Use of 2-Ethoxy(4H)-3,1-benzoxazin-4-one as a Precursor for Synthesis of Quinazoline and Quinazolinone Starting Materials

Abstract

The interactions of 2-ethoxy(4H)-3,1-benzoxazin-4-one (1) with various nitrogen nucleophiles such as ammonium acetate,  hydrazine hydrate, ethanolamine, p-phenylenediamine, o-phenylenediamine, o-tolidine, dapsone, 2-aminophenol, 4-aminophenol, 4-aminobenzoic acid and 2-aminonicotinic acid have been discussed. The reactions of 2-thoxy-(3H)-quinazolin-4-one with ethyl chloroformate, phosphorus pentasulfide, chloroacetyl chloride and phosphorus oxychloride have also been investigated. Similar reactions of 2-ethoxy-4-chloroquinazoline with hydrazine hydrate and thiosemicarbazide have been introduced. Aminolysis of the 2-ethoxy group in some of the thiadiazoloquinazolinone derivatives has been attempted. The interactions of these aminolized derivatives and the 3-aminoquinazolinone with chloroacetyl chloride have been studied. All of the synthesized derivatives have been used in a wide range as starting materials for the synthesis of novel quinazoline and/or quinazolinones which have biological activity. The structures of all these products, obtained by heterocyclic ring opening and ring closure, were inferred by the IR, MS, ¹H NMR spectral as well as elemental analyses.

Keywords: Aminothiadiazole, Benzoxazin-4-one, N-nucleophile, quinazoline, quinazolin-4-one, thiosemicarbazide.