R. Troschutz et T. Dennstedt, IMPROVED SYNTHESIS OF METHYL-SUBSTITUTED AND PHENYL-SUBSTITUTED PYRIDO-[2,3-D]PYRIMIDINE-2,4-DIAMINES, Archiv der pharmazie, 327(4), 1994, pp. 221-224
The title compounds 4b-g, 10a,b and 13 can be prepared in improved yie
lds by ''cyclocondensation'' of the 1,3-biselectrophiles 1a-e, 5b,f,g,
7b,d, 8a,b, and 12 with 2,4,6-triaminopyrimidine (2).