Air-stable CpPd(NHC)Cl (NHC = N-heterocyclic carbene) complexes as highly active precatalysts for Kumada–Tamao–Corriu coupling of aryl and heteroaryl chlorides

A very straightforward one-pot method has been developed for preparation of air-stable CpPd(NHC)Cl complexes 1a–d. This new class of well-defined NHC–Pd complexes exhibits high catalytic activity in Kumada–Tamao–Corriu cross-coupling reaction involving various aryl and heteroaryl chlorides. Notably, the less sterically encumbered NHC ligand around Pd centre showed higher catalytic activity.

Graphical abstractA very straightforward one-pot method has been developed for preparation of air-stable CpPd(NHC)Cl complexes 1a–d. This new class of well-defined NHC–Pd complexes exhibits high catalytic activity in Kumada–Tamao–Corriu cross-coupling reaction involving various aryl and heteroaryl chlorides. Notably, the less sterically encumbered NHC ligand around Pd centre showed higher catalytic activity.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► A new one-pot method for preparation of air-stable CpPd(NHC)Cl complexes has been developed. ► Compared with the previous multi-step reaction, this one-pot synthetic protocol for the target derivatives obviates the use of a glovebox and simplifies the workup. ► This new class of well-defined NHC–Pd complexes, i.e. CpPd(NHC)Cl, exhibit high catalytic activity in Kumada–Tamao–Corriu cross-coupling reaction involving a variety of aryl and heteroaryl chlorides. ► We found that NHC ligand with the less sterically constrained substituents on the imidazole nitrogens showed higher catalytic activity, which is just opposite to the previous results in other catalytic systems involving NHC ligands.