[Pd(Cl)2{P(NC5H10)(C6H11)2}2]—A Highly Effective and Extremely Versatile Palladium-Based Negishi Catalyst that Efficiently and Reliably Operates at Low Catalyst Loadings



[Pd(Cl)2{P(NC5H10)(C6H11)2}2] (1) has been prepared in quantitative yield by reacting commercially available [Pd(cod)(Cl)2] (cod=cyclooctadiene) with readily prepared 1-(dicyclohexylphosphanyl)piperidine in toluene under N2 within a few minutes at room temperature. Complex 1 has proved to be an excellent Negishi catalyst, capable of quantitatively coupling a wide variety of electronically activated, non-activated, deactivated, sterically hindered, heterocyclic, and functionalized aryl bromides with various (also heterocyclic) arylzinc reagents, typically within a few minutes at 100 °C in the presence of just 0.01 mol % of catalyst. Aryl bromides containing nitro, nitrile, ether, ester, hydroxy, carbonyl, and carboxyl groups, as well as acetals, lactones, amides, anilines, alkenes, carboxylic acids, acetic acids, and pyridines and pyrimidines, have been successfully used as coupling partners. Furthermore, electronic and steric variations are tolerated in both reaction partners. Experimental observations strongly indicate that a molecular mechanism is operative.