Synthesis and properties of 2-amino-4,6-dimethylnicotinic acid arylamides

It is shown that on boiling 2-amino-4,6-dimethylnicotinic acid arylamides with triethyl orthoformate in acetic anhydride, derivatives of 3-aryl-5,7-dimethyl-4-oxo-3,4-dihydropyrido2,3-d]pyrimidine are formed. The same compounds are obtained by ternary condensation of ethyl 2-amino-4,6-dimethylnicotinate with triethyl orthoformate and alrylamines. On reaction with urea or ammonium thiocyanate, the ethyl ester or anilides of 2-amino-4,6-dimethylnicothinic acid are converted to 2,4-dioxo- or 4-oxo-2-thio-pyrido2,3-d]pyrimidines respectively.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1384–1386, October, 1992.