An oxidative cyclization of 1‐(2‐aminophenyl)pyrrole with styrenes has been developed for the synthesis of pyrrolo[1, 2‐a]quinoxaline derivatives using I2/2‐iodoxybenzoic acid (IBX) in DMSO as an effective oxidant. I2 is found to catalyze effectively the oxidative cyclization of phenylacetylene and ethyl benzoylacetate with 1‐(2‐aminophenyl)pyrrole even in the absence of IBX to generate pyrrolo[1, 2‐a]quinoxaline derivatives under metal‐free conditions.
A metal‐free one‐pot strategy has been developed for the synthesis of 3‐aryl[1,2,4]triazolo[4,3‐a]pyridines through an oxidative cyclization of 2‐(2‐arylidenehydrazinyl)pyridines by utilizing molecular iodine in DMSO. This is the first report on the synthesis of 3‐aroyl[1,2,4]triazolo[4,3‐a]pyridines directly from α‐aryl methyl ketones or ethyl benzoylacetate or styrenes or phenylacetylenes and 2‐hydrazinylpyridines via iodine promoted oxidative cyclization. The catalytic use of iodine makes this method quite simple, more convenient and economical. Moreover, this protocol showed broad substrate scope under mild reaction conditions and could override the usage of hazardous metal reagents.magnified image
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