Group 7-12 transition-metal complexes serve as effective catalysts for the regioselective intramolecular hydroamination of aminoalkynes having the general formula RCtC(CH 2 ) n -NH 2 (n ) 3, R ) H, Ph; n ) 4, R ) H) and of 2-(phenylethynyl)aniline. Primary products are pyrrolidines and piperidines bearing an R-alkylidene functionality and 2-phenylindole, respectively. Isomerization yields the corresponding pyrrolines and 1,2-dehydropiperidines. The catalytic properties of the transition-metal complexes depend on the appropriate choice of ligand, solvent, temperature, and counteranion. Principles for identifying the most active transition-metal catalysts for the hydroamination of alkynes and for optimizing the reaction conditions are developed. The X-ray crystal structure of one catalyst, [PdCl(triphos)](CF 3 -SO 3 ), has been determined.

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Condensation of aromatic acyl compounds with N,Ndimethylformamide diethyl acetal in a pressure tube under microwave heating gives 1-aryl-3-dimethylaminoprop-2-enones in almost quantitative yields. In the presence of hydrazine, these intermediates are transferred to the corresponding 3-arylpyrazoles.

N-Heterocyclic dicarbene chelate complexes of formula [cis-CH2N(H)C=C(H)N(R)C2PdX2] (X = Br, I; R = (CH2)nOH; n = 2, 3) have been prepared and structurally characterized (for X= I, n = 2). The complexes were immobilized on a functionalized polystyrene support (Wang resin) through one of the oxygen centres. The complexes efficiently catalyze the Heck reaction of activated and non-activated arylbromides, are recyclable under aerobic conditions and exhibit hardly any leaching, which is in line with our theoretical investigations on ligand dissociation energies related to Pd0 and PdII centres.

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