Development of a method for the preparation of ruthenium indenylidene-ether olefin metathesis catalysts

Inhibition of XPO-1 Mediated Nuclear Export through the Michael-Acceptor Character of Chalcones

The nuclear export receptor exportin-1 (XPO1, CRM1) mediates the nuclear export of proteins that contain a leucine-rich nuclear export signal (NES) towards the cytoplasm. XPO1 is considered a relevant target in different human diseases, particularly in hematological malignancies, tumor resistance, inflammation, neurodegeneration and viral infections. Thus, its pharmacological inhibition is of significant therapeutic interest. The best inhibitors described so far (leptomycin B and SINE compounds) interact with XPO1 through a covalent interaction with Cys528 located in the NES-binding cleft of XPO1. Based on the well-established feature of chalcone derivatives to react with thiol groups via hetero-Michael addition reactions, we have synthesized two series of chalcones. Their capacity to react with thiol groups was tested by incubation with GSH to afford the hetero-Michael adducts that evolved backwards to the initial chalcone through a retro-Michael reaction, supporting that the covalent interaction with thiols could be reversible. The chalcone derivatives were evaluated in antiproliferative assays against a panel of cancer cell lines and as XPO1 inhibitors, and a good correlation was observed with the results obtained in both assays. Moreover, no inhibition of the cargo export was observed when the two prototype chalcones 9 and 10 were tested against a XPO1-mutated Jurkat cell line (XPO1C528S), highlighting the importance of the Cys at the NES-binding cleft for inhibition. Finally, their interaction at the molecular level at the NES-binding cleft was studied by applying the computational tool CovDock.

Hoveyda-Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors

A novel and efficient approach to the synthesis of 2-vinylbenzylamines is reported. This involves obtaining 2-vinylbenzylamine ligands from tetrahydroisoquinoline by alkylation and reduction followed by the Hofmann cleavage. The resultant 2-vinylbenzylamines allowed us to obtain new Hoveyda-Grubbs catalysts, which were thoroughly characterised by NMR, ESIMS, and X-ray crystallography. The utility of this chemistry is further demonstrated by the tests of the novel catalysts (up to 10^-2 mol %) in different metathesis reactions such as cross metathesis (CM), ring-closing metathesis (RCM) and ring-opening cross metathesis (ROCM).

Crystal structure of [1,3-bis-(2,4,6-tri-methyl-phen-yl)imidazolidin-2-yl-idene]di-chlorido-{2-[1-(di-methyl-amino)-eth-yl]benzyl-idene}ruthenium including an unknown solvate

The title compound, [RuCl2(C21H26N2)(C11H15N)], is an example of a new generation of N,N-dialkyl metallocomplex ruthenium catalysts with an N→Ru coordination bond as part of a six-membered chelate ring. The Ru atom has an Addison τ parameter of 0.234, which indicates a geometry inter-mediate between square-based pyramidal and trigonal-bipyramidal. The complex shows the usual trans arrangement of the two chloride ligands, with Ru-Cl bond lengths of 2.3397 (8) and 2.3476 (8) Å, and a Cl-Ru- Cl angle of 157.47 (3)°. The crystal structure features C-H⋯Cl, C-H⋯π and π-π stacking inter-actions. The solvent mol-ecules were found to be highly disordered and their contribution to the scattering was removed with the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9-18], which indicated a solvent cavity of volume 1096 Å3 containing approximately 419 electrons. These solvent mol-ecules are not considered in the given chemical formula and other crystal data.

Merrifield resin-assisted routes to second-generation catalysts for olefin metathesis

Phosphine-scavenging Merrifield resins can significantly facilitate the synthesis of highly active Ru metathesis catalysts, including the second-generation Grubbs, Hoveyda, and indenylidene catalysts (GII, HII, InII).

Effect of the bulkiness of indenylidene moieties on the catalytic initiation and efficiency of second-generation ruthenium-based olefin metathesis catalysts

Fast initiation and high efficiency of ruthenium indenylidene catalysts induced by steric repulsion between two ligands (SIMes ligand and bulky indenylidene ligand).

Synthesis and characterization of non-chelating ruthenium–indenylidene olefin metathesis catalysts derived from substituted 1,1-diphenyl-2-propyn-1-ols

The synthesis and characterization of four first-generation modified non-chelating indenylidene ruthenium catalysts is reported, as well as their catalytic performance in olefin metathesis reactions.

Reactivation of a Ruthenium-Based Olefin Metathesis Catalyst

1(st) Generation Hoveyda-Grubbs olefin metathesis catalyst was purposely decomposed in the presence of ethylene yielding inorganic species that are inactive in the ring-closing metathesis (RCM) of benchmark substrate diethyldiallyl malonate (DEDAM). The decomposed catalyst was treated with 1-(3,5-diisopropoxyphenyl)-1-phenylprop-2-yn-1-ol (3) to generate an olefin metathesis active ruthenium indenylidene-ether complex in 43 % yield. This complex was also prepared independently by reacting RuCl(2)(p-cymene)(PCy(3)) with organic precursor 3. The activity of the isolated reactivated catalyst in the RCM of DEDAM is similar to that of the independently prepared complex.