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■ Some Nucleophilic Substitutions in the 2,4-Dimethoxypyrido[3,2-d]pyrimidines

Hassan M. Eisa, Said M. Bayomi,* Abdel-Kader M. Ismaiel, and Mohamed M. El-Kerdawy

*Department of Medical Chemistry, Faculty of Pharmacy, University of Mansoura, Mansoura, Egypt

Abstract

Study of the reactivity of substituted pyrido[3,2-d]-pyrimidines (Ia,b), towards nucleophilic substitution reactions revealed that the methoxy substituents at 4- as well as of the ester moiety at 6-positions are readily susceptable to nucleophilic displacement. The observed selectivity enabled the preparation of 4-hydrazino-6-acid hydrazides (IIa,b). Confirmation for formation of (IIa,b) has been done by their reaction with different carbonyl compounds to give the respective hydrazones (IIIa-i) or by reactlon with nitrous acid to afford the corresponding 4-azido-6-acid azides, which underwent ring closure with the formation of tetrazole ring derivatives (IVa,b). The synthesized compounds were confirmed by elemental analyses, ¹H NMR and mass spectral data.