1
|
Sychrovský V, Šaman D, Fiala R, Humpa O, Sýkora J, Kessler P, Blechta V, Dobrev P, Schraml J. Ascorbigen A-NMR identification. Magn Reson Chem 2019; 57:1084-1096. [PMID: 31257662 DOI: 10.1002/mrc.4890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 05/03/2019] [Accepted: 05/06/2019] [Indexed: 06/09/2023]
Abstract
The connectivities of all atoms in ascorbigen A, an important metabolite, were determined unambiguously for the first time. The connectivity between carbon atoms was established by 2D INADEQUATE, and one-bond 13 C-13 C coupling constants were determined for all pairs of directly connected carbon atoms except for two strongly coupled carbon pairs. The 13 C-13 C coupling in one of the pairs was proved by a modification of standard INADEQUATE; however, the signals from the other pair were too weak to be observed. The connectivity within the two strongly coupled C-C pairs was confirmed by a combination of COSY and gHSQC; the latter experiment also identified all C-H bonds. The proton nuclear magnetic resonance (1 H NMR) spectra in dry dimethyl sulfoxide allowed identification and assignment of the signals due to NH and OH protons. The derived structure, 3-((1H-indol-3-yl)methyl)-3,3a,6-trihydroxytetrahydrofuro[3,2-b]furan-2(5H)-one, agrees with the structure suggested for ascorbigen A in 1966. The density functional theory (DFT) calculations showed that among 16 possible stereoisomers, only two complied with the almost zero value of the measured 3 J(H6-H6a). Of the two stereoisomers, 3S,3aS,6S,6aR and 3R,3aR,6R,6aS, the latter was excluded on synthetic grounds. The nuclear Overhauser effect measurements unveiled close proximity between H2' proton of the indole and the H6a proton of the tetrahydrofuro[3,2-b]furan part. Detailed structural interpretation of the measured NMR parameters by means of DFT NMR was hampered by rotational flexibility of the indole and tetrahydrofuro[3,2-b]furan parts and inadequacy of Polarizable Continuum Model (PCM) solvent model.
Collapse
Affiliation(s)
- Vladimír Sychrovský
- Institute of Organic Chemistry and Biochemistry of the CAS, Prague 6, Czech Republic
| | - David Šaman
- Institute of Organic Chemistry and Biochemistry of the CAS, Prague 6, Czech Republic
| | | | | | - Jan Sýkora
- Institute of Chemical Process Fundamentals of the CAS, Prague 6, Czech Republic
| | | | - Vratislav Blechta
- Institute of Chemical Process Fundamentals of the CAS, Prague 6, Czech Republic
| | - Petre Dobrev
- Institute of Experimental Botany of the CAS, Prague 6, Czech Republic
| | - Jan Schraml
- Institute of Chemical Process Fundamentals of the CAS, Prague 6, Czech Republic
| |
Collapse
|
2
|
Padrtova T, Marvanova P, Odehnalova K, Kubinova R, Parravicini O, Garro A, Enriz RD, Humpa O, Oravec M, Mokry P. Synthesis, Analysis, Cholinesterase-Inhibiting Activity and Molecular Modelling Studies of 3-(Dialkylamino)-2-hydroxypropyl 4-[(Alkoxy-carbonyl)amino]benzoates and Their Quaternary Ammonium Salts. Molecules 2017; 22:molecules22122048. [PMID: 29168793 PMCID: PMC6149889 DOI: 10.3390/molecules22122048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 11/08/2017] [Accepted: 11/21/2017] [Indexed: 11/16/2022] Open
Abstract
Tertiary amines 3-(dialkylamino)-2-hydroxypropyl 4-[(alkoxycarbonyl)amino]benzoates and their quaternary ammonium salts were synthesized. The final step of synthesis of quaternary ammonium salts was carried out by microwave-assisted synthesis. Software-calculated data provided the background needed to compare fifteen new resulting compounds by their physicochemical properties. The acid dissociation constant (pKa) and lipophilicity index (log P) of tertiary amines were determined; while quaternary ammonium salts were characterized by software-calculated lipophilicity index and surface tension. Biological evaluation aimed at testing acetylcholinesterase and butyrylcholinesterase-inhibiting activity of synthesized compounds. A possible mechanism of action of these compounds was determined by molecular modelling study using combined techniques of docking; molecular dynamics simulations and quantum mechanics calculations.
Collapse
Affiliation(s)
- Tereza Padrtova
- Department of Chemical Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences, Palackeho 1, 61242 Brno, Czech Republic.
| | - Pavlina Marvanova
- Department of Chemical Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences, Palackeho 1, 61242 Brno, Czech Republic.
| | - Klara Odehnalova
- Department of Chemical Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences, Palackeho 1, 61242 Brno, Czech Republic.
| | - Renata Kubinova
- Department of Natural Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences, Palackeho 1, 61242 Brno, Czech Republic.
| | - Oscar Parravicini
- Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis-IMIBIO-SL-CONICET, Chacabuco 915, San Luis 5700, Argentina.
| | - Adriana Garro
- Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis-IMIBIO-SL-CONICET, Chacabuco 915, San Luis 5700, Argentina.
| | - Ricardo D Enriz
- Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis-IMIBIO-SL-CONICET, Chacabuco 915, San Luis 5700, Argentina.
| | - Otakar Humpa
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500 Brno, Czech Republic.
| | - Michal Oravec
- Global Change Research Institute CAS, Belidla 986/4a, 60300 Brno, Czech Republic.
| | - Petr Mokry
- Department of Chemical Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences, Palackeho 1, 61242 Brno, Czech Republic.
| |
Collapse
|
3
|
Postulkova H, Chamradova I, Pavlinak D, Humpa O, Jancar J, Vojtova L. Study of effects and conditions on the solubility of natural polysaccharide gum karaya. Food Hydrocoll 2017. [DOI: 10.1016/j.foodhyd.2017.01.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
4
|
Marvanova P, Padrtova T, Pekarek T, Brus J, Czernek J, Mokry P, Humpa O, Oravec M, Jampilek J. Synthesis and Characterization of New 3-(4-Arylpiperazin-1-yl)-2-hydroxypropyl 4-Propoxybenzoates and Their Hydrochloride Salts. Molecules 2016; 21:molecules21060707. [PMID: 27258242 PMCID: PMC6273361 DOI: 10.3390/molecules21060707] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 05/16/2016] [Accepted: 05/23/2016] [Indexed: 12/05/2022] Open
Abstract
Five new 3-(4-arylpiperazin-1-yl)-2-hydroxypropyl 4-propoxybenzoates were designed and synthesized as potential dual antihypertensive agents. The compounds were prepared as free bases and subsequently transformed to hydrochloride salts. The position of protonation of nitrogen atoms in the piperazine ring of hydrochloride salts was determined by means of 13C-CP/MAS and 15N-CP/MAS NMR and IR spectroscopy. Using these solid-state analytical techniques, it was found that both nitrogen atoms were protonated when excess hydrogen chloride was used for preparation of salts. On the other hand, when the equimolar amount of hydrogen chloride was used, piperazine nitrogen substituted by aryl was protonated.
Collapse
Affiliation(s)
- Pavlina Marvanova
- Department of Chemical Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences, Palackeho 1, 61242 Brno, Czech Republic.
| | - Tereza Padrtova
- Department of Chemical Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences, Palackeho 1, 61242 Brno, Czech Republic.
| | - Tomas Pekarek
- Zentiva k.s., U kabelovny 130, 10237 Prague 10, Czech Republic.
| | - Jiri Brus
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky sq. 2, 16206 Prague 6, Czech Republic.
| | - Jiri Czernek
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky sq. 2, 16206 Prague 6, Czech Republic.
| | - Petr Mokry
- Department of Chemical Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences, Palackeho 1, 61242 Brno, Czech Republic.
| | - Otakar Humpa
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500 Brno, Czech Republic.
| | - Michal Oravec
- Global Change Research Institute CAS, Belidla 986/4a, 60300 Brno, Czech Republic.
| | - Josef Jampilek
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Comenius University, Odbojarov 10, 83232 Bratislava, Slovakia.
| |
Collapse
|
5
|
Michlovská L, Vojtová L, Humpa O, Kučerík J, Žídek J, Jančář J. Hydrolytic stability of end-linked hydrogels from PLGA–PEG–PLGA macromonomers terminated by α,ω-itaconyl groups. RSC Adv 2016. [DOI: 10.1039/c5ra26222d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Biodegradable amphiphilic PLGA–PEG–PLGA triblock copolymers end-terminated with itaconic acid (ITA) having reactive double bond were end-linked by light and swelled in water. Hydrolytical stability of prepared hydrogels was evaluated.
Collapse
Affiliation(s)
- L. Michlovská
- CEITEC – Central European Institute of Technology
- Brno University of Technology
- Brno
- Czech Republic
| | - L. Vojtová
- CEITEC – Central European Institute of Technology
- Brno University of Technology
- Brno
- Czech Republic
- SCITEG
| | - O. Humpa
- CEITEC – Central European Institute of Technology
- Masaryk University
- 625 00 Brno
- Czech Republic
| | - J. Kučerík
- University of Koblenz-Landau
- Institute of Environmental Sciences
- Soil and Environmental Chemistry
- 76829 Landau
- Germany
| | - J. Žídek
- CEITEC – Central European Institute of Technology
- Brno University of Technology
- Brno
- Czech Republic
| | - J. Jančář
- CEITEC – Central European Institute of Technology
- Brno University of Technology
- Brno
- Czech Republic
- SCITEG
| |
Collapse
|
6
|
Slanina J, Páchniková G, Carnecká M, Porubová Koubíková L, Adámková L, Humpa O, Smejkal K, Slaninová I. Identification of key structural characteristics of Schisandra chinensis lignans involved in P-glycoprotein inhibition. J Nat Prod 2014; 77:2255-63. [PMID: 25302569 DOI: 10.1021/np500521v] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The aim of the present study was to determine the structural requirements for dibenzocyclooctadiene lignans essential for P-glycoprotein inhibition. Altogether 15 structurally related lignans isolated from Schisandra chinensis or prepared by modification of their backbone were investigated, including three pairs of enantiomers. P-Glycoprotein inhibition was quantified using a doxorubicin accumulation assay in human promyelotic leukemia HL60/MDR cells overexpressing P-glycoprotein. A preliminary quantitative structure-activity relationship analysis revealed three main structural features involved in P-glycoprotein inhibition: a 1,2,3-trimethoxy moiety, a 6-acyloxy group, and the absence of a 7-hydroxy group. The most effective inhibitors, (-)-gomisin N (1) and (+)-deoxyschizandrin [(+)-2], were selected for further evaluation of their effects. Both these lignans restored the cytotoxic effect of doxorubicin in HL60/MDR cells and when combined with a subtoxic concentration of this compound increased the proportion of G2/M cells significantly, which is a usual response to treatment with this anticancer drug.
Collapse
Affiliation(s)
- Jiří Slanina
- Department of Biochemistry, Faculty of Medicine, Masaryk University , Kamenice 5, Building A16, 625 00 Brno, Czech Republic
| | | | | | | | | | | | | | | |
Collapse
|
7
|
Brezinová L, Vlasínová H, Havel L, Humpa O, Slanina J. Validated method for bioactive lignans in Schisandra chinensis in vitro cultures using a solid phase extraction and a monolithic column application. Biomed Chromatogr 2010; 24:954-60. [PMID: 20082284 DOI: 10.1002/bmc.1391] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A simple and rapid method for determination of six lignans found in plant cell cultures of Schisandra chinensis was developed and validated. The lignans were extracted from plant samples with methanol and the extracts were effectively cleaned by solid-phase extraction using Strata C18-E (Phenomenex) cartridges. Chromatographic separation was carried out on a Chromolith Performance RP-18e monolithic column (100 x 4.6 mm, Merck) using an isocratic mobile phase of acetonitrile and water in a 50:50 (v/v) ratio. The eluent was monitored at 220 nm. The baseline separation of schizandrin, gomisin A, deoxyschizandrin, gamma-schizandrin, gomisin N and wuweizisu C was achieved in a relatively short time period (20 min), which was made possible by the relatively high flow rate of the mobile phase (2 mL/min). The lower limit of quantitation was 0.1 mg/L for schizandrin and gomisin A, 0.3 mg/L for deoxyschizandrin, gamma-schizandrin, and gomisin N and 1 mg/L for wuweizisu C. The analysis of spiked samples containing six lignans provided absolute recoveries between 93 and 101% in all cases. The validated method was successfully applied to the determination of lignans in embryogenic plant cell cultures of Schisandra chinensis.
Collapse
Affiliation(s)
- Lenka Brezinová
- Department of Biochemistry, Masaryk University, Brno, Czech Republic
| | | | | | | | | |
Collapse
|
8
|
|
9
|
Vícha J, Malon M, Veselá P, Humpa O, Strnad M, Marek R. 1H-, 13C-, and 15N-NMR chemical shifts for selected glucosides and ribosides of aromatic cytokinins. Magn Reson Chem 2010; 48:318-322. [PMID: 20198611 DOI: 10.1002/mrc.2575] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The (1)H and (13)C NMR resonances of 16 purine glucosides were assigned by a combination of one- and two-dimensional NMR experiments, including gs-COSY, gs-HSQC, and gs-HMBC, in order to characterize the effect of substituent and the position of glucose unit on the NMR chemical shifts. In addition, (15)N NMR chemical shifts for selected derivatives were investigated by using (1)H-(15)N chemical shift correlation techniques. To map the influence of sugar moiety on the directly bonded nitrogen atom, selected N(9)-glucosides and their ribose analogs were compared. Characteristic long-range (1)H-(15)N coupling constants, measured by using (1)H-(15)N gradient-selected single-quantum multiple bond correlation (GSQMBC), are also reported and discussed. All compounds investigated here belong to cytokinins, an important group of plant hormones.
Collapse
Affiliation(s)
- Jan Vícha
- National Center for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5/A4, CZ-625 00 Brno, Czech Republic
| | | | | | | | | | | |
Collapse
|
10
|
Abstract
Samples of 1,3- (1) and 1,5-dicaffeoylquinic acid (2) and their hexaacetate derivatives were examined using positive and negative electrospray ionization mass spectrometry and tandem mass spectrometry. Differences in the various spectra allow the discrimination of each of the isomers. Specific losses in the spectra of 2 also permit the identification of the site of substitution of one of the caffeic acid moieties as being at the 5-position. The spectra of 3,5- (3) and 4,5-dicaffeoylquinic (4) acids and their hexaacetate derivatives were compared with those of 1 and 2 and their derivatives, and differences in ion abundances or the presence/absence of specific ions can be used to identify uniquely each of the compounds.
Collapse
Affiliation(s)
- Karl Schram
- Department of Pharmacology/Toxicology, Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Arizona, Tucson, Arizona 85721, USA.
| | | | | | | | | |
Collapse
|
11
|
Wiedermannová I, Slouka J, Humpa O, Lemr K. An anomalous course of the reduction of 2-(3-oxo-3,4-dihydro-quinoxalin-2-yl)benzene diazonium salt. Synthesis of a new quinoxalino[1,2-c][1,2,3]benzotriazine system. J Heterocycl Chem 2003. [DOI: 10.1002/jhet.5570400226] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
12
|
|
13
|
Slanina J, Táborská E, Bochořáková H, Slaninová I, Humpa O, Robinson W, Schram KH. New and facile method of preparation of the anti-HIV-1 agent, 1,3-dicaffeoylquinic acid. Tetrahedron Lett 2001. [DOI: 10.1016/s0040-4039(01)00448-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
14
|
Kubáň J, Kolarovič A, Fišera L, Jäger V, Humpa O, Prónayová N. Synthesis of Trihydroxylated Pyrrolizidine using 1,3-Dipolar Cycloaddition of d-Erythrose Derived Nitrone. Synlett 2001. [DOI: 10.1055/s-2001-18783] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
15
|
Kubáň J, Kolarovič A, Fišera L, Jäger V, Humpa O, Prónayová N, Ertl P. Stereoselectivity of 1,3-Dipolar Cycloadditions of d-Erythrose and d-Threose Derived Nitrones with Methyl Acrylate. Synlett 2001. [DOI: 10.1055/s-2001-18782] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
16
|
Revilla AL, Vrchlabský M, Humpa O, Havel J. β-Hydroxynaphthoic acid synthesis monitoring by capillary zone electrophoresis and high-performance liquid chromatography. J Chromatogr A 1999. [DOI: 10.1016/s0021-9673(98)00802-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
17
|
Kilián P, Marek J, Marek R, Tousek J, Humpa O, Slawin AMZ, Touzín J, Novosad J, Woollins JD. New P–S–N containing ring systems. Reaction of 2,4-(naphthalene-1,8-diyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide with methylbis(trimethylsilyl)amine. ACTA ACUST UNITED AC 1999. [DOI: 10.1039/a901698h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
18
|
Šibor J, Žůrek D, Marek R, Kutý M, Humpa O, Marek J, Pazdera P. 2-(3-Acylselenoureido)benzonitriles and 2-(3-Acylselenoureido)thiophene-3-carbonitriles. Preparation, Structure Elucidation, Cyclization and Retrocyclization Reactions. ACTA ACUST UNITED AC 1999. [DOI: 10.1135/cccc19991673] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Synthesis of 2-(3-acylselenoureido)benzonitriles and 2-(3-acylselenoureido)thiophene- 3-carbonitriles 5a-5f by addition of 2-aminonitriles 4a-4c to benzoyl- or 2,2-dimethyl- propanoylisoselenocyanate and their cycloaddition reactions are described. Structures of compounds 5a-5f were supported by CIMS, FTIR, 1H, 13C, 77Se and 15N NMR spectra. The parameters of 15N and 77Se nuclei were obtained from inverse 1H-X 2D HMBC and GSQMBC correlation experiments at natural abundance. Structure of compound 5b was confirmed by X-ray analysis. The geometry of 5b was optimized by ab initio RHF/DZVP quantum chemistry calculation. A very good correlation between the calculation and experimental data was found. The geometry of 5e was optimized by ab initio DFT/VWN/DZVP quantum chemistry calculation. It was found that title compounds 5a-5f do not undergo isomerization to acylisoselenoureas, in contrast to analogous ester derivatives. Fused 6-imino-6H-1,3- selenazinium salts (chlorides 6a-6f, hydrogensulfates 7a-7f and tetrafluoroborates 8a-8f) were prepared by an acid cyclization of 5a-5f. It was found that neutralization of 6a-6f, 7a-7f and 8a-8f led to their retrocyclization to 5a-5f. Selenoureas 5a-5f with equimolar amounts of methanolic potassium hydroxide afforded potassium salts 9a-9f. Only the salts 9b, 9c, 9e and 9f of the thiophene series were isolated. Their heating in methanol solution led to deacylation of isoselenoureas 10b and 10c. The in situ prepared compounds 9a and 9d cyclized and deacylated to 4-aminoquinazoline-2-selenole 11a under the same conditions. The compounds 5a-5f and 10a-10c cyclized to fused 4-aminopyrimidine-2-selenols 11a, 11b and 4-aminopyrimidine-2-selenone 12c by boiling in methanolic potassium hydroxide solution.
Collapse
|
19
|
Kilián P, Marek J, Marek R, Tou·ín J, Humpa O, Novosad J, Woollins JD. New P–S–N containing ring systems. Reaction of 2,4-(naphthalene-1,8-diyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide and its 4-methoxynaphthalene derivative with hexamethyldisilazane. ACTA ACUST UNITED AC 1998. [DOI: 10.1039/a708348c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
20
|
Dostál J, Slavík J, Potáček M, Marek R, Humpa O, Sklenář V, Toušek J, Hoffmann ED, Rozenberg R. Structural Studies of Chelirubine and Chelilutine Free Bases. ACTA ACUST UNITED AC 1998. [DOI: 10.1135/cccc19981045] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The structures of chelirubine and chelilutine free bases have been examined by 2D NMR spectroscopy and mass spectrometry. Chelirubine chloride (1a) upon treatment with Na2CO3 yielded free base which possessed the constitution of bis(5,6-dihydrochelirubin-6-yl) ether (2a). The free base of chelilutine (1b) was determined to be bis(5,6-dihydrochelilutin-6-yl) ether (2b). The aqueous NH3 treatment of chelilutine (1b) produced bis(5,6-dihydrochelilutin-6-yl)amine (3b). 6-Hydroxy-5,6-dihydrochelirubine (4a) and 6-hydroxy-5,6-dihydrochelilutine (4b) were detected only in CDCl3 solution by NMR spectroscopy. In CDCl3, the compound 2b underwent hydrolysis to 4b that was immediately followed by the reverse condensation to a diastereomer of 2b. Pseudokinetics of this reaction was followed by NMR spectroscopy and quantum chemical calculations were carried out to support the suggested type of molecular symmetry alteration. The known alkaloid dihydrochelirubine (5) was isolated for the first time from Sanguinaria canadensis.
Collapse
|
21
|
Charvát T, Potáček M, Humpa O, Marek J. Isomerization of N-aryl substituted diethyl 3-aminoglutaconates. Part I. J Mol Struct 1996. [DOI: 10.1016/0022-2860(95)09135-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|