The synthesis of the new well-defined and air-stable complex (SIPr)Pd(acac)Cl (SIPr=1,3-bis(2,6diisopropylphenyl)imidazolin-2-ylidene) is described, and the catalytic activity of this new complex has been tested in the R-arylation of ketones and in Buchwald-Hartwig amination reactions. The significant differences in catalytic performance when compared to the previously reported, unsaturated counterpart (IPr)Pd(acac)Cl (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) are discussed by means of X-ray crystallography and on the basis of their varying solution dynamics, observed by 1 H NMR spectroscopy.

The selective, anaerobic catalytic oxidation of secondary alcohols at room temperature by using an in situ (N-heterocyclic carbene)-Ni(0) system is presented. The use of non-anhydrous, non-degassed 2,4-dichlorotoluene as both the oxidant and the solvent allows for very short reaction times and very high yields. In addition, a well-defined (N-heterocyclic carbene)-Ni(0) complex was synthesized and applied to these oxidation reactions.

Concave bimacrocyclic imidazolinium ions 8 have been synthesized as precursors for N-heterocyclic carbenes 9 (NHC) in 13 to 29 % overall yields based on 2-nitroresorcinol (1). As bridgeheads, 2,6-bis(ω-alkenyloxy)anilines 3 have been synthesized from 1. Reaction of 3 with oxalyl chloride, reduction to respective diamines 5, and ring closure with triethyl orthoformate gave N,N-diaryl-substituted imidazolinium ions 6. The terminal vinyl groups were connected by

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Two bimacrocyclic imidazolinium salts of different size, precursors to respective NHCs (N-heterocyclic carbenes), were tested as precatalysts in the reaction of aromatic aldehydes or ketones with enals. The expected lactones were produced in most cases, but in the reaction of methyl 4-formylbenzoate with cinnamaldehyde, the larger bimacrocycle led to the formation of a cyclic hemiacetal, while the smaller bimacrocycle gave the anticipated lactone.