Phenyl isocyanate → 7a-(3-ethyl-5-isoxazolyl)-hexahydro-1H-pyrrolizine

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Reaction Steps

Nitropropane (0.475 mL, 5.29 mmol) and phenylisocyanate (1.0 mL, 9.5 mmol) were dissolved in benzene (10 mL) and added to a flask containing 7a-ethynyl-hexahydro-1H-pyrrolizine (358 mg, 2.65 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 (274 mg, 50%). 1H NMR (CDCl3, 300 MHz) δ1.25 (t, J=7.5 Hz, 3H), 1.75-1.92 (m, 6H), 2.15-2.25 (m, 2H), 2.60-2.69 (m, 4H), 3.13-3.20 (m, 2H), 5.98 (s, 1H); MS (CI/NH3) m/z: 207 (M+H)+.

Provenance & Evidence