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  • 1701.
    Yuan, Weiming
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rhodium-Catalyzed Geminal Oxyfluorination and Oxytrifluoro-Methylation of Diazocarbonyl Compounds2016Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, nr 29, s. 8410-8415Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new reaction for the rhodium-catalyzed geminal-difunctionalization-based fluorination is presented. The substrates are aromatic and aliphatic diazocarbonyl compounds. As the fluorine source a stable and easily accessible benziodoxole reagent was used. A variety of alcohol, phenol, and carboxylic acid reagents were employed to introduce the second functionality. The reaction was extended to trifluoromethylation using a benziodoxolon reagent. The fluorination and trifluoromethylation reactions probably proceed by a rhodium-containing onium ylide type intermediate, which is trapped by either the F or CF3 electrophiles.

  • 1702.
    Yuan, Weiming
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabo, Kalman J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Catalytic Intramolecular Aminofluorination, Oxyfluorination, and Carbofluorination with a Stable and Versatile Hypervalent Fluoroiodine Reagent2015Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 54, nr 29, s. 8533-8537Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Application of a fluoroiodine analogue of the Togni reagent was studied in fluorocyclization reactions. In the presence of a transition-metal catalyst the applied fluoroiodine reagent can be used for aminofluorination, oxyfluorination, and carbofluorination reactions. The described procedure has a very broad synthetic scope for preparation of functionalized hetero- and isocyclic compounds having a tertiary fluorine substituent.

  • 1703.
    Yuan, Weiming
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabo, Kalman J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rhodium-Catalyzed Oxy-Aminofluorination of Diazoketones with Tetrahydrofurans and N-Fluorobenzenesulfonimide2016Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 6, nr 10, s. 6687-6691Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have developed a rhodium-catalyzed oxy-aminofluorination method for transformation of diazoketones. The reaction is based on addition of tetrahydrofuran derivatives and N-fluorobenzenesulfonimide (NFSI) to the diazoketone substrate. The reaction can be performed under mild conditions with high regioselectivity. The synthetic scope involves a wide variety of diazoketones and tetrahydrofuran derivatives. The reaction is supposed to proceed via a tetrahydrofuran based onium ylide intermediate, which is formed from rhodium-carbenoid.

  • 1704.
    Zaccheus, Mona
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural and Conformational Studies of Oligo- and Polysaccharides2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The focus of this thesis is to examine the structural properties of polysaccharides produced by bacteria, as well as the dynamic and conformational behavior of a synthetically derived oligosaccharide.

    The primary structures of the O-polysaccharide repeating units of four different Escherichia coli (E. coli) strains, namely O175, O177, O103 and TD2158, as well as the first report of a capsular polysaccharide produced by lactic acid bacteria Leuconostoc mesenteroides ssp. cremoris PIA2 are reported in paper I–V. Structural analyses have been performed using a combination of nuclear magnetic resonance spectroscopy and chemical component analysis.

    The elucidated structures in paper I–III, as well as paper V, are composed of linear repeating units of varying composition and length. In paper IV, the structure of the O-polysaccharide repeating unit of E. coli TD2158 is determined to be a branched hexasaccharide structure with a heterogeneous substitution pattern, with either a β-GlcpNAc or β-Glcp residue branching to the backbone chain. Incubation with bacteriophage HK620 tailspike protein shows that the polysaccharide is selectively cleaved at the α-GlcpNAc-(1→2)-α-Rhap-linkage of the backbone chain, yielding a 9:1 ratio of β-GlcpNAc/β-Glcp containing hexasaccharides after digestion.

    In paper VI the conformational properties of a trisaccharide, which constitutes an internal epitope of the LeaLex hexasaccharide over-expressed on the surface of squamous lung cancer cells, have been analyzed using NMR spectroscopy and molecular dynamics simulations. The β-(1→3)-linkage of the trisaccharide was shown to be highly flexible.

    Fulltekst (pdf)
    Structural and Conformational Studies of Oligo- and Polysaccharides
  • 1705.
    Zaccheus, Mona
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pendrill, Robert
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jackson, Trudy A.
    Wang, An
    Auzanneau, France-Isabelle
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Conformational Dynamics of a Central Trisaccharide Fragment of the LeaLex Tumor Associated Antigen Studied by NMR Spectroscopy and Molecular Dynamics Simulations2012Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 25, s. 4705-4715Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Certain carbohydrate structures are recognized as cancer antigens, and identification of these and relevant epitopes are essential in fighting the disease. The trisaccharide beta-D-GlcpNAc-(1?3)-beta-D-Galp-(1?4)-beta-D-GlcpNAc-OMe represents a model for the central region of the LeaLex hexasaccharide and it has herein been investigated by 1D 1H,1H-NOESY experiments to obtain effective interresidue protonproton distances as well as by 2D J-HMBC experiments to determine transglycosidic 3JCH coupling constants. Molecular dynamics (MD) simulations using explicit water as solvent and three different carbohydrate force fields, namely, GLYCAM06, PARM22/SU01, and CHARMM2011, were employed for the interpretation of experimental data. Overall, the force field based MD simulations are able to reproduce the experimental data and the ? torsion angle at the beta-(1?3)-linkage is concluded to be flexible. In addition, different minor states were present for the three force fields with either anti-? or non-exo-anomeric conformations. Transitions between the exo-anomeric and the non-exo-anomeric conformations for the f torsion angle at the beta-(1?4)-linkage in one of the MD simulations were analyzed in detail. It was found that hydrogen-bonding water molecules, interresidue hydrogen bonds and the transitions between antiperiplanar and synperiplanar conformations for the tH torsion angle of an N-acetyl group were all essential in the description of the glycosidic transition process. In particular, the transition of tH may be a general way of regulating other transitions into less populated but biologically important conformational regions.

  • 1706.
    Zaccheus, Mona V.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ali, Tara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Cloeckaert, Axel
    Zygmunt, Michel S.
    Weintraub, Andrej
    Iriarte, Maite
    Moriyon, Ignacio
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    The Epitopic and Structural Characterization of Brucella suis Biovar 2 O-Polysaccharide Demonstrates the Existence of a New M-Negative C-Negative Smooth Brucella Serovar2013Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, nr 1, s. e53941-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The brucellae are Gram-negative bacteria that cause an important zoonosis. Studies with the main Brucella species have shown that the O-antigens of the Brucella smooth lipopolysaccharide are alpha-(1 -> 2) and alpha-(1 -> 3)-linked N-formyl-perosamine polysaccharides that carry M, A and C (A = M, A>M and A<M) epitopes relevant in serodiagnosis and typing. We report that, in contrast to the B. suis biovar 1 O-antigen used as a reference or to all described Brucella O-antigens, B. suis biovar 2 O-antigen failed to bind monoclonal antibodies of C (A = M), C (M>A) and M specificities. However, the biovar 2 O-antigen bound monoclonal antibodies to the Brucella A epitope, and to the C/Y epitope shared by brucellae and Yersinia enterocolitica O:9, a bacterium that carries an N-formyl-perosamine O-antigen in exclusively alpha-(1 -> 2)-linkages. By C-13 NMR spectroscopy, B. suis biovar 1 but not B. suis biovar 2 or Y.enterocolitica O:9 polysaccharide showed the signal characteristic of alpha-(1 -> 3)-linked N-formyl-perosamine, indicating that biovar 2 may altogether lack this linkage. Taken together, the NMR spectroscopy and monoclonal antibody analyses strongly suggest a role for alpha-(1 -> 3)-linked N-formyl-perosamine in the C (A = M) and C (M>A) epitopes. Moreover, they indicate that B. suis biovar 2 O-antigen lacks some lipopolysaccharide epitopes previously thought to be present in all smooth brucellae, thus representing a new brucella serovar that is M-negative, C-negative. Serologically and structurally this new serovar is more similar to Y. enterocolitica O:9 than to other brucellae.

  • 1707.
    Zaccheus, Mona V.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Broeker, Nina K.
    Lundborg, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Uetrecht, Charlotte
    Barbirz, Stefanie
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural studies of the O‐antigen polysaccharide from Escherichia coli TD2158 having O18 serogroup specificity and aspects of its interaction with the tailspike endoglycosidase of the infecting bacteriophage HK6202012Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 357, s. 118-125Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have analyzed the O-antigen polysaccharide of the previously uncharacterized Escherichia coli strain TD2158 which is a host of bacteriophage HK620. This bacteriophage recognizes and cleaves the polysaccharide with its tailspike protein (TSP). The polysaccharide preparation as well as oligosaccharides obtained from HK620TSP endoglycosidase digests were analyzed with NMR spectroscopy. Additionally, sugar analysis was performed on the O-antigen polysaccharide and MALDI-TOF MS was used in oligosaccharide analysis. The present study revealed a heterogeneous polysaccharide with a hexasaccharide repeating unit of the following structure: α-D-Glcp-(1→6|) →2)-α-L-Rhap-91→6)-α-D-Glcp-(1→4)-α-D-Ga|lp-(1→3)-α-D-GlcpNAc-(1→ β-D-Glcp/β-D-GlcpNAc-(1→3) A repeating unit with a D-GlcNAc substitution of D-Gal has been described earlier as characteristic for serogroup O18A1. Accordingly, we termed repeating units with D-Glc substitution at D-Gal as O18A2. NMR analyses of the polysaccharide confirmed that O18A1- and O18A2-type repeats were present in a 1:1 ratio. However, HK620TSP preferentially bound the D-GlcNAc-substituted O18A1-type repeating units in its high affinity binding pocket with a dissociation constant of 140 μM and disfavored the O18A2-type having a β-D-Glcp-(1→3)-linked group. As a result, in hexasaccharide preparations, O18A1 and O18A2 repeats were present in a 9:1 ratio stressing the clear preference of O18A1-type repeats to be cleaved by HK620TSP.

  • 1708.
    Zani, Lorenzo
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Adolfsson, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of novel amino-acid-derived sulfinamides and their evaluation as ligands for the enantioselective transfer hydrogenation of ketones2008Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, nr 27, s. 4655-4664Artikkel i tidsskrift (Fagfellevurdert)
  • 1709. Zerbetto, Mirco
    et al.
    d'Ortoli, Thibault Angles
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Polimeno, Antonino
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Differential Dynamics at Glycosidic Linkages of an Oligosaccharide as Revealed by C-13 NMR Spin Relaxation and Stochastic Modeling2018Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 122, nr 8, s. 2287-2294Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Among biomolecules, carbohydrates are unique in that not only can linkages be formed through different positions, but the structures may also be branched. The trisaccharide beta-D-Glcp-(1 -> 3)[beta-D-Glcp-(1 -> 2)]-alpha-D-Manp-OMe represents a model of a branched vicinally disubstituted structure. A C-13 site -specific isotopologue, with labeling in each of the two terminal glucosyl residues, enabled the acquisition of high-quality C-13 NMR relaxation parameters, T-1 and T-2, and heteronuclear NOE, with standard deviations of <= 0.5%. For interpretation of the experimental NMR data, a diffusive chain model was used, in which the dynamics of the glycosidic linkages is coupled to the global reorientation motion of the trisaccharide. Brownian dynamics simulations relying on the potential of mean force at the glycosidic linkages were employed to evaluate spectral densities of the spin probes. Calculated NMR relaxation parameters showed a very good agreement with experimental data, deviating <3%. The resulting dynamics are described by correlation times of 196 and 174 ps for the beta-(1 -> 2)- and beta-(1 -> 3)-linked glucosyl residues, respectively, i.e., different and linkage dependent. Notably, the devised computational protocol was performed without any fitting of parameters.

  • 1710. Zerbetto, Mirco
    et al.
    Kotsyubynskyy, Dmytro
    Kowalewski, Jozef
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Widmalm, Goran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Polimeno, Antonino
    Stochastic Modeling of Flexible Biomolecules Applied to NMR Relaxation: I. Internal Dynamics of Cyclodextrins; y-Cyclodextrin as a Case Study2012Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 116, nr 44, s. 13159-13171Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, we address the description of the dynamics of cyclodextrins in relation with nuclear magnetic resonance (NMR) relaxation data collected for hydroxymethyl groups. We define an integrated computational approach based on the definition and parametrization of a stochastic equation able to describe the relevant degrees of freedom affecting the NMR observables. The computational protocol merges molecular dynamics simulations and hydrodynamics approaches for the evaluation of most of the molecular parameters entering the stochastic description of the system. We apply the method to the interpretation of the C-13 NMR relaxation of the -CH2OH group of cyclodextrins. We use gamma-cyclodextrin as a case study. Results are in agreement with quantitative and qualitative analyses performed in the past with simpler models and molecular dynamics simulations. The element of novelty in our approach is in the treatment of the coupling of the relevant internal (glucopyranose ring twisting/tilting and hydroxymethyl group jumps) and global (molecular tumbling) degrees of freedom.

  • 1711. Zerbetto, Mirco
    et al.
    Polimeno, Antonino
    Kotsyubynskyy, Dmytro
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Ghalebani, Leila
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Kowalewski, Jozef
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, Avdelningen för fysikalisk kemi.
    Meirovitch, Eva
    Olsson, Ulrika
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    An integrated approach to NMR spin relaxation in flexible biomolecules: Application to β-D-glucopyranosyl-(1→6)-α-D-mannopyranosyl-OMe2009Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 131, nr 23, s. p234501-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The description of the reorientational dynamics of flexible molecules is a challenging task, in particular when the rates of internal and global motions are comparable. The commonly used simple mode-decoupling models are based on the assumption of statistical independence between these motions. This assumption is not valid when the time scale separation between their rates is small, a situation that was found to arise in oligosaccharides in the context of certain internal motions. To make possible the interpretation of NMR spin relaxation data from such molecules, we developed a comprehensive approach generally applicable to flexible rotators with one internal degree of freedom. This approach integrates a stochastic description of coupled global tumbling and internal torsional motion, quantum chemical calculations of the local potential and the local geometry at the site of the restricted torsion, and hydrodynamics-based calculations of the diffusive properties. The method is applied to the disaccharide -D-Glcp-(16)--D-[6-13C]-Manp-OMe dissolved in a DMSO-d6/D2O cryosolvent. The experimental NMR relaxation parameters, associated with the 13CH2 probe residing at the glycosidic linkage, include 13C T1 and T2 and 13C-{1H} nuclear Overhauser enhancement (NOE) as well as longitudinal and transverse dipole-dipole cross-correlated relaxation rates, acquired in the temperature range of 253–293 K. These data are predicted successfully by the new theory with only the H–C–H angle allowed to vary. Previous attempts to fit these data using mode-decoupling models failed.

  • 1712. Zerbetto, Mirco
    et al.
    Polimeno, Antonino
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Glycosidic linkage flexibility: The psi torsion angle has a bimodal distribution in alpha-L-Rhap-(1 -> 2)-alpha-L-Rhap-OMe as deduced from C-13 NMR spin relaxation2020Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 152, nr 3, artikkel-id 035103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The molecular dynamics (MD) computer simulation technique is powerful for the investigation of conformational equilibrium properties of biomolecules. In particular, free energy surfaces of the torsion angles (those degrees of freedom from which the geometry mostly depends) allow one to access conformational states, as well as kinetic information, i.e., if the transitions between conformational states occur by simple jumps between wells or if conformational regions close to these states also are populated. The information obtained from MD simulations may depend substantially on the force field employed, and thus, a validation procedure is essential. NMR relaxation data are expected to be highly sensitive to the details of the torsional free energy surface. As a case-study, we consider the disaccharide alpha-l-Rhap-(1 -> 2)-alpha-l-Rhap-OMe that features only two important torsion angles, phi and psi, which define the interglycosidic orientation of the sugar residues relative to each other, governed mainly by the exo-anomeric effect and steric interactions, respectively. In water, a psi(-) state is preferred, whereas in DMSO, it is a psi(+) state, suggesting inherent flexibility at the torsion angle. MD simulations indicated that bistable potentials describe the conformational region well. To test whether a unimodal distribution suffices or if a bimodal distribution better represents molecular conformational preferences, we performed an alchemical morphing of the torsional free energy surface and computed T-1, T-2, and NOE C-13 NMR relaxation data that were compared to experimental data. All three NMR observables are substantially affected by the morphing procedure, and the results strongly support a bimodal Boltzmann equilibrium density with a major and a minor conformational state bisected at psi approximate to 0 degrees, in accord with MD simulations in an explicit solvent.

  • 1713. Zhang, Di
    et al.
    Liu, Jianguo
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Mid Sweden University, Sweden.
    Liao, Wei-Wei
    Recent Developments in Palladium-Catalyzed Oxidative Cascade Carbocyclization2017Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, nr 10, s. 7051-7063Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this Perspective, we describe recent advances on Pd-catalyzed oxidative cascade carbocyclizations. These cascade processes enable efficient construction of the molecular complexity and structural diversity of carbocyclic compounds via introducing diverse functionalities concomitant with multiple C-C bond-formations in one-pot operations. In many cases, these processes are facilitated by Pd-catalysts alone, while cocatalysis by combination of Pd catalyst and other catalysts are also discussed, since they represent a new entry to address the preparation of functionalized cyclic compounds with high efficiency and selectivity.

  • 1714.
    Zhang, Jiji
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Metathesis Mechanism of Zinc-Catalyzed Fluorination of Alkenes with Hypervalent Fluoroiodine2017Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, nr 2, s. 1093-1100Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Density functional theory calculations are used to unravel the mechanism of the Zn-catalyzed fluorocyclization reaction of alkenes using fluoro-benziodoxole reagent. In the initial step Zn coordinates to the fluorine atom of the fluoro-benziodoxole reagent. An important activation step for the fluorination involves Zn-mediated isomerization of the benziodoxole reagent. The activation is followed by a metathesis step to form the C-F bond and a nucleophilic substitution, closing the ring to yield the final aminofluorination product. This mechanism has feasible energy barriers and accounts for the observed selectivity outcome. An alternative mechanism involving an iodocyclopropylium cation intermediate is shown to be associated with high energies.

  • 1715. Zhao, Dongbo
    et al.
    Johansson, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    In Situ Generation of Nitroso Compounds from Catalytic Hydrogen Peroxide Oxidation of Primary Aromatic Amines and Their One-Pot Use in Hetero-Diels–Alder Reactions2007Inngår i: European journal of organic chemistry, ISSN 1434-193X, nr 26, s. 4431–4436-Artikkel i tidsskrift (Fagfellevurdert)
  • 1716.
    Zhao, Dongbo
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Johansson, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    In situ generation of nitroso compounds from catalytic hydrogen peroxide oxidation of primary aromatic amines and their one-pot use in hetero-Diels-Alder reactions2007Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, Vol. -, nr 26, s. 4431-4436Artikkel i tidsskrift (Fagfellevurdert)
  • 1717.
    Zhao, Gui-Ling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Catalytic asymmetric Baylis–Hillman reactions and surroundings2010Inngår i: Catalytic Asymmetric Conjugate Reactions / [ed] Armando Córdova, Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA , 2010, 1, s. 393-438Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 1718.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    A one-pot combination of amine and heterocyclic carbene catalysis: direct asymmetric synthesis of beta-hydroxy and beta-malonate esters from alpha,beta-unsaturated aldehydes2007Inngår i: Tetrahedron Letters, Vol. 48, s. 5976-5980Artikkel i tidsskrift (Fagfellevurdert)
  • 1719.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    ECAs of organolithium reagents, Grignard reagents, and examples of Cu-catalyzed ECAs2010Inngår i: Catalytic Asymmetric Conjugate Reactions / [ed] Armando Córdova, Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA , 2010, 1, s. 145-167Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 1720.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dziedzic, Pawel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ibrahem, Ismail
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Organocatalytic asymmetric synthesis of 1,2,3-prim,sec,sec-triols2006Inngår i: Synlett, ISSN 0936-5214, nr 20, s. 3521-3524Artikkel i tidsskrift (Fagfellevurdert)
  • 1721.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dziedzic, Pawel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ullah, Farman
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, Avdelningen för strukturkemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Organocatalytic enantioselective domino synthesis of highly functionalized cyclohexanes with an all-carbon quaternary stereocenter2009Inngår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 50, nr 26, s. 3458-3462Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A highly enantioselective organocatalytic domino Michael/aldol reaction is presented. The reaction is catalyzed by chiral amines and gives access to highly functionalized cyclohexanes with one all-carbon quaternary stereocenter and multiple chiral stereocenters in high yields and 83–98% ee.

  • 1722.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Hafrén, Jonas
    Deiana, Luca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Heterogeneous "organoclick" derivatization of polysaccharides: Photochemical thiol-ene click modification of solid cellulose2010Inngår i: Macromolecular rapid communications, ISSN 1022-1336, E-ISSN 1521-3927, Vol. 31, nr 8, s. 740-744Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A simple and direct method for derivatization of solid polysaccharides is presented. The novel methodology is based on the combination of organic acid-catalyzed esterification or etherification and photochemical thiol-ene click derivatization of a heterogeneous polysaccharide. The solid cellulose was “organoclick” modified with aryl, alkyl and polyester groups, respectively. The modification allows for a highly modular and metal free surface modification of solid polysaccharides.

  • 1723.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ibrahem, Ismail
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dziedzic, Pawel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Junliang
    Bonneau, Charlotte
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    One-pot catalytic enantioselective domino nitro-Michael/Michael synthesis of cyclopentanes with four stereocenters2008Inngår i: Chemistry: a European journal, ISSN 0947-6539, Vol. 14, nr 32, s. 10007-10011Artikkel i tidsskrift (Fagfellevurdert)
  • 1724.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ibrahem, Ismail
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sundén, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Amine-catalyzed asymmetric epoxidation of alpha,beta-unsaturated aldehydes2007Inngår i: Advanced Synthesis & Catalysis, ISSN 1615-4150, Vol. 349, nr 7, s. 1210-1224Artikkel i tidsskrift (Fagfellevurdert)
  • 1725.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lin, Shuangzheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Korotvicka, Ales
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Deiana, Luca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kullberg, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Asymmetric synthesis of Maraviroc (UK-427,857)2010Inngår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 352, nr 13, s. 2291-2298Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The asymmetric synthesis of Maraviroc (UK-427,857), a chemochine receptor 5 (CCR-5) receptor antagonist, based on an expeditious organocatalytic enantioselective assembly of the chiral β-amino aldehyde key fragment is presented. The reactions were performed on a gram-scale and allow for the rapid construction of new Maraviroc analogues.

  • 1726.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rios, Ramón
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Vesely, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Organocatalytic enantioselective aminosylfenylation of alpha,beta-unsaturated aldehydes2008Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, Vol. 47, nr 44, s. 8468-8472Artikkel i tidsskrift (Fagfellevurdert)
  • 1727.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ullah, Farman
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Luca, Deiana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lin, Shuangzheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhang, Qiong
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, Avdelningen för strukturkemi.
    Ibrahem, Ismail
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dziedzic, Pawel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dynamic kinetic asymmetric transformation (DYKAT) by combined amine- and transition-metal-catalyzed enantioselective cycloisomerization2010Inngår i: Chemistry: a European Journal, ISSN 0947-6539, Vol. 16, nr 5, s. 1585-1591Artikkel i tidsskrift (Fagfellevurdert)
  • 1728.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Vesely, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rios, Ramón
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ibrahem, Ismail
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sundén, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Highly diastereo- and enantioselective catalytic domino thia-Michael/aldol reactions: Synthesis of benzothiopyrans with three contiguous stereocenters2008Inngår i: Advanced Synthesis & Catalysis, ISSN 1615-4150, Vol. 350, nr 2, s. 237-242Artikkel i tidsskrift (Fagfellevurdert)
  • 1729.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Vesely, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Junliang
    Christensen, Kirsten E.
    Bonneau, Charlotte
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Organocatalytic highly enantioselective conjugate addition of aldehydes to alkylidine malonates2008Inngår i: Advanced Synthesis & Catalysis, ISSN 1615-4150, Vol. 350, nr 5, s. 657-661Artikkel i tidsskrift (Fagfellevurdert)
  • 1730.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Xu, Yongmei
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sundén, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Sayah, Mahmoud
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Organocatalytic enantioselective conjugate addition of aldehydes to maleimides2007Inngår i: Chemical Communications, s. 734-735Artikkel i tidsskrift (Fagfellevurdert)
  • 1731.
    Zhao, Jian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jonker, Sybrand J. T.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Meyer, Denise N.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Schulz, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Tran, C. Duc
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Copper-catalyzed synthesis of allenylboronic acids. Access to sterically encumbered homopropargylic alcohols and amines by propargylboration2018Inngår i: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 9, nr 13, s. 3305-3312Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tri- and tetrasubstituted allenylboronic acids were prepared via a new versatile copper-catalyzed methodology. The densely functionalized allenylboronic acids readily undergo propargylboration reactions with ketones and imines without any additives. Catalytic asymmetric propargylborylation of ketones is demonstrated with high stereoselectivity allowing for the synthesis of highly enantioenriched tertiary homopropargyl alcohols. The reaction is suitable for kinetic resolution of racemic allenylboronic acids affording alkynes with adjacent quaternary stereocenters.

  • 1732.
    Zhao, Jian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Catalytic Borylative Opening of Propargyl Cyclopropane, Epoxide, Aziridine, and Oxetane Substrates: Ligand Controlled Synthesis of Allenyl Boronates and Alkenyl Diboronates2016Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, nr 4, s. 1502-1506Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new copper-catalyzed reaction for the stereo- and regioselective synthesis of alkenyl diboronates and allenyl boronates is presented. In this process propargyl derivatives of strained three/four-membered rings were employed as substrates and B(2)pin(2) was used as the boronate source. Selective formation of the alkenyl diboronate versus the allenyl boronate products was controlled by the choice of phosphine ligand.

  • 1733.
    Zhao, Tony
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of functionalized allylic, propargylic and allenylic compounds: Selective formation of C–B, C–C, C–CF3 and C-Si bonds2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis is focused on the development of new palladium and copper- mediated reactions for functionalization of alkenes and propargylic alcohol derivatives. The synthetic utility of the 1,2-diborylated butadienes synthesized in one of these processes has also been demonstrated.

    We have developed an efficient procedure for the synthesis of allenyl boronates from propargylic carbonates and acetates. This was achieved by using a bimetallic system of palladium and copper or silver as co-catalyst. The reactions were performed under mild conditions for the synthesis of a variety of allenyl boronates. Furthermore, the synthesis of 1,2-diborylated butadienes was achieved with high diastereoselectivity from propargylic epoxides. The reactivity of the 1,2-diborylated butadienes with aldehydes was studied. It was found that the initial allylboration reaction proceeds via an allenylboronate intermediate. The allenylboronate reacts readily with an additional aldehyde to construct 2-ethynylbutane-1,4-diols with moderate to high diastereoselectivity.

    We have also studied the copper-mediated trifluoromethylation of propargylic halides and trifluoroacetates. It was also shown that a transfer of chirality occurred when an enantioenriched starting material was used.

    In the last part of the thesis, we have described a method for palladium-catalyzed functionalization of allylic C-H bonds for the selective synthesis of allylic silanes. The protocol only works under highly oxidative conditions which suggest a mechanism involving high oxidation state palladium intermediates.

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  • 1734.
    Zhao, Tony S. N.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Copper and Palladium-Mediated Transformationsof Allylic and Propargylic Substrates2014Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This thesis is focused on the development of new palladium and copper-mediated reactions for functionalization of alkenes and propargylic alcohol derivatives. We have developed an efficient procedure for the synthesis of allenyl and propargyl boronate from propargylic carbonates and acetates. The reactions were performed under mild conditions for the synthesis of a variety of allenyl boronates. We have also observed a switch of regioselectivity for the formation of propargylic boronates using CuCl as a co-catalyst. This is, as far as we know, the first metal-catalyzed reaction for the synthesis of propargylic boronates. Furthermore, the synthesis of 1,2-diborylated butadienes was achieved with high diastereoselectivity from propargylic epoxides. A wide variety of propargylic epoxides could be converted to the corresponding dienes and this is the first catalytic protocol to form 1,2-diborylated butadienes.

    We have also studied the copper-mediated trifluoromethylation of propargylic halides and trifluoroacetates. Depending on the temperature, two different regioselective outcomes were observed. It was also shown that a transfer of chirality occurred when an enantioenriched starting material was used.

    In the last part of the thesis, we have described a method for palladium-catalyzed functionalization of allylic C-H bonds for selective synthesis of allylic silanes. The reaction is regioselective and gives only the linear allylic silane. The protocol only works under highly oxidative conditions which suggest a mechanism involving high oxidation state palladium intermediates.

  • 1735.
    Zhao, Tony S. N.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Trifluoromethylation of Propargylic Halides and Trifluoroacetates Using (Ph3P)(3)Cu(CF3) Reagent2012Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 14, nr 15, s. 3966-3969Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A copper-mediated trifluoromethylation of propargylic halides and trifluoroacetates was performed with high allenyl or propargyl selectivity. The reaction proceeds smoothly with aliphatic and aromatic substituents bearing either electron-withdrawing or -supplying groups. Preliminary mechanistic results indicate an ionic mechanism involving nucleophilic transfer of the CF3 group from the Cu complex to the propargylic substrate.

  • 1736.
    Zhao, Tony S. N.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Yuzhu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lessing, Timo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Borylation of Propargylic Substrates by Bimetallic Catalysis. Synthesis of Allenyl, Propargylic, and Butadienyl Bpin Derivatives2014Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, nr 21, s. 7563-7566Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bimetallic Pd/Cu and Pd/Ag catalytic systems were used for borylation of propargylic alcohol derivatives. The substrate scope includes even terminal alkynes. The reactions proceed stererospecifically with formal S(N)2' pathways to give allenyl boronates. Opening of propargyl epoxides leads to 1,2-diborylated butadienes probably via en allenylboronate intermediate.

    Fulltekst (pdf)
    fulltext
  • 1737.
    Zhao, Tony S. N.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhao, Jian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stereoselective Synthesis of 1,4-Diols by a Tandem Allylboration–Allenylboration Sequence2015Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 17, nr 9, s. 2290-2293Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The reaction of mono- and dialdehydes with bis-borodienes (incorporating an allylboronate unit) has been studied. It was found that the initial allylboration reaction results in an allenylboronate, which has two stereogenic units: one of them has axial chirality and the other one is a stereogenic carbon center. This reaction proceeds with high diastereoselectivity. The allenylboronate formed in the allylboration reacts with an additional aldehyde with fair to high stereoselectivity depending on the aldehyde substrate. Aromatic dialdehydes react with bis-boro-butadienes creating three new stereocenters with usually high diastereoselectivity.

  • 1738.
    Zheng, Jia
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jongcharoenkamol, Jira
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Chulabhorn Royal Academy, Thailand.
    Peters, Bram B. C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Guhl, Jasper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ponra, Sudipta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ahlquist, Mårten S. G.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Iridium-catalysed enantioselective formal deoxygenation of racemic alcohols via asymmetric hydrogenation2019Inngår i: Nature Catalysis, ISSN 2520-1158, Vol. 2, nr 12, s. 1093-1100Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Asymmetric hydrogenation of alkenes is one of the most powerful tools for the preparation of optically active compounds. However, to achieve high enantioselectivity, the starting olefin in most cases needs to be isomerically pure in either the cis or the trans form. Generally, most olefination protocols provide olefins as isomeric mixtures that are difficult to separate, and in many cases also generate lots of waste. In contrast, the synthesis of racemic alcohols is straightforward and highly atom-efficient, with products that are easier to purify. Here, we describe a strategy that enables rapid access to chiral alkanes via enantioconvergent formal deoxygenation of racemic alcohols. Mechanistic studies indicate an Ir-mediated elimination of water and subsequent in situ hydrogenation. This approach allows rapid and efficient assembly of chiral intermediates and is exemplified in the total synthesis of antidepressant sertraline and sigma(2) receptor PB 28.

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  • 1739.
    Zheng, Jia
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Margarita, Cristiana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Krajangsri, Suppachai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Asymmetric Total Synthesis of (-)-Juvabione via Sequential Ir-Catalyzed Hydrogenations2018Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 20, nr 18, s. 5676-5679Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    (-)-Juvabione, a natural sesquiterpene exhibiting juvenile insect hormone activity, was synthesized constructing the two adjacent stereogenic centers via sequential Ir-catalyzed hydrogenations. The first center is generated by hydrogenation of a styrene-type double bond (99% ee). The successive monohydrogenation of a diene intermediate constitutes the key step, granting high levels of regio- and stereocontrol (94:6 dr). This novel strategy allowed the preparation of (-)-juvabione from simple starting materials in 9 steps and 17% total yield.

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  • 1740.
    Zheng, Zhiyao
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    van der Werf, Angela
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Deliaval, Marie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selander, Nicklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of Fluorinated Amide Derivatives via a Radical N-Perfluoroalkylation-Defluorination Pathway2020Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 22, nr 7, s. 2791-2796Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A one-pot approach to fluorinated hydroxamic acid, amide, and thioamide derivatives is reported. The reaction proceeds via an N-perfluoroalkylation of nitrosoarenes with perfluoroalkanesulfinates, resulting in labile N-perfluoroalkylated hydroxylamines. By the addition of suitable additives, a controllable oxy/thiodefluorination of the fluorinated hydroxylamine intermediates was achieved. The method highlights N-perfluoroalkylated amines as versatile intermediates for further synthesis.

  • 1741.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    An Efficient Approach to Regio- and Stereodefined Fully-Substituted Alkenylsilanes by Pd-Catalyzed Allenic C(sp(3))-H Oxidation2019Inngår i: Chemistry: A European Journal, ISSN 0947-6539, Vol. 25, nr 49, s. 11566-11573Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A highly efficient palladium-catalyzed functionalization of allenylsilanes to give regio- and stereodefined fully-substituted alkenylsilanes has been developed. This oxidative coupling reaction showed good functional group compatibility with exclusive regio- and stereoselectivity. The pending olefin on the silyl group was shown to be an indispensable element for the initial allenic C(sp(3))-H bond cleavage, and performs as the directing group to control the overall selectivity. The addition of substoichiometric amounts of Et3N was found to increase the reaction rate leading to a higher reaction yield. The reaction can be easily scaled up and applied for the late-stage functionalization of natural products and pharmaceutical compounds, including amino acids and steroid derivatives. The newly introduced functional groups include aryl, alkynyl, and boryl groups. The highly strained four-membered ring, silacyclobutene was obtained when B(2)pin(2) was employed as the coupling partner. Mechanistic studies, including kinetic isotope effects, showed that the allenic C(sp(3))-H bond cleavage is the rate-limiting step.

  • 1742.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Liu, Jie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Khanh Mai, Binh
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Mid Sweden University, Sweden.
    Efficient Stereoselective Carbocyclization to cis-1,4-Disubstituted Heterocycles Enabled by Dual Pd/Electron Transfer Mediator (ETM) Catalysis2020Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 142, nr 12, s. 5751-5759Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient Pd/ETM (ETM = electron transfer mediator)-cocatalyzed stereoselective oxidative carbocyclization of dienallenes under aerobic oxidation conditions has been developed to afford six-membered heterocycles. The use of a bifunctional cobalt complex [Co(salophen)-HQ] as hybrid ETM gave a faster aerobic oxidation than the use of separated ETMs, indicating that intramolecular electron transfer between the hydroquinone unit and the oxidized metal macrocycle occurs. In this way, a class of important cis-1,4-disubstituted six-membered heterocycles, including dihydropyran and tetrahydropyridine derivatives were obtained in high diastereoselectivity with good functional group compatibility. The experimental and computational (DFT) studies reveal that the pendent olefin does not only act as an indispensable element for the initial allene attack involving allenic C(sp(3))-H bond cleavage, but it also induces a face-selective reaction of the olefin of the allylic group, leading to a highly diastereoselective formation of the product. Finally, the deuterium kinetic isotope effects measured suggest that the initial allenic C(sp(3))-H bond cleavage is the rate-limiting step, which was supported by DFT calculations.

  • 1743.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Liu, Jie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Li, Man-Bo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Anhui University, China.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-catalyzed oxidative dehydrogenative carbonylation reactions using carbon monoxide and mechanistic overviews2020Inngår i: Chemical Society Reviews, ISSN 0306-0012, E-ISSN 1460-4744, Vol. 49, nr 2, s. 341-353Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Carbon monoxide, which is an abundant and inexpensive carbonyl source, has been widely applied to synthesize carbonyl-containing compounds, for example ketones, esters, and amides. These types of compounds are ubiquitous in natural products, pharmaceuticals, as well as in functional materials. This review focuses on the palladium-catalyzed dehydrogenative C-H/X-H (X = C, N, O) carbonylation transformations under oxidative conditions. The related C-H bonds here include C(sp)-H, C(sp(2))-H, and C(sp(3))-H bonds. From a step- and atom-economy perspective, transition metal-catalyzed oxidative dehydrogenative C-H/X-H carbonylation reactions with CO constitute one of the most efficient strategies for the construction of versatile carbonyl groups, without the requirement of pre-functionalized substrates.

  • 1744.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Bin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Highly Selective Cascade C-C Bond Formation via Palladium-Catalyzed Oxidative Carbonylation-Carbocyclization-Carbonylation-Alkynylation of Enallenes2015Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, nr 37, s. 11868-11871Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A highly efficient palladium-catalyzed oxidative cascade reaction of enallenes undergoing overall four C-C bond formations has been developed. The insertion cascade proceeds via carbonylation carbocyclization carbonylation alkynylation involving sequential insertion of carbon monoxide, olefin, and carbon monoxide. Furthermore, different types of terminal alkynes and functionalized enallenes have been investigated and found to undergo the cascade reaction under mild reaction conditions.

  • 1745.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Bin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jiang, Tuo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olefin-Directed Palladium-Catalyzed Regio- and Stereoselective Oxidative Arylation of Allenes2015Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 54, nr 31, s. 9066-9069Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An olefin-directed palladium-catalyzed oxidative regio- and stereoselective arylation of allenes to afford 1,3,6-trienes has been established. A number of functionalized allenes, including 2,3- and 3,4-dienoates and 3,4-dienol derivatives, have been investigated and found to undergo the olefin-directed allene arylation. The olefin moiety has been proven to be a crucial element for the arylating transformation.

  • 1746.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Bin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Khanh Mai, Binh
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palazzotto, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Qiu, Youai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Gudmundsson, Arnar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ricke, Alexander
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Highly Selective Palladium-Catalyzed Hydroborylative Carbocyclization of Bisallenes to Seven-Membered Rings2018Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, nr 43, s. 14324-14333Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A highly selective palladium-catalyzed hydroborylative carbocyclization of bisallenes to afford seven-membered rings has been established. This ring-closing coupling reaction showed good functional group compatibility with high chemo- and regioselectivity, as seven-membered ring 3 was the only product obtained. The extensive use of different linkers, including nitrogen, oxygen, malononitrile, and malonate, showed a broad substrate scope for this approach. A one-pot cascade reaction was realized by trapping the primary allylboron compound with an aldehyde, affording a diastereomerically pure alcohol and a quaternary carbon center by formation of a new C-C bond. A comprehensive mechanistic DFT investigation is also presented. The calculations suggest that the reaction proceeds via a concerted hydropalladation pathway from a Pd(0)-olefin complex rather than via a pathway involving a defined palladium hydride species. The reaction was significantly accelerated by the coordination of the pendant olefin, as well as the introduction of suitable substituents in the bridge, due to the Thorpe-Ingold effect.

  • 1747.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Bin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Qiu, Youai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Highly Selective Construction of Seven-Membered Carbocycles by Olefin-Assisted Palladium-Catalyzed Oxidative Carbocyclization-Alkoxycarbonylation of Bisallenes2016Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, nr 46, s. 14405-14408Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An olefin-assisted palladium-catalyzed oxidative carbocyclization-alkoxycarbonylation of bisallenes to afford seven-membered carbocycles has been established. This dehydrogenative coupling reaction showed excellent substrate scope and functional group compatibility. The reaction exhibited high chemo-and regioselectivity, and ester 3 was the only product obtained. The olefin unit has been proven to be indispensable during the reaction. Moreover, intramolecular oxidative coupling suggests that the reaction proceeds via a (pallyl)palladium intermediate.

  • 1748.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Bin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Qiu, Youai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olefin-Directed Palladium-Catalyzed Regio- and Stereoselective Hydroboration of Allenes2016Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 22, nr 9, s. 2939-2943Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An olefin-directed palladium-catalyzed regio- and stereoselective hydroboration of allenes has been developed to afford fully substituted alkenylboron compounds. The reaction showed a broad substrate scope: a number of functionalized allenes, including 2,3-dienoate, 3,4-dienoate, 3,4-dienol, 1,2-allenylphosphonate, and alkyl-substituted allenes, could be used in this olefin-directed allene hydroboration. The olefin unit was proven to be an indispensable element for this transformation.

  • 1749.
    Zhu, Mingzhao
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jalalian, Nazli
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olofsson, Berit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    One-pot synthesis of diaryliodonium salts using toluenesulfonic acid - a fast entry to electron-rich diaryliodonium tosylates and triflates2008Inngår i: Synlett: Accounts and Rapid Communications in Synthetic Organic Chemistry, ISSN 0936-5214, E-ISSN 1437-2096, nr 4, s. 592-596Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A direct synthesis of symmetric and unsymmetric electron-rich diaryliodonium salts is described. The use of MCPBA and toluenesulfonic acid delivers diaryliodonium tosylates in high yields. An in situ anion exchange has also been developed, giving access to the corresponding triflate salts.

    Fulltekst (pdf)
    fulltext
  • 1750.
    Zhu, Mingzhao
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lin, Shuangzheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhao, Gui-Ling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Organocatalytic diastereoselective dibromination of alkenes2010Inngår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 51, nr 20, s. 2708-2712Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A highly diastereoselective pyrrolidine-promoted dibromination of alkenes by combination of NBS and succinimide is presented. The pyrrolidine-mediated dibromination of alkenes is higly anti-selective and gives the corresponding products in moderate to high yields and up to >25:1 dr.

3233343536 1701 - 1750 of 1772
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