[Cl:1][C:2]1[CH:10]=[CH:9][CH:8]=[C:7]2[C:3]=1[C:4]1[C:14](=O)[NH:13][C:12]([NH:16][C:17](=[O:22])[C:18]([CH3:21])([CH3:20])[CH3:19])=[N:11][C:5]=1[NH:6]2.O=P(Cl)(Cl)[Cl:25].C(Cl)(Cl)Cl.CO>C(Cl)(Cl)Cl.CO>[Cl:25][C:14]1[C:4]2[C:3]3[C:7](=[CH:8][CH:9]=[CH:10][C:2]=3[Cl:1])[NH:6][C:5]=2[N:11]=[C:12]([NH:16][C:17](=[O:22])[C:18]([CH3:21])([CH3:20])[CH3:19])[N:13]=1To 9 (2 g, 6.274 mmol) was added 30 mL of POCl3 in a 250 mL round bottom flask. The reaction mixture was refluxed at 110-120° C. for 4 hours. After this the POCl3 was evaporated and the mixture was neutralized using NH4OH. The aqueous mixture was filtered (the precipitate being the compound). The filtrate also contained some compound. Therefore, it was extracted using chloroform and ethyl acetate. The precipitate obtained was dissolved in chloroform and methanol. Both the dissolved precipitate and extracted filtrate were dried using sodium sulfate overnight. To the solution was added silica, and solvent was removed under reduced pressure to provide a silica gel plug. The plug was transferred on top of a column packed with silica gel, twenty times the weight of plug, eluted with chloroform, 1% methanol in chloroform and 5% methanol in chloroform. Fractions containing the product 10 (TLC) were pooled and evaporated to give a solid. The overall yield was 70%. TLC Rf 0.86 (chloroform-methanol 5:1), m.p. 245.6-246.1° C., 1H NMR: δ 1.24 (s, 9H, pivaloyl); 7.37-7.63 (m, 3H, phenyl); 10.32 (s, 1H, 9-NH, exch); 12.96 (s, 1H, 2-NH, exch).
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