FORMATION OF DERIVATIVES OF N-HYDROXYINDOLES, ANNELATED WITH FURAZAN AND FUROXAN RINGS
Upon reaction of 4-oxo-5-hydroxyimino-4,5,6,7-tetrahydrobenzofurazan and tetrahydrobenzofuroxan with acetylacetone, 8-acetyl-6-hydroxy-7-methylpyrrolobenzofurazan and -benzofurazan-3-oxide are formed; and upon reaction with acetoacetate, 8-ethoxycarbonyl-6-hydroxy-7-methylpyrrolobenzofurazan and -benzofurazan-3-oxide are formed.