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  • 1. Aeluri, Madhu
    et al.
    Gaddam, Jagan
    Trinath, Devarakonda V. K. S.
    Chandrasekar, Gayathri
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik.
    Kitambi, Satish Srinivas
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik. Karolinska institutet.
    Arya, Prabhat
    An Intramolecular Heck Approach To Obtain 17-Membered Macrocyclic Diversity and the Identification of an Antiangiogenesis Agent from a Zebrafish Assay2013Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 19, s. 3955-3958Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report a practical and modular approach to obtain two different types of 17-membered ring macrocyclic compounds through an intramolecular Heck reaction. These macrocyclic compounds are functionalized, that is, they contain two contiguous stereogenic hydroxy functional groups and an amino acid moiety in the macrocyclic ring skeleton. The macrocycles were then screened against a zebrafish assay to determine the antiangiogenesis activity of these small molecules. Macrocyclic compound 2.2a was identified as a potent inhibitor at 2.5 M, whereas its acyclic precursor and the other related macrocyclic compounds did not show any effect.

  • 2. Aeluri, Madhu
    et al.
    Pramanik, Chinmoy
    Chetia, Lakshindra
    Mallurwar, Naveen Kumar
    Balasubramanian, Sridhar
    Chandrasekar, Gayathri
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik.
    Kitambi, Satish Srinivas
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik. Karolinska Institute.
    Arya, Prabhat
    14-Membered Macrocyclic Ring-Derived Toolbox: The Identification of Small Molecule Inhibitors of Angiogenesis and Early Embryo Development in Zebrafish Assay2013Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 15, nr 3, s. 436-439Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    A highly practical and modular synthesis to obtain a diverse 14-membered ring-based macrocyclic toolbox is achieved. These compounds were further tested in zebrafish assays related to early embryonic development, angiogenesis, and neurogenesis, respectively. 1.4c was Identified as an antiangiogenesis agent.

  • 3.
    Antonsson, Rositha
    Södertörns högskola, Institutionen för livsvetenskaper.
    Nucleophilic aromatic substitutions using ethyl 3-mercaptopropionate as nucleophile: Scope and limitations2008Independent thesis Basic level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The scope and limitations of nucleophilic substitutions of aryl halides have been studied using ethyl 3-mercaptopropionate as nucleophile and microwave heating. A diversity of aromatic compounds have been investigated according to different types of leaving groups, regio isomers and substituents. Experimental design has been used as a tool to optimize the reaction. An electron-withdrawing group in ortho or para position of the leaving group proved to be necessary for a positive outcome of the reaction. Fluorine was, without competition, the best leaving group. Some examples of how the synthesized aryl sulfanyl propionates can be used as starting material for producing aryl thio ethers, sulfoxides and unique benzothiophenes are described.

    Fulltekst (pdf)
    FULLTEXT01
  • 4. Bauer, S H J
    et al.
    Månsson, Martin
    Södertörns högskola, Avdelning Naturvetenskap.
    Hood, D W
    Richards, J C
    Moxon, E R
    Schweda, Elke K H
    Södertörns högskola, Avdelning Naturvetenskap.
    A rapid and sensitive procedure for determination of 5-N-acetyl neuraminic acid in lipopolysaccharides of Haemophilus influenzae: a survey of 24 non-typeable H-influenzae strains2001Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 335, nr 4, s. 251-260Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In view of the importance of 5-N-acetyl neuraminic acid in bacterial pathogenesis, a sensitive, reproducible and reliable method for the determination of 5-N-acetyl neuraminic acid levels in lipopolysaccharide (LPS) is described and applied to 24 different non-typeable Haemophilus influenzae (NTHi) strains. The method involves analysis by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) of terminal 5-N-acetyl neuraminic acid residues released by neuraminidase treatment of O-deacylated LPS. The procedure is relatively fast and the instrumental effort is moderate. The results of the procedure were compared with data obtained by H-1 NMR and electrospray ionisation-mass spectrometry (ESI-MS). The analysis of LPS from 24 NTHi strains showed that 5-N-acetyl neuraminic acid was found to be a common constituent of LPS in NTHi. Only one strain (NTHi 432) did not show any sialylation. Molar ratios (LPS /5-N-acetyl neuraminic acid) ranged between 5/1 and 500/1. Several strains in which no 5-N-acetyl neuraminic acid could be determined by other methods including 1H NMR and ESI-MS were shown to contain 5-N-acetyl neuraminic acid by this HPAEC-PAD procedure. The method was applied to determine levels of terminal 5-N-acetyl neuraminic acid in LPS from NTHi strains grown under different conditions and mutant strains containing inactive LPS biosynthetic genes.

  • 5.
    Bergman, Jan
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Engqvist, Robert
    Karolinska Institute.
    Stålhandske, C
    Chemical Centre, Lund.
    Wallberg, H
    KTH.
    Studies of the reactions between indole-2,3-diones (isatins) and 2-aminobenzylamine2003Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 59, nr 7, s. 1033-1048Artikkel i tidsskrift (Fagfellevurdert)
  • 6.
    Bergman, Jan
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Janosik, T
    Koch, E
    Pelcman, B
    Acid-induced dimerization of 3-(1H-indol-3-yl)maleimides. Formation of cyclopentindole derivatives2000Inngår i: JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1, ISSN 1470-4358, nr 16, s. 2615-2621Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Acid-induced dimerizations of 3-substituted maleimides have been investigated, leading to e.g. the cyclopentindole 9 and the deeply coloured spiro compounds 24 and 25 in good yields. 3-(1H-Indol-3-yl)maleimide 6b readily gave the cycloaddition products 13-15 on treatment with appropriate dienophiles. In addition, several related 3,3-di-(1H-indol-3-yl)succinimides have been prepared and studied.

  • 7.
    Bergman, Jan
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Janosik, T
    Yudina, L
    Desarbre, E
    Lidgren, G
    Venemalm, L
    Reactions of 1,2-bis(1H-indol-2-yl)ethane: Formation of indolo[2,3-c]carbazole and cyclohept[1,2-b : 5,4-b ']bisindole derivatives2000Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 56, nr 13, s. 1911-1916Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1,2-Bis(1H-indol-2-yl)ethane (9) has been prepared and converted into indolo[2,3-c]carbazole (8) using palladium acetate in refluxing acetic acid. Reaction of 9 with CoF3 in hot TFA led to isolation of cyclohept[1,2-b:5,4-b']bisindole derivatives 11 and 12, which could be elaborated into further derivatives. Treatment of 9 with orthoesters, aldehydes and ketones under acidic conditions afforded additional bisindoles containing a seven-membered ring.

  • 8.
    Bergman, Jan
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Janosik, Tomasz
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Recent progress in the chemistry of sulfur-containing indoles2002Inngår i: Progress in Heterocyclic Chemistry, ISSN 0959-6380, Vol. 14, nr C, s. 1-18Artikkel i tidsskrift (Fagfellevurdert)
  • 9.
    Bergman, Jan
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Janosik, Tomasz
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Wahlström, Niklas
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Indolocarbazoles2001Inngår i: Advances in Heterocyclic Chemistry, ISSN 0065-2725, E-ISSN 1557-8429, Vol. 80, s. 1-71Artikkel, forskningsoversikt (Fagfellevurdert)
  • 10.
    Bergman, Jan
    et al.
    Södertörns högskola, Institutionen för livsvetenskaper.
    Johnson, Ann-Louise
    A short synthesis of the carbazole alkaloid clausine E2006Inngår i: Organic preparations and procedures international, ISSN 0030-4948, E-ISSN 1945-5453, Vol. 38, nr 6, s. 593-599Artikkel i tidsskrift (Fagfellevurdert)
  • 11.
    Bergman, Jan
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Koch, E
    Pelcman, B
    Coupling reactions of indole-3-acetic acid derivatives. Synthesis of arcyriaflavin A2000Inngår i: JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1, ISSN 1470-4358, nr 16, s. 2609-2614Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The bisindolesuccinic acid methyl ester 10 was obtained by an iodine-promoted coupling of the dianion 9. The diester was converted to the N-benzylimide 12, which was oxidatively cyclized to the indolo[2,3-a]pyrrolo[3,4-c]carbazole 15. The diester 10 could be directly transformed to the known indolocarbazole diester 27 via acid-induced intramolecular cyclization in TFA. The same methodology gave arcyriaflavin A 4 from the succinimide 18b.

  • 12.
    Bergman, Jan
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Rehn, S
    Synthesis of 4-oxo-4,5-dihydro-3H-pyrrolo[2,3-c]quinoline-1-carboxylic acid ethyl ester and its isomer 1-oxo-2,9-dihydro-1H-beta-carboline-4-carboxylic acid ethyl ester2002Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 58, nr 45, s. 9179-9185Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    4-Oxo-4,5-dihydro-3H-pyrrolo[2,3-c]quinoline-1-carboxylic acid ethyl ester was obtained when TosMIC was reacted with 3-methylene-oxindole acetic acid ethyl ester. An alternative synthesis to this pyrroloquinolone was performed via a reduction of a 2,3,4-trisubstituted pyrrole obtained in turn by treatment of a vinyl sulfone with ethyl isocyanoacetate under basic conditions. A beta-carboline, isomeric with the pyrroloquinolone, was synthesised utilizing a tosylimine.

  • 13.
    Bergman, Jan
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Wahlström, Niklas
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Yudina, L N
    Tholander, J
    Lidgren, G
    Synthesis of indolocarbazole quinones; potent aryl hydrocarbon receptor ligands2002Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 58, nr 7, s. 1443-1452Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Syntheses of indolo[2,3-b]carbazole-6,12-dione and the isomeric indolo[3,2-b]carbazole-6,12-dione, an extremely efficient inducer of the aryl hydrocarbon (Ah) receptor are described. Initial oxidation of the parent indolo[3,2-b]carbazole followed by several different ring-closing strategies produced the latter compound. Entries into syntheses of unsymmetrical 6,12-disubstituted indolo[2,3-b]carbazoles are also described.

  • 14.
    Björk, Malin
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institutet.
    Synthesis of sulfur and seleniumn heterocycles, including derivatives of imidazopyridine and benzimidazole2005Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The chemistry developed in this thesis can be divided into two parts. The first part, which is the major part of the thesis, contains syntheses towards analogues to mutagenic heterocyclic amines found in e.g. meat fried at high temperatures. The second part concentrates on the palladium-(0)catalyzed cross-coupling reactions of 4- and 5-substituted 2,1,3-benzoselenadiazoles. The heterocyclic amines described can be divided into the linear and the angular compounds. Five linear imidazo[4,5-b]pyridines were synthesised via the Friedländer reaction: 2-amino-1 - methylbenzothieno[2,3-e]imidazo[4,5-b]pyridine, 2-amino-1-methy-benzothieno [3,2-e] imidazo[4,5-b] pyridine, 2-amino-1-methylthieno[2,3-elimidazo[4,5-b]-pyridine, 2-amino-1methylthieno[3,2-e]imidazo[4,5-b]pyridine and the sulfur analogue to the cooked-food mutagen IFP, 2-amino- 1,6-dimethylthieno[2,3-e]imidazo[4,5-b]pyridine. Attempts were made to form three thienoimidazo[4,5-b]pyridines via stepwise condensation. The first condensation between creatinine and 2-nitro-3-thiophene-carbaldehyde, 3-amino-2thiophenecarbaldehyde and 4-azido3-thiophenecarbaldehyde yielded thenylidenomethyleneimidazolinones, but only one of these gave the ring closed compound 2-amino-1-methylthieno[2,3-e]imidazo[4,5-b]pyridine by a second condensation. In addition, 2-amino- 1 methyl benzoth ieno[3,2-e] imidazo[4,5 -b] pyridine was transformed into the 2-nitro- and 2-hydroxy derivative. The last linear isomer 2-amino-1methylimidazo[4,5-b]benzothiophene, was synthesized by a different route. The series of angular compounds are considered analogues to the food-mutagen IQx. A series of six homologues of 7-amino-imidazo[4,5-e]-2,1,3-benzoselenadiazoles. Four ring systems were obtained by treating 4-methylamino-3-nitro-phenylenedianmine with a range of biselectrophiles, namely: 2-amino-1-methylbenzo-thiadiazole, -triazole, -diazepinone and 2amino1 -methylimidazobenzimidazole. Among the palladium-(0)-catalyzed cros s- couplings, the Suzuki, Stille, Fleck and Sonogashira reactions were used. These were applied to 4-, or 5-bromo-2,1,3-benzoselenadiazoles. In addition, the 4- and 5-trimethyltin-2,1,3-benzoselenadiazole were synthesized.

  • 15.
    Björk, Malin
    et al.
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institutet.
    Grivas, Spiros
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institutet.
    Classical conditions of Suzuki, Stille, Heck and Sonogashira couplings applied on 4- and 5-substituted 2,1,3-benzoselenadiazolesManuskript (preprint) (Annet vitenskapelig)
  • 16.
    Björk, Malin
    et al.
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institutet.
    Grivas, Spiros
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institutet.
    Synthesis of imidazo[4,5-e]-2,1,3-benzoselenadiazoles and derivatives thereofManuskript (preprint) (Annet vitenskapelig)
  • 17.
    Björk, Malin
    et al.
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institute.
    Grivas, Spiros
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institute.
    Synthesis of novel 2-aminoimidazo[4,5-b]pyridines, including the thieno analogue of the cooked-food mutagen IFP2006Inngår i: Journal of Heterocyclic Chemistry, ISSN 0022-152X, E-ISSN 1943-5193, Vol. 43, nr 1, s. 101-109Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Eight new compounds, including three new ring systems obtained via the Friedlander condensation of ortho-aminothiophenecarbaldehydes 11, 21 and 24 with creatinine (8), are reported. The condensation afforded 1, which is the thieno analogue of the cooked-food mutagen IFP (2-amino-1,6-dimethylfuro[2,3-e]imidazo[4,5-b]pyridine), and the benzothieno[2,3-e]- and benzothieno[3,2-e]imidazo[4,5-b]pyridines 2 and 3. Attempts to condense 11 with isocreatinine (12) were unsuccessful. Desulfurization of 3 gave the known cooked-food carcinogen PhIP. The 2-nitro (4) and 2-hydroxy (5) derivatives of 3 are reported. The related 2-amino-1-methyl-imidazo[4,5-b]benzothiophene (25) was synthesized by a different route. Fully assigned H-1 and C-13 nmr data of all new compounds are reported.

  • 18.
    Björk, Malin
    et al.
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institutet.
    Grivas, Spiros
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institutet.
    Synthesis of thienoimidazo[4,5-b]pyridines and thenylidenoimidazolinones2005Inngår i: Heterocycles, ISSN 0385-5414, E-ISSN 1881-0942, Vol. 65, nr 10, s. 2369-2380Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The two isomers 2-amino-1-methylimidazo[4,5-b]thieno[3,2-e]pyridine (3) and 2-amino-1-methylimidazo[4,5-b]thieno[2,3-e]pyridine (4) were synthesized by the Friedlander reaction starting from creatinine and the appropriate aminothiophenecarbaldehydes (11 and 13). Creatinine was also condensed with 2-nitro-3-thiophenecarbaldehyde (10) in ethylene glycol to yield the 2-amino-1-methyl-5-[2-(2-nitro-3-thenylidene)]-2-imidazolin-4-one (7a), with 3-amino-2-thiophenecarbaldehyde (13) under Perkin conditions to yield 2-acetamido-5-[2-(3-acetamido-2-thenylidene)]-1-methyl-2-imidazolin-4-on e (8), and with 4-azido-3-thiophenecarbaldehyde (17) in acetic acid to yield 2-amino-5[2-(4-azido-3-thenylidene)]-1-methyl-2-imidazolin-4-one (9). The thenylidenoimidazolinonc (8) was converted into compound (4).

  • 19.
    Bredenberg, Johan
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Nilsson, L
    Modeling zinc sulfhydryl bonds in zinc fingers2001Inngår i: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 83, nr 3-4, s. 230-244Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Molecular dynamics simulations have been carried out employing three different model descriptions of the zinc sulfhydryl interactions in class II fingers. One bonded and two nonbonded models were studied. Two variant structures of the glucocorticoid receptor DNA-binding; domain and a NMR structure from a fragment of methionyl-tRNA synthetase were subjected to long-time MD simulations with these models. Our analysis is focused on comparison with experimental and quantum mechanical data, concerning the local Zn-finger and overall structural and dynamic properties for these models. All models performed M ell, but the nonbonded models appeared to reproduce the protein dynamics in better agreement with experimental data than does the bonded description.

  • 20.
    Danielsson Thorell, Helena
    Södertörns högskola, Lärarutbildningen.
    Några aspekter på kemilärares tysta kunskap2007Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Undersökningar visar att lärare, till skillnad från många andra professionella yrkesgrupper, sällan refererar till teorier när de anger vilka motiv deras praktiska verksamhet har. Den kollegiala diskussionen bland lärare är sällan av teoretisk karaktär utan handlar ofta om praktiska förhållanden . En stor del av lärarkunskapen verkar vara ”tyst”.” Tyst kunskap ska här förstås som erfarenhetsbaserad kunskap som uppnås genom praktiserande verksamhet, en typ av förtrogenhetskunskap som kräver överblick över situationen man befinner sig i. I det här arbetet studerar jag relationen mellan lärarens reflektioner om sin egen praktik i relation till lärarens syn på elevernas progression under kemilaborationer. Syftet med undersökningen är att ge några bilder av tankemönster man möter i diskussionen kring undervisningen i kemi. Tankemönster i samband med undervisning ses här som delar av lärarens tysta kunskap. Den empiriska undersökningen baseras på intervjuer med kemilärare på gymnasie- och högstadieskolor. I undersökningen identifieras några aspekter av kemilärares tysta kunskap i relation till elevers lärandeprocess under kemilaborationer. Resultaten visar en koppling till litteratur och forskning inom området för hur effektiv undervisning kan bedrivas.

    Fulltekst (pdf)
    FULLTEXT01
  • 21. Dasari, Bhanudas
    et al.
    Jogula, Srinivas
    Borhade, Ramdas
    Balasubramanian, Sridhar
    Chandrasekar, Gayathri
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik.
    Kitambi, Satish Srinivas
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik. Karolinska Institute.
    Arya, Prabhat
    Macrocyclic Glycohybrid Toolbox Identifies Novel Antiangiogenesis Agents from Zebrafish Assay2013Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 15, nr 3, s. 432-435Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    A practical and modular approach to obtain a diverse set of 14-membered macrocyclic compounds from carbohydrates is developed that utilizes functional groups at C-1 and C-5. The evaluation of this toolbox in various zebrafish assays led to the identification of 2.7f as an antianglogenesis agent.

  • 22.
    Djedovivc, Irma
    Södertörns högskola, Lärarutbildningen.
    Ämnesinnehållet i läroböcker: En undersökning av de ämnesspecifika begreppen i kemi2017Independent thesis Advanced level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    The aim of this paper is to analyse the use of subject-specific concepts in chemistry books within a chosen topic. The following questions have been formulated:

    • What subject-specific concepts are present and with what frequency?
    • In what way, do they clarify the subject-specific concepts?

    To achieve the purpose and the issues raised in the paper, the chapter will be analysed with two different content analysis. The material will then be analysed based on Vygotsky's theory of the development of scientific concepts.The results show that the chapters use different subject-specific concept.

    In addition, the amount also varied significantly. The frequency of the subject-specific concepts was low in all three chapters. The chapter had a large variety of representations, but the chapters showed no resemblance to how they were clarified. The study can be interpreted as demonstrating that the textbooks have very different subject content, which in turn, given the role of the textbook in the study, can influence the subject knowledge acquired as a student.

  • 23.
    Edin, Michaela
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Grivas, Spiros
    Södertörns högskola, Avdelning Naturvetenskap.
    On the preparation of 1,2,5-selenadiazolo [3,4-e]indole and its [3,4-f] and [3,4-g] isomers through the Batcho-Leimgruber indole synthesis2001Inngår i: ARKIVOC, ISSN 1551-7004, E-ISSN 1551-7012, Vol. 2, nr 1, s. 136-142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1,2,5-Selenadiazolo[3,4-e]indole 6 was prepared by applying the Batcho-Leimgruber indole synthesis on 4-methyl-5-nitro-2,1,3-benzoselenadiazole 9. This methodology was unsuccessful when applied to 5-methyl-6-nitro-2,1,3-benzoselenadiazole 14 for the synthesis of 1,2,5-selenadiazolo[3,4-f]indole 5. An improvement on the preparation of 1,2,5-selenadiazolo[3,4-g]indole 3 is reported. An initial study on the bromination of 3 and the Se-77-NMR chemical shifts of 3 and 6, and of their precursors are presented.

  • 24. El-Beqqali, Aziza
    et al.
    Kussak, Anders
    Södertörns högskola, Institutionen för livsvetenskaper.
    Abdel-Rehim, Mohamed
    Determination of dopamine and serotonin in human urine samples utilizing microextraction online with liquid chromatography/electrospray tandem mass spectrometry2007Inngår i: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 30, nr 3, s. 421-424Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A specific LC-MS-MS method for the determination of dopamine and serotonin (5-hydroxytryptamine; 5HT) in human urine is described. The analytes were extracted from urine and preconcentrated by microextraction in a packed syringe (MEPS). The new method is very promising, very easy to use, fully automated, of low cost, and rapid in comparison to previously used methods. The method was validated and the standard curves were evaluated by means of quadratic regression and weighted by inverse of the concentration: 1/x for the calibration range 50-4000 mu g/L. The MEPS applied polymer (silica-C8) could be used more than 300 times. The extraction recovery was about 50%. The results showed close correlation coefficients (r(2) >0.999) for all analytes in the calibration range studied. The accuracy of MEPS-LC-MS-MS was 100-101% for dopamine and 99-100% for 5HT. The interday precision (n = 3 days), expressed as the RSD%, was 6.0-7.7% for dopamine and 6.1-11% for 5HT. MEPS reduced the handling time by 12 times compared to a published method.

  • 25. El-Beqqali, Aziza
    et al.
    Kussak, Anders
    Södertörns högskola, Institutionen för livsvetenskaper.
    Abdel-Rehim, Mohamed
    Fast and sensitive environmental analysis utilizing microextraction in packed syringe online with gas chromatography-mass spectrometry - Determination of polycyclic aromatic hydrocarbons in water2006Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1114, nr 2, s. 234-238Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new sensitive, selective, fast and accurate technique for online sample preparation was developed. Microextraction in a packed syringe (MEPS) is a new miniaturised, solid-phase extraction (SPE) technique that can be connected online to GC or LC without any modifications. In MEPS approximately 1 mg of the solid packing material is inserted into a syringe (100-250 ml) as a plug. Sample preparation takes place on the packed bed. The bed can be coated to provide selective and suitable sampling conditions. The new method is very promising. It is very easy to use, fully automated, of low cost and rapid in comparison with previously used methods. The determination of polycyclic hydrocarbons (PAHs) in water was performed using MEPS as sample preparation method online with gas chromatography and mass spectrometry (MEPS-GC-MS). The results from MEPS as sample preparation were compared with other techniques such as stir bar sorptive extraction (SBSE) and solid-phase microextraction (SPME). The method was validated and the standard curves were evaluated by the means of quadratic regression and weighted by inverse of the concentration: 1/x for the calibration range 5-1000 ng/L. The MEPS applied polymer (silica-C8) could be used more than 400 times before the syringe was discarded. The extraction recovery was about 70%. The results showed close correlation coefficients (R > 0.998) for all analytes in the calibration range studied. The accuracy of MEPS-GC-MS was between 90 and 113% and the inter-day precision (n = 3 days), expressed as the relative standard deviation (RSD%), was 8-16%. MEPS reduced the handling time by 30 and 100 times compared to SPME and SBSE, respectively.

  • 26. El-Beqqali, Aziza
    et al.
    Kussak, Anders
    Södertörns högskola, Institutionen för livsvetenskaper.
    Blomberg, Lars
    Abdel-Rehim, Mohamed
    Microextraction in packed syringe/liquid chromatography/electrospray tandem mass spectrometry for quantification of acebutolol and metoprolol in human plasma and urine samples2007Inngår i: Journal of Liquid Chromatography & Related Technologies, ISSN 1082-6076, E-ISSN 1520-572X, Vol. 30, nr 4, s. 575-586Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of the present investigation was to develop a simple, fast, and sensitive method for the determination of acebutolol and metoprolol in human plasma and urine samples. The determination of acebutolol and metoprolol in plasma and urine was performed using micro extraction in packed syringe (MEPS) as a sample preparation method, online with high performance liquid chromatography and tandem mass spectrometry (LC-MS/MS). In MEPS the sampling sorbent was 1 mg polystyrene polymer, which was inserted in a 250 mu L syringe. The lower limits of quantification (LLOQ) for acebutolol and metoprolol were set to 1.0 ng/mL. The accuracy of quality control samples (QC) varied by +/- 10%, and precision (R.S.D.) had a deviation of 1.4-12% for plasma and urine samples. The calibration curve was obtained within the concentration range 1.0-100 ng/mL in both plasma and urine. The regression correlation coefficients (R-2) for plasma and urine samples were >= 0.999 for all runs. The present method is miniaturized, fully automated, robust, and can be easily used for pharmacokinetic and pharmacodynamic studies of acebutolol and metoprolol.

  • 27.
    Engqvist, Robert
    Södertörns högskola, Institutionen för kemi, biologi, geografi och miljövetenskap. Karolinska Institutet.
    Syntheses of some tri- and tetracyclic heterocycles containing an indole moiety2004Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis deals with the development of new synthetic methods leading to fused tri- and tetracyclic heterocycles, many of which have interesting biological activity such as antiviral and DNA intercalating properties. The reactions between isatins and 2-aminobenzylamine in acetic acid can give, depending on the conditions, either complex spirooxindoles or indolo[3,2-c]quinolin-6-ones. Proposed mechanisms are presented (involving a simpler form of spirooxindoles). These spirooxindoles can easily be obtained from isatins and 2-aminobenzylamine in methanol (Paper I). The previously unknown, but incorrectly claimed, linear isomer of indolo[3,2-c]quinolin-6one, i.e. indolo[2,3-b]quinolin-11-one, has been prepared for the first time by thermal (260 degrees C) cyclization of methyl 2 -phenylamino-indole-3 -carboxylate, which was in turn prepared in two steps from methyl indole-3 -carboxylate. The benzothiopyrano[2,3-b]indol-11-one and benzopyrano[2,3-b]indol-11-one could be prepared similarly (Papers I and II). Suitable 2-chloro-3-formylindoles have been used for the preparation of the alkaloids neocryptolepine, thienodolin and derivatives thereof (Papers III and IV). Finally, synthetic work towards potential metabolites of the lead compound B-220 is presented. We have described a method for reduction of the biologically interesting indolo[2,3b)quinoxalines with zinc, which are subsequently trapped with an appropriate anhydride to provide the corresponding mono or diacylated 5,1 1-dihydroindolo[2,3b]quinoxalines in good yields (paper V). Synthesis of hydroxy derivatives of B-220 can be effected from the appropriate methoxyisatins. Futher derivatives like the vinyl-, Nmethylaminoethyl- and Noxido derivatives of B-220 have also been synthesised.

  • 28.
    Engqvist, Robert
    et al.
    Södertörns högskola, Institutionen för kemi, biologi, geografi och miljövetenskap. Karolinska Institutet.
    Bergman, Jan
    Södertörns högskola, Institutionen för kemi, biologi, geografi och miljövetenskap. Karolinska Institutet.
    An improved synthesis of neocryptolepine2004Inngår i: Organic preparations and procedures international, ISSN 0030-4948, E-ISSN 1945-5453, Vol. 36, nr 4, s. 386-390Artikkel i tidsskrift (Fagfellevurdert)
  • 29.
    Engqvist, Robert
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Bergman, Jan
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Synthesis of benzothiopyrano[2,3-b]indol-11-one and benzopyrano[2,3-b]indol-11-one2003Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 59, nr 48, s. 9649-9653Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The fused heterocycles benzothiopyrano[2,3-b]indol-11-one and benzopyrano[2,3-b]indol-11-one, have been prepared from methyl 3-indole carboxylate in two steps.

  • 30.
    Engqvist, Robert
    et al.
    Södertörns högskola, Institutionen för kemi, biologi, geografi och miljövetenskap. Karolinska Institutet.
    Javaid, Atif
    Södertörns högskola, Institutionen för kemi, biologi, geografi och miljövetenskap.
    Bergman, Jan
    Södertörns högskola, Institutionen för kemi, biologi, geografi och miljövetenskap. Karolinska Institutet.
    Synthesis of thienodolin2004Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 12, s. 2589-2592Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report a total synthesis of the alkaloid thienodolin (1a), as well as its 5-chloro isomer 1b and its unsubstituted analogue 1c, in three steps from the corresponding oxindoles Ba-c. The preparation was achieved through an initial Vilsmeier-Haack-Arnold reaction (chloro-formylation) followed by protection at the indole nitrogen, creation of the fused thiophene ring by nucleophilic substitution at the 2-position and an intramolecular cyclization using mercaptoacetamide. This gave 1a, 1b and 1c in total yields of 42%, 35% and 37%, respectively.

  • 31.
    Engqvist, Robert
    et al.
    Södertörns högskola, Institutionen för kemi, biologi, geografi och miljövetenskap. Karolinska Institutet.
    Stensland, Birgitta
    AstraZeneca.
    Bergman, Jan
    Södertörns högskola, Institutionen för kemi, biologi, geografi och miljövetenskap. Karolinska Institutet.
    Reduction of indolo[2,3-b]quinoxalines2005Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 61, nr 18, s. 4495-4500Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Reduction of indolo[2,3-b]quinoxalines with zinc in the presence of an anhydride gave N,N-diacyl trapped 6,11-dihydroindolo[2,3-b]quinoxalines in 43-92% yields. When the reduction with zinc was performed in TFA/TFAA, an unexpected ring opened product was isolated in 49% yield. The structure of this product could be identified as 1,2-dihydro-1-trifluoroacetyl-3-[(2-trifluoroacetylamino)phenyl]quinoxal ine.

  • 32.
    Grivas, Spiros
    Södertörns högskola, Avdelning Naturvetenskap.
    2,1,3-benzoselenadiazoles as valuable synthetic intermediates2000Inngår i: Current organic chemistry, ISSN 1385-2728, E-ISSN 1875-5348, Vol. 4, nr 7, s. 707-726Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    N-alkyl-1,2-benzenediamines, 4-substituted-3-nitro-1,2-benzenediamines and 3,4-diamino-2-nitrophenols are readily obtained by deselenation of alkyl quaternary salts of 2,1,3-benzoselenadiazoles (bsd) and 5-substituted-4-nitro-bsd. The latter are easily obtained by nitration of 5-X-bsd (X = Me, Br, Cl, F, OMe, NHMe). Nitration of 5-fluoro-bsd yields the 4-nitro derivatives that are accompanied by substantial amounts of the corresponding 4-nitro-bsd-5-ols. ipso-Nitration of 5-fluoro-4-methyl-bsd is followed by instantaneous hydrolysis to (+/-)-4-methyl-4-nitro-bsd-5(4H)-one. Batcho-Leimgruber indole synthesis on 5-methyl-4-nitro-bsd followed by reductive deselenation of 1,2,5-selenadiazolo[3,4-g]indole affords 6,7-diaminoindole. Cyclocondensation of 3-nitro-1,2-benzenediamines with acetylacetone provides a convenient route for the preparation of 2-methyl-4-nitrobenzimidazoles. Less-accessible 6-halo-5-nitro- and 6-methoxy-5-nitroquinoxalines are efficiently synthesized by regioselective condensation of alpha-dicarbonyls with 4-halo- and 4-methoxy-3-nitro-1,2-benzenediamines. The reactive halogen atom or methoxyl group ortho to the nitro substituent renders these quinoxalines versatile intermediates to further heterocycles. The Se-77, C-13 and H-1 NMR chemical shifts of sixteen bsd derivatives, and the C-13 NMR chemical shifts of eight derivatives of 2-methylquinoxalines are presented.

  • 33.
    Gulin, Sofia
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Kussak, A
    Jansson, P E
    Widmalm, G
    Structural studies of S-7, another exocellular polysaccharide containing 2-deoxy-arabino-hexuronic acid2001Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 331, nr 3, s. 285-290Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The exocellular polysaccharide S-7, a heteropolysaccharide from Azotobacter indicus var, myxogenes has been studied using methylation analysis, Smith degradation, partial acid hydrolysis, NMR spectroscopy and mass spectrometry as the principal methods. It is concluded that the repeating unit has the following structure: -->4)-beta -D-Glcp-(1 -->4)-alpha -L-Rhap-(1 -->3)-beta -D-2-deoxy-arabino-HexpA-(1 --> 6 up arrow 1 beta -D-Glcp-(1 -->6)-beta -D-Glcp The absolute configuration of the deoxyhexuronic acid was deduced from H-1 NMR chemical shifts and is most likely D. Approximately two O-acetyl groups per repeating unit are present, one of which is presumably on the Rha residue. The structure bears great resemblance to another polysaccharide, recently studied, produced by Sphingomonas paucimobilis I-886.

  • 34.
    Gulin, Sofia
    et al.
    Södertörns högskola, Avdelning Naturvetenskap.
    Pupo, E
    Schweda, Elke K H
    Södertörns högskola, Avdelning Naturvetenskap.
    Hardy, E
    Linking mass spectrometry and slab-polyacrylamide gel electrophoresis by passive elution of lipopolysaccharides from reverse-stained gels: Analysis of gel-purified lipopolysaccharides from Haemophilus influenzae strain Rd2003Inngår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 75, nr 18, s. 4918-4924Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Haemophilus influenzae is an important cause of human disease, and its lipopolysaccharide (LPS) is known to be a major virulence factor. H. influenzae produces short-chain LPS of which the heterogeneity is often visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) using silver staining for detection. Individual bands have not previously been recovered by this method in quantities sufficient for mass spectrometry. In an attempt toward the development of sensitive mass spectrometrical strategies to be used in structural studies of H. influenzae LPS and LPS from other bacteria, we have applied here our previously described slab-PAGE-based micropurification method to obtain unmodified LPS fractions of high purity (>95%) from a crude LPS preparation of H. influenzae strain Rd. Two LPS-fractions were obtained which, after a procedure including mild acid hydrolysis, dephosphorylation, and permethylation of the resulting oligosaccharides, were subjected to tandem electrospray ionization mass spectrometry (ESI-MS/MS). The quantities of micropurified LPS fractions-the recovery of LPS in terms of total mass was 30%-were found sufficient to allow the characterization of LPS glycoforms. The ESI-MS spectra of the individual bands showed reduced heterogeneity. Furthermore, the integrity of the micropurified LPS was confirmed. The spectra-displayed molecular ions showed improved intensity, increased respective signal-to-noise ratios demonstrating the sensitivity of analysis. Consequently, both the direct determination of the molecular masses of the gel-separated LPS glycoforms and sequence analyses using ESI-MS/MS were possible.

  • 35. Hellström, Sten-Olof
    et al.
    Jää-Aro, Kai-Mikael
    Laaksonen, Aatto
    Perceptualisation of molecular dynamics data2000Konferansepaper (Annet vitenskapelig)
  • 36. Ihrén, Johan
    et al.
    Laaksonen, Aatto
    Stockholm University.
    Jää-Aro, Kai-Mikael
    KTH.
    A generic file format for molecular dynamics simulations1998Inngår i: Buletinul Științific al Universitãții Politehnica din Timișoara, ISSN 1224-600X, Vol. 43(57), nr 3, s. 251-257Artikkel i tidsskrift (Fagfellevurdert)
  • 37. Janosik, T
    et al.
    Bergman, Jan
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Oxidative coupling of indoline-2-thione or oxindole: Formation of cyclic and acyclic indole trimers2002Inngår i: Heterocycles, ISSN 0385-5414, E-ISSN 1881-0942, Vol. 57, nr 7, s. 1273-1278Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Oxidation of indoline-2-thione using p-toluenesulfonyl azide produced a modest yield of the structurally novel cyclic sulfur containing indole trimer (12). In contrast, the oxidation of oxindole with iodine instead produced an acyclic trimeric indole derivative.

  • 38.
    Janosik, Tomasz
    et al.
    Dartmouth College, Hanover, United States .
    Bergman, Jan
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Five-membered ring systems: Pyrroles and benzo derivatives2003Inngår i: Progress in Heterocyclic Chemistry, ISSN 0959-6380, Vol. 15, nr C, s. 140-166Artikkel i tidsskrift (Fagfellevurdert)
  • 39.
    Janosik, Tomasz
    et al.
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institutet.
    Bergman, Jan
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institutet.
    Five-membered ring systems: thiophenes and Se/Te analogues2005Inngår i: Progress in heterocyclic chemistry., ISSN 0959-6380, Vol. 17, s. 84-108Artikkel, forskningsoversikt (Annet vitenskapelig)
  • 40.
    Janosik, Tomasz
    et al.
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institutet.
    Bergman, Jan
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institutet.
    Five-membered ring systems: thiophenes and Se/Te analogues2007Inngår i: Progress in Heterocyclic Chemistry, ISSN 0959-6380, Vol. 18, s. 126-149Artikkel, forskningsoversikt (Annet vitenskapelig)
  • 41.
    Janosik, Tomasz
    et al.
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institutet.
    Bergman, Jan
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institutet.
    Pelkey, Erin T.
    Hobart and William Smith Colleges, Geneva, NY, United States.
    Chapter 5.2 Five-membered ring systems: Pyrroles and benzo derivatives2005Inngår i: Progress in Heterocyclic Chemistry, ISSN 0959-6380, Vol. 16, s. 128-155Artikkel, forskningsoversikt (Annet vitenskapelig)
    Abstract [en]

    This chapter discusses the progress in synthesis and chemistry of pyrroles, indoles, and related fused ring systems. Several specialized reviews on the chemistry of indoles and pyrroles have appeared during the reporting period, providing more in-depth coverage. A comprehensive review on pyrrole natural products has appeared as well as a more limited one on the synthetic chemistry involving the pyrrole natural products roseophilin and prodigiosin is illustrated in this chapter. Likewise, the synthetic efforts in the field of the pyrrole-imidazole class of alkaloids have been covered. The isolation and synthesis of indole alkaloids containing a non-rearranged monoterpenoid unit is discussed in this chapter.

  • 42.
    Janosik, Tomasz
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Bergman, Jan
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Romero, Ivan
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institute.
    Stensland, B
    Stålhandske, C
    Marques, M M B
    Santos, M M M
    Lobo, A M
    Prabhakar, S
    Duarte, M F
    Florencio, M H
    Synthetic, spectroscopic, and X-ray crystallographic studies of [1,2,7,8]tetrathiacyclododecino[4,3-b: 5,6-b': 10,9-b": 11,12-b''']tetraindoles2002Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 8, s. 1392-1396Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two conformationally different [1,2,7,8]tetrathiacyclododecino[4,3-b:5,6-b':10,9-b":11,12-b''']tetraind oles 9a and 9b have been isolated in good yields, and the existence of a third conformer 9c in solution was demonstrated by mass spectrometry and H-1 NMR spectroscopy. The interconversions of the tetraindoles 9a-c have also been studied. The conformation of 9b was confirmed by X-ray crystallography, while the conformations of 9a and 9b were assigned on the basis of spectroscopic data, and were also supported by molecular modelling studies. In addition, the elusive dithiin 3 was isolated and the structure was proven by X-ray crystallography.

  • 43.
    Janosik, Tomasz
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Johnson, Ann-Louise
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Bergman, Jan
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Synthesis of the marine alkaloids rhopaladins A, B, C and D2002Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 58, nr 14, s. 2813-2819Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The total synthesis of all four known rhopaladins, A-D, isolated from the Okinawan marine tunicate Rhopalaea sp., in two synthetic steps is described, involving an imidate based cyclization with tryptophan esters as the key step to afford the appropriately substituted imidazolinone unit. A short and efficient new synthesis of indol-3-yl-carbonyl nitriles from indol-3-yl-carboxaldehydes and trimethylsilyl cyanide, followed by oxidation with DDQ is also described.

  • 44. Janosik, Tomasz
    et al.
    Shirani, Hamid
    Wahlström, Niklas
    Malky, Ilham
    Stensland, Birgitta
    Bergman, Jan
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institute.
    Efficient sulfonation of 1-phenylsulfonyl-1H-pyrroles and 1-phenylsulfonyl-1H-indoles using chlorosulfonic acid in acetonitrile2006Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 62, nr 8, s. 1699-1707Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The sulfonation of various 1-phenylsulfonyl-1H-pyrroles and 1-phenylsulfonyl-1H-indoles using chlorosulfonic acid in acetonitrile has been studied, leading to the development of a clean and operationally simple protocol allowing direct synthesis of the corresponding 1-phenylsulfonyl-1H-pyrrole-3-sulfonyl chlorides and 1-phenylsulfonyl-1H-indole-3-sulfonyl chlorides, respectively, both of which may be easily converted to various sulfonamide derivatives by treatment with nitrogen nucleophiles. Efficient and selective removal of the phenylsulfonyl- or tosyl groups in the sulfonamide series may be achieved under mild conditions.

  • 45.
    Janosik, Tomasz
    et al.
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Stensland, B
    Bergman, Jan
    Södertörns högskola, Avdelning Naturvetenskap. Karolinska Institutet.
    Sulfur-rich heterocycles from 2-metalated benzo[b]thiophene and benzo[b]furan: Synthesis and structure2002Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 67, nr 17, s. 6220-6223Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The reaction of 2-lithiated benzo[b]thiophene with 8 equiv of elemental sulfur was found to give pentathiepino[6,7-b]benzo[d]thiophene. In contrast, treatment of 2-lithiated benzo[b]furan with sulfur under similar conditions produced the interesting ring system bis(benzo[4,5]-furo)[2,3-e:3',2'-g][1,2,3,4]tetrathiocine. Both of these new cyclic polysulfides were studied by X-ray crystallography. Two polymorphic forms of pentathiepino[6,7-b]benzo[d]thiophene were found, displaying similar conformations but different packing schemes, which was also evident from powder diffraction data.

  • 46. Jogula, Srinivas
    et al.
    Dasari, Bhanudas
    Khatravath, Mahender
    Chandrasekar, Gayathri
    Kitambi, Satish Srinivas
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik. Karolinska institutet.
    Arya, Prabhat
    Building a Macrocyclic Toolbox from C-Linked Carbohydrates Identifies Antiangiogenesis Agents from Zebrafish Assay2013Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 2013, nr 23, s. 5036-5040Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the synthesis of four different types of macrocyclic-derived glycohybrids from carbohydrates that have an amino acid moiety in the large-ring skeleton. These macrocyclic glycohybrids were obtained from -C-1H- and -C-1H-linked carbohydrates. In one series, we utilized ring-closing metathesis as the stitching technology to obtain two different macrocycles, i.e., trans equatorial-axial C-1H and C-5H and cis axial-axial C-1H and C-5H. The click approach was the key reaction in our second series to obtain two other macrocyclic compounds, i.e., trans equatorial-axial C-1H and C-5H and cis axial-axial C-1H and C-5H. The evaluation of this toolbox resulted in the identification of two unique compounds as antiangiogenesis agents in an embryonic zebrafish assay. Interestingly, in both cases, the macrocyclic compounds that have a cis relationship (i.e., axial-axial orientation) between C-1H and C-5H showed activity and their other diastereomers (i.e., equatorial-axial C-1H and C-5 H) with a trans relationship did not show any effect.

  • 47. Johnson, A L
    et al.
    Janosik, T
    Bergman, Jan
    Södertörns högskola, Avdelning Naturvetenskap.
    Synthesis of the diketopiperazine dipodazine2002Inngår i: ARKIVOC, ISSN 1551-7004, E-ISSN 1551-7012, s. 57-61Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The diketopiperazine derivative dipodazine (1), isolated from Penicillium dipodomyis, has been synthesized via a stereoselective aldol condensation from N-protected indole-3-carboxaldehyde and 1,4-diacetyl-2,5-piperazinedione (3) in the presence of cesium carbonate.

  • 48. Johnson, A. -L
    et al.
    Slätt, J.
    Janosik, T.
    Bergman, Jan
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institute.
    Stereoselective synthesis and isomerization of the indole alkaloid murrayacarine2006Inngår i: Heterocycles, ISSN 0385-5414, E-ISSN 1881-0942, Vol. 68, nr 10, s. 2165-2170Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A short and efficient stereoselective synthesis of the indole alkaloid murrayacarine is described, including studies on its acid-induced isomerization.

  • 49. Johnson, Ann-Louise
    et al.
    Bergman, Jan
    Södertörns högskola, Institutionen för livsvetenskaper. Karolinska Institute.
    Synthetic approaches towards an indole alkaloid isolated from the marine sponge Halichondria melanodocia2006Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 62, nr 47, s. 10815-10820Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The exocyclic analogue of the indole alkaloid isolated from the marine sponge Halichondria melanodocia has been prepared via olefination of a phosphonoester derived from 3-(2-bromoacyl)indole. The formation of an unexpected indolylazepine is also discussed.

  • 50.
    Johnson, Ann-Louise
    et al.
    Södertörns högskola, Institutionen för kemi, biologi, geografi och miljövetenskap. Karolinska Institute.
    Bergman, Jan
    Södertörns högskola, Institutionen för kemi, biologi, geografi och miljövetenskap. Karolinska Institute.
    Sjögren, M
    Bohlin, L
    Synthesis of barettin2004Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 60, nr 4, s. 961-965Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The indole alkaloid barettin (with bromine in 6-position), isolated from the marine sponge Geodia Barretti, has been synthesised via a Horner-Wadsworth-Emmons type reaction from 6-bromoindole-3-carboxaldehyde to introduce the dehydro-functionality. Subsequent deprotection and cyclisation afforded the natural product in Z-conformation.

12 1 - 50 of 90
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