22608-45-3Relevant articles and documents
"canopy Catalysts" for Alkyne Metathesis: Molybdenum Alkylidyne Complexes with a Tripodal Ligand Framework
Copéret, Christophe,Fürstner, Alois,Gordon, Christopher P.,Hillenbrand, Julius,Leutzsch, Markus,N?thling, Nils,Wille, Christian,Yiannakas, Ektoras
supporting information, p. 11279 - 11294 (2020/07/13)
A new family of structurally well-defined molybdenum alkylidyne catalysts for alkyne metathesis, which is distinguished by a tripodal trisilanolate ligand architecture, is presented. Complexes of type 1 combine the virtues of previous generations of silanolate-based catalysts with a significantly improved functional group tolerance. They are easy to prepare on scale; the modularity of the ligand synthesis allows the steric and electronic properties to be fine-tuned and hence the application profile of the catalysts to be optimized. This opportunity is manifested in the development of catalyst 1f, which is as reactive as the best ancestors but exhibits an unrivaled scope. The new catalysts work well in the presence of unprotected alcohols and various other protic groups. The chelate effect entails even a certain stability toward water, which marks a big leap forward in metal alkylidyne chemistry in general. At the same time, they tolerate many donor sites, including basic nitrogen and numerous heterocycles. This aspect is substantiated by applications to polyfunctional (natural) products. A combined spectroscopic, crystallographic, and computational study provides insights into structure and electronic character of complexes of type 1. Particularly informative are a density functional theory (DFT)-based chemical shift tensor analysis of the alkylidyne carbon atom and 95Mo NMR spectroscopy; this analytical tool had been rarely used in organometallic chemistry before but turns out to be a sensitive probe that deserves more attention. The data show that the podand ligands render a Mo-alkylidyne a priori more electrophilic than analogous monodentate triarylsilanols; proper ligand tuning, however, allows the Lewis acidity as well as the steric demand about the central atom to be adjusted to the point that excellent performance of the catalyst is ensured.
Robust Alkyne Metathesis Catalyzed by Air Stable d2Re(V) Alkylidyne Complexes
Cui, Mingxu,Bai, Wei,Sung, Herman H. Y.,Williams, Ian D.,Jia, Guochen
supporting information, p. 13339 - 13344 (2020/09/03)
We report in this communication the first example of catalytic alkyne metathesis reactions mediated by well-defined non-d0 alkylidyne complexes. The air-stable d2 Re(V) alkylidyne complex Re4, bearing two PO-chelating ligands and a labile pyridine ligand, could catalyze homometathesis of internal alkynes with a broad substrate scope, including alcohols, amines, and even carboxylic acids. The catalyst can tolerate heating, air, and moisture in both solid and solution states, and the catalytic metathesis reactions could proceed normally in wet solvents.
Molybdenum Alkylidyne Complexes with Tripodal Silanolate Ligands: The Next Generation of Alkyne Metathesis Catalysts
Hillenbrand, Julius,Leutzsch, Markus,Fürstner, Alois
supporting information, p. 15690 - 15696 (2019/10/28)
A new type of molybdenum alkylidyne catalysts for alkyne metathesis is described, which is distinguished by an unconventional podand topology. These structurally well-defined complexes are easy to make on scale and proved to be tolerant toward numerous functional groups; even certain protic substituents were found to be compatible. The new catalysts were characterized by X-ray crystallography and by spectroscopic means, including 95Mo NMR.
Molecular Interactions Control Quantum Chain Reactions toward Distinct Photoresponsive Properties of Molecular Crystals
Gong, Yanjun,Zhang, Yifan,Xiong, Wei,Zhang, Ke,Che, Yanke,Zhao, Jincai
supporting information, p. 10649 - 10652 (2017/08/15)
In this work, we fabricated four diphenylcyclopropenone (DPCP) crystals, which involved various molecular interactions encoded in individual molecular structures 1-4. On the basis of crystalline structural analysis and photoresponsive characterization of
A Two-Component Alkyne Metathesis Catalyst System with an Improved Substrate Scope and Functional Group Tolerance: Development and Applications to Natural Product Synthesis
Schaubach, Sebastian,Gebauer, Konrad,Ungeheuer, Felix,Hoffmeister, Laura,Ilg, Marina K.,Wirtz, Conny,Fürstner, Alois
supporting information, p. 8494 - 8507 (2016/07/11)
Although molybdenum alkylidyne complexes such as 1 endowed with triarylsilanolate ligands are excellent catalysts for alkyne metathesis, they can encounter limitations when (multiple) protic sites are present in a given substrate and/or when forcing conditions are necessary. In such cases, a catalyst formed in situ upon mixing of the trisamidomolybenum alkylidyne complex 3 and the readily available trisilanol derivatives 8 or 11 shows significantly better performance. This two-component system worked well for a series of model compounds comprising primary, secondary or phenolic -OH groups, as well as for a set of challenging (bis)propargylic substrates. Its remarkable efficiency is also evident from applications to the total syntheses of manshurolide, a highly strained sesquiterpene lactone with kinase inhibitory activity, and the structurally demanding immunosuppressive cyclodiyne ivorenolide A; in either case, the standard catalyst 1 largely failed to effect the critical macrocyclization, whereas the two-component system was fully operative. A study directed toward the quinolizidine alkaloid lythrancepine I features yet another instructive example, in that a triyne substrate was metathesized with the help of 3/11 such that two of the triple bonds participated in ring closure, while the third one passed uncompromised. As a spin-off of this project, a much improved ruthenium catalyst for the redox isomerization of propargyl alcohols to the corresponding enones was developed.
Novel Dihydroxypolyarylacetate, high hardness polycarbonate copolymer and method for preparing thereof
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Paragraph 0027-0030; 0054-0056, (2016/12/16)
The present invention relates to a novel dihydroxy polyaryl acetate and, more specifically, to a novel dihydroxy polyaryl acetate represented by chemical formula 1 (R_1-R_5 and Randprime;_1-Randprime;_5 are selected from H, OH, CH_3, an alkenyl group of C2-C6, a cycloalkylene group of C6-C12 and an arylene group of C6-C12. And n is an integer of 1-10.), a manufacturing method for a polycarbonate copolymer using the same, and a high hardness polycarbonate copolymer. The present invention is able to provide a novel dihydroxy polyaryl acetate derivative capable of being used as an impact modifier, a modifier, or a comonomer and provide a high hardness polycarbonate copolymer with excellent heat resistance.COPYRIGHT KIPO 2015
Calcium carbide as a cost-effective starting material for symmetrical diarylethynes via Pd-catalyzed coupling reaction
Chuentragool, Padon,Vongnam, Kunnigar,Rashatasakhon, Paitoon,Sukwattanasinitt, Mongkol,Wacharasindhu, Sumrit
experimental part, p. 8177 - 8182 (2011/10/31)
A convenient and cost-effective synthetic method for symmetrical diarylethynes from inexpensive calcium carbide and aryl iodide has been developed. The reaction not only proceeds with high yield and selectivity but also tolerates a wide range of functional groups. Application of this reaction has enabled the synthesis of highly functionalized oligo (phenyleneethynylenes) to be accomplished.
Photonic amplification by a singlet-state quantum chain reaction in the photodecarbonylation of crystalline diarylcyclopropenones
Kuzmanich, Gregory,Gard, Matthew N.,Garcia-Garibay, Miguel A.
, p. 11606 - 11614 (2011/03/17)
The photochemical decarbonylation of diphenylcyclopropenone (DPCP) to diphenylacetylene (DPA) proceeds with remarkable efficiency both in solution and in the crystalline solid state. It had been previously shown that excitation to the second electronic excited state (S2) of DPCP in solution proceeds within ca. 200 fs by an adiabatic ring-opening pathway to yield the S2 state of DPA, which has a lifetime of ca. 8 ps before undergoing internal conversion to S1 (Takeuchi, S.; Tahara, T. J. Chem. Phys. 2004, 120, 4768). More recently, we showed that reactions by excitation to S2 in crystalline solids proceed by a quantum chain process where the excited photoproducts transfer energy to neighboring molecules of unreacted starting material, which are able to propagate the chain. Quantum yields in crystalline suspensions revealed values of ΦDPCP = 3.3 = 0.3. To explore the generality of this reaction, and recognizing its potential as a photonic amplification system, we have synthesized nine crystalline diarylcyclopropenone derivatives with phenyl, biphenyl, naphthyl, and anthryl substituents. To quantify the efficiency of the quantum chain in the crystalline state, we determined the quantum yields of reaction for all of these compounds both in solution and in nanocrystalline suspensions. While the quantum yields of decarbonylation in solution vary from Φ = 0.0 to 1.0, seven of the nine new structures display quantum yields of reaction in the solid that are above 1. The chemical amplification that results from efficient energy transfer in the solid state, analyzed in terms of the quantum yields determined in the solid state and in solution (Φcryst/Φsoln), reveals quantum chain amplification factors that range from 3.2 to 11.0. The remarkable mechanical response of the solid-to-solid reaction previously documented with macroscopic crystals, where large single-crystalline specimens turn into fine powders, was investigated at the nanometer scale. Experiments with dry crystals of DPCP analyzed by atomic force microscopy showed the formation of DPA in the form of isolated crystalline specimens ca. 35 nm in size.
ASCORBATE, VITAMIN K3 AND HYDROXYTOLANS IN THE TREATMENT OF CANCER
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Page/Page column 19, (2009/01/23)
The combination of compounds of the hydroxytolan family with ascorbate plus naphthoquinone (Vitamin K3; VK3), or a quinone or semiquinone analogue of VK3, kill tumor cells, inhibit tumor growth and development, and treat cancer in subjects in need thereof.
