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  • 1.
    Abbas, Alaa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC.
    Palladium-Catalysed Carbonylative Synthesis of Acylamidines2014Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
  • 2. Abbasi, Alireza
    et al.
    Skripkin, Mikhail Yu.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Torapava, Natallia
    Ambidentate coordination of dimethyl sulfoxide in rhodium(III) complexes2011Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 40, nr 5, s. 1111-1118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The two dimethyl sulfoxide solvated rhodium(III) compounds, [Rh(dmso-kappa O)(5)(dmso-kappa S)](CF(3)SO(3))(3) (1 & 1* at 298 K and 100 K, respectively) and [Rh(dmso-kappa O)(3)(dmso-kappa S)(2)Cl](CF(3)SO(3))(2) (2), crystallize with orthorhombic unit cells in the space group Pna2(1) (No. 33), Z = 4. In the [Rh(dmso)(6)](3+) complex with slightly distorted octahedral coordination geometry, the Rh-O bond distance is significantly longer with O trans to S, 2.143(6) angstrom (1) and 2.100(6) angstrom (1*), than the mean Rh-O bond distance with O trans to O, 2.019 angstrom (1) and 2.043 angstrom (1*). In the [RhCl(dmso)(5)](3+) complex, the mean Rh-O bond distance with O trans to S, 2.083 angstrom, is slightly longer than that for O trans to Cl, 2.067(4) angstrom, which is consistent with the trans influence DMSO-kappa S > Cl > DMSO-kappa O of the opposite ligands. Raman and IR absorption spectra were recorded and analyzed and a complete assignment of the vibrational bands was achieved with support by force field calculations. An increase in the Rh-O stretching vibrational frequency corresponded to a decreasing trans-influence from the opposite ligand. The Rh-O force constants obtained were correlated with the Rh-O bond lengths, also including previously obtained values for other M(dmso)(6)(3+) complexes with trivalent metal ions. An almost linear correlation was obtained for the MO stretching force constants vs. the reciprocal square of the MO bond lengths. The results show that the metal ion-oxygen bonding of dimethyl sulfoxide ligands is electrostatically dominated in those complexes and that the stretching force constants provide a useful measure of the relative trans-influence of the opposite ligands in hexa-coordinated Rh(III)-complexes.

  • 3. Abdel-Hamid, Mohammed K
    et al.
    Macgregor, Kylie A
    Odell, Luke R
    Chau, Ngoc
    Mariana, Anna
    Whiting, Ainslie
    Robinson, Phillip J
    McCluskey, Adam
    1,8-Naphthalimide derivatives: new leads against dynamin I GTPase activity.2015Inngår i: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 13, nr 29Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fragment-based in silico screening against dynamin I (dynI) GTPase activity identified the 1,8-naphthalimide framework as a potential scaffold for the design of new inhibitors targeting the GTP binding pocket of dynI. Structure-based design, synthesis and subsequent optimization resulted in the development of a library of 1,8-naphthalimide derivatives, called the Naphthaladyn™ series, with compounds 23 and 29 being the most active (IC50 of 19.1 ± 0.3 and 18.5 ± 1.7 μM respectively). Compound 29 showed effective inhibition of clathrin-mediated endocytosis (IC50(CME) 66 μM). The results introduce 29 as an optimised GTP-competitive lead Naphthaladyn™ compound for the further development of naphthalimide-based dynI GTPase inhibitors.

  • 4.
    Abdel-Magied, Ahmed F.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Arafa, Wael A. A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Laine, Tanja M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Shatskiy, Andrey
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kärkäs, Markus D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Johnston, Eric V.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Substituent Effects in Molecular Ruthenium Water Oxidation Catalysts Based on Amide Ligands2017Inngår i: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 9, nr 9, s. 1583-1587Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The production of clean and sustainable energy is considered as one of the most urgent issues for our society. Mastering the oxidation of water to dioxygen is essential for the production of solar fuels. A study of the influence of the substituents on the catalytic activity of a series of mononuclear Ru complexes (2a-e) based on a tetradentate ligand framework is presented. At neutral pH, using [Ru(bpy)(3)](PF6)(3) (bpy=2,2'-bipyridine) as the terminal oxidant, a good correlation between the turnover frequency (TOF) and the Hammett sigma(meta) parameters was obtained. Additionally, a general pathway for the deactivation of Ru-based catalysts 2a-e during the catalytic oxidation of water through poisoning by carbon monoxide was demonstrated. These results highlight the importance of ligand design for fine-tuning the catalytic activity of water oxidation catalysts.

  • 5.
    Abdel-Magied, Ahmed F.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Shatskiy, Andrey
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Liao, Rong-Zhen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Laine, Tanja M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Arafa, Wael A. A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. University Fayoum, Egypt.
    Siegbahn, Per E. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kärkäs, Markus D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Bjorn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Johnston, Eric V.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Chemical and Photochemical Water Oxidation Mediated by an Efficient Single-Site Ruthenium Catalyst2016Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 9, nr 24, s. 3448-3456Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Water oxidation is a fundamental step in artificial photosynthesis for solar fuels production. In this study, we report a single-site Ru-based water oxidation catalyst, housing a dicarboxylate-benzimidazole ligand, that mediates both chemical and light-driven oxidation of water efficiently under neutral conditions. The importance of the incorporation of the negatively charged ligand framework is manifested in the low redox potentials of the developed complex, which allows water oxidation to be driven by the mild one-electron oxidant [Ru(bpy)(3)](3+) (bpy = 2,2'-bipyridine). Furthermore, combined experimental and DFT studies provide insight into the mechanistic details of the catalytic cycle.

  • 6. Abdissa, Negera
    et al.
    Fangfang, Pan
    Gruhonjic, Amra
    Gräfenstein, Jürgen
    Fitzpatrick, Paul A
    Landberg, Göran
    Rissanen, Kari
    Yenesew, Abiy
    Erdelyi, Mate
    Naphthalene Derivatives from the Roots of Pentas parvifolia and Pentas bussei.2016Inngår i: Journal of natural products (Print), ISSN 0163-3864, E-ISSN 1520-6025, Vol. 79, nr 9, s. 2181-2187Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The phytochemical investigation of the CH2Cl2/MeOH (1:1) extract of the roots of Pentas parvifolia led to the isolation of three new naphthalenes, parvinaphthols A (1), B (2), and C (3), two known anthraquinones, and five known naphthalene derivatives. Similar investigation of the roots of Pentas bussei afforded a new polycyclic naphthalene, busseihydroquinone E (4), a new 2,2'-binaphthralenyl-1,1'-dione, busseihydroquinone F (5), and five known naphthalenes. All purified metabolites were characterized by NMR and MS data analyses, whereas the absolute configurations of 3 and 4 were determined by single-crystal X-ray diffraction studies. The E-geometry of compound 5 was supported by DFT-based chemical shift calculations. Compounds 2-4 showed marginal cytotoxicity against the MDA-MB-231 human triple-negative breast cancer cell line with IC50 values ranging from 62.3 to 129.6 μM.

  • 7. Abdissa, Negera
    et al.
    Induli, Martha
    Fitzpatrick, Paul
    Alao, John Patrick
    Sunnerhagen, Per
    Landberg, Göran
    Yenesew, Abiy
    Erdelyi, Mate
    Cytotoxic quinones from the roots of Aloe dawei.2014Inngår i: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 19, nr 3, s. 3264-3273Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Seven naphthoquinones and nine anthraquinones were isolated from the roots of Aloe dawei by chromatographic separation. The purified metabolites were identified by NMR and MS analyses. Out of the sixteen quinones, 6-hydroxy-3,5-dimethoxy-2-methyl-1,4-naphthoquinone is a new compound. Two of the isolates, 5,8-dihydroxy-3-methoxy-2-methylnaphthalene-1,4-dione and 1-hydroxy-8-methoxy-3-methylanthraquinone showed high cytotoxic activity (IC₅₀ 1.15 and 4.85 µM) on MCF-7 breast cancer cells, whereas the others showed moderate to low cytotoxic activity against MDA-MB-231 (ER Negative) and MCF-7 (ER Positive) cancer cells.

  • 8.
    Acharya, P
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för bioorganisk kemi.
    Chattopadhyaya, J
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för bioorganisk kemi.
    The Hydrogen Bonding and Hydration of 2'-OH in Adenosine and Adenosine 3'-ethylphosphate.2002Inngår i: J. Org. Chem., Vol. 67, s. 1852-1865Artikkel i tidsskrift (Fagfellevurdert)
  • 9.
    Acharya, Parag
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för bioorganisk kemi.
    Studies on the Non-covalent Interactions (Stereoelectronics, Stacking and Hydrogen Bonding) in the Self-assembly of DNA and RNA2003Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis is based on ten publications (Papers I-X). The phosphodiester backbone makes DNA or RNA to behave as polyelectrolyte, the pentose sugar gives the flexibility, and the aglycones promote the self-assembly or the ligand-binding process. The hydrogen bonding, stacking, stereoelectronics and hydration are few of the important non-covalent forces dictating the self-assembly of DNA/RNA. The pH-dependent thermodynamics clearly show (Papers I and II) that a change of the electronic character of aglycone modulates the conformation of the sugar moiety by the tunable interplay of stereoelectronic anomeric and gauche effects, which are further transmitted to steer the sugar-phosphate backbone conformation in a cooperative manner. 3'-anthraniloyl adenosine (a mimic of 3'-teminal CCAOH of the aminoacyl-tRNAPhe) binds to EF-Tu*GTP in preference over 2'-anthraniloyl adenosine, thereby showing (Paper III) that the 2’-endo sugar conformation is a more suitable mimic of the transition state geometry than the 3’-endo conformation in discriminating between correctly and incorrectly charged aminoacyl-tRNAPhe by EF-Tu during protein synthesis. The presence of 2'-OH in RNA distinguishes it from DNA both functionally as well as structurally. This work (Paper IV) provides straightforward NMR evidence to show that the 2'-OH is intramolecularly hydrogen bonded with the vicinal 3'-oxygen, and the exposure of the 3'-phosphate of the ribonucleotides to the bulk water determines the availability of the bound water around the vicinal 2'-OH, which then can play various functional role through inter- or intramolecular interactions. The pH-dependent 1H NMR study with nicotinamide derivatives demonstrates (Paper V) that the cascade of intramolecular cation (pyridinium)-π(phenyl)-CH(methyl) interaction in edge-to-face geometry is responsible for perturbing the pKa of the pyridine-nitrogen as well as for the modulation of the aromatic character of the neighboring phenyl moiety, which is also supported by the T1 relaxation studies and ab initio calculations. It has been found (Papers VI-IX) that the variable intramolecular electrostatic interaction between electronically coupled nearest neighbor nucleobases (steered by their respective microenvironments) can modulate their respective pseudoaromatic characters. The net result of this pseudoaromatic cross-modulation is the creation of a unique set of aglycones in an oligo or polynucleotide, whose physico-chemical properties are completely dependent upon the propensity and geometry of the nearest neighbor interactions (extended genetic code). The propagation of the interplay of these electrostatic interactions across the hexameric ssDNA chain is considerably less favoured (effectively up to the fourth nucleobase) compared to that of the isosequential ssRNA (up to the sixth nucleobase). The dissection of the relative strength of basepairing and stacking in a duplex shows that stability of DNA-DNA duplex weakens over the corresponding RNA-RNA duplexes with the increasing content of A-T/U base pairs, while the strength of stacking of A-T rich DNA-DNA duplex increases in comparison with A-U rich sequence in RNA-RNA duplexes (Paper X).

  • 10.
    Adbo, Karina
    et al.
    Högskolan i Kalmar, Naturvetenskapliga institutionen.
    Andersson, Håkan S.
    Högskolan i Kalmar, Naturvetenskapliga institutionen.
    Ankarloo, Jonas
    Högskolan i Kalmar, Naturvetenskapliga institutionen.
    Karlsson, Jesper G.
    Högskolan i Kalmar, Naturvetenskapliga institutionen.
    Norell, M C
    Olofsson, Linus
    Högskolan i Kalmar, Naturvetenskapliga institutionen.
    Svenson, Johan
    Högskolan i Kalmar, Naturvetenskapliga institutionen.
    Örtegren, U
    Nicholls, Ian A.
    Högskolan i Kalmar, Naturvetenskapliga institutionen.
    Enantioselective synthetic receptors for Tröger’s base1999Inngår i: Bioorganic Chemistry, Vol. 27, nr 5, s. 363-371Artikkel i tidsskrift (Fagfellevurdert)
  • 11.
    Adolfsson, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal-catalyzed epoxidation of alkenes2010Inngår i: Modern Oxidation Methods / [ed] Jan-Erling Bäckvall, Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA , 2010, 2, s. 37-84Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 12.
    Adrian Meredith, Jenny
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Design and Synthesis of Inhibitors Targeting the Aspartic Proteases HIV-1 PR and BACE-12009Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis describes the synthesis of molecules designed for inhibition of two aspartic proteases, viral HIV-1 PR and human BACE-1. It also reports on the structure activity relationships of the targeted enzyme inhibitors.

    It is estimated that currently 33 million people are infected with HIV, the causative agent of AIDS. The virus targets T-lymphocytes and macrophages of the human immune system. The HIV-1 PR plays an important role in the viral replication, and by inhibiting the enzyme the disease progression can be slowed down or even halted.

    Herein is reported the design and synthesis of a series of HIV-1 PR inhibitors with novel P2 substituents of which several inhibit the enzyme in the nanomolar range. The aim of the second work was to further develop the inhibitors by the introduction of fluorine. Several attempts were performed to fluorinate different P2-substituents.

    Alzheimer’s disease (AD) is neurodegenerative, progressive and fatal disorder of the brain. It is associated with accumulation of plaques and tangles that cause impairment and functional decline of brain tissue which result in loss of memory and cognition. The plaques are mainly constituted of amyloid-β peptides that are generated in two steps from the amyloid precursor protein (APP). The cleavage sequence is initiated by the aspartic protease BACE-1, which makes the enzyme a key target in the effort of finding a therapy that aim to slow down the progression of AD.

    Herein are enclosed the development of two series of potent BACE-1 inhibitors. In the first work a synthetic strategy was developed to truncate a previously reported hydroxyethylene core structure in order to generate more drug-like inhibitors. This generated a series of truncated inhibitors where two amide bonds have been replaced with an ether - or alternatively a secondary amine linkage. A number of these inhibitors show potency against BACE-1. In the second part of the work the aim was investigate the effect of alterations in the P1 position. Five scaffolds with new P1 substituents were designed, synthesized and coupled with two different P2-P3 substituents. This resulted in a series of potent inhibitors that inhibit BACE-1 in the nanomolar range.

  • 13. 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.

  • 14.
    Afewerki, Samson
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Direct regiospecific and highly enantioselective intermolecular a-allylic alkylation of aldehydes by combination of transition metal and chiral amine catalysts2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The direct intermolecular regiospecific and highly enantioselective a-allylic alkylation of linear aldehydes by combination of achiral bench stable Pd(0) complexes and simple chiral amines as co-catalysts is disclosed. The co-catalytic asymmetric chemoselective and regiospecific a-allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2-alkyl alcohols with high enantiomeric ratios (up to 98:2 er). It is also an expeditious entry to valuable 2-alkyl substituted hemiacetals and 2-alkyl-butane-1,4-diols.

  • 15. Afewerki, Samson
    et al.
    Breistein, Palle
    Deiana, Luca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dziedzic, Pawel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ibrahem, Ismail
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Catalytic enantioselective β -alkylation of α,β-unsaturated aldehydes by combination of transition-metal- and aminocatalysis: Total synthesis of bisabolane sesquiterpenes2011Inngår i: Chemistry: a European Journal, ISSN 0947-6539, Vol. 17, nr 32, s. 8784-8788Artikkel i tidsskrift (Fagfellevurdert)
  • 16.
    Afewerki, Samson
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Breistein, Palle
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Pirttilä, Kristian
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Deiana, Luca
    Univ Stockholm, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden.
    Dziedzic, Pawel
    Univ Stockholm, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden.
    Ibrahem, Ismail
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Córdova, Armando
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Catalytic Enantioselective beta-Alkylation of alpha,beta-Unsaturated Aldehydes by Combination of Transition-Metal- and Aminocatalysis: Total Synthesis of Bisabolane Sesquiterpenes2011Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, nr 32, s. 8784-8788Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Branching out! The first co-catalytic enantioselective (up to 98:2 e.r.) β-alkylation of α,β-unsaturated aldehydes by combination of simple chiral amine and copper catalysts provides β-branched aldehydes in a one-pot protocol (see scheme). The methodology was applied to the short total syntheses of bisabolane sesquiterpenes (S)-(+)-curcumene, (E)-(S)-(+)-3- dehydrocurcumene and (S)-(+)-tumerone. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • 17. Afewerki, Samson
    et al.
    Ibrahem, Ismail
    Rydfjord, Jonas
    Breistein, Palle
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Direct Regiospecific and Highly Enantioselective Intermolecular α-Allylic Alkylation of Aldehydes by a Combination of Transition-Metal and Chiral Amine Catalysts2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 10, s. 2972-2977Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first direct intermolecular regiospecific and highly enantioselective a-allylic alkylation of linear aldehydes by a combination of achiral bench-stable Pd0 complexes and simple chiral amines as co-catalysts is disclosed. The co-catalytic asymmetric chemoselective and regiospecific a-allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2-alkyl alcohols with high enantiomeric ratios (up to 98:2 e.r.; e.r.=enantiomeric ratio). It is also an expeditious entry to valuable 2-alkyl substituted hemiacetals, 2-alkyl-butane-1,4-diols, and amines. The concise co-catalytic asymmetric total syntheses of biologically active natural products (e.g., Arundic acid) are disclosed.

  • 18.
    Afewerki, Samson
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Ibrahem, Ismail
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Rydfjord, Jonas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Breistein, Palle
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Córdova, Armando
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Direct Regiospecific and Highly Enantioselective Intermolecular α-Allylic Alkylation of Aldehydes By Combination of Transition Metal and amine Catalysts2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 10, s. 2972-2977Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first direct intermolecular regiospecific and highly enantioselective α-allylic alkylation of linear aldehydes by a combination of achiral bench-stable Pd 0 complexes and simple chiral amines as co-catalysts is disclosed. The co-catalytic asymmetric chemoselective and regiospecificα-allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2-alkyl alcohols with high enantiomeric ratios (up to 98:2 e.r.; e.r.=enantiomeric ratio). It is also an expeditious entry to valuable 2-alkyl substituted hemiacetals, 2-alkyl-butane-1,4-diols, and amines. The concise co-catalytic asymmetric total syntheses of biologically active natural products (e.g., Arundic acid) are disclosed. Go organic! Directintermolecular regiospecific and highly enantioselective α-allylic alkylation of linear aldehydes by a combination of achiral bench-stable Pd 0complexes and simple chiral amines as co-catalysts is disclosed (see scheme). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • 19. Agasti, Soumitra
    et al.
    Maity, Soham
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Maiti, Debabrata
    Palladium-Catalyzed Synthesis of 2,3-Disubstituted Benzofurans: An Approach Towards the Synthesis of Deuterium Labeled Compounds2015Inngår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 357, nr 10, s. 2331-2338Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Palladium-catalyzed oxidative annulations between phenols and alkenylcarboxylic acids produced a library of benzofuran compounds. Depending on the nature of the substitution of the phenol precursor, either 2,3-dialkylbenzofurans or 2-alkyl-3-methylene-2,3-dihydrobenzofurans can be synthesized with excellent regioselectivity. Reactions between conjugated 5-phenylpenta-2,4-dienoic acids and phenol gave 3-alkylidenedihydrobenzofuran alkaloid motifs while biologically active 7-arylbenzofuran derivatives were prepared by starting from 2-phenylphenols. More interestingly, selective incorporation of deuterium from D2O has been discovered, which offers an attractive one-step method to access deuterated compounds.

  • 20.
    Aggarwal, Varinder K.
    et al.
    Bristol University.
    Olofsson, Berit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. University of Bristol, Bristol, UK.
    Enantioselective α-arylation of cyclohexanones with diaryl iodonium salts: Application to the synthesis of (-)-epibatidine.2005Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 44, nr 34, s. 5516-5519Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The direct asym. α-arylation of prochiral ketones has been effected using chiral lithium amide bases and diaryl iodonium salts. The methodol. has been employed in a short total synthesis of the alkaloid (-)-epibatidine. [on SciFinder(R)]

  • 21.
    Agnemo, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten.
    Ligniners reaktioner med alkalisk väteperoxid1981Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Under alkaline conditions hydrogen peroxide can be used either as a 1ignin-degrading or a 1ignin-preserving bleaching agent. If heavy metal ions are present and/or silicate is absent in the reaction medium, hydrogen peroxide decomposes via hydroxyl radicals and superoxide ions to oxygen and water. These decomposition products are able to react for example with phenolic lignin structures and thereby cause a partial degradation of lignin. In such a system peroxide could act as a bleaching and delignifying agent at the same time and these properties can be utilized for the bleaching of chemical pulps.In order to elucidate the factors which influence the degradation of phenolic structures by oxidation with alkaline hydrogen peroxide the lignin model compounds-methylsyringyl alcohol was studied.By determining the first order reaction rate constants for the oxidation, the main results which were obtained indicate that phenolic lignin structures can be efficiently degraded especially if:A. The pH in the bleaching liquor is close to the pK -valueàfor hydrogen peroxide.B. The ionic strength in the bleaching medium is as high as possible.C. A fixed amount of heavy metal ions (manganese) is added to the bleaching liquor.In the presence of silicate and diethylentriaminepenta-acetic acid (DTPA) hydrogen peroxide is stabilized against decomposition. Under these conditions alkaline hydrogen peroxide is able to react only with lignin units containing conjugated carbonyl groups such as quinone, aryl-oe-carbonyl and cinnamaldehyd structures, leading to an elimination of the chromophoric structures without any substantial dissolution of lignin. In this part of work we have elucidated the kinetic behavior and the reaction products from lignin model compounds of the aryl-of- carbonyl and cinnamaldehyde types.1,2-Diarylpropan-1,3,-diol structures constitute an important building unit in native lignins. We have demonstrated that under hydrogen peroxide bleaching conditions the model compound 2,3--bis(4-hydroxy-3-methoxyphenyl)-3-ethoxy-propanol was converted to stilbenes, ûe. structures which when present in pulps may contribute to a rapid yellowing. The results obtained with model compounds under simulated lignin retaining bleaching conditions demonstrate that there are possibilities to improve the bleaching of mechanical pulps with hydrogen peroxide if:A. The remaining heavy metal ions complexed with DTPA are present in their lowest valence states.B. The concentration of hydroperoxy ions can be maintained at a high level at the lowest possible pH-value.

  • 22.
    Agrawal, Santosh
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martínez-Castro, Elisa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Marcos, Rocio
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Readily Available Ruthenium Complex for Efficient Dynamic Kinetic Resolution of Aromatic alpha-Hydroxy Ketones2014Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 16, nr 8, s. 2256-2259Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A ruthenium complex formed from commercially available [Ru(p-cymene)Cl-2](2) and 1,4-bis(diphenylphosphino)butane catalyzes the racemization of aromatic alpha-hydroxy ketones very efficiently at room temperature. The racemization is fully compatible with a kinetic resolution catalyzed by a lipase from Pseudomonas stutzeri. This is the first example of dynamic kinetic resolution of alpha-hydroxy ketones at ambient temperature in which the metal and enzyme catalysts work in concert in one pot at room temperature to give quantitative yields of esters of alpha-hydroxy ketones with very high enantioselectivity.

  • 23. Aguilera, Adriana Freites
    et al.
    Tolvanen, Pasi
    Heredia, Shuyana
    Muñoz, Marta González
    Samson, Tina
    Oger, Adrien
    Verove, Antoine
    Eränen, Kari
    Leveneur, Sebastien
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry & Reaction Engineering, Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Salmi, Tapio
    Epoxidation of fatty acids and vegetable oils assisted by microwaves catalyzed by a cation exchange resin2018Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 57, nr 11, s. 3876-3886Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Epoxidation of oleic acid and cottonseed oil was conducted in a semibatch reactor with in-situ-formed percarboxylic acid (peracetic acid or perpropionic acid), using hydrogen peroxide as an oxidizing agent and carboxylic acid (acetic acid or propionic acid) as oxygen carriers. Amberlite IR-120 was implemented as the catalyst. The system was comprised of a loop reactor, where the mixture was pumped through a single-mode cavity in which microwave irradiation was introduced. A heat exchanger was integrated into the system to replace microwave heating, to compare the results obtained via microwave heating versus conventional heating. The catalyst loading effect was studied, as well as the influence of microwave irradiation and the implementation of the SpinChem rotating bed reactor (RBR), in hopes of decreasing the influence of the internal mass transfer. The application of microwave irradiation results in an improvement of the reaction yield in the absence of a catalyst.

  • 24.
    Ahlford, Katrin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Asymmetric transfer hydrogenation of ketones: Catalyst development and mechanistic investigation2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The development of ligands derived from natural amino acids for asymmetric transfer hydrogenation (ATH) of prochiral ketones is described herein. In the first part, reductions performed in alcoholic media are examined, where it is found that amino acid-derived hydroxamic acids and thioamides, respectively, are simple and versatile ligands that in combination with [RhCp*Cl2]2 efficiently catalyze this particular transformation. Selectivities up to 97% ee of the corresponding secondary alcohols are obtained, and it is furthermore observed that the two different ligand classes, albeit based on the same amino acid scaffold, give rise to products of opposite configuration.

    The highly interesting enantioswitchable nature of the two abovementioned catalysts is studied in detail by mechanistic investigations. A structure/activity correlation analysis is performed, which reveals that the diverse behavior of the catalysts arise from different interactions between the ligands and the metal. Kinetic studies furthermore stress the catalyst divergence, since a difference in the rate determining step is established from initial rate measurements. In addition, rate constants are determined for each step of the overall reduction process.

    In the last part, catalyst development for ATH executed in water is discussed. The applicability of hydroxamic acid ligands is further extended, and catalysts based on these compounds are found to be efficient and compatible with aqueous conditions. The structurally even simpler amino acid amide is also evaluated as a ligand, and selectivities up to 90% ee are obtained in the reduction of a number of aryl alkyl ketones. The very challenging reduction of dialkyl ketones is moreover examined in the Rh-catalyzed aqueous ATH, where a modified surfactant-resembling sulfonylated diamine is used as ligand, and the reaction is carried out in the presence of SDS-micelles. A positive effect is to some extent found on the catalyst performance upon addition of phase-transfer components, especially regarding the catalytic activity in the reduction of more hydrophobic substrates.

  • 25.
    Ahlford, Katrin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Adolfsson, Ha