The synthesis, characterisation and catalytic behaviour of ruthenium indenylidene complexes bearing an N-heterocyclic carbene and triisopropylphosphite are described.

A series of N-heterocyclic carbene (NHC)/PR3 palladium(II) and palladium(0) complexes has been synthesized and fully characterized. X-ray crystallographic data have allowed comparison of ligand steric properties. The NHC ligand was found to vary its steric properties as a function of the phosphine co-ligand. These complexes display interesting catalytic properties in the Suzuki-Miyaura reaction performed in aqueous media. The pre-catalyst [PdCl2(IPr)(XPhos)] (IPr = N,N'-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene; XPhos = 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl) was found to be the most efficient system, promoting the coupling of a wide range of aryl chlorides with boronic acids in aqueous media with a typical catalyst loading of 0.03 mol%.

An efficient copper-catalyzede nantioselective conjugate addition of dimethylzinc to unsaturated 2-acyl-N-methylimidazoles has been achieved using ac hiral bidentateh ydroxyalkyl-NHC ligand. Ther eactions proceed with excellent regioselectivity (1,4 vs. 1,6 and 1,8) in extended conjugateds ystems to affordt he 1,4-adducts in high enantioselectivities. This regioselectivity could be ascertained by DFT studies highlightingt he crucial role of the imidazole ring. Thanks to the development of efficient protocols to regenerate the unsaturated 2-acyl-N-methylimidazole moiety,a ni terative process has been developed ultimately leading to 3,5,7 all-syn or anti-anti polydeoxypropionate stereodiads.Scheme 5. Applicationo ft he ACA/post-functionalizations equence involving a,b-unsaturated 2-acyl-N-methylimidazole 1h to the synthesis of (+ +)-(S)-Florhydral .Scheme 6. Synthesis of unsaturated di-andt rienic2 -acyl-Nmethylimidazole subtrates 1i-n. Scheme 7. Substrate scope for the 1,4-regioselective ACAo f dimethylzinc to poly-unsaturated 2-acyl-N-methylimidazoles 1i-n catalyzed by L1/Cu(OTf) 2 .Scheme 12. Synthesis of anti,anti 3-(S),5-(R),7-(S)a cyl-N-methylimidazole 2p.

Cp*Rh(NHC) complexes with bulky chiral bidentate NHC-carboxylate ligands were efficiently synthesized and fully characterized including solid-state structures. These unprecedented rhodium(iii) complexes demonstrated high selectivity in pyridine-directed ortho-C-H borylation of arenes under mild conditions.