[NH:1]1[CH:5]=[CH:4][N:3]=[C:2]1[CH:6]=O.[N+:8]([CH2:10][C:11]([O:13][CH2:14][CH3:15])=[O:12])#[C-:9].C1CCN2C(=NCCC2)CC1.CC(O)=O>O1CCOCC1>[N:3]1[CH:4]=[CH:5][N:1]2[C:2]=1[CH:6]=[C:10]([C:11]([O:13][CH2:14][CH3:15])=[O:12])[N:8]=[CH:9]2To a suspension of imidazole-2-carboxaldehyde (2.3 g, 23.4 mmol) in 50 mL dioxane is added to ethyl isocyanoacetate (2.9 g, 25.8 mmol) and DBU (3.9 g, 25.8 mmol). After stirring at RT for 5 days, the reaction is neutralized with 10% AcOH. The solvent is removed in vacuo. The residue is taken up in EtOAc/H2O, the aqueous layer is extracted with CHCl3, dried (MgSO4), filtered and concentrated. The residue is purified by chromatography (Biotage 40M, eluting with 5% MeOH/EtOAc). Ethyl imidazo[1,2-c]pyrimidine-7-carboxylate is obtained (1.4 g, 32%) as an off-white solid. 1H NMR (400 MHz, CDCl3) δ9.14, 8.43, 7.88, 7.81, 4.54-4.48, 1.49-1.44.
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