Arenediazonium-generated aryl radical and nitrile coupling cascade under neat and catalyst-free conditions: green synthesis of anilides.

In addition to their use as building blocks in organic synthesis, anilides are widely applied in a variety of industries, such as pharmaceutical, materials science, and agrochemical. The previously reported methods generally require transition-metal catalysts, co-catalysts, bases, solvents, and additives. Herein, we report a neat, catalyst-, and additive-free sustainable method for generating aryl radicals from arenediazonium salts and their subsequent reactions with nitriles to afford anilides under mild conditions (80 °C). The reaction features promising green chemistry metrics, including a low E-factor, a low PMI, and high mass productivity. The developed method is operationally simple and can be used for the synthesis of desired anilides in low-to-moderate and excellent yields (32-90%) with a broad substrate scope. In addition, the reaction exhibits excellent chemoselectivity, proceeding with the evolution of a nitrogen molecule to yield C-N coupling products exclusively. Furthermore, in the case of cinnamyl nitriles, the reaction was found to be 100% stereoselective, delivering only E-configured cinnamides. Mechanistic studies revealed the generation of an aryl radical via a self-sustained autoredox-active mechanism. This method of producing aryl radicals from arenediazonium ions under neat and/or catalyst-free conditions has been previously unexplored.