Chloro-derivatives of indazolo[2,3-a][3,1]benzoxazin-5-one and indazolo-[2,1-a]indazole-6,12-dione
Abstract
Treatment of azobenzene-2,2′-dicarboxylic acid with phosphorus pentachloride (the Freundler reaction) has been shown to give four major products: 8-chloroindazolo[2,3-a][3,1]benzoxazin-5-one, 2-chloroindazolo-[2,1-a]indazole-6,12-dione, 10-chloroindazolo[2,3-a][3,1]benzoxazin-5-one (α and β modifications), and a minor product, indazolo[2,1-a]indazole-6,12-dione. The structures were assigned on the basis of independent syntheses, chemical behaviour, and spectroscopic examination.