Synthesis of 4H‐3,1‐benzoxazin‐4‐ones and 4‐(3H)quinazolinones from anthranilic acids and their derivatives by the use of triphenyl phosphite and pyridine

A series of 2‐substituted 4H‐3,1‐benzoxazinones and 2,3‐disubstituted 4‐(3H)quinazolinones have been synthesized in mild conditions by the use of triphenyl phosphite and pyridine as cyclising medium. Benzox‐azinones are produced either by ring closure of 2‐(acylamino)benzoic acids or in the reaction of benzoic acid with anthranilic acids. In the presence of aniline, the reaction leads to quinazolinones.