Heterocyclic studies. Part 43. Thieno[2,3-d:4,5-d′]dipyrimidines
Abstract
5-Aminothieno[2,3-d]pyrimidine-6-carboxamides or -6-carboxylic esters have been converted into thieno[2,3-d:4,5-d′]dipyrimidines with the reagents formamide, triethyl orthoformate, urea, methyl isothiocyanate, phenyl isocyanate, and guanidine.
A 5-aminothieno[2,3-d]pyrimidine-6-carboxamide gave, on treatment with nitrous acid, the first pyrimido[5′,4′-4,5]thieno[3,2-d]-1,2,3-triazine.