A metal-free, iodine-mediated protocol has been established for the synthesis of indazoloquinoxaline derivatives using readily accessible substrates. This methodology provides a straightforward route to diverse indazoloquinoxaline derivatives, achieving moderate to good yields Control experiments reveal that the reaction relies on the in situ formation of phenylglyoxal as a key intermediate to driving the process.

Abstract

A metal-free, iodine-mediated protocol has been developed to synthesize indazoloquinoxaline derivatives from readily accessible substrates such as 2-(2H-indazol-2-yl)anilines and aryl methyl ketones. This operationally simple, one-pot reaction proceeds through iodine/DMSO-mediated C(sp³)-H oxidation of aryl methyl ketones, followed by imine formation and annulation to furnish the desired products. A wide range of aryl methyl ketones, including drug-derived substrates, were compatible in the present reaction. Further, the reaction is scalable, demonstrating its applicability on a larger scale.