- Structure-property-relationship studies with ethylene polymerization catalysts of Ti, Zr and V containing heterocyclic ligands
-
21 complexes of bis(benzimidazolyl, benzothiazolyl and benzoxazolyl)methane compounds with Zr(IV), Ti(IV), V(III) metal centers were synthesized, characterized, activated with methylalumoxane (MAO) and then tested for catalytic ethylene polymerization. The activities of the various catalysts were found to be functions of the hetero atoms in the ligand frameworks. The methylene moiety as bridging unit of the two heterocyclic ring systems gave higher catalyst activities than the corresponding 1,2-ethylidene derivatives indicating a strong influence of the bridging unit of the ligand on the catalyst activity. The activity of the catalyst system 10/MAO was investigated with different cocatalyst concentrations. The highest activity was obtained with 23/MAO (573 kg PE/mol cat h). The produced polyethylenes showed high molecular weights (up to 1.77·106 g/mol) and broad molecular weight distributions (up to PD = 64.5). This could result from different interactions of the MAO counterion with the heteroatoms of the catalyst ligand generating different active sites. These catalysts open an easy access to single-reactor multimodal polyethylene technology.
- Elagab, Hamdi Ali,Alt, Helmut G.
-
-
Read Online
- Heterocyclic substituted methanides as promising alternatives to the ubiquitous nacnac ligand
-
A series of group 13 complexes containing deprotonated bisheterocyclomethanes have been prepared and structurally as well as spectroscopically characterised. In the case of the parent neutral homo-disubstituted bisheterocyclomethanes bis-(benzoxazol-2-yl)-methane (abbreviated as (NCOC6H4)2CH2) (1) and bis-(benzothiazol-2-yl)-methane (abbreviated as (NCSC6H4)2CH2) (2), two interesting ligand systems were investigated with respect to their coordination abilities toward group 13 metals. Upon deprotonation of the acidic methylene bridge in each case a β-diketiminate-like structure is formed, where the negative charge becomes delocalised about the whole ligand framework. There is a mesomeric stabilisation between the carbanionic and the amidic resonance structure. The ligands mentioned above were treated with AlMe3, AlMe2Cl and GaMe3to achieve deprotonation of the backbone and coincidental metal complexation. The resulting complexes [Me2Al{(NCOC6H4)2CH}] (3), [Me2Al{(NCSC6H4)2CH}] (4), [ClMeAl{(NCOC6H4)2CH}] (5), [ClMeAl{(NCSC6H4)2CH}] (6), [Me2Ga{(NCOC6H4)2CH}] (7), and [Me2Ga{(NCSC6H4)2CH}] (8) were structurally characterized in the solid state by X-ray single crystal diffraction and in solution by different (heteronuclear) 1D/2D-NMR spectroscopic techniques. Each of those molecules shows a nearly planar arrangement with the group 13 metal cation coordinated by the two ring nitrogen atoms of the conjugated heterocycles. Furthermore, in this work (NCOC6H4)3C(C3H7) (9) could be isolated, which might turn out to be a promising analogue of the omnipresent trisoxazoline ligands in asymmetric catalysis.
- Dauer, David-R.,Stalke, Dietmar
-
-
Read Online
- Head-to-head bisbenzazole derivatives as antiproliferative agents: design, synthesis, in vitro activity, and SAR analysis
-
Abstract: In the present work, a series of bisbenzazole derivatives were designed and synthesized as antiproliferative agents. The antiproliferative activity of these compounds was investigated using MTT assay. Bisbenzazole derivatives showed significant antiproliferative activity against all the four tested cancer cell lines. Among the various bisbenzazole derivatives, bisbenzoxazole derivatives exhibited the most promising anticancer activity followed by bisbenzimidazole and bisbenzothiazole derivatives. All the derivatives were found to be less toxic as compared to methotrexate (positive control) in normal human cells, indicating selective and efficient antiproliferative activity of these bisbenzazole derivatives. The structure–activity relationships of heteroaromatic systems and linkers present in bisbenzazole derivatives were analyzed in detail. In silico ADMET prediction revealed that bisbenzazole is a drug-like small molecule with a favorable safety profile. Compound 31 is a potential antiproliferative hit compound that exhibits unique cytotoxic activity distinct from methotrexate. Graphic abstract: Twenty-one bisbenzoxazole derivatives have been designed synthesized and evaluated to be an antiproliferative activity against four human tumor cell lines.[Figure not available: see fulltext.]
- Ersan, Ronak Haj,Alagoz, Mehmet Abdullah,Ertan-Bolelli, Tugba,Duran, Nizami,Burmaoglu, Serdar,Algul, Oztekin
-
p. 2247 - 2259
(2020/06/27)
-
- Ti (IV) complexes of some heterocyclic ligands synthesis, characterization and ethylene polymerization activity
-
31 complexes of bis - (benzimidazole, benzothiazole and benzoxazole) compounds with Ti (IV) metal centers were synthesized, characterized, activated with methylalumoxane (MAO) and then tested for catalytic ethylene polymerization. The activities of the various catalysts were found to be functions of the hetero atoms in the ligand frameworks. The highest activity was obtained with 39/MAO (573 kg PE/mol cat. h). The produced polyethylenes showed high molecular weights (up to 1.5 × 106 g/mol) and broad molecular weight distributions (PD = 65). This could result from different interactions of the MAO counterion with the heteroatoms of the catalyst ligand generating different active sites.
- Elagab, Hamdi Ali
-
p. 681 - 700
(2016/05/09)
-
- Zr(IV) complexes of some heterocyclic ligands: Synthesis, characterization, and ethylene polymerization activity
-
Thirty-one complexes of bis-(benzimidazole, benzothiazole, and benzoxazole) compounds with Zr(IV) metal centers were synthesized, characterized, activated with methylaluminoxane (MAO), and then tested for catalytic ethylene polymerization. The activities of the various catalysts were found to be functions of the heteroatoms in the ligand frameworks and the structure around the active metal center. The highest activity was obtained with 38/MAO (424 kg E/mol cat. h). The produced polyethylenes showed high molecular weights (41/MAO, 1.9 × 106 g/mol) and broad molecular weight distributions (38/MAO, Mw = 9.64 × 105 g/mol, PD = 23). This could result from different interactions of the MAO counter ion with the heteroatoms of the catalyst ligand generating different active sites.
- Elagab, Hamdi Ali
-
p. 742 - 761
(2016/11/09)
-
- Some reactions of 2-cyanomethyl-1,3-benzothiazole with expected biological activity
-
New pyrido[2,1-b]benzothiazoles 2a,b, 3, 2-aminoquinoline 4, coumarin 5, cyclohexane 6a,b, and 2-(1,3-benzothiazol-2-yl) methylidene 7 derivatives have been prepared via the reaction of 2-cyanomethyl-1,3-benzothiazole 1 with ,-unsaturated nitriles, α-chloro ethyl acetoacetate, 2-amino benzaldehyde, 5-chlorosalicylaldehyde, α,β-unsaturated ketone, and 2-aminobenzothiol hydrochloride. 2-Thiazole derivatives 9a,b were prepared from compound 1, which was converted to thioamide derivative 8 by reaction with HCl and thioacetamide, and cyclization of this thioamide with α-halogenated ketone gave 9a,b. Reaction of compound 1 and ethylacetate to afford ketonitrile 10. Treatment of 10 with hydrazine hydrate afforded aminopyrazole derivative 11. Substituted 4-aminothiophene 13 has been synthesized by reaction of compound 1 with p-chlorophenyl isothiocyanate. The resulting product 12 was then alkylated with phenacylbromide. Phenyl-2-yl-carbonylhydroximoyl-chloride 15 was prepared by treatment of the corresponding sulfonium bromide with sodium nitrite and hydrochloric acid in dioxane. Compound 15 reacted with α-(1,3- benzothiazol-2-yl) cinnamonitrile 14 afforded the isoxazole derivatives 16. Reaction of coumarin derivative 5 with anthranilamide, pyrimidine diamine, thiosemicarbazide, acetylacetone, and hydrazine hydrate yielded quinazoline-2-one 17, purine 18, triazole 19, 2-acetyl naphthalene-2-one 20, and N-aminoquinoline-2-one 21 derivatives.
- Hassan
-
experimental part
p. 2856 - 2869
(2010/04/30)
-
- Phosphonic acids derivatives as inhibitors of protein tyrosine phosphate 1B (PTP-1B)
-
The invention encompasses the novel class of compounds represented by formula I which are inhibitors of the PTP-1B enzyme. The invention also encompasses pharmaceutical compositions and methods of treating or preventing PTP-1B mediated diseases.
- -
-
-
- Conversion of some azaheterocyclic-acetic esters and -acetonitriles into fused heterocycles
-
Various heterocyclic acid esters and nitriles of the pyridine, thiazole, and imidazole series react with 3-methylthio-4-phenyl-1,2-dithiolium perchlorate to form fused pyridinethiones or dithiolylidene esters.These esters or nitriles also react with trichloromethanesulfenyl chloride to form fused isothiazoles.
- McKinnon, David M.,Spevack, Perry,Tipples, Graham
-
p. 2339 - 2344
(2007/10/02)
-
- Reactivity of Aryl- and Heteroarylmalonates against ortho-Dinucleophiles. Triaryl(heteroaryl)methane Synthesis
-
Condensations of several aryl(heteroaryl)malonates 1 and ortho-dinucleophiles are studied as a possible synthetic approach to aryl(heteroaryl)bisheteroarylmethanes 2.
- Ramos, Teresa,Avendano, Carmen,Elguero, Jose
-
p. 247 - 249
(2007/10/02)
-
- "CROSS-COUPLING" OF 2-CHLOROBENZOTHIAZOLE WITH BENZOTHIAZOLYLALKYLMAGNESIUM BROMIDE" SYNTHESIS OF BIS(2-BENZOTHIAZOLYL)ALKANES
-
Bis(2-benzothiazolyl)alkanes have been prepared via cross-coupling of 2-chlorobenzothiazole with benzothiazolylalkylmagnesium bromide.
- Babudri, Francesco,Florio, Saverio,Ingrosso, Giovanni,Turco, Anna Maria
-
p. 2215 - 2218
(2007/10/02)
-
