Efficient cluster-based catalysts for asymmetric hydrogenation of α-unsaturated carboxylic acids.

The new clusters [H(4)Ru(4)(CO)(10)(μ-1,2-P-P)], [H(4)Ru(4)(CO)(10) (1,1-P-P)] and [H(4)Ru(4)(CO)(11)(P-P)] (P-P=chiral diphosphine of the ferrocene-based Josiphos or Walphos ligand families) have been synthesised and characterised. The crystal and molecular structures of eleven clusters reveal that the coordination modes of the diphosphine in the [H(4)Ru(4)(CO)(10)(μ-1,2-P-P)] clusters are different for the Josiphos and the Walphos ligands. The Josiphos ligands bridge a metal-metal bond of the ruthenium tetrahedron in the "conventional" manner, that is, with both phosphine moieties coordinated in equatorial positions relative to a triangular face of the tetrahedron, whereas the phosphine moieties of the Walphos ligands coordinate in one axial and one equatorial position.

Relevance of the leaving group for antitumor activity of new platinum(II) compounds containing anthracene derivatives as a carrier ligand.

A new anticancer-active platinum(II) compound [Pt(A9pyp)(dmso)(cbdca)], containing the E-1-(9-anthryl)-3-(2-pyridyl)-2-propenone ligand (abbreviated as A9pyp) has been synthesized by the replacement of the anionic chloride ligands in cis-[Pt(A9pyp)(dmso)Cl(2)] by the dianionic chelating cyclobutanedicarboxylate ligand (abbreviated as cbdca). The in vitro relevance of the leaving group of these new platinum(II) compounds has been investigated. Measurements of the time-dependent intracellular accumulation of both compounds in human ovarian carcinoma cell lines show that the leaving group affects their cellular uptake.

New coordination polymers based on the triangular [Cu3(mu3-OH)(mu-pz)3]2+ unit and unsaturated carboxylates.

By reacting copper(II) acrylate with pyrazole (Hpz), two trinuclear copper derivatives [Cu3(mu3-OH)(mu-pz)3(CH2CHCOO)2(H2O)2(Hpz)], 1, and [Cu3(mu3-OH)(mu-pz)3(CH2CHCOO)2(CH3OH)], 2, are obtained, in water and methanol respectively, while copper(II) methacrylate affords [Cu3(mu3-OH)(mu-pz)3(CH2C(CH3)COO)2], 3, independently from the solvent used. In 1 and 2 two triangular trinuclear units are connected through acrylate bridges forming hexanuclear clusters that, in the case of 2 are further connected through double syn-syn carboxylate bridges, generating a 1-D coordination polymer. In the case of 3 a different 1-D coordination polymer is obtained by alternating syn-syn and syn-anti double carboxylate bridges connecting the trinuclear clusters.

Synthesis of imidazolidin-2-one-4-carboxylate and of (tetrahydro)pyrimidin-2-one-5-carboxylate via an efficient modification of the Hofmann rearrangement.

A mild and efficient methodology for the rearrangement of protected asparagine and protected glutamine is reported; good results are obtained with a wide selection of protecting groups.