Active Palladium Colloids via Palladacycle Degradation as Efficient Catalysts for Oxidative Homocoupling and Cross-Coupling of Aryl Boronic Acids

Abstract

Active palladium colloids formed upon degradation of a palladacyclic complex (Herrmann–Beller 1 ) have been isolated for the first time and thoroughly characterized with techniques such as transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy (XPS), and extended X-ray absorption fine structure spectroscopy. The synthesized palladium colloids have been utilized as efficient catalysts for the oxidative homocoupling of aryl boronic acids. Cross-coupling of two different aryl boronic acids has also been made possible using these active palladium colloids. This is the first report of this kind of coupling between aryl boronic acids.

Aerobic Homocoupling of Arylboronic Acids Catalyzed by Regenerable Pd(II)@MIL‐88B‐NH2(Cr)

“…Finally, Kapdi and co‐workers described an aerobic procedure for the same reaction based on the use of active palladium colloids and 2 equiv. of base at high temperatures (Scheme c) …”

“…of base at high temperatures (Scheme 1c). [6] Metal-organic frameworks (MOFs) are currently some of the most widely studied materials, [14] and heterogeneous catalysts based on these materials have become increasingly popular in the last two decades. [15] MOFs are crystalline polymers made up of metallic nodes linked by polytopic organic linkers through strong coordination bonds.…”

Imine‐linked porous organic polymers showing mesoporous microspheres architectures with tunable surface roughness

“…Synthesis of A1 are according to literature . Compound A1 was obtained as white power (100 mg, 70%).…”

An Active Palladium Colloidal Catalyst for the Selective Oxidative Heterocoupling of (Hetero)Aryl Boronic Acids

“…Amongst these, are the notable examples of Cahiez and coworkers [14] for the oxidative heterocoupling of two different Grignardr eagents, [15] Zinc reagents, [16] gold(I)-catalyzed hetero- [a] V. Sable couplings of differenta lkynes reported by Shi andc o-workers [17] as wella st he copper-catalyzed heterocouplings of unsymmetrical alkynes by Lei [18] and Yin. [19] The only report to date for the heterocoupling of different aryl boronic reagents was recently published by our research group [20] (as preliminary resultsw ith al imited number of examples) to highlight the potentialo fa ctive palladiumc olloidsf or providing selective coupled products. With the aim to demonstrate the full potential of such active palladium colloidsf or the oxidative heterocoupling of different aryl boronic acids, we present herein a comprehensive study.…”