[Products of a reaction between 1H-indazol-3-ol and ethyl chloroacetate].

Ethyl esters of [(1-carbethoxymethyl-1H-indazol-3-yl)oxy]-acetic acid; (2-carbethoxy-3,4-dihydro-4-oxo-3-quinazolinacetic acid; [(1H-indazol-3-yl)oxy] acetic acid; o.aminoippuric acid; (2-carbethoxy-4-oxo-1,2,3,4--tetrahydro)-3-quinazolin acetic acid; (3-hydroxy-1H-indazol-1-yl)acetic acid; (1H-indazol-3-on-2-yl)acetic acid have been isolated and identified from a reaction between equivalent quantities of 1H-indazol-3-ol and ethyl chloroacetate in ethanol. The mechanism of their formation and, particularly, the ring enlargement of indazole to tetrahydroquinazoline is discussed. I.R. and N.M.R. spectra of these esters and of the acids obtained from them by alkaline hydrolysis are also described.