Ammonia → 2,4-Diamino-5-methyl-6-(2,5-dimethoxybenzyl)-7-chloropyrido[2,3-d]pyrimidine

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Reaction Steps

2,4-Diamino-5-methyl-6-(2,5-dimethoxybenzyl)-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine (8 g) was chlorinated by treatment with Vilsmeier reagent prepared by slowly adding thionyl chloride (28.6 ml) in dry chloroform (25 ml) to a solution of dimethylformamide (17.5 ml) in chloroform (100 ml) at 0°-5° C. The cold mixture of the pyridopyrimidine and Vilsmeier reagent was stirred, gradually allowed to reach ambient temperature and then heated at reflux for 3 hours. It was then treated with ethanolic base (80 ml) maintaining the temperature at 25°-30° C. with cooling. The brown product formed was isolated, treated further with aqueous ammonia and then recrystallized from ethanol to give 2,4-diamino-5-methyl-6-(2,5-dimethoxybenzyl)-7-chloro-pyrido[2,3-d]pyrimidine, m.p. 193°-196° (dec.).

Provenance & Evidence