[N+:1]([CH2:4][CH2:5][CH2:6][CH3:7])([O-])=[O:2].C1(N=C=O)C=CC=CC=1.[C:17]([C:19]12[CH2:26][CH2:25][CH2:24][N:23]1[CH2:22][CH2:21][CH2:20]2)#[CH:18]>C1C=CC=CC=1>[CH2:5]([C:4]1[CH:18]=[C:17]([C:19]23[CH2:26][CH2:25][CH2:24][N:23]2[CH2:22][CH2:21][CH2:20]3)[O:2][N:1]=1)[CH2:6][CH3:7]Nitrobutane (0.705 mL, 6.66 mmol) and phenylisocyanate (1.50 mL, 13.3 mmol) were dissolved in benzene (13.5 mL) and added to a flask containing 7a-ethynyl-hexahydro-1H-pyrrolizine (450 mg, 3.33 mmol, from step 13a). The solution was stirred at ambient temperature for 1 hour and at reflux for 5 hours. The mixture was cooled, filtered, concentrated and diluted with EtOAc. The solution was extracted with 6N HCl. The aqueous phase was made basic with 15% NaOH and extracted with methylene chloride. The organic extracts were combined, dried (MgSO4) and concentrated. The residue was residue was chromatographed (silica gel; CHCl3 /MeOH, 98:2) to afford an amber oil (392 mg, 53%). 1H NMR (CDCl3, 300 MHz) δ0.97 (t, J=7.5 Hz, 3H), 1.61-1.92 (m, 8H), 2.15-2.26 (m, 2H), 2.55-2.69 (m, 4H), 3.13-3.20 (m, 2H), 5.96 (s, 1H); MS (CI/NH3) m/z: 221 (M+H)+.
Wird geladen…
