Publications by authors named "Leslaw Sieron"

An unexpected course of the reaction of hexafluorocumyl alcohol dilithium derivative 2 with N-(t-butylsulfenyl)phthalimide (3) has been presented. The process proceeded under mild conditions and resulted in previously undescribed chiral spiro-system- 3',3'-bis(trifluoromethyl)-3H,3'H-1,1'-spirobis(isobenzofuran)-3-one (5) as the only product. A detailed spectral analysis of the product has been provided, and mechanistic aspects have been investigated.

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The aim of the research described in this publication is two-fold. The first is a detailed description of the synthesis of a series of compounds containing a stereogenic heteroatom, namely the optically active -stereogenic derivatives of -butylarylphoshinic acids bearing sulfur or selenium. The second is a detailed discussion dedicated to the determination of their structures by an X-ray analysis.

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Flow Mediated Skin Fluorescence (FMSF) is a new non-invasive method for assessing vascular circulation and/or metabolic regulation. It enables assessment of both vasoconstriction and vasodilation. The method measures stimulation of the circulation in response to post-occlusive reactive hyperemia (PORH).

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Herein, we describe the synthesis of a variety of chiral hybrid pyrrolidine-chromanone polycyclic derivatives. A convenient (3+2)-annulation of azomethine ylides with chromone-3-carboxylic acid realized under Brønsted base catalysis produced highly functionalized products in high yields with good stereoselectivities through asymmetric, intermolecular, and decarboxylative (3+2)-cyclization.

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In this manuscript, the first enantioselective dearomative Michael addition between α,β-unsaturated aldehydes and 2-nitrobenzofurans realized under N-heterocyclic carbene activation has been described. The reaction proceeds addition of homoenolate to Michael acceptors leading to the formation of biologically important heterocycles with high yields and stereoselectivities. Their functionalization potential has been confirmed in selected, diastereoselective transformations.

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This study demonstrates the use of organocatalytic Brønsted base activation of 5-substituted-furan-2(3)-ones to generate 2π-components for the diastereoselective [8 + 2]-cycloaddition involving 8,8-dicyanoheptafulvene as an 8π-component. The use of dienolates in a higher-order cycloaddition reaction leads to the formation of biologically relevant polycyclic products bearing a γ-butyrolactone structural motif, thus broadening the synthetic potential of Brønsted base activated higher-order cycloadditions.

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The manuscript describes an utilization of 5-substituted-furan-2(3H)-ones as pronucleophiles in an asymmetric vinylogous Michael addition to an α,β-unsaturated-γ-lactam, thus leading to hybrid molecules possessing γ-lactam and butenolide structural motifs. The transformation utilizes two potentially vinylogous pronucleophiles and has been realized by simultaneous activation of both substrates by a bifunctional organocatalyst derived from a cinchona alkaloid. Reaction occurs in a highly enantio- and diastereoselective manner and the synthetic potential of the target products has been confirmed in stereoselective transformations.

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Oscillations in the microcirculation, known as flowmotion, are a well-recognized characteristic of cutaneous blood flow. Since flowmotion reflects the microcirculatory status of the vascular system, which is very often impaired in many diseases and disorders, a quantitative assessment of skin flowmotion could potentially be used to screen for early symptoms of such conditions. In this study, skin flowmotion was monitored using the Flow Mediated Skin Fluorescence (FMSF) technique.

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In this manuscript, a novel, decarboxylative Michael reaction between α-substituted azlactones and chromone-3-carboxylic acids is described. The reaction proceeds in a sequence Michael addition followed by decarboxylative deprotonation, and it results in the formation of chromanones bearing an azlactone structural unit. The possibility of transforming an azlactone moiety into a protected α,α-disubstituted α-amino acid derivative is also demonstrated.

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In this Communication, a new approach for trienamine chemistry is described. It is based on the application of carboxylic-acid-activated dienophiles that undergo spontaneous decarboxylative protonation after the initial [4 + 2]-cycloaddition step. The utilization of such a novel cascade reaction for the synthesis of biologically relevant 3,4-dihydrocoumarins has been demonstrated.

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The crystal structures of captopril {systematic name: (2S)-1-[(2S)-2-methyl-3-sulfanylpropanoyl]pyrrolidine-2-carboxylic acid}, C(9)H(15)NO(3)S, (1), and its dimer disulfide metabolite, 1,1'-{disulfanediylbis[(2S)-2-methyl-1-oxopropane-3,1-diyl]}bis-L-proline, C(18)H(28)N(2)O(6)S(2), (2), were determined by single-crystal X-ray diffraction analysis. Compound (1) crystallizes in the orthorhombic space group P2(1)2(1)2(1), while compound (2) crystallizes in the monoclinic space group P2(1), both with one molecule per asymmetric unit. The molecular geometries of (1) and (2) are quite similar, but certain differences appear in the conformations of the five-membered proline rings and the side chains containing the sulfhydryl group.

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Three pairs of enantiomers of the unknown sulforaphane analogs bearing organofluorine substituents bonded to the sulfinyl sulfur atom and having different number of methylene groups in the central carbon chain were synthesized and fully characterized, including determination of their absolute configurations. All the new compounds were tested in vitro for their cytotoxicity against melanoma cells to show increased activity in comparison with the natural sulforaphane. The influence of the particular structural changes in the molecule on the cytotoxicity is discussed.

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The crystal structures of three new solvates of olanzapine [systematic name: 2-methyl-4-(4-methylpiperazin-1-yl)-10H-thieno[2,3-b][1,5]benzodiazepine], namely olanzapine acetic acid monosolvate, C17H20N4S·C2H4O2, (I), olanzapine propan-2-ol hemisolvate monohydrate, C17H20N4S·0.5C3H8O·H2O, (II), and olanzapine propan-2-one hemisolvate monohydrate, C17H20N4S·0.5C3H6O·H2O, (III), are presented and compared with other known olanzapine forms.

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Low-temperature X-ray diffraction experiments were employed to investigate the crystal structures of an orthorhombic polymorph of the intramolecular cyclization product of perindopril, a popular angiotensive-converting enzyme (ACE) inhibitor, namely ethyl (2S)-2-[(3S,5aS,9aS,10aS)-3-methyl-1,4-dioxo-5a,6,7,8,9,9a,10,10a-octahydro-3H-pyrazino[1,2-a]indol-2-yl]pentanoate, C19H30N2O4, (Io), and its tetragonal equivalent, (It), which was previously reported at ambient temperature [Bojarska et al. (2013). J.

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The title compound [systematic name: (1S)-2-((S)-{1-[(2S,3aS,7aS)-2-carboxyoctahydro-1H-indol-1-yl]-1-oxopropan-2-yl}azaniumyl)pentanoate monohydrate], C(17)H(28)N(2)O(5)·H(2)O, (I)·H(2)O, the active metabolite of the antihypertensive and cardiovascular drug perindopril, was obtained during polymorphism screening of perindoprilat. It crystallizes in the chiral orthorhombic space group P2(1)2(1)2(1), the same as the previously reported ethanol disolvate [Pascard, Guilhem, Vincent, Remond, Portevin & Laubie (1991). J.

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The dimethyl sulfoxide hemisolvate of perindoprilat [systematic name: (1S)-2-((S)-{1-[(2S,3aS,7aS)-2-carboxyoctahydro-1H-indol-1-yl]-1-oxopropan-2-yl}azaniumyl)pentanoate dimethyl sulfoxide hemisolvate], C(17)H(28)N(2)O(5)·0.5C(2)H(6)OS, an active metabolite of perindopril, has been synthesized, structurally characterized by single-crystal X-ray diffraction and compared with its ethanol disolvate analogue [Pascard et al. (1991).

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The two title mononuclear compounds are four-coordinate bis[N-(5-oxo-4,4-diphenyl-4,5-dihydro-1H-imidazolidin-2-ylidene)glycinato]copper(II) dimethylformamide disolvate, [Cu(C(17)H(14)N(3)O(3))(2)].2C(3)H(7)NO, (I), and five-coordinate aquabis[N-(5-oxo-4,4-diphenyl-4,5-dihydro-1H-imidazolidin-2-ylidene)glycinato]copper(II) dimethylformamide disolvate, [Cu(C(17)H(14)N(3)O(3))(2)(H(2)O)].2C(3)H(7)NO, (II).

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The structure of the title compound, C(11)H(19)NO(4), contains two crystallographically independent mol-ecules in the asymmetric unit. Both adopt the same conformation and they form pseudosymmetric R(2) (2)(8) dimers via two N-H⋯O hydrogen bonds. The dimers are linked by weak C-H⋯O inter-actions and are stacked in columns along the a axis.

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In the title dimeric compound, (C(3)H(7)N(2)S)2[Cu(2)(CHO(2))6], each Cu(II) atom has a square-pyramidal coordination, with the nonbridging formate ion at the apical position. The complex anion is located on a crystallographic inversion centre, with a Cu..

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The structure of the title compound, C(12)H(21)NO(4), contains two crystallographically independent mol-ecules in the asymmetric unit. Mol-ecules are linked into pseudosymmetric R(2) (2)(8) dimers through two N-H⋯O hydrogen bonds. The dimers are connected by weak C-H⋯O inter-actions, resulting in a three-dimensional network.

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The asymmetric unit of the title compound, (C(6)H(6)N(3))[CoCl(3)(C(6)H(5)N(3))]·H(2)O, contains two crystallographically independent cations, two anions and two water mol-ecules. The structure has been reported previously [Zhang, Li, Wang, Xie, Wang & Shen (2004 ▶). Acta Cryst E60, m498-m500] as a neutral cobalt(III) complex accompanied by unprotonated benzotriazole mol-ecules and here has been redetermined as an anionic cobalt(II) complex accompanied by protonated benzotriazole cations.

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Poly[bis-(μ(2)-formato-κO:O')(quinoxaline-κN)copper(II)].

Acta Crystallogr Sect E Struct Rep Online

December 2007

In the polymeric title copper(II) compound, [Cu(CHO(2))(2)(C(8)H(6)N(2))](n), both formato ligands are O-bidentate anions and act as bridging ligands, creating a planar polymeric arrangement. The slightly distorted square-pyramidal coordination around Cu(II) comprises four O atoms from two different formate anions as the base and a quinoxaline mol-ecule in the apical position.

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The title compound (systematic name: [2-butyl-4-chloro-1-[2'-(2-trityl-2H-tetrazol-5-yl)biphenyl-4-ylmethyl]-1H-imidazol-5-yl]methanol), C(41)H(37)ClN(6)O, crystallizes in the centrosymmetric space group P-1 with two independent molecules in the asymmetric unit. These molecules differ significantly only in the relative orientations of the rings in the biphenylyltetrazole moieties. One of the molecules shows disorder for three C atoms in the n-butyl group.

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The structures of diphenyl [3-methyl-1-(3-phenylthioureido)butyl]phosphonate and diphenyl [2-methyl-1-(3-phenylthioureido)butyl]phosphonate, both C(24)H(27)N(2)O(3)PS, are reported. In both compounds, the thiourea moiety adopts a syn-syn conformation (i.e.

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