[Br:1][C:2]1[N:7]2[CH:8]=[C:9](C(NN)=O)[N:10]=[C:6]2[C:5]([N:15]2[CH2:20][CH2:19][O:18][CH2:17][CH2:16]2)=[N:4][CH:3]=1.N([O-])=O.[Na+].[N-:25]=[N+]=[N-].[Na+].[C:29]([O-:32])([O-])=[O:30].[Na+].[Na+].[CH3:35][CH2:36]O>Cl.O>[Br:1][C:2]1[N:7]2[CH:8]=[C:9]([NH:25][C:29](=[O:30])[O:32][CH2:35][CH3:36])[N:10]=[C:6]2[C:5]([N:15]2[CH2:16][CH2:17][O:18][CH2:19][CH2:20]2)=[N:4][CH:3]=1A stirred solution of 5-bromo-8-morpholinoimidazo[1,2-a]pyrazine-2-carbohydrazide (1.5 g, 4.3 mmol, as prepared above) in 2N HCl (5 mL) was diluted with cold H2O (40 mL). An aqueous solution of NaNO2 (450 mg, 6.5 mmol) in water (2 mL) was then added dropwise while maintaining the temperature below 15° C. The mixture was stirred at rt for 2 h and treated with NaN3 (432 mg, 6.50 mmol) in water (10 mL). The resulting mixture was stirred at rt for 15 min, adjusted to pH 7 with aqueous Na2CO3 and extracted with DCM (3×20 mL). The combined DCM layers were dried over Na2SO4 and concentrated under reduced pressure. The crude product obtained was suspended in EtOH (50 mL) and heated at refluxed for 4.5 h. The reaction mixture was allowed to cool to rt, the solvent was removed under reduced pressure, and the residue obtained was purified by flash column chromatography on silica gel (4:1 DCM/EtOAc) to give ethyl (5-bromo-8-morpholinoimidazo[1,2-a]pyrazin-2-yl)carbamate.
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