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81.
Novel acridine spirocompounds, spiro[dihydroacridine-9′(10′H),5-imidazolidine]-2-thiones have been prepared by the spontaneous cyclization of 1-substituted 3-(acridin-9-ylmethyl)thioureas, which were obtained from 1-(acridin-9-yl)methanamine, N-(acridin-9-ylmethyl)propan-1-amine, and N-(acridin-9-ylmethyl)benzylamine and alkyl/aryl isothiocyanates, as continuation of our previous studies on new acridine spirocycles. Imidazolidine-2-thiones thus obtained were subsequently transformed with mesitylnitrile oxide to imidazolidine-2-one analogues, some of which partly reopened to the corresponding (acridin-9-ylmethyl)ureas. An unusual spirocyclization via a CH carbanion instead of the N-1 nitrogen has been found for 3-(acridin-9-ylmethyl)-1-(acridin-9-yl)thioureas possessing two acridine rings. Structural modifications in positions 1, 3, and 4 of the spiro ring together with 1H, 13C, and 15N NMR spectroscopy and X-ray crystallography have been employed to rationalize a general propensity of various 9-substituted acridines to undergo easy spirocyclization. 相似文献
82.
Tomasciková J Imrich J Danihel I Böhm S Kristian P Pisarcíková J Sabol M Klika KD 《Molecules (Basel, Switzerland)》2008,13(3):501-518
A series of 1-acyl-4-phenyl/(acridin-9-yl)thiosemicarbazides 3, including four new compounds, were prepared in order to study substituent effects on cyclization reactions with oxalyl chloride (producing imidazolidine-4,5-diones 4), dimethyl acetylenedicarboxylate (to give thiazolidin-4-ones 7 and 8) and autocondensation under alkaline conditions (to yield 1,2,4-triazoles 9). A positional isomer, 10 of compound 3f was also prepared. Altogether, twenty new compounds characterized and identified by IR, UV,1H, 13C and 2D NMR and quantum chemical calculations are described. The tautomerism of the products and regioselectivity of the reactions were evaluated. Compounds 3f-h,3h.2HCl, 7b,d and 10 were screened for cytotoxic activity against the L1210 leukemia cell line and all compounds, except for 3f, exhibited promising inhibitions of cell growth. 相似文献
83.
Ivan Poto
k Jn Imrich Ivan Danihel Jozef Koíek Karel Douglas Klika 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(2):o87-o92
Two methyl derivatives, five‐membered methyl 2‐{2‐[2‐(9,10‐dihydroacridin‐9‐ylidene)‐1‐methylhydrazinyl]‐4‐oxo‐4,5‐dihydro‐1,3‐thiazol‐5‐ylidene}acetate, C20H16N4O3S, (I), and six‐membered 2‐[2‐(9,10‐dihydroacridin‐9‐ylidene)‐1‐methylhydrazinyl]‐4H‐1,3‐thiazin‐4‐one, C18H14N4OS, (II), were prepared by the reaction of the N‐methyl derivative of 4‐(9,10‐dihydroacridin‐9‐ylidene)thiosemicarbazide, C14H12N4S, (III), with dimethyl acetylenedicarboxylate and methyl propiolate, respectively. The crystal structures of (I), (II) and (III) are molecular and can be considered in two parts: (i) the nearly planar acridine moiety and (ii) the singular heterocyclic ring portion [thiazolidine for (I) and thiazine for (II)] including the linking amine and imine N atoms and the methyl C atom, or the full side chain in the case of (III). The structures of (I) and (II) are stabilized by N—H...O hydrogen bonds and different π–π interactions between acridine moieties and thiazolidine and thiazine rings, respectively. 相似文献
84.
Marc Hellmuth Wilfried Imrich Werner Klöckl Peter F. Stadler 《Mathematics in Computer Science》2009,2(4):653-682
The practical application of graph prime factorization algorithms is limited in practice by unavoidable noise in the data.
A first step towards error-tolerant “approximate” prime factorization, is the development of local approaches that cover the
graph by factorizable patches and then use this information to derive global factors. We present here a local, quasi-linear
algorithm for the prime factorization of “locally unrefined” graphs with respect to the strong product. To this end we introduce
the backbone
\mathbbB (G)\mathbb{B} (G) for a given graph G and show that the neighborhoods of the backbone vertices provide enough information to determine the global prime factors. 相似文献
85.
Eva Balentov Jn Imrich Juraj Bernat Lucia Such Mria Vilkov Pavol Kristian Kalevi Pihlaja Karel D. Klika Nad'a Pranayov 《Journal of heterocyclic chemistry》2006,43(3):645-656
Acridin‐9‐yl hydrazine upon treatment with various isothiocyanates (RNCS, R = methyl, allyl, phenyl, p‐methoxy phenyl, and p‐nitro phenyl) yielded the corresponding thiosemicarbazides with acridine substituted on the carbazide‐type side. The alkyl‐substituted compounds were present in solution as equilibria consisting of the major H‐10, H‐12 tautomer (either E or Z or both about the C13‐N14 bond) and the minor H‐10, SH tautomer (either E or Z or both). The major species for the aromatic‐substituted compounds was the H‐10, H‐12 E tautomer, with the evident minor species being the H‐10, H‐12 Z tautomer. The thiosemicarbazides were each quantitatively converted into the analogous semicarbazides upon treatment with mesitylnitrile oxide wherein all structures were present in solution as the H‐10 tautomers with Z conformation about the C13‐N14 bond. Methylation of the compounds with methyl iodide yielded S‐methylated compounds wherein the Z configuration dominated in each case over the E configuration along the N12‐C13 double bond. Treatment of the thiosemicarbazides with methyl bromoacetate resulted in the formation of 1′,3′‐thiazolidin‐4′‐ones wherein the Z configuration predominated in each case over the E configuration along the N12? C13 double bond. With bromoacetonitrile as the bifunctional electrophile, the initial 1′,3′‐thiazolidin‐4′‐imines that formed spontaneously underwent Dimroth‐type rearrangement to the regiosiomeric 1′,3′‐thiazolidin‐4′‐imines. 相似文献
86.
Annamária Krajníková Róbert Gyepes Katarína Gy?ryová Jan ?ubrt Ján Imrich 《Journal of chemical crystallography》2011,41(7):1036-1043
Abstract
The binuclear zinc complex bis(2-bromobenzoato-O)-bis(μ 2 -2-bromobenzoato-O,O′)-bis(phenazone-O)-dizinc(II) (I) and the mononuclear dihydrate bis(2-bromobenzoato-O)-bis(thiourea-S)-zinc(II) (II) have been synthesized and characterized by means of elemental analysis and spectroscopic methods (IR, 1H and 13C NMR, EDS). The solid state structures of both compounds were determined by single-crystal X-ray diffractometry. Compound [Zn(2-BrC6H4COO)2(phen)]2 (phen—phenazone) (I) crystallized as a dimeric compound with a triclinic lattice (space group P − 1), where both zinc atoms, interconnected by two carboxylate groups, possess a distorted tetrahedral coordination environment. The crystallographic data of complex I: a = 9.9410(3) ?, b = 10.7309(3) ?, c = 12.9237(4) ?, α = 93.6004(17)°, β = 92.5898(11)°, γ = 116.2192(16)°, V = 1230.26(6) ?3, Z = 1. Complex [Zn(2-BrC6H4COO)2(tu)2]·2H2O (tu—thiourea) (II) crystallized with an orthorhombic lattice (space group Aba2) as a monomeric compound, where the coordination environment of the central zinc atom is a distorted tetrahedron. The crystallographic data of complex II are: a = 9.8595(3) ?, b = 19.7052(5) ?, c = 12.5908(3) ?, V = 2446.18(11) ?3, Z = 4. The modes of the carboxylate binding were assigned from the IR spectra using the magnitude of the separation between the carboxylate stretches (Δ), which correlated well with the crystal structures. The computed theoretical IR spectrum agreed well with the experimental data. 相似文献87.
88.
Ohne Zusammenfassung 相似文献
89.
Organocatalysis using chiral iodoarenes enables many different enantioselective chemical reactions with cheap, easily accessible and robust catalysts. Carbohydrates have often been used as starting materials for the synthesis of chiral ligands for transition metal catalysts. Here, we now present the synthesis of the first carbohydrate based iodoarene catalysts which can be synthesized in one step starting from known compounds. These catalysts were used for oxidative spriolactonization of 3-(1-hydroxynaphthalen-2-yl)propanoic acid to afford the corresponding spirolactone in yields up to 77% and enantiomeric ratios er up to 80:20. 相似文献
90.
Jozef Pitel Pavol Kov Imrich Hu
ek 《Physica C: Superconductivity and its Applications》2000,330(3-4):130-140
A mathematical model was developed to allow for the prediction of critical currents in Bi(2223)/Ag-sheathed tapes that consist of two groups of filaments, having crystalline texture (c-axis) predominantly in two directions orthogonal to each other and to the length of the conductor (filaments oriented parallel and perpendicular to the tape surface). Using the theory presented, it is possible to estimate the upper limit of critical currents in the tapes prepared with a two-axial rolling technique. Magnetic field and angular dependencies of critical currents were obtained at 77 K measuring tapes with various proportional representations of filaments oriented in both preferred directions, i.e., the parallel and perpendicular directions. The results of calculation indicate that the anisotropy in the Ic(B) characteristic should be reduced considerably using the two-axial rolling. Unfortunately, the effect of anisotropy reduction is accompanied by simultaneous decrease in the current-carrying capacity of the tapes. The data obtained for short tape samples were utilised to estimate the critical currents of the individual turns of a small cylindrical magnet, assembled of eight pancake coils. It is shown that only a slight increase in the critical current of the magnet can be expected if the winding should be made of the tape with reduced anisotropy in the Ic(B) characteristic. The factors that limit the increase of the magnet critical current are discussed in detail. 相似文献