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  • 101.
    Ramström, Olof
    et al.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Pei, Z C
    KTH, Superseded Departments (pre-2005), Chemistry.
    Larsson, R
    KTH, Superseded Departments (pre-2005), Chemistry.
    Hermansson, M
    KTH, Superseded Departments (pre-2005), Chemistry.
    Generation and screening of dynamic combinatorial libraries.2004In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 227, p. U158-U159Article in journal (Other academic)
  • 102.
    Ramström, Olof
    et al.
    KTH, Superseded Departments, Chemistry.
    Skudar, K.
    Haines, J.
    Patel, P.
    Bruggemann, O.
    Food analyses using molecularly imprinted polymers2001In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 49, no 5, p. 2105-2114Article, review/survey (Refereed)
    Abstract [en]

    Molecular imprinting technology(MIT) is a technique for generating polymers bearing biomimetic receptors. It offers several advantages to the agrofood industry in areas such as analysis, sensoring, extraction, or preconcentration of components. It has the potential of becoming a tool for acquiring truly simple, rapid, and robust direct measurements. In this review, the special features of MIT that have bearing on food science and technology are highlighted.

  • 103.
    Ramström, Olof
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Glyconanomaterials for Combating Bacterial Infections2015In: Chemistry A., ISSN 0947-6539, Vol. 21, no 46, p. 16310-16317Article in journal (Refereed)
    Abstract [en]

    Bacterial infections constitute an increasing problem to human health in response to build-up of resistance to present antibiotics and sluggish development of new pharmaceuticals. However, a means to address this problem is to pinpoint the drug delivery to-and into-the bacteria. This results in a high local concentration of the drug, circumventing the increasingly high doses otherwise necessary. Combined with other effectors, such as covalent attachment to carriers, rendering the drugs less degradable, and the combination with efflux inhibitors, old drugs can be revived. In this context, glyconanomaterials offer exceptional potential, since these materials can be tailored to accommodate different effectors. In this Concept article, we describe the different advantages of glyconanomaterials, and point to their potential in antibiotic "revitalization".

  • 104.
    Ramström, Olof
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Molecular imprinting - An introduction2005In: Molecularly Imprinted Materials: Science and Technology, New York: Taylor & Francis , 2005, p. 1-12Chapter in book (Refereed)
  • 105. Ren, Bo
    et al.
    Dong, Hai
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    A Carbohydrate- Anion Recognition System in Aprotic Solvents2014In: Chemistry - An Asian Journal, ISSN 1861-4728, E-ISSN 1861-471X, Vol. 9, no 5, p. 1298-1304Article in journal (Refereed)
    Abstract [en]

    A carbohydrate-anion recognition system in nonpolar solvents is reported, in which complexes form at the B-faces of -D-pyranosides with H1-, H3-, and H5-cis patterns similar to carbohydrate- interactions. The complexation effect was evaluated for a range of carbohydrate structures; it resulted in either 1:1 carbohydrate-anion complexes, or 1:2 complex formation depending on the protection pattern of the carbohydrate. The interaction was also evaluated with different anions and solvents. In both cases it resulted in significant binding differences. The results indicate that complexation originates from van der Waals interactions or weak CHA(-) hydrogen bonds between the binding partners and is related to electron-withdrawing groups of the carbohydrates as well as increased hydrogen-bond-accepting capability of the anions.

  • 106. Ren, Bo
    et al.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Zhang, Qiang
    Ge, Jiantao
    Dong, Hai
    An Iron(III) Catalyst with Unusually Broad Substrate Scope in Regioselective Alkylation of Diols and Polyols2016In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 22, no 7, p. 2481-2486Article in journal (Refereed)
    Abstract [en]

    In this study, [Fe(dibm)(3)] (dibm=diisobutyrylmethane) is shown to have unusually broad scope as a catalyst for the selective monoalkylation of a diverse set of 1,2- and 1,3-diol-containing structures. The mechanism is proposed to proceed via a cyclic dioxolane-type intermediate, formed between the iron(III) species and two adjacent hydroxyl groups. This approach represents the first transition-metal catalysts that are able to replace stoichiometric amounts of organotin reagents in regioselective alkylation. The reactions generally lead to very high regioselectivities and high yields, on par with, or better than, previous methods used for regioselective alkylation.

  • 107.
    Ren, Yansong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Hu, Lei
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Multienzymatic cascade synthesis of an enantiopure (2R,5R)-1,3-oxathiolane anti-HIV agent precursor2019In: Molecular Catalysis, ISSN 2468-8231, Vol. 468, p. 52-56Article in journal (Refereed)
    Abstract [en]

    An enantiopure (2R,5R)-1,3-oxathiolane was obtained using a multienzymatic cascade protocol. By employing a combination of surfactant-treated subtilisin Carlsberg and Candida antarctica lipase B, the absolute configuration of the resulting 1,3-oxathiolane ring was efficiently controlled, resulting in an excellent enantiomeric excess (>99%). This enantiopure 1,3-oxathiolane derivative is a key precursor to anti-HIV agents, such as lamivudine, through subsequent N-glycosylation.

  • 108.
    REN, Yansong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Hu, Lei
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Multienzymatic Cascade Synthesis of an Enantiopure (2R,5R)-1,3-Oxathiolane Anti-HIV Agent PrecursorManuscript (preprint) (Other academic)
    Abstract [en]

    An enantiopure (2R,5R)-1,3-oxathiolane derivative was obtained using amultienzymatic cascade protocol. By employing a combination of surfactant-treatedsubtilisin Carlsberg and Candida antarctica lipase B, the absolute configuration of theresulting 1,3-oxathiolane ring was efficiently controlled, resulting in an excellentenantiomeric excess (> 99%). This enantiopure 1,3-oxathiolane derivative is a keyprecursor to anti-HIV agents, such as lamivudine, through subsequent N-glycosylation.

  • 109.
    REN, Yansong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. KTH, Dept Chem Organ Chem, Stockholm, Sweden..
    Hu, Lei
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. KTH, Dept Chem Organ Chem, Stockholm, Sweden..
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. KTH, Dept Chem Organ Chem, Stockholm, Sweden..
    Multienzymatic, one-pot cascade synthesis of enantiopure lamivudine precursor (2R, 5R)-1,3-oxathiolane2016In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 252Article in journal (Other academic)
  • 110.
    REN, Yansong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Kravchenko, Oleksandr
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Configurational and Constitutional Dynamics in Enamine Molecular SwitchesManuscript (preprint) (Other academic)
    Abstract [en]

    Dual configurational and constitutional dynamics in systems based on enamine molecularswitches has been systematically studied. pH-responsive moieties, such as 2-pyridyl and 2-quinolinyl units, were required on the “stator” part, also providing enamine stability throughintramolecular hydrogen-bonding (IMHB) effects. Upon protonation or deprotonation, forward andbackward switching could be rapidly achieved. Extension of the stator π-system in the 2-quinolinylderivative provided a higher E-isomeric equilibrium ratio under neutral conditions, pointing to ameans to achieve quantitative forward/backward isomerization processes. The ‘rotor’ part of theenamine switches exhibited constitutional exchange ability with primary amines. Interestingly,considerably higher exchange rates were observed with amines containing ester groups, indicatingpotential stabilization of the transition state trough IMHB. Acids, particularly BiIII, were found toefficiently catalyze the constitutional dynamic processes. In contrast, the enamine and the formeddynamic enamine system showed excellent stability under basic conditions. This coupledconfigurational and constitutional dynamics expand the scope of dynamic C-C and C-N bonds, andpotentiates further studies and applications in the fields of molecular machinery and systemschemistry.

  • 111.
    REN, Yansong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Kravchenko, Oleksandr
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Xie, Sheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Grape, Erik
    Inge, A. Ken
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Stimuli-responsive Enaminitrile Molecular Switches as Tunable AIEgens Covering theChromaticity Space and Acting as Vapor SensorsManuscript (preprint) (Other academic)
    Abstract [en]

    A family of responsive enaminitrile molecular switches showing tunable turn-onfluorescence upon switching and aggregation is reported. Activated by addition of acid/base,isomerization around the C=C bond could be effectuated, resulting in complete, reversible switchingto the E- or Z-isomers. Typical aggregation-induced emission could be recorded for one specificstate of the different switches. By subtle tailoring of the parent structure, a series of compounds withemission covering almost the full visible color range were obtained. The switchable AIE features ofthe enaminitrile structures enabled their demonstration as solid state chemosensors to detect acidicand basic vapors, where the emission displayed an “off-on-off” effect. X-ray crystal analysis andDFT calculations suggested a restriction of intramolecular rotation mechanism, and anintramolecular charge transfer effect in the AIE luminogens.

  • 112.
    Ren, Yansong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Svensson, Per H.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. RISE Biosci & Mat, Res Inst Sweden, Forskargatan 18, S-15136 Sodertalje, Sweden..
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. Department of Chemistry, University of Massachusetts Lowell, 1 University Avenue, Lowell, MA, United States.
    A Multicontrolled Enamine Configurational Switch Undergoing Dynamic Constitutional Exchange2018In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 57, no 21, p. 6256-6260Article in journal (Refereed)
    Abstract [en]

    A multiresponsive enamine-based molecular switch is presented, in which forward/backward configurational rotation around the C=C bond could be precisely controlled by the addition of an acid/base or metal ions. Fluorescence turn-on/off effects and large Stokes shifts were observed while regulating the switching process with Cu-II. The enamine functionality furthermore enabled double dynamic regimes, in which configurational switching could operate in conjunction with constitutional enamine exchange of the rotor part. This behavior was used to construct a prototypical dynamic covalent switch system through enamine exchange with primary amines. The dynamic exchange process could be readily turned on/off by regulating the switch status with pH.

  • 113.
    Ren, Yansong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. KTH - Royal Institute of Technology.
    Xie, Sheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Grape, Erik
    Inge, A. Ken
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Multistimuli-Responsive Enaminitrile Molecular Switches DisplayingH+‑Induced Aggregate Emission, Metal Ion-Induced Turn-OnFluorescence, and Organogelation Properties2018In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, no 42, p. 13640-13643Article in journal (Refereed)
    Abstract [en]

    Multistimuli-responsive enaminitrile-based configurational switches displaying aggregation-induced emission (AIE), fluorescence turn-on effects, and supergelation properties are presented. The E-isomers dominated (>97%) in neutral/basic solution, and the structures underwent precisely controlled switching around the enamine C═C bond upon addition of acid/base. Specific fluorescence output was observed in response to different external input in the solution and solid states. In response to H+, configurational switching resulted in complete formation of the nonemissive Z-H+-isomers in solution, however displaying deep-blue to blue fluorescence (ΦF up to 0.41) in the solid state. In response to CuII in the solution state, the E-isomers exhibited intense, turn-on, blue-green fluorescence, which could be turned off by addition of competitive coordination. The acid/base-activated switching, together with the induced AIE-effects, further enabled the accomplishment of a responsive superorganogelator. In nonpolar solvents, a blue-fluorescent supramolecular gel was formed upon addition of acid to the E-isomer suspension. The gelation could be reversed by addition of base, and the overall, reversible process could be repeated at least five cycles.

  • 114.
    Sakulsombat, Morakot
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Angelin, Marcus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Caraballo, Rémi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    A Dynamic Multicomponent Approach for One-Pot Synthesis of 3-Thioisoindolinones2013In: Israel Journal of Chemistry, ISSN 0021-2148, Vol. 53, no 1-2, p. 127-132Article in journal (Refereed)
    Abstract [en]

    A dynamic multicomponent reaction concept has been successfully applied to the syntheses of 3-thioisoindolinones and tricyclic gamma-lactams. The reactions were efficiently designed and operated in the absence of any catalyst under mild reaction conditions, resulting in the convenient variation of substituents on the N- and S-positions of the target products.

  • 115.
    Sakulsombat, Morakot
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Angelin, Marcus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Tandem reversible addition-intramolecular lactonization for the synthesis of 3-functionalized phthalides2010In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 51, no 1, p. 75-78Article in journal (Refereed)
    Abstract [en]

    A new tandem process based on reversible nucleophilic addition and intramolecular lactonization of methyl 2-formylbenzoate leads to the efficient synthesis of 3-functionalized phthalides, which are important precursors for the synthesis of quinone skeletons via Hauser–Kraus annulation. The reactions are successfully carried out under mild conditions in single operations.

  • 116.
    Sakulsombat, Morakot
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Vongvilai, Pornrapee
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Efficient Asymmetric Synthesis of 1-Cyano-tetrahydroisoquinolines from Lipase Dual Activity and Opposite Enantioselectivities in alpha-Aminonitrile Resolution2014In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 36, p. 11322-11325Article in journal (Refereed)
    Abstract [en]

    Dual promiscuous racemization/amidation activities of lipases leading to efficient dynamic kinetic resolution protocols of racemic alpha-aminonitrile compounds are described. alpha-Amidonitrile products of high enantiomeric purity could be formed in high yields. Several lipases from different sources were shown to exhibit the dual catalytic activities, where opposite enantioselectivities could be recorded for certain substrates.

  • 117.
    Sakulsombat, Morakot
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Vongvilai, Pornrapee
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    In Situ Evaluation of Lipase Performances Through Dynamic Asymmetric Cyanohydrin Resolution2011In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 9, no 4, p. 1112-1117Article in journal (Refereed)
    Abstract [en]

    A dynamic resolution process based on multiple reversible cyanohydrin formation coupled to lipase-mediated transesterification is demonstrated. The resulting process resulted in the efficient evaluation of complex lipase performances in asymmetric cyanohydrin acylate synthesis. Dynamic systems were generated and resolved in situ, and the effects of the reaction conditions could be directly monitored for the overall system. By this concept, the enzyme activity, chemo- and stereoselectivity for all involved substrates could be simultaneously evaluated.

  • 118.
    Sakulsombat, Morakot
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhang, Yan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Dynamic Asymmetric Hemithioacetal Transformation by Lipase-Catalyzed gamma-Lactonization: In Situ Tandem Formation of 1,3-Oxathiolan-5-one Derivatives2012In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, no 20, p. 6129-6132Article in journal (Refereed)
    Abstract [en]

    Dynamic hemithioacetal systems were efficiently generated in organic solvents and subsequently allowed to react with a range of lipases. This resulted in direct, dynamic asymmetric transformation of the systems, leading to optically active 1,3-oxathiolan-5-one products. The tandem process identified lipase-catalyzed lactonization as a useful method for the resolution of optimal constituents with high chemo- and stereoselectivities.

  • 119.
    Sakulsombat, Morakot
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Zhang, Yan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Dynamic systemic resolution2012In: Constitutional Dynamic Chemistry / [ed] Barboiu M., Springer Berlin/Heidelberg, 2012, Vol. 322, p. 55-86Chapter in book (Refereed)
    Abstract [en]

    Dynamic Systemic Resolution is a powerful technique for selecting optimal constituents from dynamic systems by applying selection pressures, either externally by addition of target entities, or internally within the system constraints. This concept is a subset of Constitutional Dynamic Chemistry, and the dynamic systems are generally based on reversible covalent interactions between a range of components where the systems are maintained under thermodynamic control. In the present chapter, the concept will be described in detail, and a range of examples will be given for both selection classes. For external pressure generation, target enzymes, in aqueous and/or organic solution, have been used to demonstrate the resolution processes. In a first example, a dynamic transthiolesterification system was generated in aqueous solution at neutral pH, and resolved by hydrolysis using serine hydrolases (cholinesterases). In organic solution, lipase-catalyzed acylation was chosen to demonstrate asymmetric resolution in different dynamic systems, generating chiral ester and amide structures. By use of such biocatalysts, the optimal constituents were selectively chosen and amplified from the dynamic systems in one-pot processes. In internal selection pressure resolution, self-transformation and crystallization-induced diastereomeric resolution have been successfully used to challenge dynamic systems. The technique was, for example, used to identify the best diastereomeric substrate from a large and varied dynamic system in a single resolution reaction.

  • 120.
    Schaufelberger, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hu, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Trans-Symmetric Dynamic Covalent Systems: Connected Transamination and Transimination Reactions2015In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 27, p. 9776-9783Article in journal (Refereed)
    Abstract [en]

    The development of chemical transaminations as a new type of dynamic covalent reaction is described. The key 1,3-proton shift is under complete catalytic control and can be conducted orthogonally to, or simultaneous with, transimination in the presence of an amine to rapidly yield two-dimensional dynamic systems with a high degree of complexity evolution. The transamination-transimination systems are proven to be fully reversible, stable over several days, compatible with a range of functional groups, and highly tunable. Kinetic studies show transamination to be the rate-limiting reaction in the network. Furthermore, it was discovered that readily available quinuclidine is a highly potent catalyst for aldimine transaminations. This study demonstrates how connected dynamic reactions give rise to significantly larger systems than the unconnected counterparts, and shows how reversible isomerizations can be utilized as an effective diversity-generating element.

  • 121.
    Schaufelberger, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Dynamic combinatorial organocatalysis: Discovery-oriented screening of self-correcting catalyst libraries2014In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 248Article in journal (Other academic)
  • 122.
    Schaufelberger, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Dynamic Covalent Organocatalysts Discovered from Catalytic Systems through Rapid Deconvolution Screening2015In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 36, p. 12735-12740Article in journal (Refereed)
    Abstract [en]

    The first example of a bifunctional organocatalyst assembled through dynamic covalent chemistry (DCC) is described. The catalyst is based on reversible imine chemistry and can catalyze the Morita-Baylis-Hillman (MBH) reaction of enones with aldehydes or N-tosyl imines. Furthermore, these dynamic catalysts were shown to be optimizable through a systemic screening approach, in which large mixtures of catalyst structures were generated, and the optimal catalyst could be directly identified by using dynamic deconvolution. This strategy allowed one-pot synthesis and in situ evaluation of several potential catalysts without the need to separate, characterize, and purify each individual structure. The systems were furthermore shown to catalyze and re-equilibrate their own formation through a previously unknown thiourea-catalyzed transimination process.

  • 123.
    Schaufelberger, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kinetic Self-Sorting of Dynamic Covalent Catalysts with Systemic Feedback Regulation2016In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 25, p. 7836-7839Article in journal (Refereed)
    Abstract [en]

    Constructing small molecule systems that mimic the functionality exhibited in biological reaction networks is a key objective of systems chemistry. Herein, we report the development of a dynamic catalytic system where the catalyst activity is modulated through a dynamic covalent bond. By connecting a thermodynamically controlled rearrangement process to resolution under kinetic control, the catalyst system underwent kinetic self sorting, resulting in amplification of a more reactive catalyst while establishing a catalytic feedback mechanism. The dynamic catalyst system furthermore responded to catalytic events by self-perturbation to regulate its own activity, which in the case of upregulation gave rise to systemic autocatalytic behavior.

  • 124.
    Schaufelberger, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Programmed Error-Correction within Dynamic Catalyst Systems for the Morita-Baylis-Hillman reactionManuscript (preprint) (Other academic)
    Abstract [en]

    The understanding of complex reaction networks of small molecules with emergent systemic functionality is integral to both systems chemistry and origin-of-life studies. In this work, a dynamic catalytic system of nucleophilic catalysts for the Morita-Baylis-Hillman (MBH) reaction is demonstrated, exhibiting self-resolution behavior along with thermodynamically driven error-correction. A class of readily reversible MBH adducts from substrates with internal H-transfer capabilities is furthermore presented, displaying rate accelerations of retro-MBH reactions up to 10 000 times. The retro-MBH reaction was used as a design element in a self-resolving dynamic catalytic system, yielding a transient product that was eventually transformed into a more stable thermodynamic product. This study demonstrates efficient self-sorting of complex small molecular catalytic systems.

  • 125.
    Schaufelberger, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Seigel, Karolina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Biomimetic Hydrogen Bonding Catalysis of Imine Exchange for Rapid Equilibration of Dynamic SystemsManuscript (preprint) (Other academic)
    Abstract [en]

    The reversibility of imine bonds has been exploited to great effect in the field of dynamic covalent chemistry, for example in the preparation of dynamic systems for a wide variety of applications. However, acid catalysis is commonly needed for efficient equilibration of imine mixtures. Herein, it is demonstrated that hydrogen bond donors, such as thioureas and squaramides, can catalyze the equilibration of dynamic imine systems under unprecedentedly mild conditions. Catalysis occurs in a range of solvents and in the presence of many sensitive additives, showing moderate to good rate accelerations for both imine metathesis and transimination with amines, hydrazines and hydroxylamines. Furthermore, the catalyst proved simple to immobilize, introducing both reusability and extended control of the equilibration process.

  • 126.
    Schaufelberger, Fredrik
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Timmer, Brian J. J.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Resolving a Reactive Organometallic Intermediate from Dynamic Directing Group Systems by Selective C-H Activation2018In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 1, p. 101-104Article in journal (Refereed)
    Abstract [en]

    Catalyst discovery from systems of potential precursors is a challenging endeavor. Herein, a new strategy applying dynamic chemistry to the identification of catalyst precursors from C-H activation of imines is proposed and evaluated. Using hydroacylation of imines as a model reaction, the selection of an organometallic reactive intermediate from a dynamic imine system, involving many potential directing group/metal entities, is demonstrated. The identity of the amplified reaction intermediate with the best directing group could be resolved in situ by ESI-MS, and coupling of the procedure to an iterative deconvolution protocol generated a system with high screening efficiency.

  • 127.
    Schaufelberger, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Timmer, Brian J. J.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Resolving a Reactive Organometallic Intermediate from Dynamic Directing Group Systems by Selective C-H ActivationManuscript (preprint) (Other academic)
    Abstract [en]

    Catalyst discovery from systems of potential precursors is a challenging endeavor. Herein, a new strategy applying dynamic chemistry to the identification of catalyst precursors from C-H activation of imines is proposed and evaluated. Using hydroacylation of imines as a model reaction, the selection of an organometallic reactive intermediate from a dynamic imine system, involving many potential directing group/metal entities, is demonstrated. The identity of the amplified reaction intermediate with the best directing group could be resolved in situ via ESI-MS, and coupling of the procedure to an iterative deconvolution protocol generated a system with high screening efficiency.

  • 128.
    Sundhoro, Madanodaya
    et al.
    Univ Massachusetts Lowell, Chem, Lowell, MA USA..
    Jeon, Seaho
    Univ Massachusetts Lowell, Chem, Lowell, MA USA..
    Hao, Nanjing
    Univ Massachusetts Lowell, Dept Chem, Lowell, MA USA..
    Park, Jaehyeung
    Univ Massachusetts Lowell, Dept Chem, Lowell, MA USA..
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry (closed 20110630).
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. Royal Inst Technol, Dept Chem, Stockholm, Sweden..
    Yan, Mingdi
    Univ Massachusetts Lowell, Dept Chem, Lowell, MA USA..
    Perfluorophenyl azide-mediated Staudinger reaction and application in probing cell surface glycans2015In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 250Article in journal (Other academic)
  • 129. Sundhoro, Madanodaya
    et al.
    Jeon, Seaho
    Park, Jaehyeung
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Univ Massachusetts Lowell, USA.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Univ Massachusetts Lowell, USA.
    Perfluoroaryl Azide Staudinger Reaction: A Fast and Bioorthogonal Reaction2017In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 56, no 40, p. 12117-12121Article in journal (Refereed)
    Abstract [en]

    We report a fast Staudinger reaction between perfluoroaryl azides (PFAAs) and aryl phosphines, which occurs readily under ambient conditions. A rate constant as high as 18m(-1)s(-1) was obtained between methyl 4-azido-2,3,5,6-tetrafluorobenzoate and methyl 2-(diphenylphosphanyl)benzoate in CD3CN/D2O. Furthermore, the iminophosphorane product was stable toward hydrolysis and aza-phosphonium ylide reactions. This PFAA Staudinger reaction proved to be an excellent bioothorgonal reaction. PFAA-derivatized mannosamine and galactosamine were successfully transformed into cell-surface glycans and efficiently labeled with phosphine-derivatized fluorophore-conjugated bovine serum albumin.

  • 130.
    Timmer, Brian J. J.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Flos, Marta Abellan
    Vincent, Stephane
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Well-defined 3D carbohydrate nanoplatforms: Synthesis, characterization, and lectin interaction2014In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 248Article in journal (Other academic)
  • 131.
    Timmer, Brian J.J.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Flos, M. Abellan
    Jorgensen, L. Monster
    Proverbio, D.
    Altun, S.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Aastrup, T.
    Vincent, S. P.
    Spatially well-defined carbohydrate nanoplatforms: synthesis, characterization and lectin interaction study2016In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 52, no 83, p. 12326-12329Article in journal (Refereed)
    Abstract [en]

    Two novel dodecasubstituted carbohydrate nanoplatforms based on molecular Borromean rings and dodecaamine cages have been prepared for use in evaluating the importance of the spatial distribution of carbohydrates in their interaction with lectins. The binding affinities of the glyconanoplatforms were characterized using quartz crystal microbalance technology and compared with a monovalent reference and dodecaglycosylated fullerenes.

  • 132.
    Timmer, Brian J.J.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Flos, M. Abellán
    Altun, Samuel
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Aastrup, Teodor
    Vincent, Stéphane
    Key Factors for Multivalency Effects in Carbohydrate Nanoplatform-Lectin InteractionsManuscript (preprint) (Other academic)
  • 133.
    Timmer, Brian J.J.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kravchenko, Oleksandr
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Selective Cross Metathesis of Highly Functionalized Substrates in Aqueous MediaManuscript (preprint) (Other academic)
  • 134.
    Timmer, Brian J.J.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Acid-Assisted Direct Olefin Metathesis of Unprotected Carbohydrates in WaterManuscript (preprint) (Other academic)
  • 135.
    Timmer, Brian
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. Univ Massachusetts, Dept Chem, 1 Univ Ave, Lowell, MA 01854 USA;Linnaeus Univ, Dept Chem & Biomed Sci, S-39182 Kalmar, Sweden.
    Acid-Assisted Direct Olefin Metathesis of Unprotected Carbohydrates in Water2019In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 25, no 63, p. 14408-14413Article in journal (Refereed)
    Abstract [en]

    The ability to use unprotected carbohydrates in olefin metathesis reactions in aqueous media is demonstrated. By using water-soluble, amine-functionalized Hoveyda-Grubbs catalysts under mildly acidic aqueous conditions, the self-metathesis of unprotected alkene-functionalized alpha-d-manno- and alpha-d-galactopyranosides could be achieved through minimization of nonproductive chelation and isomerization. Cross-metathesis with allyl alcohol could also be achieved with reasonable selectivity. The presence of small quantities (2.5 vol %) of acetic acid increased the formation of the self-metathesis product while significantly reducing the alkene isomerization process. The catalytic activity was furthermore retained in the presence of large amounts (0.01 mm) of protein, underlining the potential of this carbon-carbon bond-forming reaction under biological conditions. These results demonstrate the potential of directly using unprotected carbohydrate structures in olefin metathesis reactions under mild conditions compatible with biological systems, and thereby enabling their use in, for example, drug discovery and protein derivatization.

  • 136.
    Timmer, Brian
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Schaufelberger, Fredrik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Hammarberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Franzen, Johan.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Dinér, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Simple and Effective Integration of Green Chemistry and Sustainability Education into an Existing Organic Chemistry Course2018In: Journal of Chemical Education, ISSN 0021-9584, E-ISSN 1938-1328, Vol. 95, no 8, p. 1301-1306Article in journal (Refereed)
    Abstract [en]

    Green chemistry and sustainable development have become increasingly important topics for the education of future chemists. The cross-disciplinary nature of green chemistry and sustainable development often means these subjects are taught in conjunction with other subjects, such as organic chemistry and chemical engineering. Herein, a straightforward and efficient approach for vertical integration of green chemistry concepts within existing undergraduate organic chemistry courses is shown. The gradual self-evaluation, "greenification", and reassessment of an organic chemistry course at KTH Royal Institute of Technology from 2013 to 2017 is described, with particular focus on the laboratory course and a novel green chemistry project designed to promote sustainability thinking and reasoning. The laboratory project, which can also be conducted as an independent organic chemistry laboratory exercise, required students to critically evaluate variations of the same Pechmann condensation experiment according to the twelve principles of green chemistry. The course evaluation shows that, after the modifications, students feel more comfortable with the topics "green chemistry" and "sustainability" and consider these topics more important for their future careers. Furthermore, the ability of students to discuss and critically evaluate green chemistry parameters improved considerably as determined from the laboratory project reports.

  • 137. Tyagi, Anuradha
    et al.
    Wang, Xin
    Deng, Lingquan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Photogenerated carbohydrate microarrays to study carbohydrate-protein interactions using surface plasmon resonance imaging2010In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 26, no 2, p. 344-350Article in journal (Refereed)
    Abstract [en]

    A photochemical strategy to generate carbohydrate microarrays on flat sensor surfaces, and to study the protein-binding effects of these arrays by surface plasmon resonance imaging is described. The approach was validated using a panel of carbohydrate-binding proteins. The coupling agents, thiol-functionalized perfluorophenyl azides, allow the covalent attachment of underivatized carbohydrates to gold surfaces by a fast photochemical reaction. Carbohydrate microarrays composed of 3,6-di-O-(alpha-D-mannopyranosyl)-D-mannopyranose (Man3), 2-O-alpha-D-mannopyranosyl-D-mannopyranose (Man2), D-mannose (Man), D-glucose (Glc), and D-galactose (Gal) were constructed, and the binding studies were carried out in real-time using surface plasmon resonance imaging. Results showed that the immobilized carbohydrate ligands retained their binding affinities with lectins, the rank order of which was consistent with that of the free ligands in solution. The detection limit of Man3, Man2, Man, and Glc with the lectin Concanavalin A was measured to be 0.29 nM, 0.18 nM, 0.61 nM, and 3.1 nM, respectively. In addition, soybean agglutinin and Griffonia simplicifolia lectin II were tested on the array, and the results were consistent with the binding selectivity of these lectins with the carbohydrate ligands.

  • 138.
    Uppalapati, Suji
    et al.
    University of Massachusetts Lowell, United States.
    Kong, Na
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Norberg, Oscar
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. University of Massachusetts Lowell, United States.
    Ionization of covalent immobilized poly(4-vinylphenol) monolayers measured by ellipsometry, QCM and SPR2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 343, p. 166-171Article in journal (Refereed)
    Abstract [en]

    Covalently immobilized poly(4-vinylphenol) (PVP) monolayer films were fabricated by spin coating PVP on perfluorophenyl azide (PFPA)-functionalized surfaces followed by UV irradiation. The pH-responsive behavior of these PVP ultrathin films was evaluated by ellipsometry, quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). By monitoring the responses of these films to pH in situ, the ionization constant of the monolayer thin films was obtained. The apparent plc, value of these covalently immobilized PVP monolayers, 13.4 by SPR, was 3 units higher than that of the free polymer in aqueous solution.

  • 139.
    Vongvilai, Pornrapee
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Angelin, Marcus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Larsson, Rikard
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Dynamic Combinatorial Resolution: Direct Asymmetric Lipase-Mediated Screening of a Dynamic Nitroaldol Library2007In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 46, no 6, p. 948-950Article in journal (Refereed)
    Abstract [en]

    (Chemical Equation Presented) A disturbance in the library: The nitroaldol (Henry) reaction was developed as an efficient C-C bond-forming route to dynamic combinatorial libraries (DCLs). These DCLs generated under thermodynamic control were coupled in a one-pot process with kinetically controlled lipase-mediated transesterification (see scheme). The asymmetric resolution of the DCLs by the enzyme led to enantiomerically pure β-nitroacetates in high yield.

  • 140.
    Vongvilai, Pornrapee
    et al.
    KTH, School of Chemical Science and Engineering (CHE).
    Angelin, Marcus
    KTH, School of Chemical Science and Engineering (CHE).
    Larsson, Rikard
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Dynamic combinatorial resolution: Direct substrate identification in asymmetric lipase-mediated transacylations.2009In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 238Article in journal (Other academic)
  • 141.
    Vongvilai, Pornrapee
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Larsson, Rikard
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Direct Asymmetric Dynamic Kinetic Resolution by Combined Lipase Catalysis and Nitroaldol (Henry) Reaction2008In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 350, no 3, p. 448-452Article in journal (Refereed)
    Abstract [en]

    The asymmetric synthesis of β-nitroalkanol derivatives was simply achieved by a combined nitroaldol (Henry) reaction with lipase-catalyzed transesterification in high yield and enantiomeric purity (up to 92% and 99% ee) through a direct one-pot procedure.

  • 142.
    Vongvilai, Pornrapee
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Linder, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry (closed 20110630).
    Sakulsombat, Morakot
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Humble, Maria Svedendahl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry (closed 20110630).
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Racemase Activity of B. cepacia Lipase Leads to Dual-Function Asymmetric Dynamic Kinetic Resolution of alpha-Aminonitriles2011In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 50, no 29, p. 6592-6595Article in journal (Refereed)
    Abstract [en]

    Applaudable promiscuity: Racemase-type activity discovered for B. cepacia lipase with N-substituted α-aminonitriles is proposed to involve a C-C bond-breaking/forming mechanism in the hydrolase site of the enzyme, as supported by experimental data and calculations. This promiscuous activity in combination with the transacylation activity of the enzyme enabled the asymmetric synthesis of N-methyl α-aminonitrile amides in high yield (see scheme).

  • 143.
    Vongvilai, Pornrapee
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Dynamic Asymmetric Multicomponent Resolution: Lipase-Mediated Amidation of a Double Dynamic Covalent System2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 40, p. 14419-14425Article in journal (Refereed)
    Abstract [en]

    The Strecker reaction is one of the most important multicomponent reactions developed, leading to alpha-aminonitriles that are versatile substrates for many synthetic applications. In the present study, this reaction type has been applied to a double dynamic covalent resolution protocol, leading to efficient C-C- and C-N-bond generation as well as chiral discrimination. The combination of transimination with iminecyanation enabled the dynamic exchange in more,than one direction around a single stereogenic center of restricted structure. This multiple exchange process could generate a vast range of compounds from a low number of starting materials in very short time. The resulting double dynamic covalent systems, created under thermodynamic control, were subsequently coupled in a one-pot process with kinetically controlled lipase-mediated transacylation. This resulted in complete resolution of the dynamic systems, yielding the optimal N-acyl-alpha-aminonitriles for the enzyme, where the individual chemoenzymatic reactions could produce enantiomerically pure acylated N-substituted alpha-aminonitriles in good yields.

  • 144.
    Vongvilai, Pornrapee
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sakulsombat, Morakot
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    In Situ Evaluation of Lipase Performances Through Dynamic Asymmetric Cyanohydrin ResolutionManuscript (preprint) (Other academic)
  • 145. Wang, Xin
    et al.
    Liu, Li-Hong
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Engineering Nanomaterial Surfaces for Biomedical Applications2009In: Experimental biology and medicine (Maywood, N.J.: Print), ISSN 1535-3702, E-ISSN 1535-3699, Vol. 234, no 10, p. 1128-1139Article in journal (Refereed)
    Abstract [en]

    Nanomaterials, possessing unique physical and chemical properties, have attracted much interest and generated wide varieties of applications. Recent investigations of functionalized nanomaterials have expanded into the biological area, providing a versatile platform in biomedical applications such as biomolecular sensing, biological imaging, drug delivery and disease therapy. Bio-functions and bio-compatibility of nanomaterials are realized by introducing synthetic ligands or natural biomolecules onto nanomaterials, and combining ligand-receptor biological interactions with intrinsic nanomaterial properties. Common strategies of engineering nanomaterial surfaces involve physisorption or chemisorption of desired ligands. We developed a phollochemically initiated surface coupling chemistry, bringing versatility and simplicity to nanomaterial functionalization. The method was applied to attach underivatized carbohydrates efficiently on gold and iron oxide nanoparticles, and the resulting glyconanoparticles were successfully used as a sensitive biosensing system probing specific interactions between carbohydrates and proteins as well as bacteria. Exp Biol Med 234:1128-1139, 2009

  • 146. Wang, Xin
    et al.
    Matei, Elena
    Deng, Lingquan
    Koharudin, Leonardus
    Gronenborn, Angela M.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    Sensing lectin-glycan interactions using lectin super-microarrays and glycans labeled with dye-doped silica nanoparticles2013In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 47, p. 258-264Article in journal (Refereed)
    Abstract [en]

    A new microarray platform, based on lectin super-microarrays and glycans labeled with dye-doped nanoparticles, has been developed to study glycan-lectin interactions. Glycan ligands were conjugated onto fluorescein-doped silica nanoparticles (FSNPs) using a general photocoupling chemistry to afford FSNP-labeled glycan probes. Lectins were printed on epoxy slides in duplicate sets to generate lectin super-microarrays where multiple assays could be carried out simultaneously in each lectin microarray. Thus, the lectin super-microarray was treated with FSNP-labeled glycans to screen for specific binding pairs. Furthermore, a series of ligand competition assays were carried out on a single lectin super-microarray to generate the dose-response curve for each glycan-lectin pair, from which the apparent affinity constants were obtained. Results showed 4-7 orders of magnitude increase in affinity over the free glycans with the corresponding lectins. Thus, the glycan epitope structures having weaker affinity than the parent glycans could be readily identified and analyzed from the lectin super-microarrays.

  • 147. Wang, Xin
    et al.
    Matei, Elena
    Deng, Lingquan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Gronenborn, Angela M.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Multivalent glyconanoparticles with enhanced affinity to the anti-viral lectin Cyanovirin-N2011In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 47, no 30, p. 8620-8622Article in journal (Refereed)
    Abstract [en]

    Low-mannose (LM) structures were coupled to gold nanoparticles (Au NPs) to amplify the affinity of LMs with Cyanovirin-N (CV-N) lectins and to study the structures of CV-N variants CVN(Q50C) and CVN(MutDB).

  • 148. Wang, Xin
    et al.
    Matei, Elena
    Gronenborn, Angela M.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Direct Measurement of Glyconanoparticles and Lectin Interactions by Isothermal Titration Calorimetry2012In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 84, no 10, p. 4248-4252Article in journal (Refereed)
    Abstract [en]

    Glyconanomaterials have shown high potential in applications including bioanalysis and nanomedicine. Here, a quantitative analytical technique, based on isothermal titration calorimetry, was developed to characterize the interactions between glyconanoparticles and lectins. By titrating lectins into the glyconanoparticle solution, the apparent dissociation constant, thermodynamic parameters, and the number of binding sites were derived simultaneously. For the glyconanoparticles-lectin binding pairs investigated, a 3-5 order of magnitude affinity enhancement over the free ligand-lectin interactions was observed which can be attributed to the multivalent ligand presentation on the nanoparticles. The impact of ligand density was also studied, and results showed that the affinity increased with the number of glycans on the nanoparticle.

  • 149.
    Wang, Xin
    et al.
    Portland State University, United States .
    Norberg, Oscar
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Deng, Lingquan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. Portland State University, United States .
    Synthesis of Glyconanomaterials via Photo-Initiated Coupling Chemistry2011In: Petite and sweet: glyco-nanotechnology as a bridge to new medicines, American Chemical Society (ACS), 2011, Vol. 1091, p. 49-67Conference paper (Refereed)
    Abstract [en]

    Glyconanomaterials, broadly defined as carbohydrate-presenting structures below 100 nm in size, exhibit remarkable chemical and physical properties with high potential for modern biomedical applications. In this chapter, current synthetic approaches for fabricating glyconanomaterials are summarized, with special emphasis on a novel photocoupling strategy to conjugate carbohydrates onto a wide variety of nanomaterials. Based on the photochemically induced reaction of perfluorophenylazide, different glyconanomaterials were efficiently synthesized, and the resulting structures used in a range of applications. The results demonstrate that this approach to carbohydrate presentation at nanomaterial surfaces leads to efficient and selective binding to cognate proteins, enabling new applications in carbohydrate-lectin recognition, profiling, biosensing, screening, cell imaging, and bacteria detection.

  • 150. Wang, Xin
    et al.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    A photochemically initiated chemistry for coupling underivatized carbohydrates to gold nanoparticles2009In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 19, no 47, p. 8944-8949Article in journal (Refereed)
    Abstract [en]

    The sensitive optoelectronic properties of metal nanoparticles make nanoparticle-based materials a powerful tool to study fundamental biorecognition processes. Here we present a new and versatile method for coupling underivatized carbohydrates to gold nanoparticles (Au NPs) via the photochemically induced reaction of perfluorophenylazide (PFPA). A one-pot procedure was developed where Au NPs were synthesized and functionalized with PFPA by a ligand-exchange reaction. Carbohydrates were subsequently immobilized on the NPs by a fast light activation. The coupling reaction was efficient, resulting in high coupling yield as well as high ligand surface coverage. A colorimetric system based on the carbohydrate-modified Au NPs was used for the sensitive detection of carbohydrate-protein interactions. Binding and cross-reactivity studies were carried out between carbohydrate-functionalized Au NPs and lectins. Results showed that the surface-bound carbohydrates not only retained their binding affinities towards the corresponding lectin, but also exhibited affinity ranking consistent with that of the free ligands in solution.

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