[NH2:1][C:2]([NH2:4])=[NH:3].Cl.C[O-].[Na+].N[C:10]1[C:15]([C:16]#[N:17])=[CH:14][C:13]([C:18]#[N:19])=[CH:12][N:11]=1.C1CCCCC1.CCOC(C)=O>CCO>[NH2:3][C:2]1[N:4]=[C:16]([NH2:17])[C:15]2[CH:14]=[C:13]([C:18]#[N:19])[CH:12]=[N:11][C:10]=2[N:1]=1Guanidine·HCl (2.66 g, 27.8 mmol) was added to a solution of NaOMe (sodium methoxide) (1.50 g, 27.8 mmol) in absolute EtOH (180 mL). The mixture was stirred at 20°-23° C. for 15 minutes before 5 (2.00 g, 13.9 mmol) was added. After a 24-hour reflux period with rapid stirring, TLC (cyclohexane-EtOAc, 1:1) showed absence of 5. The solid filtered from the cooled mixture was washed on the funnel with H2O and EtOH; yield 95% (2.45 g). A sample of this material (1.0 g) was stirred with near-boiling Me2SO (dimethyl sulfoxide) (250 mL), and the slightly cloudy solution was filtered (Celite) to give a clear, pale-yellow filtrate which was then concentrated by evaporation in vacuo (to about 60 mL). Addition of EtOH (200 mL) gave 7 as a light yellow solid (880 mg); 1H NMR (Me2SO-d6) δ6.97 (2, NH2), 7.84 (s, NH2), 8.87 and 8.91 (two d, 5-H and 7-H, J=2 Hz).
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