[C:1]([O:5][C:6]([NH:8][C:9]1[N:10]=[C:11]([C:15]([O:17]C)=[O:16])[N:12]([CH3:14])[CH:13]=1)=[O:7])([CH3:4])([CH3:3])[CH3:2].[OH-].[Na+]>C1COCC1.O.O>[C:1]([O:5][C:6]([NH:8][C:9]1[N:10]=[C:11]([C:15]([OH:17])=[O:16])[N:12]([CH3:14])[CH:13]=1)=[O:7])([CH3:4])([CH3:2])[CH3:3]Methyl 4-(tert-butoxycarbonylamino)-1-methyl-1H-imidazole-2-carboxylate (5.0 g, 19.59 mmol) in 120 ml of 1:1 THF/H2O was added 8 g of NaOH in 30 ml of water. The mixture was stirred overnight, concentrated, diluted with water, extracted with EtAc/Hexane (1:1). The aqueous solution was adjusted to pH 4.0 with 20% H3PO4 and extracted with EtAc (4×60 ml). The organic solutions were combined, dried over MgSO4, filtered, evaporated and crystallized with ethanol/EtAc/Hexane to afford 3.85 g (81%) of the title product. 1H NMR (DMSO) 9.32 (s, 1H), 7.29 (s, 1H), 3.57 (s, 3H), 1.42 (s, 9H); 13C NMR 172.45, 159.78, 136.93, 135.44, 132.85, 79.50, 35.57, 28.07; MS m/z− 240.8 (M−H).
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