反应详情

A stirred solution of alcohol 132 (2.45 g, 5.61 mmol) in anhydrous DMF (25 mL) under N2 at 0° C. was treated with 60% NaH (388 mg, 9.70 mmol), then quickly degassed and resealed under N2. After stirring at room temperature for 2 h, the reaction was cooled (CO2/acetone), quenched with ice/aqueous NaHCO3 (20 mL), diluted with ice-water (150 mL) and extracted with EtOAc (8×80 mL). The extracts were washed with brine (100 mL) and then evaporated to dryness and the residue was chromatographed on silica gel. Elution with 0-25% EtOAc/petroleum ether firstly gave foreruns, and then further elution with 25% EtOAc/petroleum ether gave 2-nitro-7-{[(triisopropylsilyl)oxy]methyl}-6,7-dihydro-5H-imidazo[2,1-b][1,3]oxazine (133) (1.77 g, 89%) as a pale yellow solid: mp (CH2Cl2/pentane) 121-123° C.; 1H NMR (CDCl3) δ7.42 (s, 1H), 4.45 (m, 1H), 4.17 (ddd, J=12.3, 5.8, 3.7 Hz, 1H), 4.06 (ddd, J=12.3, 10.3, 5.4 Hz, 1H), 4.03 (dd, J=10.7, 4.1 Hz, 1H), 3.95 (dd, J=10.7, 5.8 Hz, 1H), 2.37 (dddd, J=14.5, 5.5, 3.6, 2.8 Hz, 1H), 2.27 (dtd, J=14.5, 10.1, 5.8 Hz, 1H), 1.17-1.03 (m, 21H). Anal. (C16H29N3O4Si) C, H, N.

1. customquickly degassed
2. temperaturethe reaction was cooled (CO2/acetone)
3. customquenched with ice/aqueous NaHCO3 (20 mL)
4. additiondiluted with ice-water (150 mL)
5. extractionextracted with EtOAc (8×80 mL)
6. washThe extracts were washed with brine (100 mL)
7. customevaporated to dryness
8. customthe residue was chromatographed on silica gel
9. washElution with 0-25% EtOAc/petroleum ether firstly gave foreruns
10. washfurther elution with 25% EtOAc/petroleum ether