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  • 1.
    Albers, Michael F
    et al.
    Department of Chemical Biology, Max-Planck Institute of Molecular Physiology.
    van Vliet, Bart
    Hedberg, Christian
    Amino acid building blocks for efficient Fmoc solid-phase synthesis of peptides adenylylated at serine or threonine2011In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 13, no 22, p. 6014-6017Article in journal (Refereed)
    Abstract [en]

    The first straightforward building block based (non-interassembly) synthesis of peptides containing adenylylated serine and threonine residues is described. Key features include final global acidolytic protective group removal as well as full compatibility with standard Fmoc solid-phase peptide synthesis (SPPS). The described Thr-AMP SPPS-building block has been employed in the synthesis of the Thr-adenylylated sequence of human GTPase CDC42 (Ac-SEYVP-T(AMP)-VFDNYGC-NH(2)). Further, we demonstrate proof-of-concept for the synthesis of an Ser-adenylylated peptide (Ac-GSGA-S(AMP)-AGSGC-NH(2)) from the corresponding adenylylated serine building block.

  • 2.
    Andersson, Hans
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Banchelin, Thomas Sainte-Luce
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Das, Pralay
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gustafsson, Magnus
    Acadia Pharmaceuticals AB, Medeon Science Park S-20512, Malmö, Sweden.
    Olsson, Roger
    Acadia Pharmaceuticals AB, Medeon Science Park S-20512, Malmö, Sweden.
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Complete regioselective addition of grignard reagents to pyrazine N-oxides, toward an efficient enantioselective synthesis of substituted piperazines2010In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 12, no 2, p. 284-6Article in journal (Refereed)
    Abstract [en]

    A conceptually new one-pot strategy for the synthesis of protected substituted piperazines via the addition of Grignard reagents to pyrazine N-oxides is presented. This strategy is high yielding (33-91% over three steps), step-efficient, and fast. The synthesized N,N-diprotected piperazines are convenient to handle and allow for orthogonal deprotection at either nitrogen for selective transformations. In addition, this is a synthetic route to enantiomerically enriched piperazines by using a combination of phenyl magnesium chloride and (-)-sparteine, which resulted in enantiomeric excesses up to 83%.

  • 3.
    Barange, Deepak Kumar
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johnson, Magnus T.
    Cairns, Andrew G.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Olsson, Roger
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Regio- and Stereoselective Alkylation of Pyridine-N-oxides: Synthesis of Substituted Piperidines and Pyridines2016In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 18, no 24, p. 6228-6231Article in journal (Refereed)
    Abstract [en]

    Regio- and stereoselective addition of alkyl Grignard reagents to pyridine-N-oxides gave C2-alkylated N-hydroxy-1,2,5,6-tetrahydropyridines and trans-2,3-disubstituted N-hydroxy-1,2,5,6-tetrahydropyridines in good to excellent yields. These intermediates were aromatized or alternatively reduced in one-pot methodologies for efficient syntheses of alkylpyridines or piperidines, respectively. These reactions have a broad substrate scope and short reaction times.

  • 4.
    Hussain, Munawar
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Banchelin, Thomas Sainte-Luce
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Andersson, Hans
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Olsson, Roger
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Enantioselective synthesis of substituted piperidines by addition of aryl Grignard reagents to pyridine N-oxides2013In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 15, no 1, p. 54-57Article in journal (Refereed)
    Abstract [en]

    The synthesis of optically active piperidines by enantioselective addition of aryl Grignard reagents to pyridine N-oxides and lithium binolate followed by reduction is reported for the first time. The reaction results in high yields (51-94%) in combination with good ee (54-80%). Some of these products were subsequently recrystallized, affording enhanced optical purities (>99% ee).

  • 5.
    Krzyzanowski, Adrian
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Saleeb, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Elofsson, Mikael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Synthesis of Indole-, Benzo[ b]thiophene-, and Benzo[ b]selenophene-Based Analogues of the Resveratrol Dimers Viniferifuran and (±)-Dehydroampelopsin B.2018In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 20, no 21, p. 6650-6654Article in journal (Refereed)
    Abstract [en]

    A convenient synthetic strategy to obtain viniferifuran and (±)-dehydroampelopsin B analogues based on the heterocyclic cores of indole, benzo[ b]thiophene, and benzo[ b]selenophene is presented. The key transformations utilized in the described syntheses include Sonogashira couplings, Cacchi and alkyne electrophilic cyclizations, Horner-Wadsworth-Emmons (HWE) reaction, chemoselective Suzuki-Miyaura couplings, and acid-promoted intramolecular cyclization to form the seven-membered ring of (±)-dehydroampelopsin B.

  • 6.
    Mogemark, Mickael
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Elofsson, Mikael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kihlberg, Jan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Monitoring Solid-Phase Glycoside Synthesis with 19F NMR Spectroscopy2001In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 3, no 10, p. 1463-1466Article in journal (Refereed)
    Abstract [en]

    A simple and efficient method for monitoring and optimizing carbohydrate synthesis on polymeric support by using 19F NMR spectroscopy is described. The method relies on the use of fluorinated variants of protective groups that are in common use in oligosaccharide synthesis.

  • 7.
    Mogemark, Mickael
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gustafsson, Linda
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bengtsson, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Elofsson, Mikael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kihlberg, Jan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    A fluorinated selenide linker for solid-phase synthesis of n-pentenyl glycosides2004In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 6, no 26, p. 4885-4888Article in journal (Refereed)
    Abstract [en]

    A fluorine-labeled selenide linker for installing terminal isolated olefins has been synthesized in high overall yield. The resin-bound linker could be glycosylated both with glycosyl trichloroacetimidates and glycosyl fluorides. The linker did not decompose after oxidation with tBuOOH but underwent beta-elimination when it was subjected to heat. This allowed the released n-pentenyl glycoside 15 to be isolated in excellent yield and purity after filtration.

  • 8.
    Moodie, Lindon W. K.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Chammaa, Samy
    Kindahl, Tomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hedberg, Christian
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Palladium-Mediated Approach to Coumarin-Functionalized Amino Acids2017In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 19, no 11, p. 2797-2800Article in journal (Refereed)
    Abstract [en]

    Incorporation of the fluorogenic l-(7-hydroxycoumarin-4-yl)ethylglycine into proteins is a valuable biological tool. Coumarins are typically accessed via the Pechmann reaction, which requires acidic conditions and lacks substrate flexibility. A Pd-mediated coupling is described between o-methoxyboronic acids and a glutamic acid derived (Z)-vinyl triflate, forming latent coumarins. Global deprotection with BBr3 forms the coumarin scaffold in a single step. This mild and scalable route yielded five analogues, including a probe suitable for use at lower pH.

  • 9. Pandey, Sunil Kumar
    et al.
    Guttormsen, Yngve
    Haug, Bengt Erik
    Hedberg, Christian
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bayer, Annette
    A Concise Total Synthesis of Breitfussin A and B2015In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 17, no 1, p. 122-125Article in journal (Refereed)
    Abstract [en]

    The first total synthesis of breitfussin A and B is described. The approach features two palladium-catalyzed cross-couplings installing the indole and pyrrole onto the oxazole core and selective lithiation/iodination of a common indole-oxazole fragment providing 2,4-diiodinated or 2-iodinated oxazoles as potential precursors for breitfussin A and B, respectively. An unexpected acid promoted deiodination was utilized in the synthesis of breitfussin B. Comparison of the synthetic material with previously reported spectral data of isolated breitfussin A and B verified the structure of the breitfussin framework.

  • 10.
    Pemberton, Nils
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Emtenäs, Hans
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Domaille, Peter J
    Greenberg, William A
    Levin, Michael D
    Zhu, Zuolin
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Cycloaddition of 2-thiazolines and acyl ketenes under acidic conditions results in bicyclic 1,3-oxazinones and not 6-acylpenams as earlier reported2005In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 7, no 6, p. 1019-1021Article in journal (Refereed)
    Abstract [en]

    Optically active 2-thiazolines 4 were previously reported to react with acyl Meldrum's acid derivatives 5 under acidic conditions (HCl (g) in benzene) to stereoselectively give 6-acylpenams 1. Recently we have discovered that the structure elucidation of these compounds was incorrect. Thus, we report new data showing that instead of acyl -lactams, the optically active isomers 3R,9R-1,3-oxazinones 3a-g are obtained stereoselectively in 38-93% yields.

  • 11.
    Pemberton, Nils
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jakobsson, Lotta
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Synthesis of multi ring-fused 2-pyridones via an acyl-ketene imine cyclocondensation2006In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 8, no 5, p. 935-938Article in journal (Refereed)
    Abstract [en]

    Polycyclic ring-fused 2-pyridones (5a−e and 9a−e) have been prepared via a microwave-assisted acyl-ketene imine cyclocondensation. Starting from 3,4-dihydroisoquinolines (4a−b) or 3,4-dihydroharman (8), fused 2-pyridones could be prepared in a one-step procedure. By using either Meldrum's acid derivatives (1a−d) or 1,3-dioxine-4-ones (7a−b) as acyl-ketene sources, mono- or disubstitution of the fused 2-pyridone ring could be accomplished. As an application of the method, a formal synthesis of the indole alkaloid sempervilam was performed.

  • 12.
    Sellstedt, Magnus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    A novel heterocyclic Scaffold formed by ring expansion of a cyclic Sulfone to Sulfonamides2009In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 11, no 23, p. 5470-5472Article in journal (Refereed)
    Abstract [en]

    A novel heterocyclic scaffold with a peptidomimetic backbone structure has been synthesized. The scaffold is formed by insertion of primary amines into a cyclic sulfone to give the corresponding ring-expanded sulfonamides. By varying the amine component, a series of potentially biologically interesting compounds has been synthesized.

  • 13.
    Sellstedt, Magnus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    A three-component reaction forming naphthyridones: synthesis of lophocladine analogs2011In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 13, no 19, p. 5278-5281Article in journal (Refereed)
    Abstract [en]

    A three-component reaction forming dihydro 2,7-naphthyridine-1-ones has been developed. These unstable dihydro intermediates can be either oxidized or reduced to form naphthyridones or tetrahydro naphthyridones, respectively. The reaction tolerates a large variety of aldehydes and amines, and the produced compounds are analogs of the natural product lophocladine A.

  • 14.
    Singh, Pardeep
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Cairns, Andrew G.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Adolfsson, Dan E.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ådén, Jörgen
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sauer, Uwe H.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Synthesis of Densely Functionalized N-Alkenyl 2-Pyridones via Benzyne-Induced Ring Opening of Thiazolino-Fused 2-Pyridones2019In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 21, p. 6946-6950Article in journal (Refereed)
    Abstract [en]

    We report the synthesis of 6-arylthio-substituted-N-alkenyl 2-pyridones by ring opening of bicyclic thiazolino-2-pyridones with arynes. Varied functionalization was used to investigate scope and substituent influences on reactivity. Selected conditions favor thioether ring opening over [4 + 2] cycloaddition and an unusual aryne incorporating ring expansion. Deuterium labeling was used to clarify observed reactivity. Using the knowledge, we produced drug-like molecules with complex substitution patterns and show how thioether ring opening can be used on scaffolds with competing reactivities.

  • 15.
    Singh, Pardeep
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Chorell, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Krishnan, K Syam
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kindahl, Tomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ådén, Jörgen
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wittung-Stafshede, Pernilla
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Synthesis of multiring fused 2‑pyridones via a nitrene insertion reaction: fluorescent modulators of α‑synuclein amyloid formation2015In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 17, no 24, p. 6194-6197Article in journal (Refereed)
    Abstract [en]

    An efficient, straightforward method for the synthesis of thiazolo-2-pyridone embedded peptidomimetic polyheterocycles via a catalyst-free, microwave-assisted, intramolecular C−H amination reaction is reported. All the synthesized polyheterocycles were evaluated for their fluorescent properties and effect on α-synuclein amyloid formation.

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