Synthesis of 6-oxo-6,7,8,9-tetrahydro-10H-pyrimido-[5,4-b][1,4]benzoxazines and 6-oxo-6,7,8,9-tetrahydropyrimido[4,5-b][1,4]benzodioxanes

Reaction of 5-hydroxy-6-aminopyrimidines with 2-bromohydroresorcinol and bromodimedone in DMF in the presence of sodium hydride gave 6,7,8,9-tetrahydro-10H-pyrimido[5,4-b][1,4]benzoxazines. When 4-chloro-5-hydroxy-6-aminopyrimidine was treated with bromodimedone the principal products were 6,7,8,9-tetrahydropyrimido[4,5-b][1,4]benzodioxanes. The nucleophilic substitution of the chlorine atom in position 4 of the tetrahydropyrimidobenzoxazines by amines, sodium alkanoates, and thiourea has been studied and the corresponding amines and alkoxy- and thio derivatives of this tricyclic system obtained. Center for the Chemistry of Medicinal Substances, All Russian Chemico-Pharmaceutical Science Research Institute, Moscow 119815. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1411–1417, October, 1998.