反应详情

5-Bromo-2-fluoropyridine (91) (0.25 mL, 2.43 mmol) was added to a solution of alcohol 101 (200 mg, 1.01 mmol) in anhydrous DMF (4.5 mL) under N2 at 0° C. The resulting mixture was treated with 60% NaH (64 mg, 1.60 mmol), then quickly degassed and resealed under N2. Further 5-bromo-2-fluoropyridine (91) (0.25 mL, 2.43 mmol) was added and the mixture was stirred at room temperature for 2 h, and then cooled (CO2/acetone), quenched with ice/aqueous NaHCO3 (15 mL), added to brine (40 mL) and extracted with CH2Cl2 (8×40 mL). The combined extracts were evaporated to dryness and the residue was chromatographed on silica gel. Elution with CH2Cl2 firstly gave foreruns, and then further elution with 0-1.5% EtOAc/CH2Cl2 gave 2-{[(5-bromo-2-pyridinyl)oxy]methyl}-2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b][1,3]oxazole (102) (130 mg, 36%) as a cream solid: mp (CH2Cl2/hexane) 151-153° C.; 1H NMR (CDCl3) δ 8.17 (dd, J=2.5, 0.5 Hz, 1H), 7.68 (dd, J=8.8, 2.5 Hz, 1H), 7.52 (s, 1H), 6.60 (dd, J=8.7, 0.6 Hz, 1H), 4.58 (d, J=12.0 Hz, 1H), 4.50 (d, J=12.0 Hz, 1H), 4.41 (d, J=10.2 Hz, 1H), 4.01 (d, J=10.2 Hz, 1H), 1.76 (s, 3H). Anal. (C12H11BrN4O4) C, H, N.

1. customquickly degassed
2. customquenched with ice/aqueous NaHCO3 (15 mL)
3. additionadded to brine (40 mL)
4. extractionextracted with CH2Cl2 (8×40 mL)
5. customThe combined extracts were evaporated to dryness
6. customthe residue was chromatographed on silica gel
7. washElution with CH2Cl2 firstly gave foreruns
8. washfurther elution with 0-1.5% EtOAc/CH2Cl2