| 1. |
- Lindström, Anton, et al.
(författare)
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Hierarchical PLS modeling for predicting the binding of a comprehensive set of structurally diverse protein-ligand complexes.
- 2006
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Ingår i: Journal of Chem Inf Model. - : American Chemical Society (ACS). - 1549-9596. ; 46:3, s. 1154-1167
-
Tidskriftsartikel (refereegranskat)abstract
- A new approach is presented for predicting ligand binding to proteins using hierarchical partial-least-squares regression to latent structures (Hi-PLS). Models were based on information from the 2002 release of the PDBbind database containing (after in-house refinement) high-resolution X-ray crystallography and binding affinity (Kd or Ki) data for 612 protein-ligand complexes. The complexes were characterized by four different descriptor blocks: three-dimensional (3D) structural descriptors of the proteins, protein-ligand interactions according to the Validate scoring function, binding site surface areas, and ligand 2D and 3D descriptors. These descriptor blocks were used in Hi-PLS models, generated using both linear and nonlinear terms, to relate the characterizations to pKd/i. The results show that each of the four descriptor blocks contributed to the model, and the predictions of pKd/i of the internal test set gave a root-mean-square error of prediction (RMSEP) of 1.65. The data were further divided according to the structural classification of the proteins, and Hi-PLS models were constructed for the resulting subclasses. The models for the four subclasses differed considerably in terms of both their ability to predict pKd/i (with RMSEPs ranging from 0.8 to 1.56) and the descriptor block that had the strongest influence. The models were validated with an external test set of 174 complexes from the 2003 release of the PDBbind database. The overall results show that the presented Hi-PLS methodology could facilitate the difficult task of predicting binding affinity.
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| 2. |
- Åberg, Veronica, 1976-, et al.
(författare)
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Microwave-assisted decarboxylation of bicyclic 2-pyridone scaffolds and identification of A beta-peptide aggregation inhibitors
- 2005
-
Ingår i: Organic and biomolecular chemistry. - London, U.K. : Royal Society of Chemistry. - 1477-0520 .- 1477-0539. ; 3:15, s. 2817-2823
-
Tidskriftsartikel (refereegranskat)abstract
- A reagent-free microwave-assisted decarboxylation procedure for carboxylic acid functionalized bicyclic 2-pyridones has been developed. This new method, based on microwave heating at 220 degrees C for 600 seconds in N-methyl pyrrolidone (NMP), proved to be practical and very efficient, resulting in decarboxylated 2-pyridones in near-quantitative yields. The decarboxylated products and the intermediate 2-pyridones in the form of carboxylic acid methyl esters and carboxylic acids were screened for their effect on A beta-peptide aggregation. Two out of the 21 2-pyridones described in this study inhibited amyloid formation of the Alzheimer A beta(1-40) peptide. The effect was seen even at a 4 : 1 ratio of 2-pyridone and monomeric A beta-peptide.
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| 3. |
- Adolfsson, Dan E., 1989-, et al.
(författare)
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Enhanement of amyloid fibril binding by ring expansion of thiazolino fused 2-pyridone peptidomimetics
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Thiazolino fused 2-pyridones undergo thiazoline ring opening by reaction with 2-nitrobenzyl bromide through thi- oether attack, and base promoted fragmentation of the resulting sulfonium ions. Subsequent deprotonation of the benzylic carbon and intramolecular 1,4-addition leads to ring closure, generating dihydrothiazine fused 2-pyridones by net ring expansion of the thiazoline ring. Application of the ring expansion procedure to the pyridine and pyrimidine fused thiazolino 2-pyridones provided compounds with enhanced fibril binding activity.
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| 4. |
- Adolfsson, Dan E., 1989-, et al.
(författare)
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Intramolecular Povarov Reactions for the Synthesis of Chromenopyridine fused 2-Pyridone Polyheterocycles Binding to α-Synuclein and Amyloid-β fibrils
- 2020
-
Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 85:21, s. 14174-14189
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A BF3×OEt2 catalyzed intramolecular Povarov reaction was used to synthesize a library of 15 chromenopyridine fused thiazolino-2-pyridone peptidomimetics. The reaction works with a range of O-alkylated salicylaldehydes and amino functionalized thiazolino-2-pyridones, to generate polyheterocycles with diverse substitution. The synthesized compounds were screened for their ability to bind α-synuclein and amyloid β fibrils in vitro. Analogs substituted with a nitro group bind to mature amyloid fibrils, and the activity moreover depends on the positioning of this functional group.
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| 5. |
- Adolfsson, Dan E., 1989-
(författare)
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Synthesis of Ring-fused Peptidomimetics : Interacting with Amyloid Fibrils
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Parkinson's and Alzheimer's disease are the two most common neurological disorders in humans. Both conditions involve progressive death of neurons in the central nervous system, decline in bodily functions and eventually (and invariably), death. So far, no cure exists and the available treatments can only ease symptoms. Despite substantial investments in research, the biomolecular processes are still far from fully understood. However, both diseases are associated with formation of fibrillar protein aggregates called amyloid deposits. Whereas Alzheimer’s disease involves aggregation of the Tau and Amyloid β proteins, α-Synuclein fibrilization plays a key role in Parkinson's disease. Although they are chemically distinct, the deposits consist of protein fibres with similar morphology and fold. Small molecules, such as the thiazoline fused 2-pyridones herein presented, can interfere with the formation of amyloid fibres, or bind to them. Besides having potential for diagnostication and treatment, such small molecules constitute valuable tool compounds in future research, to unravel the mechanisms of amyloid formation and pathology. The first step towards successful treatment, diagnostication and prevention of Alzheimer's and Parkinson's disease is understanding the causes and underlying mechanisms better. This thesis narrates the synthesis and development of novel chemical structures: multi ring fused peptidomimetics with the ability to bind mature amyloid fibrils, consisting of α-Synuclein or Amyloid β. The first project (articles I, III and VI) describes method development for the extension of bicyclic thiazolino 2-pyrdiones by fusion with aromatic nitrogen heterocycles, which enables the desired amyloid binding properties. Derivatisations of the newly generated central scaffold, and variation of the multiple attached substituents, were subsequently performed in efforts to improve binding strength and solubility, and gain selectivity towards certain fibrils. One of the most promising amyloid fibril binders was evaluated in a human cell line and in mice, and found to be protective against accelerator induced neurotoxicity. One pyrimidine fused compound moreover indicated potent inhibition of Amyloid b aggregation. The second project (articles II, IV and V) focuses on development of methods to modify the thiazoline ring. Ring opening induced by electrophiles generates N-alkenyl 2-pyridones but decreases amyloid binding potency. Introduction of a cyclobutane moiety fused with the thiazoline ring is better tolerated, and adds a terminal alkene moiety that can be exploited in future chemical modifications. Expansion of the five membered thiazoline ring to a six membered dihydrothiazine ring, equipped with a nitrophenyl substituent, provides compounds with enhanced fibril binding capacity, which further inhibits Amyloid β fibril formation in vitro. Taken together, the synthetic methodologies allow construction and late stage modification of complex fused heterocycles, with several points of variation. Thus, the developed methods may be of future value in our laboratories and elsewhere.
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| 6. |
- Aliashkevich, Alena, 1990-
(författare)
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Molecular mechanisms and biological consequences of the production of non-canonical D-amino acids in bacteria
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Most bacteria possess a vital net-like macromolecule – peptidoglycan (PG). PG encases bacteria around the cytoplasmic membrane to withstand the high internal turgor pressure and thereby protect the cell from bursting. In addition, PG is a major morphological determinant of bacteria being both required and sufficient to maintain cell shape. During cell growth PG hydrolysis and synthesis are tightly controlled to keep proper cell shape and integrity at all times. Given the essentiality of PG for bacterial growth and survival, the synthesis of this polymer is a major target of many natural and synthetic antibiotics (e.g. penicillins, glycopeptides).For a long time, PG composition was considered to be conserved and static, however it’s now being recognized as a dynamic and plastic macromolecule. The structure and chemistry of PG is influenced by a myriad of environmental cues that include interkingdom/interspecies interactions. Recently, it was found that a wide set of non-canonical D-amino acids (D-amino acids different from D-Ala and D-Glu, NCDAAs) are produced and released to the extracellular milieu by diverse bacteria. In Vibrio cholerae these NCDAAs are produced by broad-spectrum racemase enzyme (BsrV) and negatively regulate PG synthesis through their incorporation into PG. We have shown that in addition to D-Met and D-Leu, which were reported previously, V. cholerae also releases high amounts of D-Arg, which inhibits a broader range of phylogenetically diverse bacteria. Thus, NCDAAs affect not only the producer, but might target other species within the same environmental niche. However, in contrast to D-Met, D-Arg targets cell wall independent pathways. We have shown that non-proteinogenic amino acids also can be racemized by Bsr. A plant amino acid L-canavanine (L-CAN) is converted into D-CAN by a broad-spectrum amino acid racemase (BSAR) of the soil bacterium Pseudomonas putida and subsequently released to the environment. D-CAN gets highly incorporated into the PG of Rhizobiales (such as Agrobacterium tumefaciens, Sinorhizobium meliloti) thereby affecting the overall PG structure, bacterial morphogenesis and growth fitness. We found that detrimental effect of D-CAN in A. tumefaciens can be suppressed by a single amino acid substitution in the cell division PG transpeptidase penicillin-binding protein 3a (PBP3a). Rhizobiales are a polar-growing species that encode multiple LD-transpeptidases (LDTs), enzymes that normally perform PG crosslinking, but that can also incorporate NCDAAs into termini of the PG peptides. As these species incorporate high amounts of D-CAN in their PG, we hypothesized that LDTs might represent the main path used by NCDAAs to edit A. tumefaciens’ PG and cause their detrimental effects. Therefore, we decided to further explore the significance of LDT proteins for growth and morphogenesis in A. tumefaciens. While in the Gram-negative model organism E. coli LDT proteins are non-essential under standard laboratory conditions, we found that A. tumefaciens needs at least one LDT for growth out of the 14 putative LDTs encoded in its genome. Moreover, clustering the LDT proteins based on their sequence similarity revealed that A. tumefaciens has 7 LDTs that are exclusively present among Rhizobiales. Interestingly, the loss of this group of LDTs (but not the rest) leads to reduced growth, lower PG crosslinkage and rounded cell phenotype, which suggests that this group of Rhizobiales- specific LDTs have a major role in maintaining LD-crosslinking homeostasis, which in turn is important for cell elongation and proper shape maintenance in A. tumefaciens.
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| 7. |
- Almqvist, Andreas, et al.
(författare)
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An Abbott curve based rough surface contact mechanics approach
- 2005
-
Ingår i: Proceedings of the World Tribology Congress III - 2005. - New York : American Society of Mechanical Engineers. ; , s. 397-398
-
Konferensbidrag (refereegranskat)abstract
- In this way all the height information of the surface profile is preserved and not only a few parameters, like Ra, Rq, Rz, Rsk, etc. The aim of this work is to investigate how classes of surfaces based on a single Abbott curve perform in terms of contact mechanical parameters like the real area of contact. The result shows that surfaces taken from a class of random surfaces generated from a specific Abbott curve behaves similar in a contact mechanics simulation. That is, the distribution of for example the real area of contact within such a class is compact, having a small deviation from its mean.This implies that it is possible to simulate classes of surfaces based on Abbott curves and to use the results to predict contact mechanical properties of real surface topographies.
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| 8. |
- Almqvist, Andreas, et al.
(författare)
-
Development of a lubrication simulation model
- 2009
-
Ingår i: Svenska mekanikdagarna. - Stockholm : Svenska nationalkommittén för mekanik. ; , s. 74-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 9. |
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| 10. |
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| 11. |
- Almqvist, Andreas, et al.
(författare)
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On the dry elasto-plastic contact of nominally flat surfaces
- 2007
-
Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 40:4, s. 574-579
-
Tidskriftsartikel (refereegranskat)abstract
- A model to be used for numerical simulation of the contact of linear elastic perfectly plastic rough surfaces was developed. Energy dissipation due to plastic deformation is taken into account. Spectral theory and an FFT-techique are used to facilitate the numerical solution process. Results of simulations using four two-dimensional profiles with different topographies in contact with a rigid plane for a number loads are reported. From the results it is clear that the real area of contact (Ar) changes almost linearly with load and is only slightly affected by the difference in topography. A plasticity index is defined as the ratio of plastically deformed area (Ap) and Ar. Plastic deformation occurs even at low loads and there is a significant difference in plasticity index between the surface profiles considered. An investigation on how the spectral content of the surface profile influences the results presented is also performed. This is to ensure that the metrological limitations of the optical profilerused to measure the surfaces do not have a significant influence. It is concluded that the highest frequencies of the measured profile have a negligible influence on the real area of contact.
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| 12. |
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| 13. |
- Almqvist, Fredrik, et al.
(författare)
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An Improved Procedure for the Synthesis of Bicyclo[2.2.2]octane- 2,6-dione
- 1993
-
Ingår i: Synthetic Communications. - : Informa UK Limited. - 0039-7911 .- 1532-2432. ; 23:11, s. 1499-1505
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Tidskriftsartikel (refereegranskat)abstract
- Conjugate addition of Meldrum's acid to 2-cyclohexenone followed by direct cyclization in PPA/acetic acid constitutes a shorter, more reproducible and higher yielding route to bicyclo[2.2.2]octane-2,6-dione than previous methods. The crude dione could be used as substrate for the baker's yeast reduction to (IR, 4S, 6S)-bicyclo[2.2.2]octane-6-ol-2-one.
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| 14. |
- Almqvist, Fredrik, et al.
(författare)
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Neighboring Group Participation in a Regio- and Stereoselective Chlorination of a Bicyclo[2.2.2]octanone
- 1996
-
Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 1520-6904 .- 0022-3263. ; 61:20, s. 6947-6951
-
Tidskriftsartikel (refereegranskat)abstract
- The zinc chloride-mediated acetylation of the optically active silyl enol ether 2a gave the beta-diketone 3a (48%) together with the regio- and stereoselectively chlorinated compound 4 (27%). The yield of 4 increased to 70% by starting from the O-acetyl derivative 2c. The chlorination most likely occurs via neighboring group participation by the endo acetoxy group.
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Almqvist, Fredrik, et al.
(författare)
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Spirobicyclo[2.2.2]octane derivatives: mimetics of baccatin III and paclitaxel (Taxol)
- 2004
-
Ingår i: Organic & Biomolecular Chemistry. - : Royal Society of Chemistry (RSC). - 1477-0520 .- 1477-0539. ; 2:21, s. 3085-3090
-
Tidskriftsartikel (refereegranskat)abstract
- The formylated spirobyclic alcohol 8a was computer modeled to be a mimetic of paclitaxel. In this model, the formyl group was used as a truncated paclitaxel side chain in order to reduce the computational work. Compound 8c, carrying the paclitaxel side chain, was synthesized in six steps from optically active 1,3-diketone 12. Microtubule stabilization was not observed for 8c, indicating that the model needs to be adjusted.
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| 19. |
- Almqvist, Fredrik, et al.
(författare)
-
Spirobicyclo[2.2.2]octane derivatives: mimetics of baccatin III and paclitaxel (Taxol)
- 2004
-
Ingår i: Organic and Biomolecular Chemistry. - 1477-0539. ; 2:21, s. 3085-3090
-
Tidskriftsartikel (refereegranskat)abstract
- The formylated spirobyclic alcohol 8a was computer modeled to be a mimetic of paclitaxel. In this model, the formyl group was used as a truncated paclitaxel side chain in order to reduce the computational work. Compound 8c, carrying the paclitaxel side chain, was synthesized in six steps from optically active 1,3-diketone 12. Microtubule stabilization was not observed for 8c, indicating that the model needs to be adjusted.
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| 20. |
- Almqvist, Fredrik, et al.
(författare)
-
Spirobicyclo[2.2.2]octane derivatives: mimetics of baccatin III and paclitaxel (Taxol)
- 2004
-
Ingår i: ORGANIC & BIOMOLECULAR CHEMISTRY. - : Royal Society of Chemistry (RSC). - 1477-0520 .- 1477-0539. ; 2:21, s. 3085-90
-
Tidskriftsartikel (refereegranskat)abstract
- The formylated spirobyclic alcohol 8a was computer modeled to be a mimetic of paclitaxel. In this model, the formyl group was used as a truncated paclitaxel side chain in order to reduce the computational work. Compound 8c, carrying the paclitaxel side chain, was synthesized in six steps from optically active 1,3-diketone 12. Microtubule stabilization was not observed for 8c, indicating that the model needs to be adjusted.
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| 21. |
- Almqvist, Fredrik, et al.
(författare)
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Synthesis of Optically Active endo, endo Bicyclo[2.2.2]octane-2,5- diol, Bicyclo[2.2.2]octan-2,5-dione and Related Compounds
- 1996
-
Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 1520-6904 .- 0022-3263. ; 61:11, s. 3794-3798
-
Tidskriftsartikel (refereegranskat)abstract
- Optically active C-2-symmetric (1S,2S,4S,5S)-bicyclo[2.2.2]octane-2,5-diol ((+)-12; 98% ee) and several selectivity protected optically active intermediates useful for synthetic transformations were synthesized via a 1,2-carbonyl transposition route starting from the easily available optically active (1R,4S,6S)-6-hydroxybicyclo[2.2.2]octan-2-one ((-)-2). The synthetic route also allowed the preparation of optically active (1S,4S)-bicyclo[2.2.2]octane-2,5-dione ((+)-14; 98% ee).
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| 22. |
- Andersson, Emma K., et al.
(författare)
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Modulation of Curli Assembly and Pellicle Biofilm Formation by Chemical and Protein Chaperones
- 2013
-
Ingår i: Chemistry and Biology. - : Elsevier. - 1074-5521 .- 1879-1301. ; 20:10, s. 1245-1254
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Tidskriftsartikel (refereegranskat)abstract
- Enteric bacteria assemble functional amyloid fibers, curli, on their surfaces that share structural and biochemical properties with disease-associated amyloids. Here, we test rationally designed 2-pyridone compounds for their ability to alter amyloid formation of the major curli subunit CsgA. We identified several compounds that discourage CsgA amyloid formation and several compounds that accelerate CsgA amyloid formation. The ability of inhibitor compounds to stop growing CsgA fibers was compared to the same property of the CsgA chaperone, CsgE. CsgE blocked CsgA amyloid assembly and arrested polymerization when added to actively polymerizing fibers. Additionally, CsgE and the 2-pyridone inhibitors prevented biofilm formation by Escherichia coli at the air-liquid interface of a static culture. We demonstrate that curli amyloid assembly and curli-dependent biofilm formation can be modulated not only by protein chaperones, but also by "chemical chaperones."
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| 23. |
- Andersson, Hans, et al.
(författare)
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Complete regioselective addition of grignard reagents to pyrazine N-oxides, toward an efficient enantioselective synthesis of substituted piperazines.
- 2010
-
Ingår i: Organic letters. - : American Chemical Society (ACS). - 1523-7052 .- 1523-7060. ; 12:2, s. 284-6
-
Tidskriftsartikel (refereegranskat)abstract
- 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%.
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| 24. |
- Andersson, Hans, et al.
(författare)
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Efficient, mild and completely regioselective synthesis of substituted pyridines
- 2010
-
Ingår i: Chemical Communications. - : RSC Publishing. - 1359-7345 .- 1364-548X. ; 46:19, s. 3384-3386
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Tidskriftsartikel (refereegranskat)abstract
- Addition of Grignard reagents to pyridine N-oxides in THF at low temperature (-78 to -20 °C) and treatment with TFAA provides an efficient general procedure for synthesis of substituted pyridines. The method is compatible with a range of functional groups such as esters, halogens and nitriles.
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| 25. |
- Andersson, Hans, 1978-
(författare)
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Reaction Between Grignard reagents and Heterocyclic N-oxides : Synthesis of Substituted Pyridines, Piperidines and Piperazines
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the development of new synthetic methodologies for preparation of bioactive interesting compounds, e.g. substituted pyridines, piperidines or piparazines. Thesecompounds are synthesized from commercially available, cheap and easily prepared reagents, videlicet the reaction between Grignard reagents and heterocyclic N-oxides. The first part of this thesis deals with an improvement for synthesis of dienal-oximes and substituted pyridines. This was accomplished by a rapid addition of Grignard reagents to pyridine N-oxides at rt. yielding a diverse set of substituted dienal-oximes. During these studies, it was observed that the obtained dienal-oxmies are prone to ring-close upon heating. By taking advantage of this, a practical synthesis of substituted pyridines was developed. In the second part, an ortho-metalation of pyridine N-oxides using Grignard reagents is discussed. The method can be used for incorporation of a range of different electrophiles, including aldehydes, ketones and halogens. Furthermore, the importance for incorporation of halogens are exemplified through a Suzuki–Miyaura coupling reaction of 2-iodo pyridine N-oxides and different boronic acids. Later it was discovered that if the reaction temperature is kept below -20 °C, the undesired ringopening can be avoided. Thus, the synthesis of 2,3-dihydropyridine N-oxide, by reacting Grignard reagents with pyridine N-oxides at -40 °C followed by sequential addition of aldehyde or ketone, was accomplished. The reaction provides complete regio- and stereoselectivity yielding trans-2,3-dihydropyridine N-oxides in good yields. These intermediate products could then be used for synthesis of either substituted piperidines, by reduction, or reacted in a Diels–Alder cycloaddtion to give the aza-bicyclo compound. In the last part of this thesis, the discovered reactivity for pyridine N-oxides, is applied on pyrazine N-oxides in effort to synthesize substituted piperazines. These substances are obtained by the reaction of Grignard reagents and pyrazine N-oxides at -78 °C followed by reduction and protection, using a one-pot procedure. The product, a protected piperazine, that easily can be orthogonally deprotected, allowing synthetic modifications at either nitrogens in a fast and step efficient manner. Finally, an enantioselective procedure using a combination of PhMgCl and (-)-sparteine is discussed, giving opportunity for a stereoselective synthesis of substituted piperazines.
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| 26. |
- Andersson, Hans, et al.
(författare)
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Reaction of pyridine N-oxides with Grignard reagents: a stereodefined synthesis of substituted dienal oximes
- 2007
-
Ingår i: Tetrahedron Letters. - : Elsevier BV. - 0040-4039. ; 48, s. 6941-4
-
Tidskriftsartikel (refereegranskat)abstract
- Rapid addition of Grignard reagents to pyridine N-oxides under mild conditions gave stereodefined dienal oximes in good to excellent yields. This reaction provides an efficient access to substituted olefins with defined stereochemistry that are potentially of interest as bioactives themselves or as versatile synthetic intermediates.
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| 27. |
- Andersson, Hans, et al.
(författare)
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Reactions between Grignard reagents and heterocyclic N-oxides : stereoselective synthesis of substituted pyridines, piperidines, and piperazines
- 2011
-
Ingår i: Organic and biomolecular chemistry. - : Royal Society of Chemistry (RSC). - 1477-0520 .- 1477-0539. ; 9, s. 337-346
-
Tidskriftsartikel (refereegranskat)abstract
- In this perspective we discuss the recent developments of stereoselective synthesis of substituted pyridines, piperidines, and piperazines from cheap and commercially readily available starting materials. Pyridine N-oxides and pyrazine N-oxides are reacted with alkyl, aryl, alkynyl and vinyl Grignard reagents to give a diverse set of heterocycles in high yields. Optically active substituted piperazines are obtained by an asymmetric reaction from pyrazine N-oxides using sparteine as chiral ligand. In addition, a stereoselective synthesis of dienal-oximes from the reaction between pyridine N-oxides and Grignard reagents is presented, which results in a useful intermediate for the synthesis of a diverse set of compounds.
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| 28. |
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| 29. |
- Andersson, Hans, et al.
(författare)
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Selective synthesis of 2-substituted pyridine N-oxides via directed ortho-metallation using Grignard reagents
- 2008
-
Ingår i: Tetrahedron Letters. - : Elsevier BV. - 0040-4039 .- 1359-8562. ; 49:48, s. 6901-3
-
Tidskriftsartikel (refereegranskat)abstract
- Addition of i-PrMgCl to pyridine N-oxides in THF at −78 °C generates selectively an ortho-metallated species, which can be trapped with various electrophiles to generate 2-substituted pyridine N-oxides. Furthermore, by applying a double metal-catalyzed cross-coupling, direct arylation of the pyridine N-oxides is achieved.
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| 30. |
- Andersson, Hans, et al.
(författare)
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Synthesis of 2-Substituted Pyridines via a Regiospecific Alkylation, Alkynylation, and Arylation of Pyridine N-Oxides
- 2007
-
Ingår i: Organic Letters. - : American Chemical Society (ACS). - 1523-7060 .- 1523-7052. ; 9:7, s. 1335-7
-
Tidskriftsartikel (refereegranskat)abstract
- Sequential addition of Grignard reagents to pyridine N-oxides in THF at room temperature followed by treatment with acetic anhydride at 120 C afforded 2-substituted pyridines in good to high yields. Furthermore, by exchanging acetic anhydride for DMF in the second step, 2-substituted pyridine N-oxides were obtained, as intermediates suitable for addition of a second Grignard reagent for the synthesis of 2,6-disubstituted pyridines.
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| 31. |
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| 32. |
- Andersson, Magnus, et al.
(författare)
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Physical Properties of Biopolymers Assessed by Optical Tweezers : Analysis of folding and refolding of bacterial pili
- 2008
-
Ingår i: ChemPhysChem. - : Wiley-VCH Verlagsgesellschaft. - 1439-4235 .- 1439-7641. ; 9:2, s. 221-235
-
Tidskriftsartikel (refereegranskat)abstract
- Bacterial adhesion to surfaces mediated by specific adhesion organelles that promote infections, as exemplified by the pili of uropathogenic E. coli, is studied mostly at the level of cell-cell interactions and thereby reflects the averaged behavior of multiple pili. The role of pilus rod structure has therefore only been estimated from the outcome of experiments involving large numbers of organelles at the same time. It has, however, lately become clear that the biomechanical behavior of the pilus shafts play an important, albeit hitherto rather unrecognized, role in the adhesion process. For example, it has been observed that shafts from two different strains, even though they are similar in structure, result in large differences in the ability of the bacteria to adhere to their host tissue. However, in order to identify all properties of pilus structures that are of importance in the adhesion process, the biomechanical properties of pili must be assessed at the single-molecule level. Due to the low range of forces of these structures, until recently it was not possible to obtain such information. However, with the development of force-measuring optical tweezers (FMOT) with force resolution in the low piconewton range, it has lately become possible to assess forces mediated by individual pili on single living bacteria in real time. FMOT allows for a more or less detailed mapping of the biomechanical properties of individual pilus shafts, in particular those that are associated with their elongation and contraction under stress. This Mi- nireview presents the FMOT technique, the biological model system, and results from assessment of the biomechanical properties of bacterial pili. The information retrieved is also compared with that obtained by atomic force microscopy.
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| 33. |
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| 34. |
- Andree, Maria, et al.
(författare)
-
Knowledge Products from Close-To-Practice Research
- 2024
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Ingår i: Round table presentation at the NERA-conference, 6-8 March, Malmö University.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- ‘Close-to-practice research’ has received increased attention across the Nordic countries. Following the British Education Research Association (BERA), the notion of ‘close-to-practice research’ is used to refer to educational research that is based on problems in practice, often involves researchers working in partnership with practitioners in schools and addresses issues of relevance to practitioners. This roundtable focuses on how close-to-practice research can contribute to the knowledge base of the teaching profession by bringing together perspectives from didactics, school improvement and educational policy. More specifically, the interest is directed toward what characterizes the knowledge produced through practice-based research that may have significance for teachers' professional knowledge base and practice. The roundtable conversation builds on a previous analysis of what kinds of knowledge products are generated in didactic close-to-practice research where teachers and researchers work together within the research environment Stockholm Teaching & Learning Studies. As a result of this analysis a typology of knowledge products was proposed including: (i) descriptions of knowing, (ii) teaching design, (iii) didactic examples and (iv) methodological tools. It has been proposed that additional knowledge products may be developed, such as artifacts to be used in teaching (e.g. lesson plans, visual representations). The roundtable will include the following points of discussion: 1) a brief presentation of the typology, 2) challenging and developing the typology of knowledge products proposed by previous research by investigating different cases of close-to-practice research from traditions of action research and practice-developing research within subject-didactics, and 3) discussing how the notion of knowledge products may contribute to advancing the conversation on cumulativity in the field of educational research in general, and in relation to syntheses of close-to-practice research in particular. The participants will be engaged in conversations on the desirability and feasibility of striving towards cumulativity.
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| 35. |
- Arja, Katriann, 1985-
(författare)
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Multimodal Porphyrin-Based Conjugates : Synthesis and characterization for applications as amyloid ligands, photodynamic therapy agents and chiroptical materials
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Organic compounds that interact both with certain biological targets and display specific photophysical properties can be utilized as molecular tools to visualize and possibly effect disease related processes taking place in living organisms. In this regard, porphyrins are a class of naturally occurring molecules that possess intriguingly interesting photophysical properties where they can act as luminescent probes by emitting detectable light, as well as photosensitizers in the light mediated therapy called photodynamic therapy. In this thesis, the porphyrin structure has been synthetically combined with other molecule classes to achieve compounds with desirable multimodal characteristics.Firstly, luminescent conjugated oligothiophenes (LCOs) that have extensively, and with great success, been utilized as fluorescent ligands for amyloid formations, have been conjugated to porphyrins to render oligothiophene porphyrin hybrids (OTPHs) comprising two optically active modalities. When applied as fluorescent amyloidophilic dyes for visualization of amyloid-β (Aβ), one of the pathological hallmarks in Alzheimer’s disease, an enhanced optical assignment of distinct aggregated forms of Aβ was afforded. Thus, properly functionalized OTPHs could give us more information about pathological processes underlying devastating disorders, such as Alzheimer’s disease. In addition, the OTPHs can be associated with synthetic peptides inducing peptide folding into certain three-dimensional helical structures giving rise to novel optically active materials.Secondly, this thesis also embraces porphyrins’ potential as photosensitizers in photodynamic therapy to kill cancer cells. Grounded on the prerequisites for an optimal photosensitizer, we designed porphyrin-based conjugates equipped with common carbohydrates for improved cancer cell selectivity and with a fluorinated glucose derivative, 2-fluoro 2-deoxy glucose, for advantageous metabolism in cancer cells. Furthermore, incorporation of a radioisotopic fluorine-18 atom into the glycoporphyrins could give the means for diagnostic use of the conjugates in positron emission tomography (PET).In order to tether together the above-mentioned molecular moieties in a controlled fashion, we developed a robust synthetic strategy for asymmetrical functionalization of porphyrin core. The method involves chlorosulfonation of this otherwise inert tetrapyrrolic structure, followed by alkynylation. Parallelly to amide coupling reactions, copper(I)-catalyzed alkyne azide cycloaddition is used for fast and high-yielding late-stage conjugations. Overall, this thesis demonstrates how combining different molecular moieties in synthetic organic chemistry yields novel molecules with combined and improved multimodal properties for biological and medicinal applications, guided by the design-by-function methodology.
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| 36. |
- Barange, Deepak Kumar, et al.
(författare)
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Regio- and Stereoselective Alkylation of Pyridine-N-oxides : Synthesis of Substituted Piperidines and Pyridines
- 2016
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Ingår i: Organic Letters. - : American Chemical Society (ACS). - 1523-7060 .- 1523-7052. ; 18:24, s. 6228-6231
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 37. |
- Basu, Basudeb, et al.
(författare)
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Organic Polymeric Resins Embedded with Pd NPs : Newly Designed, Efficient and Chemoselective Catalyst for Reduction of Nitrobenzenes
- 2017
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Ingår i: Current Organocatalysis. - : Bentham Science Publishers. - 2213-3372 .- 2213-3380. ; 4:1, s. 48-61
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Tidskriftsartikel (refereegranskat)abstract
- Background: Organic polymer supported palladium nanoparticles (NPs) are important for use as heterogeneous catalyst in various organic reactions. This works describes Pd Nps immobilized on to polystyrene-based ion-exchange resin surface for use as catalyst in the reduction of nitrobenzenes. The heterogeneous catalyst was found useful for hydrogenation of nitro group under both catalytic transfer hydrogenation (CTH) as well as by using molecular hydrogen (H2).Methods: The catalyst was prepared from Amberlite IRA 900 Cl after rinsing with formic acid (10%) and subsequent treatment with Na2PdCl4 in DMF. The resulting Pd Nps immobilized resins was designated as VersaCat Pd and used for CTH of nitrobenzenes in the presence of H-donors (sodium formate, formic acid, hydrazine hydrate) and also for hydrogenation with H2 gas. The catalyst was characterized by FT-IR, MAS-NMR, SEM, TEM and XPS and surface morphologies were studied before and after the reaction.Results: Hydrogenations of nitrobenzenes under CTH using different H-source and direct use of H2 gas were achieved successfully with good to excellent yields. Reactions were performed under mild conditions and high degree of chemoselectivity was also observed. The catalyst was recyclable, used for six consecutive runs with appreciable conversions and showed higher activity (> 3 times) in terms of metalcontent than commercially available Pd/C (10%) in the hydrogenation of nitrobenzenes using H2 gas. The TEM images showed that Pd Nps are evenly distributed with size 50-200 mm on polymeric matrices and there was no significant changes observed after the first catalytic run. However, considerable rupture of the polymeric surface occurred after six runs, as seen from SEM studies.Conclusion: The present study establishes high catalytic efficiency and chemoselectivity of the newly developed organic polystyrene-based resin-soaked Pd NPs (VersaCat Pd) in the reduction of nitrobenzenes. Both CTH and hydrogenation using H2 gas were successfully done. Interestingly, hydrazine hydrate offered excellent control over chemoselectivity under CTH conditions and allowed clean conversion from nitro to amine, while keeping a chloro substitutent unaffected. Hydrogenation using molecular H2 gave maximum TOF. Easy preparation, high efficacy, TOF, chemoselectivity, and versatile applications are notable features for this heterogeneous palladium catalyst (VersaCat Pd). These features are often required in chemical industries.
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| 38. |
- Basu, Basudeb, et al.
(författare)
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Palladium supported on a Polyionic Resin as an efficient, ligand-free, and recyclable catalyst for Heck, Suzuki-Miyaura, and Sonogashira reactions
- 2009
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Ingår i: Synthesis (Stuttgart). - Stuttgart, New York : Georg Thieme Verlag. - 0039-7881 .- 1437-210X. ; :7, s. 1137-1146
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Tidskriftsartikel (refereegranskat)abstract
- Polyionic Amberlite resin formate (ARF), derived from commercially available Amberlite resin chloride by simple rinsing with aqueous formic acid, could be soaked with palladium(0) from palladium salts, the formate counteranion being the reducing source. The resulting Amberlite resin formate supported with palladium(0), ARF-Pd, showed excellent catalytic activity in Heck, Suzuki-Miyaura, and Sonogashira couplings with a range of substrates. The catalyst may be recovered easily and quantitatively without leaching and recycled; it was tested for five runs without any significant loss of activity.
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| 39. |
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| 40. |
- Bengtsson, Christoffer, et al.
(författare)
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Asymmetric Synthesis of 2,4,5-Trisubstituted (2)-Thiazolines
- 2013
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 19:30, s. 9916-9922
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Tidskriftsartikel (refereegranskat)abstract
- (2)-Thiazolines are interesting heterocycles that display a wide variety of biological characteristics. They are also common in chiral ligands used for asymmetric syntheses and as synthetic intermediates. Herein, we present asymmetric routes to 2,4,5-trisubstituted (2)-thiazolines. These (2)-thiazolines were synthesized from readily accessible/commercially available ,-unsaturated methyl esters through a Sharpless asymmetric dihydroxylation and an ON acyl migration reaction as key steps. The final products were obtained in good yields with up to 97% enantiomeric excess.
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| 41. |
- Bengtsson, Christoffer, et al.
(författare)
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Design, synthesis and evaluation of triazole functionalized Ring-fused 2-pyridones as antibacterial agents
- 2012
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Ingår i: European Journal of Medicinal Chemistry. - : Elsevier. - 0223-5234 .- 1768-3254. ; 54, s. 637-646
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Tidskriftsartikel (refereegranskat)abstract
- Antibacterial resistance is today a worldwide problem and the demand for new classes of antibacterial agents with new mode of action is enormous. In the strive for new antibacterial agents that inhibit pilus assembly, an important virulence factor, routes to introduce triazoles in position 8 and 2 of ring-fused bicyclic 2-pyridones have been developed. This was made via Sonogashira couplings followed by Huisgen 1,3-dipolar cycloadditions. The method development made it possible to introduce a diverse series of substituted triazoles and their antibacterial properties were tested in a whole cell pili-dependent biofilm assay. Most of the twenty four candidates tested showed low to no activity but interestingly three compounds, one 8-substituted and two 2-substituted, showed promising activities with EC50’s between 9-50 μM.
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| 42. |
- Bengtsson, Christoffer, et al.
(författare)
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Regioselective Halogenations and Subsequent Suzuki-Miyaura Coupling onto Bicyclic 2-Pyridones
- 2010
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Ingår i: The Journal of organic chemistry. - : American Chemical Society. - 1520-6904 .- 0022-3263. ; 75:3, s. 972-5
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Tidskriftsartikel (refereegranskat)abstract
- A selective synthesis of 6-bromo-8-iodo dihydro thiazolo ring-fused 2-pyridones is described. These halogenated 2-pyridones are selectively arylated by sequential Suzuki-Miyaura couplings. This approach can advantageously be used to synthesize focused libraries of substituted ring-fused 2-pyridones, a class of compounds with novel antibacterial properties.
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| 43. |
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| 44. |
- Bengtsson, Christoffer, 1979-
(författare)
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Synthesis of substituted Ring-Fused 2-Pyridones and applications in chemical biology
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Antibiotics have been extensively used to treat bacterial infections since Alexander Fleming’s discovery of penicillin 1928. Disease causing microbes that have become resistant to antibiotic drug therapy are an increasing public health problem. According to the world health organization (WHO) there are about 440 000 new cases of multidrug-resistant tuberculosis emerging annually, causing at least 150 000 deaths. Consequently there is an immense need to develop new types of compounds with new modes of action for the treatment of bacterial infections.Presented herein is a class of antibacterial ring-fused 2-pyridones, which exhibit inhibitory effects against both the pili assembly system in uropathogenic Escherichia coli (UPEC), named the chaperone usher pathway, as well as polymerization of the major curli subunit protein CsgA, into a functional amyloid fibre. A pilus is an organelle that is vital for the bacteria to adhere to and infect host cells, as well as establish biofilms. Inhibition of the chaperone usher pathway disables the pili assembly machinery, and consequently renders the bacteria avirulent.The focus of this work has been to develop synthetic strategies to more efficiently alter the substitution pattern of the aforementioned ring-fused 2-pyridones. In addition, asymmetric routes to enantiomerically enriched key compounds and routes to compounds containing BODIPY and coumarin fluorophores as tools to study bacterial virulence mechanisms have been developed. Several of the new compounds have successfully been evaluated as antibacterial agents. In parallel with this research, manipulations of the core structure to create new heterocycle based central fragments for applications in medicinal chemistry have also been performed.
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| 45. |
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| 46. |
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| 47. |
- Bharate, Jaideep B., et al.
(författare)
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K2S2O8-mediated coupling of 6-amino-7-aminomethyl-thiazolino-pyridones with aldehydes to construct amyloid affecting pyrimidine-fused thiazolino-2-pyridones
- 2021
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Ingår i: Organic and biomolecular chemistry. - : The Royal Society of Chemistry. - 1477-0520 .- 1477-0539. ; 19:44, s. 9758-9772
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Tidskriftsartikel (refereegranskat)abstract
- We herein present the synthesis of diversely functionalized pyrimidine fused thiazolino-2-pyridones via K2S2O8-mediated oxidative coupling of 6-amino-7-(aminomethyl)-thiazolino-2-pyridones with aldehydes. The developed protocol is mild, has wide substrate scope, and does not require transition metal catalyst or base. Some of the synthesized compounds have an ability to inhibit the formation of Amyloid-β fibrils associated with Alzheimer's disease, while others bind to mature amyloid-β and α-synuclein fibrils.
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| 48. |
- Borell, Anton, 1991-
(författare)
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In Between Competing Ideals : On the Relationships among Accounting, NPM, and Welfare
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- We know that public organizations today are expected to manage activities on multiple, and somewhat incongruent ideals. Since the development of the New Public Management (NPM) wave, public organizations have been increasingly subject to governance by markets, economic frugality and outputs for the purpose of improving efficiency. At the same time, they are also required to manage their daily work according to the ideals of needs, equity and professional expertise, which have traditionally been foundational to the realization of a welfarian agenda. Together, these requirements make up dual expectations of public organizations as well as the accounting technologies used to manage them: a form of paradoxical management that seeks to measure, evaluate and document both efficiency and welfare. But how do actors realize these plural ideals in practice? And what is the role of accounting in this? These are some of the aspects and problems with control that lie at the very heart of this dissertation.Based on 41 interviews and 28 observations in a Swedish school context, this dissertation shows how the paradoxical expectations become manifest in the design and use of accounting technologies. On the one hand, it shows how school actors attempt to integrate welfare and NPM in practice by relying on accounting technologies, which results in hybrid outcomes. On the other hand, the dissertation also shows the fragility of such a style of governance, which continuously leads to failures and breakdowns that actors have to readdress as a consequence of attempting to achieve competing ideals by relying on accounting.By leaning on governmentality as a metatheoretical framework, this dissertation contributes to some new understandings of control in public sector contexts. First, in contrast to the literature on colonization, which suggests that the expansive use of accounting is a direct threat to welfarian ideals, this dissertation shows that accounting can equally serve as a means for welfarian ideals to eclipse NPM. Second, in contrast to the stream of separation that treats the loose or minimal use of accounting as a mechanism for sealing off welfare from NPM-led intrusions, the dissertation shows that even a marginal or loose application of accounting can in fact be conceived as a threat to welfarian ideals. Third, this dissertation also provides additional understanding in relation to the hybridity approach, not only by illuminating how NPM and welfare were brought together through various hybrids, but also by showing how these hybrids were facilitated by accounting technologies, whose functions served to make integration a practically viable outcome amenable to both breakdowns and reintegration. Overall, the dissertation thus contributes to current knowledge on public sector governance in general, and more specifically about the relationships among accounting, NPM, and welfare, in terms of their entanglement, disentanglement, interdependencies, and modes of reproduction in public sector life, a gap also echoed by recent calls in research.
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| 49. |
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| 50. |
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