ChemInform Abstract: Some Transformations of 3-Amino-4-alkoxycarbonyl-6-hydroxy-2H-1- benzopyran-2-ones. The Synthesis of (1)Benzopyrano(3,4-d)(1,3)oxazine and (1)Benzopyrano(3,4-d)pyrimidine Derivatives

Acylation of 4-alkoxycarbonyl-3-amino-6-hydroxy-2H-1-benzopyran-2-one derivatives (I) gave under mild conditions the O-substituted derivatives , N,O-disubstituted derivative and N,N-disubstituted derivative . The compound I was transformed with benzoyl chloride under more drastic conditions into a derivative of a new heterocyclic system 2-benzopyrano[3,4-d][1,3]oxazin. The derivatives of 1-benzopyrano[3,4-d]pyrimidine were prepared from I through the corresponding N-heteroarylformamidines and N-heteroarylformamide oximes or by cyclization of thiourea derivative .