Transition-Metal Catalyst Free Oxidative Radical Arylation of -Methylpyrrole.

This study represents an expansion of the application of catalysis in air through conventional coupling and free radical processes. A reactive free aryl radical intermediate was generated via the oxidation of an activated Ar-NH-NH bond by air as a simple and readily available oxidant. For this purpose, the usability of phenylhydrazine and phenylhydrazine hydrochloride salt reagents for the direct arylation of pyrrole with aryl radicals was investigated. The facile coupling of -methylpyrrole with aryl radicals was easily applied for the convenient direct synthesis of C-2 arylated pyrroles without a transition-metal catalyst.