71%) of a white solid which was stored in a refrigerator and processed further after 1-2 days. Allowing the solid to stand in an open flask in sunlight resulted in the color changing to greyish green. Rf=0.25 (EtOAc/hexane, 20:1). 1H NMR: (200 MHz, CDCl3): δ=2.05 (m, 4H, H-7,8), 3.18 (m, 4H, H-6,9), 7.79 (d, 3J=5.8 Hz, 1H), 8.72 (d, 3J=5.8 Hz, 1H), 9.38 (s, 1H) ppm. 13C NMR (75 MHz, CDCl3): δ=22.8 (CH2, C-7,8), 33.7 (CH2, C-6,9), 121.2 (CH), 136.9 (Cq), 144.1 (Cq), 146.8 (CH), 153.9 (CH), 156.8 (Cq) 159.9 (Cq) ppm. GC-MS (EI): RT 8.44 min, m/e (%) 186 (11), 185 (M+, 100), 184 (39), 183 (3), 182 (3), 171 (2), 170 (21), 169 (4), 158 (2), 157 (5), 156 (5) 131 (2), 104 (2), 103 (4), 78 (3), 76 (4), 67 (2), 64 (2), 51 (2), 50 (6); IR (KBr): ν=3435 (vs), 2947 (s), 2864 (m), 1594 (s), 1557 (w), 1461 (w), 1421 (m), 1385 (s), 1365 (w), 1330 (w), 1297 (m), 1211 (m), 1140 (w), 979 (m), 949 (w), 901 (m), 849 (m), 679 (w), 629 (w), 570 (w), 412 (w) cm−1. HRMS (EI): calculated for C11H11N3 185.0953 [M+], found: 185.0935
