Electromagnetic Mill Promoted Mechanochemical Solvent-Free Palladium-Catalyzed Borylation of Aryl Bromides

Abstract

The electromagnetic mill (EMM) promoted mechanochemical solvent-free palladium-catalyzed borylation of aryl bromides using low palladium catalyst loading (0.05−0.5 mol %) was realized. This protocol exhibits many advantages, such as broad substrate scope, good functional group tolerance, short reaction times, no additional heating, and practical gram-scale synthesis. This EMM system not only showed excellent prospects for industrial application but also unlocked broad areas of solventfree solid-state metal-catalyzed syntheses.

Synthesis and Characterization of Dibenzothieno[a,f]pentalenes Enabling Large Antiaromaticity and Moderate Open-Shell Character through a Small Energy Barrier for Bond-Shift Valence Tautomerization

“…In Scheme , the synthetic route for mesityl derivatives 6b / 7b is summarized. According to our previous studies, , a palladium-catalyzed Suzuki–Miyaura cross-coupling of 8 with 5- or 6-(benzo­[ b ]­thiophenyl)­boronic acid esters , furnished diester 9 / 10 . Reduction of the ester moieties in 9 / 10 with i Bu 2 AlH afforded diol 11 / 12 , and subsequent oxidation gave dialdehyde 13 / 14 .…”

“…In Scheme 1, the synthetic route for mesityl derivatives 6b/7b is summarized. According to our previous studies, 56,57 a palladium-catalyzed Suzuki−Miyaura crosscoupling of 8 with 5-or 6-(benzo[b]thiophenyl)boronic acid esters 76,77 important. First, we attempted the deprotonation of 17/18 using nBuLi, which had clearly given the corresponding dianions in our previous syntheses of diareno[a,f ]pentalenes, 52,53,56,57 but insoluble materials were precipitated and failed to characterize them.…”

Recent Expedition in Pd‐ and Rh‐Catalyzed C(Ar)−B Bond Formations and Their Applications in Modern Organic Syntheses

“…Under this catalyst system, steric bulky 4‐bromo‐3,5‐dimethylisoxazole reacted with B 2 pin 2 smoothly to obtain the desired borylative product in 78 % yield (Scheme 4b). Electromagnetic mill was also applicable in solvent‐free borylation of aryl bromides under low Pd loading (0.05–0.5 mol % Pd) [33] . The steric hindered 9‐bromoanthracene was successfully coupled with B 2 pin 2 using Pd/DavePhos catalyst system.…”

Electromagnetic mill promoted mechanochemical palladium-catalyzed solid state cyanation of aryl bromides using non-toxic K4[Fe(CN)6]

“…[38][39][40][41] Very recently, our group focused on developing novel electromagnetic mill promoted organic reactions, which could realize solid-state transformations without solvent or heating. 42,43 The success of solid-state Suzuki-Miyaura cross-coupling and solvent-free borylation of aryl bromides under the EMM conditions encouraged us to develop new transformations under this new concept.…”