Guanidine Hydrochloride → 2,4-Diaminopyrido[2,3-d]pyrimidine-6-carbonitrile

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Reaction Steps

Guanidine·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).

Provenance & Evidence