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  • 1.
    Abdelhamid, Hani
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Wilk-Kozubek, Magdalena
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Ahmed, M. El-Zohry
    Valiente, Alejandro
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bermejo-Gomez, Antonio
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mudring, Anja-Verena
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Luminescence Properties for a Family of Highly Stable Lanthanide Metal-Organic FrameworksManuskript (preprint) (Övrigt vetenskapligt)
  • 2.
    Adolfsson, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal-catalyzed epoxidation of alkenes2010Ingår i: Modern Oxidation Methods / [ed] Jan-Erling Bäckvall, Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA , 2010, 2, s. 37-84Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 3.
    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-12009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    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.

  • 4.
    Adrian Meredith, Jenny
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Björklund, Catarina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Adolfsson, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Edlund, Michael
    Jansson, Katarina
    Lindberg, Jimmy
    Vrang, Lotta
    Hallberg, Anders
    Institutionen för läkemedelskemi, Uppsala universitet.
    Rosenquist, Åsa
    Samuelsson, Bertil
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Design and Synthesis of BACE-1 Inhibitors Containing a New Hydroxyethylene (HE) Scaffold: Potent activities in a cellular assayManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    In a preceding report from our group we disclosed the development of a novel HE transition state isostere with a difluorophenoxymethyl side chain in the P1 position and a methoxy group in the P1’ position furnishing highly potent inhibitors of BACE-1 (i.e. lead compound 1), which moreover exhibit very promising selectivity over cathepsin D. In a continuation of this work with the aim at improving on the cell-based activity and pharmacokinetic properties, we have further developed the SAR for the P1 side chain of inhibitor 1 whereby the P1 side chain oxygen has been substituted for an amine, a carbon or a bond. The chemistry developed for the previous HE inhibitor structure 1 has now been extended to readily accommodate the introduction of new P1 side chains into this new HE scaffold. These modifications have given rise to several highly potent inhibitors where the most potent displayed a BACE-1 Ki value of 0.2 nM and a cell-based Aβ40 IC50 value of 9 nM. Thus, regarding the enzyme inhibition in the cell assay a more than 600-fold improvement compared to compound 1 was achieved via minor structural alterations.

  • 5.
    Ahlford, Katrin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Asymmetric transfer hydrogenation of ketones: Catalyst development and mechanistic investigation2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    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.

  • 6.
    Ahlford, Katrin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rhodium-catalyzed asymmetric transfer hydrogenation of ketones. Ligand development and mechanistic investigation2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 7.
    Ahlford, Katrin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ryberg, Per
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Adolfsson, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Nordin, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mechanistic investigation of enantioswitchable catalysts for asymmetric transfer hydrogenation2010Ingår i: Abstracts of Papers, 239th ACS National Meeting, San Francisco , CA, United States, March 21-25, 2010, Washington: American Chemical Society , 2010Konferensbidrag (Övrigt vetenskapligt)
  • 8.
    Ahlsten, Nanna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal-catalysed enol formation from allylic alcohols: Isomerisation, C−C and C−F bond formations 2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis describes the isomerisation of allylic alcohols into enols and enolates catalysed by transition metal complexes. The transformation has been used to prepare both unsubstituted and α-substituted carbonyl compounds. Significant attention has been given to the mechanistic aspects of the reactions.

    In the first part of this thesis, an environmentally benign procedure for the redox isomerisation of allylic alcohols into ketones is described. The reaction takes place in water and at room temperature using a cationic rhodium complex in combination with water-soluble phosphines. A variety of allylic alcohols could be isomerised in high yields using this procedure.

    The second part describes the combination of an allylic alcohol isomerisation with a C−C bond formation, catalysed by a rhodium complex. In this way, allylic alcohols were coupled with aldehydes and N-tosyl imines forming aldol and Mannich-type products. In addition, homoallylic and bishomoallylic alcohols were for the first time isomerised into the corresponding enolates and coupled using this methodology.

    In the third part of this thesis, the isomerisation of allylic alcohols was coupled with a C−F bond formation using an iridium complex and electrophilic fluorinating reagents. This novel transformation was used to convert allylic alcohols into single regioisomers of α-fluoroketones. The reaction is tolerant to air and water and takes place at room temperature.

    All of the reactions described take place under mild conditions, are operationally simple, and utilise catalysts formed in situ from commercially available metal complexes and ligands.

  • 9.
    Ahlsten, Nanna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal-catalysed isomerisation of allylic alcohols: Applications to C−C, C−F and C−Cl bond formation2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The focus of this thesis has been to develop selective and atom-economical methods for carbon-carbon and carbon-heteroatom bond formation, and to some extent improve on existing findings in this area. More specifically, methods for the catalytic generation of enolates from allylic alcohols and their in situ functionalisation with electrophilic reagents are described.  

    In the first part of this thesis, a method for the Rh-catalysed redox-isomerisation of allylic alcohols into carbonyl compounds under environmentally benign conditions is described. The reaction takes place at room temperature, in the absence of acids or bases, using water as the only solvent, and it is applicable to both primary and secondary allylic alcohols.

    The second part describes the combination of an isomerisation reaction of allylic alcohols with a C−C bond formation, catalysed by a rhodium complex. In this way, allylic alcohols were coupled with aldehydes and N-tosylimines to give aldol and Mannich-type products. In addition to allylic alcohols, homoallylic and bishomoallylic alcohols could be used as enolate precursors, and this is the first report where the latter two substrate types have been used in such a reaction.       

    In the remaining parts of the thesis, an iridium-catalysed isomerisation of allylic alcohols has been combined with an electrophilic halogenation step to provide a conceptually new method for the synthesis of α-halogenated carbonyl compounds. In this way, α-fluoro and α-chloroketones have been synthesised as single constitutional isomers, with the regiochemistry of the final products determined by the position of the double bond in the allylic alcohols. The reactions are tolerant to air, run in water-organic solvent mixtures, and proceed at room temperature.

  • 10.
    Ahlsten, Nanna
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bermejo-Gómez, Antonio
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of α-chlorinated ketones and aldehydes: Iridium-catalyzed tandem 1,3-H shift/chlorination of allylic alcoholsManuskript (preprint) (Övrigt vetenskapligt)
  • 11.
    Ahlsten, Nanna
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rhodium-catalysed coupling of allylic, homoallylic, and bishomoallylic alcohols with aldehydes and N-tosylimines2010Ingår i: Abstracts of Papers, 239th ACS National Meeting, San Francisco, CA, United States, March 21-25, 2010, American Chemical Society , 2010Konferensbidrag (Övrigt vetenskapligt)
  • 12.
    Alam, Rauful
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Catalytic Regio- and Stereoselective Reactions for the Synthesis of Allylic and Homoallylic Compounds2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis is focused on two main areas of organic synthesis, palladium-catalyzed functionalization of alkenes and allylic alcohols, as well as development of new allylboration reactions.

    We have developed a palladium-catalyzed selective allylic trifluoroacetoxylation reaction based on C−H functionalization. Allylic trifluoroacetates were synthesized from functionalized olefins under oxidative conditions. The reactions proceed under mild conditions with a high level of diastereoselectivity. Mechanistic studies of the allylic C−H trifluoroacetoxylation indicate that the reaction proceeds via (η3-allyl)palladium(IV) intermediate.

    Palladium-catalyzed regio- and stereoselective synthesis of allylboronic acids from allylic alcohols has been demonstrated. Diboronic acid B2(OH)4 was used as the boron source in this process.

    The reactivity of the allylboronic acids were studied in three types of allylboration reactions: allylboration of ketones, imines and acyl hydrazones. All three processes are conducted under mild conditions without any additives. The reactions proceeded with remarkably high regio- and stereoselectivity.

    An asymmetric version of the allylboration of ketones was also developed. In this process chiral BINOL derivatives were used as catalysts. The reaction using γ-disubstituted allylboronic acids and various aromatic and aliphatic ketones afforded homoallylic alcohols bearing two adjacent quaternary stereocenters with excellent regio-, diastereo- and enantioselectivity (up to 97:3 er) in high yield. The stereoselectivity in the allylboration reactions could be rationalized on the basis of the Zimmerman-Traxler TS model.

  • 13.
    Alam, Rauful
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-catalyzed Allylic C-H and C-OH Functionalization. Reactions of the Obtained Allylboronic Acids2014Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This thesis is focused on the studies of two major transformations. The first transformation deals with the development of palladium-catalyzed selective allylic trifluoroacetoxylation reactions based on C-H functionalization, whereas the second comprises the synthesis and isolation of allylboronic acids using diboronic acid B2(OH)4 as boron source. Both reactions proceed with a very high regio- and stereoselectivity. The mechanistic studies of the allylic C-H trifluoroacetoxylation indicate that the reaction proceeds via (η3-allyl)palladium intermediate.

    The reactivity of the allylboronic acids was studied with ketone and imine substrates. Unlikeother boronates (such as allyl-Bpin derivatives), allylboronic acids react with ketones and imines without any additives under neutral and mild conditions (typically at room temperature). The regio- and stereoselectivity of this reaction is remarkably high. Using functionalized allylboronic acids (prepared in the above mentioned Pd-catalyzed reactions) homoallylic alcohols and amines with adjacent tertiary and quaternary centers could be obtained with high selectivity. Interestingly, both the ketones and the imines reacted with anti-stereoselectivity. This was surprising for the imines. Our mechanistic study has shown that the acyclic aldimines undergo cis/trans isomerization prior to the allylation reaction.

  • 14.
    Ali, Tara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural Studies of O-Polysaccharides from Diarrhoeal Escherichia coli2007Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This thesis describes the structural analysis of O-polysaccharides from the Gram-negative bacterium Escherichia coli that is a diarrhoeal pathogen. The Escherichia coli serotypes investigated were O178, O171, O166 and O128. The methods used in these studies were nuclear magnetic resonance spectroscopy and component analysis.

    All analysed serotypes had pentasaccharide repeating units. E. coli strain O128 and O166 was shown to have the topology of four carbohydrate residues in the backbone while the 5-residue backbone is found in E. coli O178 and O171.

    The biological repeating units have been determined for the analysed polysaccharides and it was shown that all of the serotypes studied had a 3-substituted N-acetylgalactosamine residue at the reducing end. From this it was deduced that the terminal end of E. coli O171 and O128 have sialic acid and blood type antigens, respectively. This should make E. coli O171 and O128 less recognizable to the immune system as a foreign invader. This can result in that E. coli O171 and O128 may evade the immune system more easily.

  • 15.
    Alpe, Marianne
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of oligosaccharides related to the capsular polysaccharides of Streptococcus pneumoniae serotype 9 and of Cryptococcus neoformans2003Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In the present investigation, synthesis of oligosaccharides corresponding to structural elements present in the capsular polysaccharides of Streptococcus pneumoniae and Cryptococcus neoformans has been achieved. The first two sections describe the synthesis of spacer-equipped oligosaccharides corresponding to structures from the CPS of Streptococcus pneumoniae serotypes 9N, 9A and 9L, the production of which involved synthetic challenges such as the construction of β-ManNAc and α-GlcA linkages. The former challenge was met by employing azide displacement of a 2-O-triflate substituent on a β-glucoside, whereas the latter task was accomplished utilizing thioethyl glucuronic acid donors in the presence of various promoters. The pentasaccharide product obtained correspond to the complete repeating unit of the CPS of serotype 9A.

    The last two sections of this thesis describe the construction of thioglycoside di- and trisaccharide building blocks containing α-Man, β-Xyl, β-GlcA and 6-O-acetyl motifs, as well as subsequent assembly of these building blocks into oligosaccharides corresponding to the repeating units of the capsular polysaccharide of the yeast Cryptococcus neoformans. The GlcA moiety was introduced via trichloroacetimidate coupling involving the peracetylated glucuronic acid methyl ester donor, after which the subsequent necessary benzylation was performed with the di- and trisaccharides. All of the target oligosaccharides were synthesized as amino-spacer glycosides in order to make conjugation to a carrier protein possible.

  • 16.
    Anderlund, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dinuclear Manganese Complexes for Artificial Photosynthesis: Synthesis and Properties2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis deals with the synthesis and characterisation of a series of dinuclear manganese complexes. Their ability to donate electrons to photo-generated ruthenium(III) has been investigated in flash photolysis experiments followed by EPR-spectroscopy. These experiment shows several consecutive one-electron transfer steps from the manganese moiety to ruthenium(III), that mimics the electron transfer from the oxygen evolving centre in photosystem II.

    The redox properties of these complexes have been investigated with electro chemical methods and the structure of the complexes has been investigated with different X-ray techniques. Structural aspects and the effect of water on the redox properties have been shown.

    One of the manganese complexes has been covalently linked in a triad donor-photosensitizer-acceptor (D–P–A) system. The kinetics of this triad has been investigated in detail after photo excitation with both optical and EPR spectroscopy. The formed charge separated state (D–P–A+) showed an unusual long lifetime for triad based on ruthenium photosensitizers.

    The thesis also includes a study of manganese-salen epoxidation reactions that we believe can give an insight in the oxygen transfer mechanism in the water oxidising complex in photosystem II.

  • 17.
    Anderlund, Magnus F.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Högblom, Joakim
    Shi, Wei
    Huang, Ping
    Eriksson, Lars
    Weihe, Högni
    Styring, Stenbjörn
    Åkermark, Björn
    Magnuson, Ann
    Synthesis, Structure and Redox Chemistry of a Dinuclear Manganese Complex with a Novel Unsymmetric N5O2 LigandManuskript (Övrigt vetenskapligt)
  • 18.
    Angles d'Ortoli, Thibault
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Assembling and Unraveling Carbohydrates Structures: Conformational analysis of synthesized branched oligosaccharides2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Advances in the elaboration of vaccines and enzyme inhibitors rely on acquiring more knowledge about protein-carbohydrate binding events. Furthermore, the relationships between biological function and the three-dimensional properties of large glycans can be studied by focusing on the structural components they contained, namely, by scaling down the system under analysis. Chemical methods are useful assets as they allow the isolation and determination of epitopes; these small and recognizable fragments that lead to very specific interactions. In this thesis, biologically relevant saccharides were obtained using recently developed concepts in carbohydrate synthesis and NMR spectroscopy was used to unravel their conformational preferences.

    In paper I, the convergent synthesis of the tetrasaccharide found in the natural product solaradixine is described. Reactivity enhanced disaccharide glycosyl donors were coupled to a disaccharide acceptor in a 2 + 2 fashion. The computer program CASPER was subsequently used to verify the synthesized structure.

    The conformation arming concept employed in paper I was further investigated in paper II. An NMR-based methodology enabled the determination of the ring conformations of a set of donors. Subsequently, glycosylation reactions were performed and yields were correlated to donors ring shapes. Perturbations in the rings shape caused by bulky silyl ether protective groups were sufficient to boost the potency of several donors. As a matter of fact, complex branched oligosaccharides could be obtained in good to excellent yields.

    In paper III, NMR spectroscopy observables were measured to elucidate the ring shape, the mutual orientation of the rings across the glycosidic bond and the positions of the side chains of 5 trisaccharides found in larger structures. With the aid of molecular dynamics simulations, their overall conformational propensities were revealed.

    Finally, the software CASPER prediction skills were improved by adding, inter alia, NMR information of synthesized mono- and disaccharides to its database. Unassigned chemical shifts from polysaccharides served as input to challenge its ability to solve large carbohydrate structures.

  • 19.
    Angles d'Ortoli, Thibault
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mobarak, Hani
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ståhle, Jonas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Hamark, Christoffer
    Fontana, Carolina
    Engström, Olof
    Apostolica, Patricia
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Complete 1H and 13C NMR chemical shift assignments of mono- to tetrasaccharides as basis for NMR chemical shift predictions of oligo- and polysaccharides using the computer program CASPERManuskript (preprint) (Övrigt vetenskapligt)
  • 20.
    Aydin, Juhanes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Fine-tuning of the catalytic activity and selectivity of palladium pincer complexes2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis is focused on optimization of the catalytic properties of so-called pincer complexes. This work involved synthesis of a large variety of palladium pincer complexes, which were applied in various organic transformations. Optimization of the catalytic properties (also called fine-tuning) was directed to increase the catalytic activity as well as the chemo- and stereo-selectivity of the complexes. This could be achieved by varying the heteroatoms in the terdentate pincer ligand, by changing the electronic properties of the coordinated aryl moiety and by implementing chiral functionalities in the pincer complexes.

    In the cross-coupling reaction of vinyl epoxides and aziridines with organoboronic acids the chemoselectivity of the reaction could be increased by employment of pincer complexes instead of commonly used palladium(0) catalysts. Furthermore, application of a methoxy substituent in the aromatic subunit of the complex considerably increased the activity of the pincer complex catalyst.

    Fine-tuning of the stereoselectivity in electrophilic allylation reactions was achieved using a wide variety of BINOL and biphenanthrol based pincer complexes. The synthesis of these highly stable chiral palladium complexes was accomplished by using an efficient modular approach. The highest enantioselectivity (85% ee) was obtained by applying biphenanthrol based pincer complexes.

    We have presented the first palladium pincer complex catalyzed condensation of sulfonimines with isocyanoacetate. Variation of the heteroatoms in the terdentate ligand of the complex strongly influenced the stereoselectivity of the catalytic transformation. The highest stereoselectivity was obtained by using phosphine based pincer complexes. We have also succeeded to isolate and fully characterize the key intermediate of this reaction.

  • 21.
    Aydin, Juhanes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Novel Pincer Complex-Catalyzed Transformations: Including Asymmetric Catalysis2009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis is focused on the development of new pincer complex-catalyzed transformations. Optimization of the catalytic properties (fine-tuning) was directed to increase the catalytic activity as well as the chemo-, stereo- and enantioselectivity of the complexes. This was achieved by varying the heteroatoms in the terdentate pincer ligand, by changing the electronic properties of the coordinated aryl moiety and by implementing chiral functionalities in the pincer complexes.

    In the cross-coupling reaction of vinyl epoxides and aziridines with organoboronic acids the chemoselectivity of the reaction could be increased by employment of pincer complexes instead of commonly used Pd(0) catalysts. Furthermore, the introduction of a methoxy substituent in the aromatic subunit of the complex considerably increased the activity of the pincer complex catalyst.

    Fine-tuning of the enantioselectivity in electrophilic allylation reactions was achieved by using a wide variety of new BINOL- and biphenanthrol-based pincer complexes. The highest enantioselectivity (85% ee) was obtained by applying biphenanthrol-based pincer complexes.

    Stereoselective pincer complex-catalyzed condensation of sulfonylimines with isocyanoacetate could be achieved under mild reaction conditions. By application of chiral PCP catalysts, 2-imidazolines could be obtained with up to 86% ee.

    A new pincer complex-catalyzed C-H bond functionalization based reaction between organonitriles and sulfonylimines affords homoallylic amines and beta-aminonitriles in high yields. The asymmetric version of this process affords beta-aminonitriles with up to 71% ee.

    In the last chapter, a pincer complex-catalyzed redox coupling reaction is described. In this highly regio- and stereoselective process the integrity of the pincer catalysts is fully retained. This catalytic reaction proceeds with a high level of functional group tolerance, as allylic acetate and aryl halide functionalities are retained.

  • 22.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Senthil Kumar, Kuppusamy
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mechanistic studies of the palladium pincer complex-catalyzed condensation of sulfonimines and isocyanoacetate to imidazoline derivatives2008Ingår i: Abstracts of Papers, 235th ACS National Meeting, New Orleans, LA, United States, April 6-10, 2008, 2008Konferensbidrag (Övrigt vetenskapligt)
  • 23.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Enantioselective palladium pincer complex catalyzed carbon carbon coupling reactions between tosylimines and various nucleophiles2008Ingår i: Abstracts of Papers, 236th ACS National Meeting, Philadelphia, PA, United States, August 17-21, 2008, Washington, DC: American Chemical Society , 2008Konferensbidrag (Övrigt vetenskapligt)
  • 24.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mechanistic considerations for the enantioselective palladium pincer complex catalyzed carbon-carbon coupling reactions2008Ingår i: Abstracts of Papers, 236th ACS National Meeting, Philadelphia, PA, United States, August 17-21, 2008, Washington, DC: American Chemical Society , 2008Konferensbidrag (Övrigt vetenskapligt)
  • 25.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wallner, Olov A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olsson, Vilhelm J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Application of BINOL based pincer-complexes for palladium-catalyzed transformations2007Ingår i: Abstracts of Papers, 233rd ACS National Meeting, Chicago, IL, United States, March 25-29, 2007, 2007Konferensbidrag (Övrigt vetenskapligt)
  • 26.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wallner, Olov A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olsson, Vilhelm J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium pincer complex catalyzed asymmetric transformations of sulfonimines2007Ingår i: Abstracts of Papers, 233rd ACS National Meeting, Chicago, IL, United States, March 25-29, 2007, 2007Konferensbidrag (Övrigt vetenskapligt)
  • 27.
    Ayesa Alvarez, Susana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Design and Synthesis of Amine Building Blocks and Protease Inhibitors2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The first part of this thesis addresses the design and synthesis of amine building blocks accomplished by applying two different synthetic procedures, both of which were developed using solid-phase chemistry. Chapter 1 presents the first of these methods, entailing a practical solid-phase parallel synthesis route to N-monoalkylated aminopiperidines and aminopyrrolidines achieved by selective reductive alkylation of primary and/or secondary amines. Solid-phase NMR spectroscopy was used to monitor the reactions for which a new pulse sequence was developed. The second method, reported in Chapter 2, involves a novel approach to the synthesis of secondary amines starting from reactive alkyl halides and azides. The convenient solid-phase protocol that was devised made use of the Staudinger reaction in order to accomplish highly efficient alkylations of N-alkyl phosphimines or N-aryl phosphimines with reactive alkyl halides.

    The second part of the thesis describes the design and synthesis of three classes of protease inhibitors targeting the cysteine proteases cathepsins S and K, and the serine protease hepatitis C virus (HCV) NS3 protease. Chapter 4 covers the design, solid-phase synthesis, and structure-activity relationships of 4-amidofurane-3-one P1-containing inhibitors of cathepsin S and the effects of P3 sulfonamide groups on the potency and selectivity towards related cathepsin proteases. This work resulted in the discovery of highly potent and selective inhibitors of cathepsin S. Two parallel solid-phase approaches to the synthesis of a series of aminoethylamide inhibitors of cathepsin K are presented in Chapter 5. Finally, Chapter 6 reports peptide-based HCV NS3 protease inhibitors containing a non-electrophilic allylic alcohol moiety as P1 group and also outlines efforts to incorporate this new template into low-molecular-weight drug-like molecules.

  • 28.
    Ayesa, Susana
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Maltseva, Tatiana
    Rakos, Laszlo
    Hamelink, Elisabeth
    Classon, Björn
    Samuelsson, Bertil
    Investigation of Allylic Alcohols in the P1 Position of Inhibitors of Hepatitis C Virus NS3 ProteaseManuskript (Övrigt vetenskapligt)
  • 29. Back, Marcus
    et al.
    Nyhlén, Jonas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kvarnström, Ingemar
    Rosenquist, Åsa
    Samuelsson, Bertil
    Design, synthesis and SAR of potent statin-based β-secretase inhibitors: Exploration of P1 phenoxy and benzyloxy residues2007Konferensbidrag (Övrigt vetenskapligt)
  • 30.
    Balan, Daniela
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    The three-component aza-Baylis-Hillman reaction: development and application2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The current thesis presents the optimization and generalization of the Baylis-Hillman reaction applied to in situ generated imines, i.e. a three-component aza- Baylis-Hillman reaction. We found that the title reaction proceeds most efficiently in the presence of a combination of catalysts, i.e. 3-hydroxyquinuclidine (0.15 equiv) and titanium isopropoxide (0.02 equiv), together with molecular sieves (4 Å; activated powder; 200 mg/mmol substrate) at ambient temperature.

    Our study of the scope and limitations of this reaction, revealed that arylaldehydes and sulfonamides are the only imine precursors which both generate the corresponding imines in situ and facilitate a further reaction with the Michael acceptor in a Baylis-Hillman fashion. Among the Michael acceptors tested, acrylates and acrylonitrile demonstrate high reactivity, while acrylamides and β-substituted acrylates do not participate in the reaction.

    The optimized conditions applied to the above range of substrates results in good-to-excellent yields of the desired amine-products (53-94%) and very high chemoselectivity (83- >99%). Furthermore, the reaction times observed under these conditions are considerably shorter than those previously reported for the aza-Baylis-Hillman reaction.

    In the development of a stereoselective version of the title reaction, the use of a chiral catalyst proved to be most effective. Thus, an enantiomeric excess up to 74% can be obtained with β-Isocupreidine. With chiral imine precursors or chiral acrylates, the diastereoselectivity attained was poor. No asymmetric induction was observed when chiral Lewis acids were employed as a co-catalyst.

    The α-methylene-β-amino acid derivatives obtained via the three-component aza-Baylis-Hillman reaction were subjected to further transformation. Carbon chain elongation at the olefinic end of the amine-adduct was attempted. For this purpose, the Miyaura borylation protocol could be successfully applied. The subsequent Suzuki-type cross-coupling reaction resulted predominantly in hydrolysis of the boronate intermediate, together with formation of the amine-adduct via β-hydride elimination. The optimal conditions for this latter reaction remain to be found.

    Finally, 2,5-dihydropyrroles have been synthesized from aza-Baylis-Hillman adducts, via a short and efficient route in which the key step is a microwave-assisted ring-closing metathesis of the N-allylated amine-adducts.

  • 31.
    Bartholomeyzik, Teresa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Investigation of Selectivity in Palladium-Catalyzed Oxidative Arylating Carbocyclization of Allenynes.Manuskript (preprint) (Övrigt vetenskapligt)
  • 32.
    Bartholomeyzik, Teresa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium(II)-Catalyzed Oxidative Carbocyclization/Functionalization of Allenynes2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The selective formation of carbon-carbon bonds constitutes a key transformation in organic synthesis with useful applications in pharmaceutical or material industry. A particularly versatile tool for carbon-carbon as well as carbon-heteroatom bond formation is palladium catalysis, which allows for mild and selective routes even towards complex structures.

    The work in this thesis describes the development and the mechanistic investigation of a palladium(II)-catalyzed oxidative carbocyclization/functionalization methodology, which converts 1,5-allenynes into either arylated or borylated carbocycles. To this end, either boronic acids or B2pin2 are employed and 1,4-benzoquinone serves as the stoichiometric oxidant. These protocols provide access to two products, a cyclic triene and a cyclic vinylallene. Their formation is dependent on the substrate structure as the latter product requires a propargylic C–H bond to be present in the substrate. Based on kinetic isotope effects, mechanisms involving either an initial allenic or propargylic C–H abstraction, respectively, were proposed. Full control of product selectivity to give either trienes or vinylallenes was achieved by modifying the reaction conditions with additives. Using substoichiometric amounts of BF3·OEt2 leads selectively to borylated or arylated vinylallenes. Under arylating conditions the reaction is zero order in allenyne and oxidant, and first order in phenylboronic acid. Transmetalation and, to some extent, propargylic C–H cleavage were found to be turnover-limiting. The selective reaction towards functionalized trienes was achieved by addition of either substoichiometric LiOAc·2H2O (borylation) or excess amounts of H2O (arylation). For the latter case, a kinetic study revealed an unusually slow catalyst activation. Lower concentrations of H2O gave product mixtures, and it was shown that vinylallenes are formed with either boronic acid or boroxine, whereas the formation of trienes requires boronic acid.

  • 33.
    Bartholomeyzik, Teresa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium(II)-Catalyzed Oxidative Carbocyclization/Functionalization of Allenynes2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Palladium catalysis has emerged as an outstanding tool in synthetic organic chemistry for the mild and selective formation of carbon-carbon and carbon-heteroatom bonds. This thesis has been directed towards the extension of palladium(II)-catalyzed carbocyclization chemistry under oxidative conditions. An oxidative carbocyclization/functionalization methodology utilizing boron-containing transmetalation reagents was exploited to convert 1,5-allenynes into either arylated or borylated carbocycles. Two protocols were developed that use minimal amounts of Pd(OAc)2, stoichiometric para-benzoquinone as the oxidant and either bis(pinacolato)diboron or different arylboronic acids under mild conditions. A wide substrate scope is applicable to both methods. When the allenyne substrate bears a propargylic hydrogen, two isomeric functionalized carbocycles can be formed. By controlling the reaction conditions the reaction can be directed towards either of these two isomeric products. Kinetic isotope effect studies suggest that the mechanism leading to the different products proceeds through allylic or propargylic C-H bond cleavage, respectively. Moreover, it was observed that water has an interesting effect on the product selectivity when arylboronic acids are used in the oxidative carbocyclization of allenynes.

  • 34.
    Bartholomeyzik, Teresa
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Deng, Youqian
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selective Palladium-catalyzed oxidative carbocyclization of allenynes2013Ingår i: Abstracts of Papers of The American Chemical Society, American Chemical Society (ACS), 2013Konferensbidrag (Övrigt vetenskapligt)
  • 35.
    Bartholomeyzik, Teresa
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pendrill, Robert
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jiang, Tuo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Complex Kinetics in a Palladium(II)-Catalyzed Oxidative Carbocyclization: Untangling of Competing Pathways, Pre-Catalyst Activation, and Product MixturesManuskript (preprint) (Övrigt vetenskapligt)
  • 36.
    Bartoszewicz, Agnieszka
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Building molecular complexity via tandem Ru-catalyzed reactions of allylic alcohols2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 37.
    Bartoszewicz, Agnieszka
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal-catalysed hydrogen transfer processes for C-C and C-N bond formation: Synthetic studies and mechanistic investigations2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis focusses on synthetic studies and mechanistic investigations into reactions involving hydrogen-transfer processes.

    In the first part, the development of an efficient method for the synthesis of β-hydroxy ketones (aldols) and β-amino ketones (Mannich products) from allylic alcohols and aldehydes is described. These reactions use  Ru(η5-C5Ph5)(CO)2Cl as the catalyst. The reaction parameters were optimised in order to suppress the formation of undesired by-products. Neutral and mild reaction conditions enabled the synthesis of a variety of aldol products in up to 99% yield, with a good syn/anti ratio. The influence of the stereoelectronic properties of the catalyst on the reaction outcome was also studied. Based on the results obtained, a plausible reaction mechanism has been proposed, involving as the key steps the 1,4-addition of hydride to α,β-unsaturated ketones and the formation of ruthenium (Z)-enolates.

    In the second part of this thesis, a ruthenium-catalysed tandem isomerisation/C-H activation reaction is presented. A number of ruthenium complexes, phosphine ligands, and additives were evaluated in order to establish the optimal reaction conditions. It was found that the use of a stable ruthenium catalyst, Ru(PPh3)3Cl2, together with PtBu3 and HCO2Na resulted in an efficient tandem transformation. Using this procedure, a variety of ortho-alkylated ketones were obtained in excellent yields. Moreover, homoallylic alcohols could also be used as starting materials for the reaction, which further expands the substrate scope. Mechanistic investigations into the isomerisation part of the process were carried out.

    The last project described in the thesis deals with the design and preparation of novel bifunctional iridium complexes containing an N-(2-hydroxy-isobutyl)-N-Heterocyclic carbene ligand. These complexes were used as catalysts to alkylate amines using alcohols as latent electrophiles. The catalytic system developed here was found to be one of the most active systems reported to date, allowing the reaction to be performed at temperatures as low as 50 °C for the first time. A broad substrate scope was examined. Combined experimental and theoretical studies into the reaction mechanism are consistent with a metal-ligand bifunctional activity of the new catalyst.

  • 38.
    Bartoszewicz, Agnieszka
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kalek, Marcin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stawinski, Jacek
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of nucleoside phosphorothio-, phosphorodithio- and phophoroselenoate diesters via oxidative esterification of the corresponding H-phosphonate analogues2008Ingår i: Collection Symposium Series, Vol. 10, 2008, s. 219-223Konferensbidrag (Övrigt vetenskapligt)
  • 39.
    Bermejo-Gómez, Antonio
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ahlsten, Nanna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of 4,5-disubstituted 2-amino-1,3-thiazoles from α,β-unsaturated ketones: Preparation of 5-Benzyl-4-methyl-1,3-thiazol-2-amine hydrochlorideManuskript (preprint) (Övrigt vetenskapligt)
  • 40.
    Bielawski, Marcin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Diaryliodonium Salts: Development of Synthetic Methodologies and α-Arylation of Enolates2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis describes novel reaction protocols for the synthesis of diaryliodonium salts and also provides an insight to the mechanism of α-arylation of carbonyl compounds with diaryliodonium salts.

     The first chapter gives a general introduction to the field of hypervalent iodine chemistry, mainly focusing on recent developments and applications of diaryliodonium salts.

    Chapter two describes the synthesis of electron-rich to electron-poor diaryliodonium triflates, in moderate to excellent yields from a range of arenes and iodoarenes.

    In chapter three, it is described that molecular iodine can be used together with arenes in a direct one-pot, three-step synthesis of symmetric diaryliodonium triflates. A large scale synthesis of bis(4-tert-butylphenyl)iodonium triflate is also described, controlled and verified by an external research group, further demonstrating the reliability of this methodology.

    The fourth chapter describes the development of a sequential one-pot synthesis of diaryliodonium salts from aryl iodides and boronic acids, furnishing symmetric and unsymmetric, electron-rich to electron-poor diaryliodonium tetrafluoroborates in moderate to excellent yields. This method was developed to overcome the regiochemical limitations imposed by the reaction mechanism in the protocols described in the preceding chapters.

    Chapter five describes a one-pot synthesis of heteroaromatic iodonium salts under similar conditions described in chapter two.

    The final chapter describes the reaction of enolates with chiral diaryliodonium salts or together with a phase transfer catalyst yielding racemic products. DFT calculations were performed, which revealed a low lying energy transition state (TS) between intermediates, which is believed to be responsible for the lack of selectivity observed in the experimental work. It is also proposed that a [2,3] rearrangement is preferred over a [1,2] rearrangement in the α-arylation of carbonyl compounds.

    The synthetic methodology described in this thesis is the most generally applicable, efficient and high-yielding to date for the synthesis of diaryliodonium salts, making these reagents readily available for various applications in synthesis.

  • 41.
    Bielawski, Marcin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Efficient and High-Yielding Routes to Diaryliodonium Salts2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis summarizes three novel and general reaction protocols for the synthesis of diaryliodonium salts. All protocols utilize mCPBA as oxidant and the acids used are either TfOH, to obtain triflate salts, or BF3•Et2O that gives the corresponding tetrafluoroborate salts in situ.

    Chapter two describes the reaction of various arenes and aryl iodides, delivering electron-rich and electron-deficient triflates in moderate to excellent yields.

    In chapter three, it is shown that the need of aryl iodides can be circumvented, as molecular iodine can be used together with arenes in a direct one-pot, three-step synthesis of symmetric diaryliodonium triflates.

    The final and fourth chapter describes the development of a sequential one-pot reaction from aryl iodides and boronic acids, delivering symmetric and unsymmetric, electron-rich and electron-deficient iodonium tetrafluoroborates in moderate to excellent yields. This protocol was developed to overcome mechanistic limitations existing in the protocols described in chapter two and three.

    The methodology described in this thesis is the most general, efficient and high-yielding existing up to date, making diaryliodonium salts easily available for various applications in synthesis.

  • 42.
    Bielawski, Marcin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhu, Mingzhao
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olofsson, Berit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Efficient and general one-pot synthesis of diaryliodonium triflates: scope and limitations2007Ingår i: SIS Report: The 10th Symposium on Iodine Science, Chiba University, Japan 2007, 2007, s. 19-22Konferensbidrag (Övrigt vetenskapligt)
  • 43.
    Björklund, Catarina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Design and Synthesis of BACE-1 Inhibitors: Novel Compounds Targeting an Aspartic Protease Important in the Pathogenesis of Alzheimer’s Disease2009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis deals with the design and synthesis of protease inhibitors targeting the aspartic protease BACE-1 (β-site APP cleaving enzyme-1), an enzyme important in the pathogenesis of Alzheimer’s disease. The inhibitors are evaluated with respect to inhibition data, in a structure-activity relationship part.

    Alzheimer’s disease is a disabling, progressive and ultimately fatal form of dementia afflicting approximately 40 percent of the population over 80 years, with over 30 million people suffering from Alzheimer’s disease worldwide. This makes Alzheimer’s disease the most common form of dementia. The identification of the amyloid-β peptide (Aβ) as the main constituent of extracellular plaques, which characterize Alzheimer’s disease, suggests that Aβ plays a vital role in the pathology of Alzheimer’s disease. The formation of Aβ occurs when amyloid-β precursor protein (APP) is cleaved by β-secretase (BACE-1) and γ-secretase, which differ in length by 39-42 amino acids. This suggests that β-secretase is a suitable target for the development of therapeutics against Alzheimer’s disease.

    The synthetic work of this thesis comprises development of BACE-1 inhibitors containing a hydroxyethylene (HE) central core transition state isostere. The target molecules were readily synthesized from chiral carbohydrate starting materials. Highly potent inhibitors were produced by varying the substituents coupled to the HE central core. Selecting an aryloxymethyl P1 side-chain and a methoxy P1’ side-chain resulted in exceptionally potent BACE-1 inhibitors that also exhibit high selectivity over cathepsin D. In a further development, the ether oxygen linkage in the P1 side-chain was removed, resulting in a carba analogue, providing improved potency in a cell-based assay.

  • 44.
    Bogár, Krisztián
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthetic Transformations via Metal- and Enzyme-Catalyzed Dynamic Kinetic Resolution2007Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis deals with the preparation of a new half-sandwich type ruthenium(II)- catalyst for racemization of optically active secondary alcohols and the development of a highly efficient method in combination with lipases such as Candida antarctica lipase B and Pseudomonas cepacia lipase for dynamic kinetic resolution of various functionalized alcohols under mild reaction conditions.

    It was shown that the RuCl(CO)25-C5Ph5) complex can racemize optically active aliphatic and aromatic secondary alcohols at room temperature in rather short times. Different parameters, such as the nature of the catalyst, catalyst loading and solvent effect were studied. After the optimization steps, the Ru-catalyzed racemization of (S)-1-phenylethanol in the presence of Candida antarctica lipase B was also investigated. The compatibility of the metal- and enzyme-catalyzed reactions led to a highly efficient coupled catalytic system for transformation of racemic alcohols to their enantiomerically pure acetates. This protocol was applied for a wide range of secondary alcohols. It was shown that in the case of allylic alcohols the obtained enantiopure allylic acetates are useful compounds for synthesis of α-methyl carboxylic acids such as (R)-Flurbiprofen and acyloin acetates. Highly selective dynamic kinetic asymmetric transformation of 3,5-piperidine diol to deliver various 3,5-dioxygenated piperidines is also described.

  • 45. Bogár, Krisztián
    et al.
    Krumlinde, Patrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Hydrogenized Wilkinson´s Catalyst for Transfer Hydrogenation of Carbonyl CompoundsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Combining the advantages of homogeneous and heterogeneous catalysis is possible by heterogenization of homogeneous transition metal complexes based on a grafting/anchoring technique. Wilkinson’s catalyst ((RhCl(PPh3)3) immobilized on common silica showed high activity and selectivity in transfer hydrogenation reactions of different carbonyl compounds in isopropanol. Reactions conducted at reflux in isopropanol afforded the corresponding carbinols in high yields in short reaction times. The heterogeneous feature of the catalyst allows easy recovery and efficient reuse in the same reaction up to 5 times without loss of catalytic activity.

  • 46.
    Bogár, Krisztián
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, B.
    Bäckvall, Jan-E.
    Large Scale Metalloenzymatic Dynamic Kinetic Resolution of (rac)-1-PhenylethanolManuskript (Övrigt vetenskapligt)
  • 47. Borgström, Magnus
    et al.
    Shaikh, Nizamuddin
    Johansson, Olof
    Anderlund, Magnus F.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Styring, Stenbjörn
    Åkermark, Björn
    Magnuson, Ann
    Hammarström, Leif
    Light Induced Magnanese Oxidation and Long-lived Charge Separation in a Mn2II,II-RuII-acceptor triadManuskript (Övrigt vetenskapligt)
  • 48.
    Borén, Linnéa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Enantioselective Synthesis of Sec-Alcohol Derivatives and Diols via Combined Ruthenium and Enzyme Catalysis2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The first part of this thesis describes the synthesis of enantiopure secondary alcohol derivatives. These syntheses are carried out via the combination of an enzyme as a resolution catalyst and a ruthenium catalyst as a racemization catalyst, in what is called dynamic kinetic resolution (DKR). By varying the resolution catalyst enantio-complementary processes can be obtained. A lipase (PS-C II) catalyzed DKR of γ-hydroxyamides gave the corresponding (R)-acetates in high yields and with high enantioselectivity. The synthetic usefulness of these obtained (R)-acetates was demonstrated by the synthesis of (R)-5-methyltetrahydrofurane-2-one. A protease (Subtilisin Carlsberg) catalyzed DKR of various secondary alcohols gave the corresponding (S)-acetates in high yields and with high enantioselectivity. In the second part of this thesis the DKR process has been extended into a dynamic kinetic asymmetric transformation (DYKAT) of diols. Various 1,5- and 1,4-diols were transformed into enantiopure diacetates in a lipase (CALB and PS-C II) catalyzed DYKAT. The synthetic utility of the obtained enantiopure diacetates were demonstrated by the synthesis of various enantiopure disubstituted heterocycles.

  • 49.
    Buitrago, Elina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal catalyzed reduction of ketones2010Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 50.
    Buitrago, Elina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal-catalyzed reduction of carbonyl compounds: Fe, Ru and Rh complexes as powerful hydride mediators2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    A detailed mechanistic investigation of the previously reported ruthenium pseudo-dipeptide-catalyzed asymmetric transfer hydrogenation (ATH) of aromatic ketones was performed. It was found that the addition of alkali metals has a large influence on both the reaction rate and the selectivity, and that the rate of the reaction was substantially increased when THF was used as a co-solvent. A novel bimetallic mechanism for the ruthenium pseudo-dipeptide-catalyzed asymmetric reduction of prochiral ketones was proposed.

    There is a demand for a larger substrate scope in the ATH reaction, and heteroaromatic ketones are traditionally more challenging substrates. Normally a catalyst is developed for one benchmark substrate, and a substrate screen is carried out with the best performing catalyst. There is a high probability that for different substrates, another catalyst could outperform the one used. To circumvent this issue, a multiple screen was executed, employing a variety of ligands from different families within our group’s ligand library, and different heteroaromatic ketones to fine-tune and to find the optimum catalyst depending on the substrate. The acquired information was used in the formal total syntheses of (R)-fluoxetine and (S)-duloxetine, where the key reduction step was performed with high enantioselectivities and high yield, in each case.

    Furthermore, a new iron-N-heterocyclic carbene (NHC)-catalyzed hydrosilylation (HS) protocol was developed. An active catalyst was formed in situ from readily available imidazolium salts together with an iron source, and the inexpensive and benign polymethylhydrosiloxane (PMHS) was used as hydride donor. A set of sterically less demanding, potentially bidentate NHC precursors was prepared. The effect proved to be remarkable, and an unprecedented activity was observed when combining them with iron. The same system was also explored in the reduction of amides to amines with satisfactory results.

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