Log in

Relevant bibliographies by topics / “Ring-opened” derivatives / Journal articles

To see the other types of publications on this topic, follow the link: “Ring-opened” derivatives.

Journal articles on the topic '“Ring-opened” derivatives'

Author: Grafiati

Published: 10 September 2021

Last updated: 12 February 2022

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic '“Ring-opened” derivatives.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Andreani, Aldo, Alberto Leoni, Alessandra Locatelli, Rita Morigi, Mirella Rambaldi, Jean-Claude Gehret, Serena Traniello, Alessio Cariani, and Susanna Spisani. "Ring-Opened Analogs of Indomethacin Affecting Human Neutrophil Functions." Collection of Czechoslovak Chemical Communications 64, no. 2 (1999): 299–312. http://dx.doi.org/10.1135/cccc19990299.

Full text

Abstract:

A series of ring-opened analogs of indomethacin was synthesized and tested in vitro (at concentrations ranging from 10-9 to 10-5 mol/l) on human neutrophil functions. Two compounds lacking the carboxylic group were subjected to the same tests and one of these showed unexpected activity. Among the acidic derivatives, compound 12 bearing the same substituents as indomethacin 10 (methoxy and 4-chlorobenzoyl groups) was the most active: it significantly lowered neutrophil responses in all five bioassays and at the three concentrations considered.

APA, Harvard, Vancouver, ISO, and other styles

2

Hiromi, Sano, Mio Shigeru, Kumagawa Yuko, Kitagawa Junko, Shindou Masahiro, Honma Toyokuni, and Sugai Soji. "Synthesis and Herbicidal Activity of Opened Hydantoin-ring Derivatives of Hydantocidin." Bioscience, Biotechnology, and Biochemistry 60, no. 7 (January 1996): 1198–200. http://dx.doi.org/10.1271/bbb.60.1198.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Angell, E. Charles, David St C. Black, and Naresh Kumar. "13C NMR study ofN-acyl- andN-sulphonyl-isatins and their ring-opened derivatives." Magnetic Resonance in Chemistry 30, no. 1 (January 1992): 1–5. http://dx.doi.org/10.1002/mrc.1260300102.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Ramaswamy, Sowmianarayanan, and Allan C. Oehlschlager. "Efficient synthesis of exo- and endo-brevicomin from a single precursor." Canadian Journal of Chemistry 67, no. 5 (May 1, 1989): 794–96. http://dx.doi.org/10.1139/v89-120.

Full text

Abstract:

Diastereoselective reduction of 2-propionyl-6-methyl-3,4-dihydropyran and its ring opened derivatives, followed by acidic work-up, gives mixtures rich (>9:1) of either exo- or endo-brevicomin. Keywords: exo- and endo-brevicomin, diastereoselective ketone reduction.

APA, Harvard, Vancouver, ISO, and other styles

5

HE, Huaizhen, Yingzhuan ZHAN, Jie ZHANG, and Tao WANG. "Synthesis and Anti-tumor Activities of Lactone Ring-Opened Taspine Coumarin Ester Fluorescent Derivatives." Acta Agronomica Sinica 29, no. 1 (2012): 75. http://dx.doi.org/10.3724/sp.j.1095.2011.00054.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Song, Ming-Xia, Yu-Shan Huang, Qiu-Gui Zhou, Xian-Qing Deng, and Xiao-Dong Yao. "Synthesis of ring-opened derivatives of triazole-containing quinolinones and their antidepressant and anticonvulsant activities." Bioorganic Chemistry 106 (January 2021): 104505. http://dx.doi.org/10.1016/j.bioorg.2020.104505.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Barak, Ruth, Adam Vincze, Peter Bel, S. P. Dutta, and Girish B. Chedda. "Mass spectrometric investigation of the presence of 7-methyl ring-opened guanine derivatives in urine." Chemico-Biological Interactions 86, no. 1 (January 1993): 29–40. http://dx.doi.org/10.1016/0009-2797(93)90109-c.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Wagner, Gabriele, Uwe Verfürth, Rudolf Herrmann, and Carl Krüger. "Ring-Opening of (-)-Camphorsulfonimide Derivatives and (+)-Fenchonesulfonimide by Nitronium Tetrafluoroborate." Zeitschrift für Naturforschung B 49, no. 8 (August 1, 1994): 1150–58. http://dx.doi.org/10.1515/znb-1994-0822.

Full text

Abstract:

Treating a derivative of (-)-camphorsulfonimide (CA name: (3aS)-8,8-dimethyl-4,5,6,7- tetrahydro-3H-3a.6-methano-2,1-benzisothiazole 2,2-dioxide) or the isomeric (+)-fenchonesulfonimide with nitronium tetrafluoroborate in acetonitrile does not lead to the expected products of cationic reactions, e.g. of the Ritter reaction for halogenated compounds, but provokes a cleavage of the sulfonimide group with the formation of a ring-opened product containing a sulfonyl fluoride and a nitroimine group. The reaction does occur only in the presence of solid nitronium tetrafluoroborate. but not after prior dissolution of the reagent. An X-ray structure of the product from (1 S)-3-endo-bromocamphorsulfonimide confirms this unusual reaction.

APA, Harvard, Vancouver, ISO, and other styles

9

Tudek, B., M. Graziewicz, O. Kazanova, T. H. Zastawny, T. Obtułowicz, and J. Laval. "Mutagenic specificity of imidazole ring-opened 7-methylpurines in M13mp18 phage DNA." Acta Biochimica Polonica 46, no. 3 (September 30, 1999): 785–99. http://dx.doi.org/10.18388/abp.1999_4151.

Full text

Abstract:

The most abundant lesion formed in DNA upon modification with methylating agents 7-methylguanine, under alkaline conditions is converted into 2,6-diamino-4-hydroxy-5N-methyl-formamidopyrimidine (Fapy-7MeGua). We have previously shown that treatment of dimethylsulfate methylated DNA with NaOH creates mutagenic base derivatives leading to a 60-fold increase in the frequency of A-->G transitions and a 2-3-fold increase of G-->T and G-->C transversions. We have analyzed which lesions lead to these mutations. We compared mutagenic spectra in the lacZ gene of M13mp18 phage DNA modified with dimethylsulfate and NaOH after selective elimination of damaged bases from molecules used for transfection into SOS-induced E. coli. Partial elimination of Fapy-7MeGua from phage DNA performed by its digestion with formamidopyrimidine-DNA glycosylase resulted in a 2-3-fold decrease of G-->T and G-->C transversions. Selective depurination of methylated bases (9 h, 37 degrees C, pH 7.0) resulting in almost complete loss of 7MeAde as demonstrated by HPLC analysis of [3H]MNU alkylated phage DNA used as a probe, caused a dramatic, 9-fold decrease of A-->G transitions. Alkali-catalysed rearrangement of 7MeAde was followed by HPLC analysis of [3H]MNU alkylated poly(A) and poly(dA). After incubation of these oligonucleotides in NaOH, 7MeAde disappeared from both chromatograms, but only in polyA, 2 new peaks migrating with retention time different from that of 1MeAde, 3MeAde or 7MeAde were detected, suggesting formation of two rotameric forms of Fapy-7MeAde as observed for Fapy-7MeGua. Thus the miscoding lesion, giving rise to A-->G transitions derived from 7MeAde was Fapy-7MeAde. Fapy-7MeGua was at least an order of magnitude less mutagenic, but in SOS-induced cells it gave rise to G-->T and G-->C transversions.

APA, Harvard, Vancouver, ISO, and other styles

10

Beckett, Kirsten S., Justin G. Bendall, Richard C. Cambie, Peter S. Rutledge, Michael F. Walker, and Paul D. Woodgate. "Oxidation Products of Totara-8,11,13-trien-13-ol Derivatives." Australian Journal of Chemistry 50, no. 9 (1997): 933. http://dx.doi.org/10.1071/c96209.

Full text

Abstract:

Reaction of 7-oxototara-8,11,13-trien-13-yl acetate (3) with acetic anhydride-perchloric acid affords the γ-pyrone (8) in addition to the previously reported acetyl derivative (4). Baeyer–Villiger oxidations of the ketones (3) or (5) have given starting material or complex mixtures, but the ε-lactone (9) and the rearranged product (11) were isolated from two experiments with (3). Oxidation of 13-methoxytotara-8,11,13-triene (2) with Jones reagent gives the 7-oxo derivative (5) and a low yield of a ring B opened substituted p-benzoquinone (13). Pathways to (11) and (13) are proposed.

APA, Harvard, Vancouver, ISO, and other styles

11

Toda, Fumio, Koichi Tanaka, and Naohide Takamoto. "Evidence that naphthocyclobutene, phenanthrodicyclobutene, and anthrodicyclobutene derivatives are not contaminated by their cyclobutene ring-opened isomers." Tetrahedron Letters 42, no. 45 (November 2001): 7979–82. http://dx.doi.org/10.1016/s0040-4039(01)01561-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Abashzadeh, S., M. H. Hajimiri, F. Atyabi, M. Amini, and R. Dinarvand. "Novel physical hydrogels composed of opened-ring poly(vinyl pyrrolidone) and chitosan derivatives: Preparation and characterization." Journal of Applied Polymer Science 121, no. 5 (March 29, 2011): 2761–71. http://dx.doi.org/10.1002/app.33800.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Möhrle, H., and R. Nießen. "Reaktionen von Isochinolinium-Salzen mit Hydroxylamin-Derivaten, 1. Mitteilung. N-(Nitrophenyl)-substituierte Verbindungen/Reactions of Isoquinolinium Salts with Hydroxylamine Derivatives, 1st Communication. N-(Nitrophenyl) Substituted Compounds." Zeitschrift für Naturforschung B 54, no. 2 (February 1, 1999): 225–33. http://dx.doi.org/10.1515/znb-1999-0211.

Full text

Abstract:

N-(Nitrophenyl) substituted isoquinolinium salts reacted with nucleophiles of the hydroxylamine type to different products depending on the electron withdrawing strength of the substituent. Mononitro compound 8 produced only the cyclic hydroxylamine 9a, the trinitroderivative 5 solely the ring cleaved oximes. The dinitro substance 1 held an intermediate position and gave rise to a labile cyclic hydroxylamine and a more stable ring opened Z-enamine; hydroxylamine ethers generated cyclic products which showed in dimethylsulfoxide ring chain isomerism with the tautomers.

APA, Harvard, Vancouver, ISO, and other styles

14

Griesbeck, Axel G., and Samir Bondock. "Photocycloaddition of 5-Methoxyoxazoles to Aldehydes and ?-Keto Esters: A Comprehensive View on Stereoselectivity, Triplet Biradical Conformations, and Synthetic Applications of Paternò–Büchi Adducts." Australian Journal of Chemistry 61, no. 8 (2008): 573. http://dx.doi.org/10.1071/ch08168.

Full text

Abstract:

The photocycloaddition of carbonyl compounds (aldehydes and keto esters, respectively) with 5-methoxyoxazoles bearing substituents at C2 and C4 is described with respect to regio- and diastereoselectivity. In all cases the reactions proceed with excellent regioselectivity and with high to moderate (exo) diastereoselectivity independent of the nature of the excited carbonyl compound. The products can be easily ring-opened to give α-amino, β-hydroxy carboxylic acid derivatives.

APA, Harvard, Vancouver, ISO, and other styles

15

Ivanova, Jekaterīna, Fabrizio Carta, Daniela Vullo, Janis Leitans, Andris Kazaks, Kaspars Tars, Raivis Žalubovskis, and Claudiu T. Supuran. "N -Substituted and ring opened saccharin derivatives selectively inhibit transmembrane, tumor-associated carbonic anhydrases IX and XII." Bioorganic & Medicinal Chemistry 25, no. 13 (July 2017): 3583–89. http://dx.doi.org/10.1016/j.bmc.2017.04.007.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Frister, Hermann, and Eckhard Schlimme. "Ringöffnungsreaktionen an bioreaktiven Lactamsystemen / Ring Opening Reactions of Bioreactive Lactam Systems." Zeitschrift für Naturforschung C 42, no. 5 (May 1, 1987): 603–12. http://dx.doi.org/10.1515/znc-1987-0518.

Full text

Abstract:

Abstract 1-β-ᴅ-Ribofuranosylpyrrolidin-2,5-dione (9) was synthesized by ribosylation of N-silylated succinimide (7) with 1,2,3,5-tetra-O-acetyl-β-ᴅ-ribofuranose in acetonitril in the presence of tin tetrachloride. The compounds 9, 1-β-ᴅ-ribofuranosyl-l-H-pyrrol-2,5-dione (5) and N-methyl- maleinimide (2) were converted with ammonia to the ring-opened components 16. 14 and 15. The bioreactivity of the N-maleinimide derivatives 2 and 5 with respect to addition and ring-opening reactions with amino acid side chains containing either thiol or amino groups was shown in model reactions with glutathion (compds. 17,18) and lysine (compds. 19, 20). The ring opening reaction of 3-methyl-3-phenyl-1-β-ᴅ-ribofuranosylpyrrolidin-2,5-dione (11) with lysine yields 21, thus demonstrating the possibility of glycosuccinylation of amino groups in proteins.

APA, Harvard, Vancouver, ISO, and other styles

17

Chang, Fang-Pin, Shyh-Shyun Huang, Tzong-Huei Lee, Chi-I. Chang, Tzong-Fu Kuo, Guan-Jhong Huang, and Yueh-Hsiung Kuo. "Four New Iridoid Metabolites Have Been Isolated from the Stems of Neonauclea reticulata (Havil.) Merr. with Anti-Inflammatory Activities on LPS-Induced RAW264.7 Cells." Molecules 24, no. 23 (November 23, 2019): 4271. http://dx.doi.org/10.3390/molecules24234271.

Full text

Abstract:

One new iridoid, namely neonanin C (1) one monocyclic iridoid ring-opened derivative namely neonanin D (2), two new bis-iridoid derivatives namely reticunin A (3) and reticunin B (4) with sixteen known compounds (5–20) were isolated from the stems of Neonauclea reticulata (Havil.) Merr. These new structures were determined by the detailed analysis of spectroscopic data and comparison with the data of known analogues. Compounds 1–20 were evaluated for inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages cell line. The results showed that all compounds exhibited no obvious cytotoxicity compared to the control group and five compounds including isoboonein (7), syringaresinol (10), (+)-medioresinol (12), protocatechuic acid (14) and trans-caffeic acid (15) exhibited inhibitory activities with IC50 values at 86.27 ± 3.45; 9.18 ± 1.90; 76.18 ± 2.42; 72.91 ± 4.97 and 95.16 ± 1.20 µg/mL, respectively.

APA, Harvard, Vancouver, ISO, and other styles

18

Mlostoń, Grzegorz, Jakub Wręczycki, Katarzyna Urbaniak, Dariusz M. Bieliński, and Heinz Heimgartner. "The Fluoride Anion-Catalyzed Sulfurization of Thioketones with Elemental Sulfur Leading to Sulfur-Rich Heterocycles: First Sulfurization of Thiochalcones." Molecules 26, no. 4 (February 5, 2021): 822. http://dx.doi.org/10.3390/molecules26040822.

Full text

Abstract:

Fluoride anion was demonstrated as a superior activator of elemental sulfur (S8) to perform sulfurization of thioketones leading to diverse sulfur-rich heterocycles. Due to solubility problems, reactions must be carried out either in THF using tetrabutylammonium fluoride (TBAF) or in DMF using cesium fluoride (CsF), respectively. The reactive sulfurizing reagents are in situ generated, nucleophilic fluoropolysulfide anions FS(8−x)−, which react with the C=S bond according to the carbophilic addition mode. Dithiiranes formed thereby, existing in an equilibrium with the ring-opened form (diradicals/zwitterions) are key-intermediates, which undergo either a step-wise dimerization to afford 1,2,4,5-tetrathianes or an intramolecular insertion, leading in the case of thioxo derivatives of 2,2,4,4-tetramethylcyclobutane-1,3-dione to ring enlarged products. In reactions catalyzed by TBAF, water bounded to fluoride anion via H-bridges and forming thereby its stable hydrates is involved in secondary reactions leading, e.g., in the case of 2,2,4,4-tetramethyl-3-thioxocyclobutanone to the formation of some unexpected products such as the ring enlarged dithiolactone and ring-opened dithiocarboxylate. In contrast to thioketones, the fluoride anion catalyzed sulfurization of their α,β-unsaturated analogues, i.e., thiochalcones is slow and inefficient. However, an alternative protocol with triphenylphosphine (PPh3) applied as a catalyst, offers an attractive approach to the synthesis of 3H-1,2-dithioles via 1,5-dipolar electrocyclization of the in situ-generated α,β-unsaturated thiocabonyl S-sulfides. All reactions occur under mild conditions and can be considered as attractive methods for the preparation of sulfur rich heterocycles with diverse ring-size.

APA, Harvard, Vancouver, ISO, and other styles

19

Auner, Norbert, and Hans-Uwe Steinberger. "Silaheterocyclen, XXXI [1]. Spaltung von 2-Silanorbornenen: Ein einfacher Weg zu Cyclopentenylderivaten von Organochlorsilanen und zu 2-Silanorbornanen / Silaheterocycles, XXXI [1]. Allyl Cleavage of 2-Silanorbornenes: A Facile Synthesis of Cyclopentenyl- Compounds of Organochlorosilanes and of 2-Silanorbornanes." Zeitschrift für Naturforschung B 49, no. 12 (December 1, 1994): 1743–54. http://dx.doi.org/10.1515/znb-1994-1220.

Full text

Abstract:

The exo/endo[4+2]-cycloadducts of Cl2Si=CHCH2tBu and cyclopentadiene 1 are transformed into the Si-dimethoxy- and chloro-methyl-substituted derivatives 2 and 4. In the case of the 2-silabicyclo[2.2.1] compounds 2 (R1 = R2 = OCH3), 3 (R1 = R2 = CH3) and 4 (R1 = Cl; R2 = CH3) the allyl cleavage with HCl/ether gives the ring opened products 8, 9, and 10 in good yields. The reaction can also be carried out with HBr/ether. In 1 the cleavage of the allyl-silicon bond is disfavoured due to the two chlorine atoms at silicon. Instead HCl adds to the C=C double bond and stereospecifically gives the exo-6-chloro-2,2-dichloro-3-exo/endo-neopentyl-2-silabicyclo[2.2.1]heptanes 5. When the stronger acid CF3SO3H is used no addition to the double bond is observed but only the allyl cleavage takes place to give the triflate 7. The ring opened cyclopentene compounds can be reduced by LiAlH4 to give the corresponding Si-H-compounds 19 and 20. Intramolecular hydrosilylation of 19 leads to the exo/endo-2,2-dimethyl-3-neopentyl-2-silabicyclo[2.2.1]heptanes 21 and so the former bicyclic structure is regenerated.

APA, Harvard, Vancouver, ISO, and other styles

20

Bennamane, Norah, Oualid Talhi, Artur Silva, Brahim Cherfaoui, Houria Lakhdari, Rachid Ameraoui, Filipe Almeida Paz, Khaldoun Bachari, Gilbert Kirsch, and Kolli Nejar-Bellara. "Dibenzo[b,e][1,4]diazepin-1-ones and their Ring-Opened Derivatives: Revisited Synthesis, 2D NMR and Crystal Structure." Synlett 28, no. 17 (July 13, 2017): 2247–52. http://dx.doi.org/10.1055/s-0036-1590306.

Full text

Abstract:

The synthesis of 2,3,4,5,10,11-hexahydro-1H-dibenzo[b,e][1,4]diazepin-1-ones was revisited and a catalyst-free method was established, by exploring the reactivity of 3-[(2-aminoaryl)amino]dimedones towards carbonylated electrophiles. 2D NMR and single-crystal X-ray diffraction studies were used to characterize the structures unequivocally and to review the mechanism leading to the formation of supposed positional isomers. The action of 3-[(2-aminoaryl)amino]dimedones on chromene-3-carboxylic acid, fumaryl, and oxalyl chloride has led to dibenzo[b,e][1,4]diazepin-1-one ring opening to produce novel Z-configured enaminone and linear diamides.

APA, Harvard, Vancouver, ISO, and other styles

21

Li, Xuejiao, Xinxin Wang, Longfei Miao, Yuying Guo, Renbin Yuan, and Hongqi Tian. "Design, synthesis, and neuroprotective effects of novel hybrid compounds containing edaravone analogue and 3-n-butylphthalide ring-opened derivatives." Biochemical and Biophysical Research Communications 556 (June 2021): 99–105. http://dx.doi.org/10.1016/j.bbrc.2021.03.171.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Grlziewicz, Maria-Anna, Tomasz H. Zastawny, and Barbara Tudek. "P XVII B.1 Imidazole ring-opened purines — They are weaker inhibitors of DNA replication than oxidative derivatives of pyrimidines." Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 379, no. 1 (September 1997): S172. http://dx.doi.org/10.1016/s0027-5107(97)83214-9.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Al-Samak, Basma, Valia Amir-Ebrahimi, Andrew G. Carvill, James G. Hamilton, and John J. Rooney. "Determination of the Tacticity of Ring-opened Metathesis Polymers of Norbornene and Norbornadiene by13C NMR Spectroscopy of their Hydrogenated Derivatives." Polymer International 41, no. 1 (September 1996): 85–92. http://dx.doi.org/10.1002/(sici)1097-0126(199609)41:1<85::aid-pi582>3.0.co;2-y.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Bremner, JB, and KN Winzenberg. "Photosolvolysis of Bridgehead Quaternary Ammonium Salts. III. Synthesis of Some 3-Benzazecine, 1H-2,6-Benzoxazecine and 2H-3,6-Benzoxazecine Derivatives and a 2H-1,4-Oxazocine Derivative." Australian Journal of Chemistry 38, no. 11 (1985): 1591. http://dx.doi.org/10.1071/ch9851591.

Full text

Abstract:

Photosolvolysis of a mixture of cis - and trans-9,10-dimethoxy-5-methyl- 1,3,4,6,7,11b-hexahydro-2H-benzo[a] quinolizinium iodide (2) in methanol gave, after workup, a very low yield of 8,10,11-trimethoxy-3-methyl- 1,2,3,4,5,6,7,8-octahydro-3-benzazecine (3a). Similarly 1,10,11 trimethoxy-6-methyl-3,4,5,6,7,8-hexahydro-1H-2,6-benzoxazecine (8a) and 1,10,11-trimethoxy-6-methyl-1,4,5,6,7,8-hexahydro-2H-3,6-benzoxazecine (16a) were obtained in fair and low yields respectively from the N- methyl tetrahydro-2H,6H-[1,3] oxazino [2,3-a] isoquinolinium (7a) and hexahydro [1,4] oxazino [3,4-a] isoquinolinium (15) iodide precursors; a 1- methyl derivative (8b) of (8a) was also prepared. The ring-opened products 3-[N-2-{(4,5-dimethoxy-2-dimethoxymethyl)-phenyl}ethyl-N-methyl]aminopropan-1-ol (9a) and 3-[N-2-{(4,5-dimethoxy-2-1′,1′- dimethoxyethyl )-phenyl}ethyl-N-methyl]aminopropan-1-ol (9b) were also obtained from the [1,3] oxazino [2,3-a]- isoquinolinium salt derivatives. Photolysis of (2) and 9,10-dimethoxy-5-methyl-1,3,4,6,7,11b-hexa-hydro[1,4] oxazino [3,4-a] isoquinolinium iodide (15) in acidified aqueous solution afforded, after workup, the benzazecin-8-ol (3b) and hexahydro-2H-3,6-benzoxazecin-1-ol (16b) products respectively, but again in very low yield. Some mechanistic rationalizations of these results are given.Photosolvolysis of 7a-(3,4-dimethoxy)phenyl-4-methyl-2,3,5,6,7,7a- hexahydropyrrolo [2,1-b] oxa-zolium iodide (22) in methanol afforded a high yield of 8-methoxy-4-methyl-8-(3,4-dimethoxy)-phenyl-3,4,5,6,7,8- hexahydro-2H-1,4-oxazocine (24) in a new ring-destruction approach to this ring system. From 13C n.m.r . data, the twist-boat-chair conformation was tentatively assigned to (24) in (D)chloroform solution.

APA, Harvard, Vancouver, ISO, and other styles

25

Vejdělek, Zdeněk, Jan Metyš, Jiří Holubek, Miloš Buděšínský, Emil Svátek, Oluše Matoušová, and Miroslav Protiva. "Potentional anxiolytics and hypnotics: 1-(Alkanesulfonamidoalkyl)-6-aryl-8-halogeno-s-triazolo[4,3-a]-1,4-benzodiazepines and related compounds." Collection of Czechoslovak Chemical Communications 53, no. 1 (1988): 132–44. http://dx.doi.org/10.1135/cccc19880132.

Full text

Abstract:

7-Chloro-5-phenyl-1,3-dihydro-1,4-benzodiazepin-2-thione and its 5-(2-chlorophenyl) and 7-bromo-5-(2-chlorophenyl)analogues were reacted with N-(methanesulfonyl)- and N-(ethanesulfonyl)glycine and –alanine hydrazides (X-XIII) in boiling butanol to give the title compounds Iabc - IVabc. The alanine-derived substances IIIabc and IVabc were characterized by 1H NMR spectra as mixtures of two diastereoisomers. Similar reactions of 5-methylimidazole-4-carboxylic acid hydrazide (XIV) gave the s-triazolo[4,3-a]-1,4-benzodiazepines Vabc together with their ring-opened precursors XVI and XVII. The compounds prepared showed the activity profile of the anxiolytic and hypnotic 4H-s-triazolo[4,3-a]-1,4-benzodiazepine derivatives.

APA, Harvard, Vancouver, ISO, and other styles

26

Möhrle, H., and R. Nießen. "Reaktionen von Isochinolinium-Salzen mit Hydroxylamin-Derivaten, 3. Mitteilung. Mechanismus der Aminoxid-Bildung / Reactions of Isoquinolinium Salts with Hydroxylamine Derivatives, 3rd Communication. Mechanism of Amine Oxide Generation." Zeitschrift für Naturforschung B 54, no. 7 (July 1, 1999): 913–22. http://dx.doi.org/10.1515/znb-1999-0715.

Full text

Abstract:

2-Methylpapaverinium iodide (1) reacted with hydroxylamine to papaverine-N-oxide (2), but without a detectable intermediate and only in moderate yield, caused by the steric hindrance of the 1-substituent. The ring opened product of 2-dinitrophenylisoquinolinium salt with hydroxylamine, the enamine-oxime 3b gave rise to a 3-substituted cyclic nitrone (6), when heated with triethylamine. This alkali-stable compound was transformed with acid quantitatively to isoquinoline-N-oxide (4). The enaminonitrile 9c, treated with triethylamine showed cyclization to the iminoisoquinoline 10, which by loss of nitrous acid produced the tetracyclic azaindole 11. The 2-methoxyisoquinolinium salt 16 was cleaved with O-methylhydroxylamine to the resistant di(O-methyloximes) (20a/b), unable to form the amine oxide 4. From these and former results, a mechanism for the ring opening of cycliminium salts and the recyclization to amine oxides was proposed.

APA, Harvard, Vancouver, ISO, and other styles

27

Trant, John F., and Tomas Hudlicky. "Ring-opening of hindered cyclic epoxides with potassium carboxylates in the presence of conjugate acids." Canadian Journal of Chemistry 91, no. 12 (December 2013): 1179–85. http://dx.doi.org/10.1139/cjc-2013-0386.

Full text

Abstract:

During attempts to ring-open a highly hindered epoxide, traditional methods were found to be ineffective. An alternative strategy for opening epoxides was implemented that employed a potassium carboxylate in the presence of its conjugate acid in a solvent mixture containing polar and potassium-sequestering components. A systematic analysis of the components of the reaction mixture indicated that the addition of the conjugate acid was the most important feature for providing good conversion. This reaction appears to be general for most classes of carboxylic acids including cinnamic, aromatic, and highly hindered carboxylic acids (30%–79% yield) and only fails with weak carboxylate nucleophiles. Three highly substituted and hindered cyclohexene oxide derivatives were examined for reactivity and the reaction conditions appear to tolerate a variety of functional groups to provide the ring-opened species. This pH-moderate system proved useful for hindered cyclic epoxides when all other techniques failed and should prove general to a wide spectrum of epoxide and carboxylic acid partners in those cases where the use of a strong Lewis or protic acid catalyst, or a strong basic nucleophile, is inappropriate.

APA, Harvard, Vancouver, ISO, and other styles

28

Amir-Ebrahimi, V., D. A. K. Corry, J. G. Hamilton, and J. J. Rooney. "Determination of the tacticities of ring-opened metathesis polymers of symmetrical 5,6-disubstituted derivatives of norbornene and norbornadiene from the 13C NMR spectra of their hydrogenated derivatives." Journal of Molecular Catalysis A: Chemical 133, no. 1-2 (July 1998): 115–22. http://dx.doi.org/10.1016/s1381-1169(98)00101-0.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Khan, Faiz Ahmed, Regina Czerwonka, and Hans-Ulrich Reissig. "Pd-Catalyzed Reactions of Donor−Acceptor-Substituted Cyclopropanes and Their Ring-Opened Derivatives: Attempted Heck Cyclization and Novel One-Pot Enolate Arylations." European Journal of Organic Chemistry 2000, no. 21 (November 2000): 3607–17. http://dx.doi.org/10.1002/1099-0690(200011)2000:21<3607::aid-ejoc3607>3.0.co;2-n.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Oku, Naoya, Miyako Matsumoto, Kohsuke Yonejima, Keijiroh Tansei, and Yasuhiro Igarashi. "Sacrolide A, a new antimicrobial and cytotoxic oxylipin macrolide from the edible cyanobacterium Aphanothece sacrum." Beilstein Journal of Organic Chemistry 10 (August 7, 2014): 1808–16. http://dx.doi.org/10.3762/bjoc.10.190.

Full text

Abstract:

Macroscopic gelatinous colonies of freshwater cyanobacterium Aphanothece sacrum, a luxury ingredient for Japanese cuisine, were found to contain a new oxylipin-derived macrolide, sacrolide A (1), as an antimicrobial component. The configuration of two chiral centers in 1 was determined by a combination of chiral anisotropy analysis and conformational analysis of different ring-opened derivatives. Compound 1 inhibited the growth of some species of Gram-positive bacteria, yeast Saccharomyces cerevisiae and fungus Penicillium chrysogenum, and was also cytotoxic to 3Y1 rat fibroblasts. Concern about potential food intoxication caused by accidental massive ingestion of A. sacrum was dispelled by the absence of 1 in commercial products. A manual procedure for degrading 1 in raw colonies was also developed, enabling a convenient on-site detoxification at restaurants or for personal consumption.

APA, Harvard, Vancouver, ISO, and other styles

31

Sallenave, X., S. Delbaere, S. Ahmed, G. Vermeersch, and J. L. Pozzo. "5-Ureido-3,3-diphenyl-3H-naphtho[2,1-b]pyrans: Photoswitchable self-assembling architectures." International Journal of Photoenergy 6, no. 4 (2004): 169–73. http://dx.doi.org/10.1155/s1110662x04000212.

Full text

Abstract:

5-Ureido-3,3-diphenyl-3H-naphtho[2,1-b]pyrans have been synthesized and their photochromic properties have been quantified using UV-Visible spectroscopy. The urea pattern is responsive for the selfassembling properties under both colourless and coloured forms whereas the corresponding amino derivatives do not show any aggregative properties. The geometries of the different states have been assigned using1Hand19FNMR spectroscopies, and thereafter their respective kind of aggregates could be proposed through the different inter- and intramolecular interactions. Upon UV irradiation, the pyranic ring is opened and the resulting photogenerated carbonyl group is competing with the urea in the self-assembling process and consequently strongly affects the supramolecular assemblies. The inter- and intramolecular contributions have been quantified through 1D and 2D NMR experiments along with the variation in the concentration.

APA, Harvard, Vancouver, ISO, and other styles

32

Nawrot, Barbara, Beata Rębowska, Olga Michalak, Marek Bulkowski, Damian Błaziak, Piotr Guga, and Wojciech J. Stec. "1,3,2-Oxathiaphospholane approach to the synthesis of P-chiral stereodefined analogs of oligonucleotides and biologically relevant nucleoside polyphosphates." Pure and Applied Chemistry 80, no. 8 (January 1, 2008): 1859–71. http://dx.doi.org/10.1351/pac200880081859.

Full text

Abstract:

Among the various classes of modified nucleotides and oligonucleotides, phosphorothioate analogs, in which the sugar-phosphate backbone is modified by the substitution of a sulfur atom for one of the nonbridging oxygen atoms, have been most extensively studied in both in vitro and in vivo experiments. However, this substitution induces P-chirality of the dinucleoside phosphorothioate moiety. Consequently, even short phosphorothioate oligonucleotides synthesized using standard chemical methods exist as mixtures of many diastereoisomers. In our laboratory, the oxathiaphospholane (OTP) method has been developed for a stereocontrolled synthesis of oligo(deoxyribonucleoside phosphorothioate)s. Recently, this approach has been extended to ribonucleoside derivatives, and stereodefined phosphorothioate diribonucleotides were incorporated into oligomers suitable for mechanistic studies on deoxyribozymes. Next, it was found that the OTP ring can be opened with nucleophiles as weak as the phosphate or pyrophosphate anion, giving rise to nucleoside α-thiopolyphosphates. Surprisingly, the reaction between nucleoside OTP and O,O-dialkyl H-phosphonate or O,O-dialkyl H-phosphonothioate led to nucleoside 5'-O-(α-thio-β-O,O-dialkyl-hypophosphate) or 5'-O-(α,β-dithio-β-O,O-dialkyl-hypophosphate), respectively, i.e., derivatives containing a direct P-P bond.

APA, Harvard, Vancouver, ISO, and other styles

33

Khan, Faiz Ahmed, Regina Czerwonka, and Hans-Ulrich Reissig. "ChemInform Abstract: Pd-Catalyzed Reactions of Donor-Acceptor-Substituted Cyclopropanes and Their Ring-Opened Derivatives: Attempted Heck Cyclization and Novel One-Pot Enolate Arylations." ChemInform 32, no. 7 (May 30, 2010): no. http://dx.doi.org/10.1002/chin.200107090.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Vigroux, Alain, Michel Bergon, and Chantal Zedde. "Cyclization-Activated Prodrugs: N-(Substituted 2-hydroxyphenyl and 2-hydroxypropyl)carbamates Based on Ring-Opened Derivatives of Active Benzoxazolones and Oxazolidinones as Mutual Prodrugs of Acetaminophen." Journal of Medicinal Chemistry 38, no. 20 (September 1995): 3983–94. http://dx.doi.org/10.1021/jm00020a012.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Guo, Zijian, Trevor W. Hambley, Piedad del Socorro Murdoch, Peter J. Sadler, and Urban Frey. "Chelate-ring-opened adducts of [Pt(en)(Me-Mal-O,O′)] (en = ethane-1,2-diamine, Me-Mal = 2-methylmalonate) with methionine derivatives: relevance to the biological activity of platinum anticancer agents." Journal of the Chemical Society, Dalton Transactions, no. 4 (1997): 469–78. http://dx.doi.org/10.1039/a604210d.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Lamberth, Clemens, Sarah Sulzer-Mosse, and Peter Kubizna. "Synthesis of Ring-Opened Analogues of Oxysterol-Binding Protein-Inhibiting Piperidinyl-thiazole Fungicides." Synlett 28, no. 17 (June 29, 2017): 2277–80. http://dx.doi.org/10.1055/s-0036-1588473.

Full text

Abstract:

Novel aminoethyl-, aminopropyl-, and aminobutyl-substituted thiazole-4-carboxamides have been prepared which are ring-opened analogues of piperidinyl-thiazole fungicides. Depending of the chain length, completely different synthetic approaches had to be chosen which vary from a Sonogashira coupling with a 2-bromothiazole derivative to a thiazole ring construction from different β- and δ-amino acids.

APA, Harvard, Vancouver, ISO, and other styles

37

Chen, Chuan, Cui-Cui Wang, Zhong Wang, Wen-Yue Geng, Hui Xu, Xiao-Mei Song, and Du-Qiang Luo. "Cytotoxic activity of a synthetic deoxypodophyllotoxin derivative with an opened D-ring." Journal of Asian Natural Products Research 18, no. 5 (January 6, 2016): 486–94. http://dx.doi.org/10.1080/10286020.2015.1131679.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Tait, Katrina, Samuel Koh, Nicolas Blanchard, and William Tam. "Ruthenium-catalyzed ring-opening reaction of a 3-aza-2-oxabicyclo[2.2.1]hept-5-ene with amines — an unexpected mode of ring-opening." Canadian Journal of Chemistry 97, no. 4 (April 2019): 310–16. http://dx.doi.org/10.1139/cjc-2018-0444.

Full text

Abstract:

The ruthenium-catalyzed ring-opening reaction of a 3-aza-2-oxabicyclo[2.2.1]hept-5-ene with amines was investigated. In the presence of an amine and a ruthenium catalyst, the N–O bond is cleaved, forming a ring-opened allylic alcohol product. Through a possible ruthenium-catalyzed redox isomerization, the allylic alcohol is transformed into a saturated carbonyl product. This unexpected mode of ruthenium-catalyzed ring-opening reaction of a 3-aza-2-oxabicyclo[2.2.1]hept-5-ene leads to the formation of a cyclopentanone derivative in moderate yields.

APA, Harvard, Vancouver, ISO, and other styles

39

Oetterli, René M., Lucas Prieto, Bernhard Spingler, and Felix Zelder. "Synthesis of a B Ring Opened 7,8-seco-Vitamin B12 Derivative with Grob Fragmentation." Organic Letters 15, no. 18 (August 30, 2013): 4630–33. http://dx.doi.org/10.1021/ol401572j.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Legouin, Béatrice, and Jean-Louis Burgot. "Isolation and structural data of the opened ring derivative of a 1,2,4-triazolothieno-1,4-diazepine." Journal of Heterocyclic Chemistry 37, no. 1 (January 2000): 127–29. http://dx.doi.org/10.1002/jhet.5570370121.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Chow, Yuan L., and Xiao-Yun Liu. "The photocycloaddition of naphthoates with acetylacetone; dramatic acid promotions of product quantum yields." Canadian Journal of Chemistry 69, no. 8 (August 1, 1991): 1261–72. http://dx.doi.org/10.1139/v91-189.

Full text

Abstract:

In acetonitrile and methanol, methyl 1- and methyl 2-naphthoate (1- and 2-NpCO2CH3) underwent [2 + 2] photocycloaddition with acetylacetone (acacH) from a reactive species derived from the lowest spectroscopic singlet excited state to give cyclobutane derivatives such as 9 that ring-opened to afford addition products of acetyl and acetonyl moieties at the 7,8-position for 1-NpCO2CH3 (2 and 3) and the 1,2-position for 2-NpCO2CH3 (7). Further irradiation of 3 and 7 caused a deep-seated rearrangement of 3 to give 4 and an intramolecular addition of 7 to give the caged product 8. The photocycloaddition quantum yields were increased remarkably in the presence of a trace amount (< 0.001 M) of protic acids. For example, the limiting quantum yield of 2 and 3 with Фadducts = 0.033 (in the absence) increased to Фadducts > 0.5 under comparable conditions in the presence of [H2SO4] = 0.001 M, approaching the maximum asymptotically at about this concentration; the increases of the quantum yield could not be correlated with H2SO4 concentrations. The acid promotion of the product formation elevated the photocycloaddition to a significantly useful preparative reaction. The photocycloaddition of 2-NpCO2CH3 was quenched by tributylamine, dimethylaniline, and methyl iodide, and could not be initiated by typical triplet sensitization. Strong fluorescence of 2-NpCO2CH3 at 358 nm in CH3CN was quenched by acetylacetone, tributylamine, dimethylaniline, and methyl iodide, the last of which concurrently enhanced the phosphorescence intensity of 2-NpCO2CH3. In the presence of [H2SO4] > 0.005 M the fluorescence intensity at 358 nm was quenched and a new fluorescence at 470 nm corresponding to protonated 12-NpCO2CH3 appeared. However, in the [H2SO4] < 0.002 M region, the new fluorescence was not observed, indicating that the protonation scarcely occurred. The Stern–Volmer constant, obtained by the quantum yield monitor, of the 2-NpCO2CH3 photocycloaddition with acacH was more than an order of magnitude smaller than that obtained by the quenching of 2-NpCO2CH3 fluorescence by acacH. The discrepancies outlined above clearly demonstrate that the reactive intermediate of the photocycloaddition is not the exciplex of the spectroscopic singlet excited species of 12-NpCO2CH3 and acacH, but one that is derived from the exciplex. It is speculated that this unknown reactive intermediate interacts with a proton to promote the photocycloaddition. Key words: photocycloaddition of naphthoates, photorearrangement of styryl ketones, acid catalysis of quantum yields, fluorescence of protonated naphthoates, acid enhancement of singlet quenching.

APA, Harvard, Vancouver, ISO, and other styles

42

El Ashry, E. S. H., L. F. Awad, H. Abdel Hamid, and Y. El Kilany. "Synthetic Potential Inherent in D-Isoascorbic Acid as a Precursor for Pyridazine and Furo[3,2-c]pyridazine Ring Systems with Two Asymmetric Centers." Zeitschrift für Naturforschung B 54, no. 8 (August 1, 1999): 1061–67. http://dx.doi.org/10.1515/znb-1999-0815.

Full text

Abstract:

Reaction of D-erythro-2,3-hexodiulosono-1,4-lactone-2,3-bis(phenylhydrazone) (2) with an iodine, triphenylphosphine and imidazole mixture afforded the furo[3,2-c]pyridazine derivative 11. Condensation of 6-bromo-6-deoxy-D-erythro-2,3-hexodiulosono-1,4-lactone with phenylhydrazine gave the bishydrazones 6, and 8 or the furo[3,2-c]pyridazine (11) depending on the reaction conditions. The lactone ring in 11 could be opened by treatment with alkali to give the pyridazine derivative 9. Lactonization of the later with simultaneous acetylation by acetic anhydride afforded the lactone derivative 14. Alkali treatment of 6 gave the pyrazolindione derivative 13 that gave upon reation with HBr/AcO H the dibromide 15. The assigned structures were based on spectral analysis. The activity of compounds 11 and 14 against hepatitis B virus has been studied.

APA, Harvard, Vancouver, ISO, and other styles

43

Sheu, Chimin, Ping Kang, Saeed Khan, and Christopher S. Foote. "Low-Temperature Photosensitized Oxidation of a Guanosine Derivative and Formation of an Imidazole Ring-Opened Product." Journal of the American Chemical Society 124, no. 15 (April 2002): 3905–13. http://dx.doi.org/10.1021/ja011696e.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Legouin, Beatrice, and Jean-Louis Burgot. "ChemInform Abstract: Isolation and Structural Data of the Opened Ring Derivative of a 1,2,4-Triazolothieno-1,4-diazepine." ChemInform 31, no. 27 (June 7, 2010): no. http://dx.doi.org/10.1002/chin.200027045.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

KOIKE, MASAHIRO, RYO NORIKURA, TAKEO YOSHIMORI, SHINYA FUTAGUCHI, and KOICHI SUGENO. "Biopharmaceutical characterization of 450191-S, a ring-opened derivative of 1,4-benzodiazepine. I Active metabolite levels in rat plasma." Journal of Pharmacobio-Dynamics 9, no. 7 (1986): 563–69. http://dx.doi.org/10.1248/bpb1978.9.563.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Wang, Xiaoli, Linna Wang, Tingting Li, Zhangjian Huang, Yisheng Lai, Hui Ji, Xiaolong Wan, Jinyi Xu, Jide Tian, and Yihua Zhang. "Novel Hybrids of Optically Active Ring-Opened 3-n-Butylphthalide Derivative and Isosorbide as Potential Anti-Ischemic Stroke Agents." Journal of Medicinal Chemistry 56, no. 7 (April 2, 2013): 3078–89. http://dx.doi.org/10.1021/jm4001693.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Speina, Elz˙bieta, Jarosław M. Cieśla, Jacek Wójcik, Monika Bajek, Jarosław T. Kuśmierek, and Barbara Tudek. "The Pyrimidine Ring-opened Derivative of 1,N6-Ethenoadenine Is Excised from DNA by theEscherichia coliFpg and Nth Proteins." Journal of Biological Chemistry 276, no. 24 (March 20, 2001): 21821–27. http://dx.doi.org/10.1074/jbc.m100998200.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Wu, Jianbing, Wei Yin, Yinqiu Zhang, Hui Ye, Yunman Li, Jide Tian, Zhangjian Huang, and Yihua Zhang. "Design and synthesis of the ring-opened derivative of 3-n-butylphthalide-ferulic acid-glucose trihybrids as potential anti-ischemic agents." Chinese Chemical Letters 31, no. 7 (July 2020): 1881–86. http://dx.doi.org/10.1016/j.cclet.2020.02.031.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Speina, E., J. M. Cieśla, J. Wòjcik, J. T. Kuśmierek, and B. Tudek. "The pyrimidine ring-opened derivative of l,N6-ethenoade-nine is repaired in DNA by the Escherichia coli Fpg and Nth proteins." Biochemical Society Transactions 28, no. 5 (October 1, 2000): A168. http://dx.doi.org/10.1042/bst028a168b.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Yin, Wei, Li Lan, Zhangjian Huang, Jing Ji, Jiangen Fang, Xiaoli Wang, Hui Ji, Sixun Peng, Jinyi Xu, and Yihua Zhang. "Discovery of a ring-opened derivative of 3-n-butylphthalide bearing NO/H2S-donating moieties as a potential anti-ischemic stroke agent." European Journal of Medicinal Chemistry 115 (June 2016): 369–80. http://dx.doi.org/10.1016/j.ejmech.2016.03.044.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!