Reaction Steps
27 (1.20 g, 6.34 mmol), 40 ml of pyridine, 30 ml (32.36 g, 317 mmol, ρ=1.082 g/ml) of acetic anhydride and 0.234 g (25 mol %) of PPY were introduced into a 250 ml round-bottomed flask while cooling in ice. The reaction mixture was heated to an oil bath temperature of 100° C. and maintained at this temperature for 48 hours. The reaction was followed by TLC on basic aluminum oxide (EtOAC/MeOH, 10:1). After cooling to room temperature, the solvent was distilled off under reduced pressure and the crude product obtained was purified by flash chromatography on basic aluminum oxide (EtOAc/MeOH, 10:1). This gave a dark yellow solid (1.17 g, 4.31 mmol, 68%). Rf=0.45 (EtOAC/MeOH, 10:1). 1H NMR: (400 MHz, CDCl3): δ=1.34 (m, 4H), 1.60 (d, 4H), 2.23 (s, 3H, H3C—CO—N), 2.27 (s, 3H, H3C—CO—N), 4.74 (m, 1H), 4.85 (m, 1H), 7.25 (d, 3J=5.6 Hz, 1H, H-4), 8.41 (d, 3J=5.6 Hz, H-3), 8.49 (s, 1H, H-1) ppm. 13C NMR (75 Hz, CDCl3): δ=21.7, 21.9 (C-7,8), 23.1, 23.6 (H3C—CO—N), 28.4, 28.5 (C-6,9), 55.2, 56.0 (CH, C-5a,9a), 119.6 (C-4), 130.8 (Cq, C-10a), 141.6 (Cq, C-4a), 147.1, 147.2 (C-1, C-3) 169.1, 169.2 (C═O) ppm. GC-MS (EI): RT 10.45 min, m/e (%) 274 (13), 273 (M+, 58), 232 (15), 231 (100), 230 (42), 216 (5), 214 (5), 213 (5), 203 (3), 202 (4), 190 (13), 189 (84), 188 (45), 173 (5), 172 (6), 160 (7), 159 (5), 158 (5), 147 (8), 146 (40) 134 (6), 133 (13), 132 (15), 120 (7), 43 (9); IR (neat): ν=2940 (m), 1660 (vs), 1587 (m), 1559 (w), 1498 (s), 1448 (w), 1427 (w), 1388 (m), 1353 (w), 1337 (m), 1289 (s); 1270 (s), 1248 (s), 1248 (m), 1220 (w), 1183 (w), 1102 (w), 1036 (m), 978 (m), 857 (w), 839 (w) 777 (w) cm−1. HRMS (EI): calculated for C11H15N3 273.1477 [M+], found: 273.1482.
