Synthesis of polynuclear heterocycles. Part 4. Imidazo[4,5-g][3,1]benzoxazinones, imidazo[4,5-g]quinazolinones, imidazo[4,5-g]quinazolinediones, and imidazo[4,5-f]indazolinones

Abstract

Several new, 1,2-disubstituted 6-aminobenzimidazole-5-carboxylic acids and their ethyl esters have been prepared. The amino-acids react with acyl halides in pyridine solution to give 7-arylimidazo[4,5-g][3,1]benzoxazin-5-ones, with urea or potassium cyanate to give imidazo[4,5-g]quinazoline-5,7-diones, and with formamide to give imidazo[4,5-g]quinazolin-5-ones. 6-Amino- and 6-acylamino-imidazo[4,5-g]quinazolin-5-ones have been synthesised by reacting the acylated amino-esters with hydrazine, or by cyclising the derived amino-hydrazides with an acylating agent. Imidazo[4,5-f]indazolin-5-ones are obtained by the action of ethanolic hydrazine hydrate on 6-azido-5-ethoxycarbonylbenzimidazoles.