[Si]([O:8][CH2:9][CH:10]1[O:14][C:13]2=[N:15][C:16]([N+:18]([O-:20])=[O:19])=[CH:17][N:12]2[CH2:11]1)(C(C)(C)C)(C)C.Cl.N>CCO.CO>[N+:18]([C:16]1[N:15]=[C:13]2[N:12]([CH:17]=1)[CH2:11][CH:10]([CH2:9][OH:8])[O:14]2)([O-:20])=[O:19]
A suspension of silyl ether 89 (503 mg, 1.68 mmol) in a solution of 1% HCl in 95% EtOH (desilylation conditions described by Cunico et al., 1980) (27 mL) was stirred at room temperature for 6 h, and then stored at 4° C. for 2.5 d. The resulting solution was neutralised by dropwise addition of 7M NH3 in MeOH (2 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 2-5% MeOH/CH2Cl2 gave (6-nitro-2,3-dihydroimidazo[2,1-b][1,3]oxazol-2-yl)methanol (90) (reported by Sehgal et al., 1981 via reaction of 2,4-dinitroimidazole and glycidol) (299 mg, 97%) as a white solid (after trituration with CH2Cl2): mp (CH2Cl2) 166-169° C.; 1H NMR [(CD3)2SO] δ 8.10 (s, 1H), 5.40 (m, 1H), 5.27 (t, J=5.6 Hz, 1H), 4.36 (dd, J=10.5, 8.8 Hz, 1H), 4.11 (dd, J=10.5, 6.4 Hz, 1H), 3.80 (ddd, J=12.8, 5.4, 3.0 Hz, 1H), 3.65 (dd, J=12.8, 5.8, 3.9 Hz, 1H). Anal. (C6H7N3O4) C, H, N.
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