As alternatives to the common tertiary phosphine/Pd systems, well-defined N-heterocyclic carbene–Pd complexes have been proven to be highly efficient precatalysts for intermolecular direct annalution of o-haloanilines and ketones at lower catalyst loadings. A highly efficient and practical protocol for synthesis of functionalized indoles was developed using (IPr)Pd(acac)Cl as catalyst. Both o-bromoanilines and o-chloroanilines gave rise to efficient coupling under the reaction conditions. Related to acyclic ones, cyclic ketones coupled more effectively with o-haloanilines. With [Pd(IPr)₂] as catalyst, the base-sensitive groups including OH and CO₂H groups could be tolerated. Copyright © 2011 John Wiley & Sons, Ltd.

A new class of well-defined N-heterocyclic carbene (NHC)-(cyclopentadiene)palladium chloride complexes such as CpPd(NHC)Cl wasw synthesized from the readily available starting NHC-palladium(II) chloride dimers. These air-stable, coordinatively saturated NHC-Pd complexes bearing the cyclopentadiene (Cp) unit exhibit high catalytic activity in the room temperature Suzuki–Miyaura and Buchwald–Hartwig cross-coupling reactions involving unactive aryl chlorides as the substrates. In addition, they are found to be extremely efficient catalysts in the deboronation homocoupling of arylboronic acids at room temperature.