Cross-Coupling Biarylation of Nitroaryl Chlorides Through High Speed Ball Milling.

Solvent-free reaction using a high-speed ball milling technique has been applied to the classical Ullmann coupling reaction. Cross-coupling biarylation of several nitroaryl chlorides was achieved in good yields when performed in custom-made copper vials through continuous shaking without additional copper or solvent. Cross-coupling products were obtained almost pure and NMR-ready. These reactions were cleaner than solution phase coupling which require longer reaction time in high boiling solvents, and added catalysts as well as lengthy extraction and purification steps. Gram quantities of cross biaryl compounds have been synthesized with larger copper vials, a proof that this method can be used to reduce industrial waste and for sustainability.

Regioselective Nitration of Halogenated Benzo[c]cinnolines and Benzenoids.

Electrophilic nitration of halo-substituted benzo[c]cinnolines and benzenoids has been achieved regioselectively. The nitro group entry was always ortho to the halo group or/and the aromatic ring. This regioselective electrophilic ortho-nitration was accomplished in mixed acid/mild temperature conditions. Regioselectivity ortho to the halo/ring group(s) was observed with or without proximal steric hindrance. Chlorides and bromides worked equally well in directing these high-yielding ortho-selective reactions.

Synthesis of Substituted 2,2'-Dinitrobiphenyls by a Novel Solvent-Free High Yielding Ullmann Coupling Biarylation.

Solvent-free reaction using a high-speed ball milling technique has been applied to the classical Ullmann coupling reaction for the first time. Biarylation of 2-iodonitrobenzene was achieved in quantitative yield when performed in a custom-made copper vial through continuous shaking without additional copper or solvent. The product was solid, NMR ready and required no lengthy extraction for purification. This reaction was cleaner, and faster than solution phase coupling which requires longer reaction time in high boiling solvents, added copper catalyst, and lengthy extraction and purification steps. Gram quantities of the biaryl compound were synthesized in larger copper vials. This is a general method that can be used to effectively reduce industrial waste en route to sustainability.