Mixed N-heterocyclic carbene and phosphine palladium complexes for telomerization of butadiene with methanol

A series of hydrophilic palladium-NHC complexes have been prepared and evaluated in the telomerization of butadiene with methanol under mild conditions (50 °C) in the presence or absence of water. Palladium complexes bearing mixed NHC-phosphine or zwitterionic imidazolinium ligands exhibited high efficiency in pure methanol (TON up to 59,000). Unfortunately, they could not be used for the télomérisation of butadiene with hydrosoluble substrate as they are inactive in the presence of water. On the other hand, catalyst prepared in situ from Pd(OAc)2 and IMes.Cl was active in biphasic conditions and TON up to 10,200 was then achieved.

Graphical abstractMixed carbene–phosphine palladium complexes were prepared and evaluated in the telomerization of butadiene with methanol under mild conditions. These catalysts exhibited very high activity under anhydrous conditions. In biphasic conditions, only complexes prepared in situ from palladium salts and IMes.Cl were active and TON up to 10,200 was then achieved.Figure optionsDownload full-size imageDownload as PowerPoint slide