2-Carbethoxy-4H-3,1-benzoxazin-4-one. 1. Synthesis and reaction mechanism of formation
The possibility was examined of using various condensing agents in the intramolecular cyclization reaction of ethyl ester of 2-carbomalonanilic acid into 2-carboethoxymethyl-4H-3,1-benzoxazin-4-one. It was found that the optimal reagent is dicyclohexylcarbodiimide. By using NMR spectroscopy and deutero-exchange it was shown that the cyclization proceeds with the participation of the hydroxyl group of the carboxyl and a proton of the amide function.