反应详情

A suspension of silyl ether 133 (1.627 g, 4.58 mmol) in a solution of 1% HCl in 95% EtOH (desilylation conditions described by Cunico et al., 1980) (58 mL) was stirred at room temperature for 35 h. The resulting solution was cooled (CO2/acetone), neutralised by dropwise addition of 7 M NH3 in MeOH (7 mL) with stirring, and then concentrated to dryness and the residue was chromatographed on silica gel. Elution with 0-2% MeOH/CH2Cl2 firstly gave foreruns, and then further elution with 2% MeOH/CH2Cl2 gave (2-nitro-6,7-dihydro-5H-imidazo[2,1-b][1,3]oxazin-7-yl)methanol (134) (877 mg, 96%) as a pale yellow solid: mp (THF/MeOH/CH2Cl2/hexane) 179-181° C.; 1H NMR [(CD3)2SO] δ 8.04 (s, 1H), 5.12 (t, J=5.8 Hz, 1H), 4.48 (dtd, J=10.2, 4.7, 2.5 Hz, 1H), 4.13 (ddd, J=12.5, 5.8, 3.0 Hz, 1H), 4.04 (ddd, J=12.4, 11.0, 5.1 Hz, 1H), 3.64 (m, 2H), 2.18 (dtd, J=14.4, 5.0, 2.8 Hz, 1H), 2.03 (dtd, J=14.4, 10.6, 5.7 Hz, 1H). Anal. (C7H9N3O4) C, H, N.

1. stirringwith stirring
2. concentrationconcentrated to dryness
3. customthe residue was chromatographed on silica gel
4. washElution with 0-2% MeOH/CH2Cl2 firstly gave foreruns
5. washfurther elution with 2% MeOH/CH2Cl2