Reaction Steps
29 (0.250 g, 1.15 mmol) and 10 ml of THF were placed in a 100 ml Schlenk flask. The solution was cooled to −78° C., 0.51 ml of n-BuLi (1.27 mmol, 1.1 eq; 2.5 M in hexane) were added and the reaction solution was stirred without cooling for 30 minutes. After 30 minutes, the reaction solution was cooled back down to −78° C. and 0.09 ml (0.109 g, 1.4 mmol, ρ=1.1051 g/ml) of acetyl chloride were added, the cooling bath was removed and the mixture was stirred without cooling for 1 hour. The reaction was subsequently stopped by means of 4 ml and extracted three times with 20 ml of DCM. The combined organic phases were dried over Na2SO4 and the solvent was distilled off on a rotary evaporator. The crude product was purified on silica gel (EtOAc/MeOH, 10:2) to give 48 mg (0.18 mmol, 16%) of a colorless solid. Rf=0.16 (EtOAc/NEt3, 10:1). 1H NMR: (300 MHz, CDCl3): δ=1.19 (t, 3J=7.2 Hz, 3H, H3C—CH2—N-5), 1.24 (m, 2H), 1.45 (m, 2H), 1.58 (m, 2H), 1.74 (m, 1H), 2.18 (m, 1H), 3.34 (m, 2J=14.4 Hz, 3J=7.2 Hz, 1H, H3C—CHAB—N-5), 3.53 (m, 1H, C—H), 3.57 (m, 2J=15.2 Hz, 3J=7.2 Hz, 1H, H3C—CHAB—N-5), 4.90 (bs, 1H, C—H), 6.62 (d, 3J=5.6 Hz, 1H, H-4), 8.12 (s, 1H, H-1), 8.08 (d, 3J=5.6 Hz, 1H, H-3). 13C NMR (100 MHz, CDCl3): δ=12.4 (H3C—CH2—N-5), 18.9 (C-7), 22.8 (H3C—CO—N-10), 24.7 (C-8), 25.8 (C-6), 28.5 (C-9), 40.0 (H3C—CH2—N-5), 48.7 (C-9a), 53.7 (C-5a), (C-4), 106.4 (C-4), 120.1 (Cq, C-10a), 145.1, 145.2 (C-1, Cq, C-4a), 147.1 (C-3), 167.1 (C═O) ppm. GC-MS (EI): RT 10.39 min, m/e (%) 260 (11), 259 (M+, 100), 230 (8), 218 (9), 217 (79), 216 (40), 203 (4), 202 (23), 203 (3), 202 (23), 201 (4), 189 (6), 188 (31), 187 (4), 186 (3), 174 (11), 162 (4), 161 (6), 160 (5), 158 (4), 148 (5), 146 (6), 136 (3), 132 (4), 131 (12), 120 (6), 43 (3); IR (neat): ν=3398 (s), 2933 (s), 2863 (m), 1731 (m), 1637 (vs), 1595 (vs), 1512 (s), 1546 (w), 1449 (m), 1397 (s), 1365 (s), 1334 (m), 1285 (s), 1239. (m), 1198 (m), 1168 (vs), 1123 (w), 1067 (w), 1068 (w), 1016 (w), 802 (vs), 718 (w), 668 (m). HRMS (EI): calculated for C15H21N3O 259.1685 [M+], found: 259.1687.
