Regioselectivity in the Sonogashira coupling of 4,6-dichloro-2-pyrone.

The Sonogashira cross-coupling of 4,6-dichloro-2-pyrone with terminal acetylenes proceeds in good yields and high regioselectivity for the 6-position; dibenzylidene acetone (dba) type ligands play a non-innocent role in reactions mediated by Pd(dba)2/PPh3; theoretical studies indicate that C-6 oxidative addition is favoured both kinetically and thermodynamically.

Synthesis of heterobimetallic Ru-Mn complexes and the coupling reactions of epoxides with carbon dioxide catalyzed by these complexes.

The heterobimetallic complexes [(eta5-C5H5)Ru(CO)(mu-dppm)Mn(CO)4] and [(eta5-C5Me5)Ru(mu-dppm)(mu-CO)2Mn(CO)3] (dppm = bis-diphenylphosphinomethane) have been prepared by reacting the hydridic complexes [(eta5-C5H5)Ru(dppm)H] and [(eta5-C5Me5)Ru(dppm)H], respectively, with the protonic [HMn(CO)5] complex. The bimetallic complexes can also be synthesized through metathetical reactions between [(eta5-C5R5)Ru(dppm)Cl] (R = H or Me) and Li+[Mn(CO)5]-. Although the complexes fail to catalyze the hydrogenation of CO2 to formic acid, they catalyze the coupling reactions of epoxides with carbon dioxide to yield cyclic carbonates.

Theoretical study of reaction pathways for the rhodium phosphine-catalysed borylation of C-H bonds with pinacolborane.

The reaction mechanism of the rhodium-phosphine catalysed borylation of methyl-substituted arenes using pinacolborane (HBpin) has been investigated theoretically using DFT calculations at the B3PW91 level. Factors affecting selectivity for benzylic vs. aromatic C-H bond activation have been examined.

Structural analysis of five-coordinate transition metal boryl complexes with different d-electron configurations.

The site preference of boryl ligands in five-coordinate transition metal boryl complexes has been investigated with the aid of density functional theory calculations. The preferred site for a boryl ligand depends on the electron count of the complex under consideration. Our studies show that the very strong sigma-donating boryl ligands choose to occupy coordination sites such that those orbitals accommodating metal d electrons have minimal metal-boryl sigma-antibonding character.