[CH3:1][N:2]([CH3:13])[C:3]1[CH:8]=[CH:7][CH:6]=[C:5]([N+:9]([O-:11])=[O:10])[C:4]=1[CH3:12].[CH3:14]N(C(N(C)C)N(C)C)C.Cl.[NH2:25][NH:26][C:27]([NH2:29])=[O:28].Cl>CN(C=O)C.O>[CH3:1][N:2]([CH3:13])[C:3]1[CH:8]=[CH:7][CH:6]=[C:5]([N+:9]([O-:11])=[O:10])[C:4]=1[CH2:12][CH:14]=[N:25][NH:26][C:27]([NH2:29])=[O:28]
To a stirred solution of N,N-dimethyl-2-methyl-3-nitroaniline (5.40 g, 30 mmol) in dry DMF (30 ml) was added tris(dimethylamino)methane (6.54 g, 45 mmol) and the mixture was heated to 115° C. under N2 for 4 h. The progress of the reaction was monitored by TLC [EtOAc-hexanes (1:3)]. The dark red solution was cooled in an ice bath, diluted with DMF (20 ml) and a solution of semicarbazide hydrochloride (3.51 g, 31.5 mmol) and conc. HCl (5.4 ml) in water (50 ml) was added. Stirring was continued for 30 min and the pH was raised to 5.0 and after stirring at 0° C. for 30 min, the pH was further raised to 7.5. The precipitated yellow solid was filtered, washed with ice-cold water and ether and dried under vacuum. Recrystallisation from aq. EtOH afforded 31 as yellow microcrystals (3.93 g, 49%), mp 156-157° C. (Found: C, 49.65; H, 5.70; N. 26.14. C11H15N5O3 requires C, 49.81; H, 5.70; N, 26.39%); νmax (Nujol)/cm−1 3450, 3160, 1720, 1600, 1525, 1350.
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