Sodium hydride → (6S)-6-[(5-Chloro-2-pyrazinyl)methoxy]-2-nitro-6,7-dihydro-5H-imidazo[2,1-b][1,3]oxazine

Participants

Reaction Conditions

Reaction Steps

Triethylamine (4.17 mL, 3.0 mmol) and mesyl chloride (1.57 mL, 2.00 mmol) were added to a solution of (5-chloro-2-pyrazinyl)methanol (1.44 g, 10.0 mmol) in anhydrous THF (20 mL) at 0° C. The mixture was stirred at 0° C. for 0.5 h then partitioned between EtOAc/water. The organic fraction was dried (MgSO4) and the solvent was removed under reduced pressure to give the crude mesylate. The mesylate was dissolved in acetone (40 mL), sodium iodide (7.5 g, 50 mmol) was added and the mixture was refluxed for 1 h. The solvent was removed under reduced pressure and the residue was partitioned between EtOAc/water. The residue was chromatographed on silica gel (DCM) to give 2-chloro-5-(iodomethyl)pyrazine. Sodium hydride (60% w/w, 0.36 g, 9.0 mmol) was added to a solution of (S)-2-nitro-6,7-dihydro-5H-imidazo[2,1-b][1,3]oxa-zin-6-ol (0.93 g, 5.02 mmol) and 2-chloro-5-(iodomethyl)pyrazine (1.54 g, 6.05 mmol) in DMF (10 mL) at −78° C. The mixture was stirred at 0° C. for 1 h and then quenched with ice. EtOAc (200 mL) was added, the organic layer was dried (MgSO4) and concentrated under reduced pressure. The residue was chromatographed on silica gel, eluting with a gradient (0-5%) MeOH/EtOAc to give the title compound (1.015 g, 65%) as a white solid. APCI MS m/z 312.6 (M+H). 1H NMR (400 MHz, (CD3)2SO) δ 8.76 (d, J=1.4 Hz, 1H), 8.50 (d, J=1.4 Hz, 1H), 8.02 (s, 1H), 4.85 (d, J=13.7 Hz, 1H), 4.81 (d, J=13.7 Hz, 1H), 4.70 (td, J=12.1, 2.6 Hz, 1H), 4.49 (bd, J=12.0 Hz, 1H), 4.29-4.38 (m, 2H), 4.25 (dd, J=13.5, 3.3 Hz, 1H).

Provenance & Evidence