Ligands In Palladium-catalyzed Reactions Research Articles

Theoretical study of the electron-donating effects of thiourea ligands in catalysis

Thiourea and its derivatives often act as strong electron-donating ligands in palladium-catalyzed reactions. Density functional theory calculations were performed to investigate the electronic effects of thiourea ligands in palladium complexes, and a p–d–π interaction model is proposed. In this model, a Pd(d)S(p) interaction is responsible for the increased binding of π acceptor ligands such as CO and olefins, which are present in important intermediates in Pd-catalyzed reactions. This d–p interaction is a four-electron, two-orbital interaction; it raises the energy of the Pd(dyz) orbital, bringing it closer to the π* orbital of the CO or olefin ligand, and increases back donation. Thiourea-ligated transition metals are therefore favorable for the binding of acidic π ligands.

P*,P*-Bidentate Diamidophosphite Ligands in Palladium-Catalyzed Reactions

Two diamidophospite ligands were used in palladium-catalyzed allylic sulfonylation, alkylation, amination, etherification, and desymmetrization reactions. The novel ligands take ­advantage of the chirogenic phosphorus donor atoms, which create a more efficient chiral environ­ment around the metal.

Assessment of the Activity of 8-Diphenylphosphino-8'-methoxy-1,1'- binaphthyl as a Ligand for Palladium-Catalyzed Reactions.

A monodentate phosphine, 8-diphenylphosphino-8'-methoxy-1, 1'-binaphthyl, was shown to be active as a ligand in palladium-catalyzed reactions, including the reduction of allylic carbonates with formic acid, hydrosilylation of a terminal olefin, and hydroboration of but-1-en-3-yne, even though it has a highly hindered lone pair.