The Newborn Surface of Dull Metals in Organic Synthesis. Bismuth-Mediated Solvent-Free One-Step Conversion of Nitroarenes to Azoxy- and Azoarenes

Abstract

When milled together with bismuth shots, nitroarenes are readily converted to azoxy- and/or azoarenes depending on substrates and conditions employed. Simple extraction with organic solvent followed by evaporation of the resulting dark pasty solid gave the product in good yield.

Dehydrogenation of the NH−NH Bond Triggered by Potassium tert‐Butoxide in Liquid Ammonia

“…[1] The recent past has witnessed numerous methods for the synthesis of aromatic azo compounds such as oxidative coupling of anilines, [2] reduction of nitroaromatics, [3] coupling of diazo salts with aromatic compounds, [4] and the Mills reaction.…”

CHAPTER 3. Oxidation and Reduction by Solid Oxidants and Reducing Agents using Ball-Milling

“…22 A solvent-free, one-step reduction of nitroarenes to azoxy and azoarenes using bismuth shots or lead shots under milling conditions was first described by Suzuki and co-workers. 23 The reaction was highly chemoselective, and gave good yields in short reaction times (Scheme 3.18). Although the reaction with Bi shot gave azoxyarenes as major products in aerobic conditions, azoarenes were predominantly formed under the protection of a nitrogen atmosphere (Table 3.11).…”

Metal-catalyzed organic reactions using mechanochemistry

“…Examples of such metalmediated reactions include the oxidative homocoupling of phenols catalyzed by FeCl 3 ·6H 2 O, 84 the Mn(OAc) 3 -mediated formation of benzofuranone and dihydrobenzofuran derivatives, 85 the mechanochemical self-aldol reaction of valeraldehyde facilitated by aluminum, 86 the chlorination of hydrocarbons by CuCl 2 in a ball mill 87 and reduction of nitro groups by elementary metals. 88 Due to the space limitations, and the existence of excellent reviews and studies addressing such reactions in more detail, 1,89 we have decided to highlight only the most recent contributions to this field.…”