Hydroxylamine → Amitifadine

Participants

Reaction Steps

Title compound 487 (4.63 g, 18.81 mmol) was dissolved in isopropyl acetate (24.5 mL). The above crude amino alcohol solution in isopropyl acetate was slowly subsurface-added to a solution of thionyl chloride (1.61 ml, 22.06 mmol) in isopropyl acetate (17.5 mL) at ambient temperature over 2 hours. After aging additional 1-5 h, 5.0 N sodium hydroxide (16.4 mL) was added over 1 hour while the batch temperature was maintained at <30° C. with external cooling. The two-phase reaction mixture was stirred for 1 hour at ambient temperature to allow pH to stabilize (usually to 8.5-9.0) with sodium hydroxide pH titration. The organic phase was washed with 40% aqueous isopropanol (21 mL) followed by water (10.5 mL). Concentrated HCl (1.69 mL) was added. The aqueous isopropyl acetate was azeotropically concentrated in vacuum to ca. 24.5 mL. Methylcyclohexane (17.5 mL) was added dropwise over 2 hours. Compound did not crystallize out. The pH was adjusted to neutral and organic layer was separated. The organic layer was washed with water and brine, dried over magnesium sulfate, filtered and evaporated. The residue was purified by ISCO (EtOAc to 60% MeOH in EtOAc, 40 g silica column) to afford title compound 488 (1.8 g, 42%) as a thick yellow oil. 1H NMR (CD3OD) δ (ppm): 7.44 (d, J=8.4 Hz, 1H), 7.41 (d, J=2.2 Hz, 1H), 7.18 (dd, J=8.4, 2.2 Hz, 1H), 3.31-3.30 (m, 2H), 3.23-3.17 (m, 2H), 1.97-1.93 (m, 1H), 1.20-1.04 (m, 2H). MS (m/z)=228.15 (M+H)

Provenance & Evidence