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  • 1.
    Angelin, Marcus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Crystallization-induced secondary selection from a tandem driven dynamic combinatorial resolution process2008In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 73, no 9, p. 3593-3595Article in journal (Refereed)
    Abstract [en]

    Crystallization-induced secondary selection from a tandem driven dynamic combinatorial library is presented. In a one-pot experiment, an initial nitroaldol equilibrium was kinetically driven by a tandem reaction resulting in a subsequent dynamic library of diastereoisomers. This library was then further driven by a phase change, resulting in amplification and isolation of a highly diastereomerically enriched and synthetically interesting isoindolinone.

  • 2.
    Angelin, Marcus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Rahm, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Diastereoselective One-Pot Tandem Synthesis of 3-Substituted Isoindolinones: A Mechanistic Investigation2010In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 17, p. 5882-5887Article in journal (Refereed)
    Abstract [en]

    The mechanism of a base-catalyzed one-pot reaction of 2-cyanobenzaldehyde and primary nitroalkanes, to produce 3-substituted isoindolinones, has been investigated. A route starting with a nitroaldol (Henry) reaction, followed by a subsequent cyclization and rearrangement, was supported by intermediate analogue synthesis and DFT calculations. Direct diastereoselective crystallization from the reaction mixture was also achieved and studied for a number of substrates. Furthermore, the 3-substituted isoindolinones are an interesting group of compounds, both present important natural products, as well as being precursors to other valuable building blocks.

  • 3. Belda, O.
    et al.
    Kaiser, N. F.
    Bremberg, U.
    Larhed, M.
    Hallberg, A.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Highly stereo- and regioselective allylations catalyzed by Mo-pyridylamide complexes: Electronic and steric effects of the ligand2000In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 65, no 18, p. 5868-5870Article in journal (Refereed)
  • 4. Bergman, J.
    et al.
    Pettersson, B.
    Hasimbegovic, V.
    Svensson, Per H.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. AstraZeneca R&D, Pharmaceut Dev, Sweden.
    Thionations using a P4S10-pyridine complex in solvents such as acetonitrile and dimethyl sulfone2011In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 76, no 6, p. 1546-1553Article in journal (Refereed)
    Abstract [en]

    Tetraphosphorus decasulfide (P 4S 10) in pyridine has been used as a thionating agent for a long period of time. The moisture-sensitive reagent has now been isolated in crystalline form, and the detailed structure has been determined by X-ray crystallography. The thionating power of this storable reagent has been studied and transferred to solvents such as acetonitrile in which it has proven to be synthetically useful and exceptionally selective. Its properties have been compared with the so-called Lawesson reagent (LR). Particularly interesting are the results from thionations at relatively high temperatures (̃165 °C) in dimethyl sulfone as solvent. Under these conditions, for instance, acridone and 3-acetylindole could quickly be transformed to the corresponding thionated derivatives. Glycylglycine similarly gave piperazinedithione. At these temperatures, LR is inefficient due to rapid decomposition. The thionated products are generally cleaner and more easy to obtain because in the crystalline reagent, impurities which invariably are present in the conventional reagents, P 4S 10 in pyridine or LR, have been removed.

  • 5. Bergman, Jan
    et al.
    Arewang, Carl-Johan
    Svensson, Per H.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. SP Process Development, Sweden .
    Oxidative Ring Expansion of Spirocyclic Oxindole Derivatives2014In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 79, no 19, p. 9065-9073Article in journal (Refereed)
    Abstract [en]

    Oxidation of the spirocyclic oxindole derivative, isamic acid 1, led to decarboxylation and ring expansion to quinazolino[4,5-b]quinazoline-6,8-dione 7 rather than, as previously believed, its isomer 6. The structure of 7 was confirmed by X-ray crystallography. Condensation of isatin (indole-2,3-dione) and 2-aminobenzamide led to the spirocyclic molecule, spiro[3H-indole-3,2'(1H)quinazoline]-2,4'(1H,3H)dione 8, which was also identified as an intermediate in the oxidation of isamic acid. Mild hydrolysis of 7 gave the 10-membered molecule 22. Isamic acid could easily be converted to N-nitrosoisamic acid, which when heated in ethanol underwent a ring expansion to a hydroximino derivative, 38, of compound 6. The structure of 38 was confirmed by X-ray crystallography.

  • 6.
    Blid, Jan
    et al.
    KTH, Superseded Departments, Chemistry.
    Brandt, Peter
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Lewis Acid Mediated [2,3]-Sigmatropic Rearrangement of Allylic alpha-Amino Amides2004In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 69, no 9, p. 3043-3049Article in journal (Refereed)
    Abstract [en]

     Boron trifluoride and BBr3 mediated [2,3]-sigmatropic rearrangements of allylic alpha-amino amides have been developed affording secondary amines in good yields. (E)-Crotyl and (E)-cinnamyl alpha-amino amides 2b and 2c exhibit excellent syn-diastereoselectivity upon rearrangement with either Lewis acid. The allylic amine 2a forms upon treatment with BF3 or BBr3 a five-membered heterocylic complex in which a single halide anion has been displaced by the carbonyl oxygen atom. The structures of the Lewis acid-amine complexes were elucidated using NMR spectroscopy. A plausible reaction mechanism, based on DFT calculations, is presented. Thus, BF3- or BBr3-complexed allylic amines 2 are shown to preferentially proceed, after deprotonation, via an endo transition state.

  • 7.
    Blid, Jan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Panknin, Olaf
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Tuzina, Pavel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lewis acid mediated asymmetric 2,3 -sigmatropic rearrangement of allylic amines. Scope and mechanistic investigation2007In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, no 4, p. 1294-1300Article in journal (Refereed)
    Abstract [en]

    [GRAPHIC] The first asymmetric [2,3]-sigmatropic rearrangement of achiral allylic amines has been realized by quaternization of the amines with an enantiomerically pure diazaborolidine and subsequent treatment with Et3N. The resultant homoallylic amines were obtained in good yields and excellent ee's. The observed diastereo- and enantioselectivities were rationalized by invoking a kinetically controlled process, and support for this model was obtained from an NMR spectroscopic investigation of the chiral Lewis acid-substrate complex. The structure of the Lewis acid-product complex was established by X-ray crystallographic analysis and supported the proposed mechanism.

  • 8.
    Borg, Tessie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Tuzina, Pavel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lewis Acid-Promoted Addition of 1,3-Bis(silyl)propenes to Aldehydes: A Route to 1,3-Dienes2011In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 76, no 19, p. 8070-8075Article in journal (Refereed)
    Abstract [en]

    The Lewis acid-promoted addition of 1,3-bis(silyl)-propenes to aldehydes to provide the corresponding (E)-1,3-dienes in excellent stereoselectivity and good to excellent yields is reported. The procedure is mild, base-free, and operationally straightforward.

  • 9. Bouchet, Aude
    et al.
    Brotin, Thierry
    Linares, Mathieu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Cavagnat, Dominique
    Buffeteaeu, Thierry
    Enantioselective Complexation of Chiral Propylene Oxide by an Enantiopure Water-Soluble Cryptophane2011In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 76, no 10, p. 4178-4181Article in journal (Refereed)
    Abstract [en]

    ECD and NMR experiments show that the complexation of propylene oxide (PrO) within the cavity of an enantiopure water-soluble cryptophane 1 in NaOH solution is enantioselective and that the (R)-PrO@PP-1 diastereomer is more stable than the (S)-PrO@PP-1 diastereomer with a free energy difference of 1.7 kJ/mol. This result has been confirmed to by molecular dynamics (MD) and ab initio calculations. The enantioselectivity is preserved in LiOH and KOH solutions even though the binding constants decrease, whereas PrO is not complexed in CsOH solution.

  • 10. Bouchet, Aude
    et al.
    Brotin, Thierry
    Linares, Mathieu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Cavagnat, Dominique
    Buffeteau, Thierry
    Conformational Effects Induced by Guest Encapsulation in an Enantiopure Water-Soluble Cryptophane2011In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 76, no 5, p. 1372-1383Article in journal (Refereed)
    Abstract [en]

    A new water-soluble cryptophane 1 derivative (penta-hydroxyl cryptophane-A) has been synthesized from cryptophanol-A and the chiroptical properties of its two enantiomers M M-1 and P P-1 have been studied by polarimetry, electronic circular dichroism (ECD), and vibrational circular dichroism (VCD). Cryptophane 1 shows specific circular dichroism responses upon complexation that depend on the size of the guest and on the nature of the counterion (Li+, Na+, K+, Cs+) present in the solution. In LiOH and NaOH solutions, chiroptical changes induced by the encapsulation of guests and by the presence of cations in the vicinity of hosts can be interpreted from molecular dynamics (MD) and ab initio calculations by subtle conformational changes of the bridges. In KOH solution, the exchange dynamics is dependent on the size of the guest molecules, whereas in CsOH solution no encapsulation effect is observed whatever the size of the guest molecule. This last behavior comes from the fact that host 1 exhibits a very high affinity for cesium cations.

  • 11. Brotin, Thierry
    et al.
    Montserret, Roland
    Bouchet, Aude
    Cavagnat, Dominique
    Linares, Mathieu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Buffeteau, Thierry
    High Affinity of Water-Soluble Cryptophanes for Cesium Cations2012In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 77, no 2, p. 1198-1201Article in journal (Refereed)
    Abstract [en]

    Exceptionally high affinity for cesium cations was achieved in aqueous solution using two enantiopure cryptophanes. Complexation of cesium was evidenced by Cs-133 NMR spectroscopy and by electronic circular dichroism (ECD). Binding constants as high as 6 X 10(9) M-1 have been measured by isothermal titration calorimetry (ITC). Very strong complexation of rubidium cations (K similar to 10(6) M-1) has also been measured. Chiral hosts allowed the detection of the two cations at low concentrations (mu M) using ECD.

  • 12.
    Caraballo, Rémi
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Deng, Lingquan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Amorim, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    pH-Dependent Mutarotation of 1-Thioaldoses in Water. Unexpected Behavior of (2S)-D-Aldopyranoses2010In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 18, p. 6115-6121Article in journal (Refereed)
    Abstract [en]

    The pH-dependent mutarotation of 1-thioaldopyranoses in aqueous media has been investigated. Anomerization readily occurred at lower and neutral pH for all aldopyranoses studied, whereas mainly for (2S)-D-aldopyranoses at higher pH. 1-Thio-D-mannopyranose and 1-thio-D-altropyranose showed very strong pH dependence where the anomeric equilibrium ratios changed dramatically from a preference for the beta-anomer at lower pH to the alpha-anomer at higher pH.

  • 13. Carlqvist, P.
    et al.
    Eklund, R.
    Brinck, Tore
    KTH, Superseded Departments, Chemistry.
    A theoretical study of the uncatalyzed and BF3-assisted Baeyer-Villiger reactions2001In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 66, no 4, p. 1193-1199Article in journal (Refereed)
    Abstract [en]

    The mechanisms for the uncatalyzed and boron trifluoride (BF3) assisted Baeyer-Villiger reactions between acetone and hydrogen peroxide have been investigated using high level ab initio [MP2 and CCSD(T)] and density functional theory (B3LYP) methods. Both steps in the uncatalyzed reaction are found to have very high transition state energies. It is clear that detectable amounts of the Crieege intermediate or the products cannot be formed without the aid of a catalyst. The main function of BF3 in both the addition step and the rearrangement (migration) step is to facilitate proton transfer. In the addition step the complexation of hydrogen peroxide with BF3 leads to an increased acidity of the attacking OH group, while in the rearrangement step BF3 takes active part in the proton-transfer process. This latter step is found to be rate determining with an activation free energy of 17.7 kcal/mol in organic solution. The products of the reaction are BF2OH, hydrogen fluoride, and methyl acetate. Thus, BF3 is not directly regenerated from the reaction.

  • 14.
    Carlqvist, Peter
    et al.
    KTH, Superseded Departments, Chemistry.
    Ostmark, H.
    Brinck, Tore
    KTH, Superseded Departments, Chemistry.
    Computational study of the amination of halobenzenes and phenylpentazole. A viable route to isolate the pentazolate anion?2004In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 69, no 9, p. 3222-3225Article in journal (Refereed)
    Abstract [en]

    Amination of halobenzenes, which proceeds via the benzyne intermediate (1), has been studied using quantum chemical methods. The computational data are in agreement with experimentally observed trends in reactivity and provide a qualitative explanation for the observed hydrogen isotope effects. To investigate if this is a viable way to isolate the pentazolate anion (2), the reactivities of the halobenzenes have been compared to phenylpentazole (3). The reaction energetics for phenylpentazole become favorable after complexation with Zn2+.

  • 15. Ding, Yubin
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Li, Tong
    Zhu, Weihong
    Xie, Yongshu
    alpha-Monoacylated and alpha,alpha '- and alpha,beta '-Diacylated Dipyrrins as Highly Sensitive Fluorescence "Turn-on" Zn2+ Probes2013In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 78, no 11, p. 5328-5338Article in journal (Refereed)
    Abstract [en]

    With the purpose of developing readily synthesized CHEF (chelation-enhanced fluorescence) type Zn2+ probes with relatively simple molecular structures and excellent sensing behavior, p-anisoyl chloride was used for the acylation of 5-(pentafluorophenyl)dipyrromethane. Interestingly, the alpha,beta'-diacylated product PS2 with a unique substitution mode was obtained in high yield in addition to the normal a-substituted mono- and diacylated products PSI and PS3. Further oxidation of PS1-PS3 afforded dipyrrins S1-S3. Crystal structure and H-1 NMR measurements of S2 demonstrate the existence of a pure tautomer, which is consistent with DFT calculations. S1-S3 show highly Zn2+ selective "turn-on" fluorescence based on a CHEF mechanism by the formation of 2:1 (probe:metal) Zn2+ complexes. The emission colors can be easily tuned from green to red by changing the dipyrrin substitution modes. Furthermore, these probes demonstrate fast responses and wide applicable pH ranges. Among them, S2 shows the highest Zn2+ sensitivity, with a detection limit of 4.4 x 10(-8) M.

  • 16.
    Dong, Hai
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Pei, Zhichao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Angelin, Marcus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Byström, Styrbjörn
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Efficient Synthesis of β-D-Mannosides and β-D-Talosides by Double Parallel or Double Serial Inversion2007In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, no 10, p. 3694-3701Article in journal (Refereed)
    Abstract [en]

    A neighboring equatorial ester group plays a highly important role in the Lattrell-Dax (nitrite-mediated) carbohydrate epimerization reaction, inducing the formation of inversion compounds in good yields. On the basis of this effect, efficient synthetic routes to beta-D-mannosides and beta-D-talosides, from the corresponding beta-D-galactosides and beta-D-glucosides, have been designed. The present routes are based on multiple regioselective acylation via the respective stannylene intermediates, followed by inversions to the corresponding manno- and talopyranoside structures by nitrite or acetate substitution. It was found that the ester group was able to induce the inversion of its two neighboring groups in high yields following either a double parallel or a double serial inversion process. By combination of direct inversion, and neighboring- as well as remote-group participation, several beta-D-mannoside and beta-D-taloside derivatives were very conveniently obtained in good yields.

  • 17.
    Dong, Hai
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Pei, Zhichao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Byström, Styrbjörn
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Reagent-dependent regioselective control in multiple carbohydrate esterifications2007In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, no 4, p. 1499-1502Article in journal (Refereed)
    Abstract [en]

    Regioselective control in organotin-mediated multiple acylation of carbohydrates is presented. The acylation reagent could be efficiently used to direct the product formation. Reagent-dependent thermodynamic and kinetic control and dynamic assistance mechanisms are suggested, resulting in the efficient preparation of building blocks that normally require many steps with traditional synthesis.

  • 18.
    Dong, Hai
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Pei, Zhichao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Stereospecific Ester Activation in Nitrite-Mediated Carbohydrate Epimerization2006In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, no 8, p. 3306-3309Article in journal (Refereed)
    Abstract [en]

    The Lattrell-Dax method of nitrite-mediated substitution of carbohydrate triflates is an efficient method to generate structures of inverse configuration. In the present study, epimerization of gluco- and galactopyranoside derivatives to the corresponding allo- and gulopyranoside structures by triflation/nitrite treatment has been investigated. It was found that a neighboring ester group was essential for the reactivity of the nitrite-mediated triflate, inversion. Furthermore, a good inversion yield also depended on the relative configuration of the neighboring ester group to the triflate. Only with the ester group in the equatorial position, whatever the configuration of the triflate, did the reaction proceed smoothly, whereas a neighboring axial ester group proved largely inefficient. The results were subsequently used to predict the inversion of glucopyranoside derivatives to the mannopyranoside epimers.

  • 19. Dong, Hai
    et al.
    Zhou, Yixuan
    Pan, Xiaoliang
    Cui, Fengchao
    Liu, Wei
    Liu, Jingyao
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Stereoelectronic Control in Regioselective Carbohydrate Protection2012In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 77, no 3, p. 1457-1467Article in journal (Refereed)
    Abstract [en]

    Organotin-mediated regioselective protection has been extensively used in organic synthesis for many years. However, the mechanistic origin of the resulting regioselectivity is still not clear. By the comparison of the steric and stereoelectronic effects controlling the geometry of five-membered rings formed from neighboring group participation, from intramolecular acyl group migration, or from orthoester transesterification on pyranoside rings, a theory on the pattern resulting from the reaction with dibutyltin oxide is presented. It is thus suggested that the regioselectivity of organotin-mediated protection is controlled by analogous steric and stereoelectronic effects as in neighboring group participation and acyl group migration, mainly dependent on the stereoelectronic effects of the pyranoside itself, and not related to complex stannylene structures. An organotin protection mechanism is also suggested, emanating from steric and stereoelectronic effects, nucleophilicity, and organotin acyl migration.

  • 20. Faure, Regis
    et al.
    Saura-Valls, Marc
    Brumer, Harry, III
    Planas, Antoni
    Cottaz, Sylvain
    Driguez, Hugues
    Synthesis of a library of xylogluco-oligosaccharides for active-site mapping of xyloglucan endo-transglycosylase2006In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, no 14, p. 5151-5161Article in journal (Refereed)
    Abstract [en]

    [GRAPHICS] Complex oligosaccharides containing R-D-xylosyl-(1 -> 6)-beta-D-glucosyl residues and unsubstituted beta-(1 -> 4)-linked D-glucosyl units were readily synthesized using enzymatic coupling catalyzed by the Cel7B E197A glycosynthase from Humicola insolens. Constituting this library required four key steps: ( 1) preparing unprotected building blocks by chemical synthesis or enzymatic degradation of xyloglucan polymers; (2) generating the donor synthon in the enzymatic coupling by temporarily introducing a lactosyl motif on the 4-OH of the terminal glucosyl units of the xylogluco-oligosaccharides; ( 3) synthesizing the corresponding R-fluorides, followed by their de-O-acetylation and the glycosynthase-catalyzed condensation of these donors onto various acceptors; and (4) enzymatically releasing lactose or galactose from the reaction product, affording the target molecules in good overall yields. These complex oligosaccharides proved useful for mapping the active site of a key enzyme in plant cell wall biosynthesis and modification: the xyloglucan endo-transglycosylase (XET). We also report some preliminary enzymatic results regarding the efficiency of these compounds.

  • 21.
    Fjellander, Ester
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Szabó, Zoltán
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Atropoisomerism in Phosphepines and Azepines2009In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 74, no 23, p. 9120-9125Article in journal (Refereed)
    Abstract [en]

    Free energy barriers to biaryl tropoinversion in metal complexes with tropos phosphepine and azepine ligands were determined by temperature-dependent P-31 NMR inversion-transfer experiments and line shape analysis of the temperature-dependent H-1 NMR spectra, respectively. The barrier in the PdCl2 complex of the azepine ligand was found to be slightly higher than that of the corresponding free ligand. Studies of a tridentate azepine ligand Suggested that Configurational change takes place without prior decoordination from the metal.

  • 22.
    Frölander, Anders
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lutsenko, Serghey
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Privalov, Timofei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Conformational preferences and enantiodiscrimination of phosphino-4-(1-hydroxyalkyl)oxazoline-metal-olefin complexes resulting from an OH-metal hydrogen bond2005In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 70, no 24, p. 9882-9891Article in journal (Refereed)
    Abstract [en]

    Phosphinooxazolines carrying (1-hydroxy-1-phenyl)methyl and (1-methoxy-1-phenyl)methyl substituents in the 4 position of the oxazoline ring exhibit contrasting behavior in Pd-and Ir-catalyzed allylic alkylations. Whereas catalysts with the methoxy-containing ligand generally provide products with high ee's, use of catalysts prepared from the hydroxy-containing ligand results in products with low ee's or even racemates. DFT calculations suggest the presence of a hydrogen bond with Pd(0) as the proton acceptor in the hydroxy-containing olefin-Pd(0) complexes, which induces a conformational change in the ligand, leading to different stereoselectivity.

  • 23.
    Hagberg, Daniel P.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Marinado, Tannia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Karlsson, Karl Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Nonomura, Kazeteru
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Qin, Peng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Boschloo, Gerrit
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Tuning the HOMO and LUMO Energy Levels of Organic Chromophores For Dye Sensitized Solar Cells2007In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, no 72, p. 9550-9556Article in journal (Refereed)
    Abstract [en]

    A series of organic chromophores have been synthesized in order to approach optimal energy level composition in the TiO2-dye-iodide/triiodide system in the dye-sensitized solar cells. HOMO and LUMO energy level tuning is achieved by varying the conjugation between the triphenylamine donor and the cyanoacetic acid acceptor. This is supported by spectral and electrochemical experiments and TDDFT calculations. These results show that energetic tuning of the chromophores was successful and fulfilled the thermodynamic criteria for dye-sensitized solar cells, electrical losses depending on the size and orientation of the chromophores were observed.

  • 24.
    Hammar, Peter
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Ghobril, Cynthia
    Wagner, Alain
    Baati, Rachid
    Himo, Fahmi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Theoretical Mechanistic Study of the TBD-Catalyzed Intramolecular Aldol Reaction of Ketoaldehydes2010In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 14, p. 4728-4736Article in journal (Refereed)
    Abstract [en]

    The intramolecular aldol reaction of acyclic ketoaldehydes catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) is investigated using density functional theory calculations. Compared to the aldol reaction catalyzed by proline, the use of TBD provides a unique and unusual complete switch of product selectivity. Three mechanistic pathways are proposed and evaluated. In the favored mechanism TBD catalyzes the reaction through proton transfer in two steps, enolization and C-C bond formation. The computationally predicted stereochemical outcome of the reaction is in agreement with experimental findings. Additionally, these studies provide new insights into the activation mode of bifunctional guanidine catalysts in aldol reactions.

  • 25.
    Hertzberg, Robin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    One-step preparation of O-(α-bromoacyl) cyanohydrins by minor enantiomer recycling: Synthesis of 4-amino-2(5H)-furanones2013In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 78, no 18, p. 9174-9180Article in journal (Refereed)
    Abstract [en]

    O-(α-Bromoacyl) cyanohydrins were prepared in a single step from a range of different aldehydes in combination with α-bromoacyl cyanides. By the use of a cyclic procedure where the two minor diastereoisomers from a chiral Lewis acid-catalyzed reaction undergo Candida antarctica lipase B (CALB)-catalyzed hydrolysis followed by dehydrocyanation to regenerate the starting material, the products were obtained in good to high yields and in most cases with excellent diastereoselectivites. The synthetic importance of these compounds was demonstrated by the synthesis of 4-amino-2(5H)-furanones, a class of compounds that have shown both biological activity and utility as synthetic intermediates. This transformation was achieved by an intramolecular Blaise reaction, which gave the products in high to excellent yields and enantiomeric ratios.

  • 26.
    Hertzberg, Robin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Santiago, Guillermo Monreal
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Synthesis of the beta(3)-Adrenergic Receptor Agonist Solabegron and Analogous N-(2-Ethylamino)-beta-amino Alcohols from O-Acylated Cyanohydrins - Expanding the Scope of Minor Enantiomer Recycling2015In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 80, no 5, p. 2937-2941Article in journal (Refereed)
    Abstract [en]

    A novel methodology to produce highly enantioenriched N-(2-ethylamino)-beta-amino alcohols was developed. These compounds were obtained from O-(alpha-bromoacyl) cyanohydrins, which were synthesized by the minor enantiomer methodology employing a Lewis acid and a biocatalyst, followed by nucleophilic substitution with amines and reduction. The importance of the developed methodology was demonstrated by completing a highly enantioselective total synthesis of the beta(3)-adrenergic receptor agonist Solabegron.

  • 27.
    Himo, Fahmi
    et al.
    KTH, Superseded Departments, Biotechnology.
    Demko, Z. P.
    Noodleman, L.
    Density functional theory study of the intramolecular 2+3 cycloaddition of azide to nitriles2003In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 68, no 23, p. 9076-9080Article in journal (Refereed)
    Abstract [en]

    Density functional theory calculations using the hybrid functional B3LYP have been performed to study tetrazole formation by intramolecular [2 + 3] dipolar cycloaddition of organic azides and nitriles. Experimental reactivity trends are explained and rationalized in terms of a number of parameters, such as strain, tether length, and solvation and entropy effects. Interestingly, no correlation was found between the overall free energies and the free energies of activation of the reactions, due to the significant difference in strain and geometry between the transition states and products.

  • 28.
    Hirner, Sebastian
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Synthesis of alpha-Amino Amides via N,O-Acetals Derived from Weinreb Amides2009In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 74, no 20, p. 7798-7803Article in journal (Refereed)
    Abstract [en]

    An easy and straightforward synthesis of alpha-amino amides via a base-mediated rearrangement of modified Weinreb amides into N,O-acetals is presented. Subsequent arylation, alkylation, alkenylation, or alkynylation of this intermediate affords the corresponding alpha-amino amides in excellent yields. Furthermore, a more generalized protocol for the alpha-arylation of Weinreb amides lacking an alpha-amino moiety is also discussed.

  • 29.
    Hu, Lei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ren, Yansong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Chirality Control in Enzyme-Catalyzed Dynamic Kinetic Resolution of 1,3-Oxathiolanes2015In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 80, no 16, p. 8478-8481Article in journal (Refereed)
    Abstract [en]

    The origin of enantioenrichment in enzyme-catalyzed dynamic kinetic resolution of 1,3-oxathiolane derivatives, key intermediates for asymmetric lamivudine synthesis, was elucidated. The chirality control could be determined by chiral HPLC and NOE NMR spectroscopy using a modified 1,3-oxathiolane compound obtained through enzyme-catalyzed selective hydrolysis. Solvent-dependent stereoselectivity was observed under biphasic conditions using different organic solvents with phosphate buffer.

  • 30. Kumar, Sangit
    et al.
    Johansson, Henrik
    Kanda, Takahiro
    Engman, Lars
    Muller, Thomas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    Bergenudd, Helena
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    Pedulli, Franco
    Amorati, Riccardo
    Valgimigli, Luca
    Catalytic Chain-Breaking Pyridinol Antioxidants2010In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 3, p. 716-725Article in journal (Refereed)
    Abstract [en]

    The synthesis of 3-pyridinols carrying alkyltelluro, alkylseleno, and alkylthio groups is described together with a detailed kinetic, thermodynamic, and mechanistic Study of their antioxidant activity. When assayed for their capacity to inhibit azo-initiated peroxidation of linoleic acid in a water/chlorobenzene two-phase system, tellurium-containing 3-pyridinols were readily regenerable by N-acetylcysteine contained in the aqueous phase. The best inhibitors quenched peroxyl radicals more efficiently than alpha-tocopherol, and the duration of inhibition was limited only by the availability of the thiol reducing agent. fn homogeneous phase, inhibition of styrene autoxidation absolute rate constants k(inh) for quenching of peroxyl radical were as large as 1 x 10(7) M-1 s(-1), thus Outperforming the best phenolic antioxidants including alpha-tocopherol. Tellurium-containing 3-pyridinols could be quantitatively regenerated in homogeneous phase by N-tert-butoxycarbonyl cysteine methyl ester, a lipid-soluble analogue of N-acetylcysteine. In the presence of an excess of the thiol, a catalytic mode of action was observed, similar to the one in the two-phase system. Overall, compounds bearing the alkyltelluro moiety ortho to the OH group were much more effective antioxidants than the corresponding para isomers. The origin of the high reactivity of these compounds was explored using pulse-radiolysis thermodynamic measurements, and a mechanism for their unusual antioxidant activity was proposed. The tellurium-containing 3-pyridinols were also found to catalyze reduction of hydrogen peroxide in the presence of thiol reducing agents, thereby acting as multifunctional (preventive and chain-breaking) catalytic antioxidants.

  • 31. Langlet, Abraham
    et al.
    Bergman, Jan
    Wellmar, Ulf
    Bemm, Ulf
    Goede, P.
    Romero, I.
    Lattypov, Nikolaj
    Nitration of 2-substituted pyrimidine-4,6-diones, structure and reactivity of 5,5-gem-dinitropyrimidine-4,6-diones2002In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 67, no 22, p. 7833-7838Article in journal (Refereed)
    Abstract [en]

    Nitration of some 2-substituted pyrimidine-4,6-diones in sulfuric acid was studied, which afforded previously unknown 5,5-gem-dinitropyrimidine-4,6-diones in high yields. The gem-dinitro products were easily attacked by nucleophiles with concomitant formation of gem-dinitroacetyl derivatives, which in turn could be further hydrolyzed to salts of dinitromethane and triureas.

  • 32. Li, Hong
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Wu, Ying
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Qu, Da-Hui
    A Musclelike [2](2)Rotaxane: Synthesis, Performance, and Molecular Dynamics Simulations2014In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 79, no 15, p. 6996-7004Article in journal (Refereed)
    Abstract [en]

    A novel bistable symmetric [2](2)rotaxane was prepared by a threading-followed-by-stoppering strategy and characterized with H-1, C-13, and 2D ROESY NMR spectroscopy and HR-ESI spectrometry. The symmetric [2] (2)rotaxane system consists of an anthracene-based bis(crown ether) as macrocycles, and each of the two dibenzo[24]crown-8 (DB24C8) rings is threaded by the pendant substituents a symmetrically substituted central rotatable ferrocene subunit that possesses two distinguishable recognition sites for the DB24C8 ring: namely, a dibenzylammonium site and an N-methyltriazolium site. The uniform shuttling motion of the thread relative to the two DB24C8 rings in [2](2)rotaxane can be driven by external acid base stimuli, which was evidenced by H-1 and 2D ROESY NMR spectroscopy. Furthermore, molecular dynamics simulations of the [2](2)rotaxane were carried out both in protonated (stretched) and in neutral (contracted) forms. The calculated percentage change in molecular length of the [2](2)rotaxane between the two end-capping bis(methoxyl)phenyl groups is about 48% in the two different states (in acetone), which is much larger than the percentage change (similar to 27%) in human muscle. Moreover, in the two states, the C*-Cp-Cp-C* dihedral angles are computed as -177 degrees in the stretched state and -112 degrees in the contracted state, indicating a correlation between the translational and rotational motions of the [2](2)rotaxane.

  • 33. Liljenberg, Magnus
    et al.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry (closed 20110630).
    Herschend, Björn
    Rein, Tobias
    Rockwell, Glen
    Svensson, Mats
    Validation of a Computational Model for Predicting the Site for Electrophilic Substitution in Aromatic Systems2010In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 14, p. 4696-4705Article in journal (Refereed)
    Abstract [en]

    We have investigated the scope and limitations of a method for predicting the regioisomer distribution in electrophilic aromatic substitution reactions that are under kinetic control. This method is based on calculation of the relative stabilities of the sigma-complex intermediates using density functional theory. Predictions from this method can be used quantitatively for halogenations; it agreed to an accuracy of about 1 kcal/mol with experimental observations in 10 of the 11 investigated halogenation reactions. For nitrations, the method gave useful predictions for heterocyclic substrates. The method failed for nitration of monosubstituted benzenes, and we expect that more elaborate model systems, including explicit solvent molecules, will be necessary to obtain quantitatively useful predictions for such cases. For Lewis acid promoted Friedel Crafts acylations, the method can be expected to give qualitatively correct predictions, that is, to point out the dominating isomer. For substrates where the regioisomeric outcome is highly dependent on the reaction conditions, the method can only be of qualitative use if the concentration of the free Lewis acid is high during the reaction. We have also compared the predictive capacity of the method to that of a modern reactivity index, the average local ionization energy, I(r). The latter method is found to predict the regisolectivity in halogenations and nitrations qualitatively correctly if the positions for the I(r) minima (I-S,I-min) are not too sterically hindered but fails for qualitative predictions of F C reactions. The downscaled I-S,I-min values also perform well for the quantitative prediction of regioisomer distributions of halogenations. The accuracy is slightly lower than that for the new method.

  • 34. Liljenberg, Magnus
    et al.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry (closed 20110630).
    Herschend, Björn
    Rein, Tobias
    Tomasi, Simone
    Svensson, Mats
    Predicting Regioselectivity in Nucleophilic Aromatic Substitution2012In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 77, no 7, p. 3262-3269Article in journal (Refereed)
    Abstract [en]

    We have investigated practical and computationally efficient methods for the quantitative prediction of regioisomer distribution in kinetically controlled nucleophilic aromatic substitution reactions. One of the methods is based on calculating the relative stabilities of the isomeric sigma-complex intermediates using DFT. We show that predictions from this method can be used quantitatively both for anionic nucleophiles with F- as leaving group, as well as for neutral nucleophiles with HF as leaving group. The sigma-complex approach failed when the leaving group was Cl/HCl or Br/HBr, both for anionic and neutral nucleophiles, because of difficulties in finding relevant sigma-complex structures. An approach where we assumed a concerted substitution step and used such transition state structures gave quantitatively useful results. Our results are consistent with other theoretical works, where a stable sigma-complex has been identified in some cases, whereas others have been indicated to proceed via a concerted substitution step.

  • 35.
    Linder, Mats
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Stepwise Diels-Alder: More than Just an Oddity? A Computational Mechanistic Study2012In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 77, no 15, p. 6563-6573Article in journal (Refereed)
    Abstract [en]

    We have employed hybrid DFT and SCS-MP2 calculations at the SMD-PCM–6-311++G(2d,2p)//6-31+G(d) level to investigate the relationship between three possible channels for forming a Diels–Alder adduct from a highly nucleophilic diene and moderately to highly electrophilic dienophiles. We discuss geometries optimized using the B3LYP and M06-2X functionals with the 6-31+(d) basis set. The transition states and intermediates are characterized on the basis of geometric and electronic properties, and we also address the possibility of predicting detectability of a zwitterionic intermediate based on its relative stability. Our results show that a conventional Diels–Alder transition state conformation yields intermediates in all four investigated cases, but that these are too short-lived to be detected experimentally for the less activated reactants. The stepwise trans pathway, beginning with a conjugate addition-like transition state, becomes increasingly competitive with more activated reactants and is indeed favored for the most electrophilic dienophiles. Addition of a trans diene leads to a dead-end as the trans intermediates have insurmountable rotation barriers that prohibit formation of the second bond, unless another, heterocyclic intermediate is formed. We also show that introduction of a hydrogen bond donating catalyst favors a stepwise pathway even for less activated dienophiles.

  • 36.
    Liu, Jian Quan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. Jiangsu Normal Univ, Jiangsu Key Lab Green Synth Funct Mat, Sch Chem & Mat Sci, Xuzhou 221116, Jiangsu, Peoples R China.
    Chen, Xinyi
    Shatskiy, Andrey
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Kärkäs, Markus D.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Wang, Xiang-Shan
    Silver-Mediated Synthesis of Substituted Benzofuran- and Indole-Pyrroles via Sequential Reaction of ortho-Alkynylaromatics with Methylene Isocyanides2019In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 84, no 14, p. 8998-9006Article in journal (Refereed)
    Abstract [en]

    A silver-mediated reaction between 2-ethynyl-3-(1-hydroxyprop-2-yn-1-yl)phenols or 2-ethyn-yl-3-(1-hydroxy-prop-2-yn-1-yl)anilines and methylene isocyanides has been developed. A sequential 5-endo-dig cyclization and [3 + 2] cycloaddition process is proposed. This synthetic strategy is atom- and step-efficient and applicable to a broad scope of substrates, allowing the synthesis of valuable substituted benzofuran- and indole-pyrroles in moderate to high yields.

  • 37. Löfstedt, Joakim
    et al.
    Franzén, Johan
    Bäckvall, Jan-Erik
    Carbon-carbon bond formation in regio- and stereoselective palladium-catalyzed cyclization of allene-substituted conjugated dienes2001In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 66, no 24, p. 8015-8025Article in journal (Refereed)
    Abstract [en]

    Regio- and stereoselective palladium-catalyzed reactions of allene-substituted 1,3-dienes 1 in acetic acid at room temperature lead to cyclization with formation of a carbon-carbon bond between the middle carbon of the allene and the terminal carbon of the 1,3-diene. Two different types of reactions, both that constitute 1,4-carboacetoxylations of the 1,3-diene, have been developed. In one of the reactions, Pd(II) catalyzes the oxidation of 1 to bicyclic compounds 2, and in the other, Pd(0) catalyzes the transformation of 1 to bicyclic compounds 3. The products 2 are useful for further synthetic transformations and undergo Diels-Alder reactions with dienophiles to give polycyclic ring systems.

  • 38.
    Malkoch, Michael
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Hallman, Kristina
    KTH, Superseded Departments, Chemistry.
    Lutsenko, Serghey
    KTH, Superseded Departments, Chemistry.
    Hult, Anders
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Malmström, Eva
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Dendritic oxazoline ligands in enantioselective palladium-catalyzed allylic alkylations2002In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 67, no 23, p. 8197-8202Article in journal (Refereed)
    Abstract [en]

    First to fourth generation dendritic substituents based on 2,2-bis(hydroxymethyl)propionic acid and (1R,2S,5R)-menthoxyacetic acid were attached to 2-(hydroxymethyl)pyridinooxazoline and his[4-(hydroxymethyl)oxazoline] compounds. The new ligands obtained were assessed in palladium-catalyzed allylic alkylations. The first type of ligands exhibited enantioselectivity similar to that of a benzoyl ester derivative, whereas the latter type of ligands afforded products with higher selectivity than the analogous benzoyl ester. The activity of the dendritic catalysts decreased with increasing generation.

  • 39.
    Neimert-Andersson, Kristina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Blomberg, Eva
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231).
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Stereoselective Synthesis of Polyhydroxyl Surfactants. Stereochemical Influence on Langmuir Monolayers2004In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 69, no 11, p. 3746-3752Article in journal (Refereed)
    Abstract [en]

    Herein is described the synthesis of surfactants featuring polyhydroxylated head groups. Three head groups were prepared via consecutive stereoselective dihydroxylations of a diene. By coupling of these with lipophilic tail groups six novel surfactants have been prepared. The monolayers prepared from four of these have been investigated at the air-water interface. Significant differences were observed between monolayers consisting of enantiomerically pure surfactants contra racemates as well as between diastereomers.

  • 40.
    Neimert-Andersson, Kristina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sauer, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Borg, Tessie
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Söderlind, Erik
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Synthesis of New Sugar-Based Surfactants and Evaluation of their Haemolytic Activities2006In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, no 9, p. 3623-3626Article in journal (Other academic)
    Abstract [en]

    The synthesis of four sugar-based surfactants derived from glucose and (R)-12-hydroxystearic acid is described. The surfactants have a hydroxy group in the hydrophobic part, which is either free or acylated using acetyl chloride, hexanoyl chloride, or myristoyl chloride. Three of the synthesized surfactants are water-soluble and are evaluated with respect to their CMCs and hemolytic activities. The fourth surfactant has limited water solubility and is not further included in the study. The investigated surfactants are all hemolytic close to their respective CMC indicating that their use in parenteral formulations may be limited. Nevertheless, surfactants having the proposed structure appear as promising alternatives to existing solubilizing agents for pharmaceutical applications.

  • 41. Ning, Zhijun
    et al.
    Zhang, Qiong
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Wu, Wenjun
    Pei, Hongcui
    Liu, Bo
    Tian, He
    Starburst triarylamine based dyes for efficient dye-sensitized solar cells2008In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 73, no 10, p. 3791-3797Article in journal (Refereed)
    Abstract [en]

    We report here on the synthesis and photophysical/electrochemical properties of a series of novel starburst triarylamine-based organic dyes (S1, S2, S3, and S4) as well as their application in dye-sensitized nanocrystalline TiO2 solar cells (DSSCs). For the four designed dyes, the starburst triarylamine group and the cyanoacetic acid take the role of electron donor and electron acceptor, respectively. It was found that the introduction of starburst triarylamine group to form the D-D-pi-A configuration brought about superior performance over the simple D-pi-A configuration, in terms of bathochromically extended absorption spectra, enhanced molar extinction coefficients and better thermo-stability. Moreover, the HOMO and LUMO energy levels tuning can be conveniently accomplished by alternating the donor moiety, which was confirmed by electrochemical measurements and theoretical calculations. The DSSCs based on the dye S4 showed the best photovoltaic performance: a maximum monochromatic incident photon-to-current conversion efficiency (IPCE) of 85%, a short-circuit photocurrent density (J(sc)) of 13.8 mA cm(-2), an open-circuit photovoltage (V-oc) of 0.63 V, and a fill factor (ff) of 0.69, corresponding to an overall conversion efficiency of 6.02% under 100 mW cm(-)2 irradiation. This work suggests that the dyes based on starburst triphenylamine donor are promising candidates for improvement of the performance of the DSSCs.

  • 42. Närhi, Katja
    et al.
    Franzén, Johan
    Bäckvall, Jan-E
    An unexpectedly mild thermal alder-ene-type cyclization of enallenes2006In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, no 7, p. 2914-2917Article in journal (Refereed)
    Abstract [en]

    A mild, thermal Alder-ene reaction of enallenes has been developed. The allenic double bond acts as the "ene" and generates a carbon-carbon bond to an unactivated olefinic "enophile" in DMF at 120 degrees C to give [n.3.0] bicyclic systems (n = 3-5) in good yields. Except for a minor [2 + 2] cycloaddition byproduct, the reaction proceeded with complete atom economy, as there is no requirement of a catalyst or additional reactants, and no waste products are formed in the process.

  • 43. Ofsson, B.
    et al.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Divergent synthesis of D-erythro-sphingosine, L-threo-sphingosine, and their regioisomers2003In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 68, no 6, p. 2514-2517Article in journal (Refereed)
    Abstract [en]

    Starting from a vinyl epoxide, a divergent synthesis of four sphingosine isomers is described. The remaining four isomers can easily be synthesized using the same methodology. Although numerous syntheses of sphingosine have been published, this is the first general route leading to all eight isomers in this important compound class. The synthetic strategy relies on regioselective opening of a vinyl epoxide and a vinylaziridine in the allylic position.

  • 44. Olofsson, B.
    et al.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    A regio- and stereodivergent route to all isomers of vic-amino alcohols2002In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 67, no 24, p. 8574-8583Article in journal (Refereed)
    Abstract [en]

    Vicinal amino alcohols are substructures in several important natural products. They are also frequently employed ligands in asymmetric synthesis. Many enantioselective syntheses of vic-amino alcohols have been reported, but each structure has required its own synthetic route. This study presents a synthetic strategy leading to all eight possible isomers of a given beta-amino alcohol, starting from vinyl epoxides. The developed strategy focuses on the propensity of vinyl epoxides and vinylaziridines to be selectively ring-opened at the allylic position by suitable hard nucleophiles. Within this strategy, a novel large-scale aminolysis reaction and the synthesis of a trisubstituted N-H vinylaziridine are detailed.

  • 45. Osmialowski, Borys
    et al.
    Zakrzewska, Anna
    Jedrzejewska, Beata
    Grabarz, Anna
    Zalesny, Robert
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Wroclaw Univ Technol, Fac Chem, Poland.
    Bartkowiak, Wojciech
    Kolehmainen, Erkki
    Influence of Substituent and Benzoannulation on Photophysical Properties of 1-Benzoylmethyleneisoquinoline Difluoroborates2015In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 80, no 4, p. 2072-2080Article in journal (Refereed)
    Abstract [en]

    A series of 1-benzoylmethyleneisoquinoline difluoroborates were synthesized, and their photophysical properties were determined. The effect of the substituent and benzoannulation on their properties was investigated to make a comparison with recently published results focused on related quinolines. The photophysical properties of isoquinoline derivatives differ from those of quinolines, and the most pronounced differences are found for the fluorescence quantum yields. Both experimental and theoretical approaches were used to explain the observed photophysical properties.

  • 46.
    Pei, Zhichao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Dong, Hai
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Solvent-dependent, kinetically controlled stereoselective synthesis of 3- and 4- thioglycosides2005In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 70, no 17, p. 6952-6955Article in journal (Refereed)
    Abstract [en]

    Facile approaches to prepare 3- and 4-thioglycosides of the galacto, gulo, and gluco type from the parent triflates are presented. The dependencies of the solvent and the protecting group pattern, as well as the configuration of the neighboring and leaving groups, have been studied for these reactions. The results clearly show that the efficient stereo-selective synthesis of methyl 3-thin-galactoside depends highly on the solvent and the nucleophile concentration.

  • 47. Ren, Bo
    et al.
    Rahm, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Cornell Univiversity, USA .
    Zhang, Xiaoling
    Zhou, Yixuan
    Dong, Hai
    Regioselective Acetylation of Diols and Polyols by Acetate Catalysis: Mechanism and Application2014In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 79, no 17, p. 8134-8142Article in journal (Refereed)
    Abstract [en]

    We propose a principle for H-bonding activation in acylation of hydroxyl groups, where the acylation is activated by the formation of hydrogen bonds between hydroxyl groups and anions. With the guidance of this principle, we demonstrate a method for the selective acylation of carbohydrates. By this method, diols and polyols are regioselectively acetylated in high yields under mild conditions using catalytic amounts of acetate. In comparison to other methods involving reagents such as organotin, organoboron, organosilicon, organobase, and metal salts, this method is more environmentally friendly, convenient, and efficient and is also associated with higher regioselectivity. We have performed a thorough quantum chemical study to decipher the mechanism, which suggests that acetate first forms a dual H-bond complex with a diol, which enables subsequent monoacylation by acetic anhydride under mild conditions. The regioselectivity appears to originate from the inherent structure of the diols and polyols and their specific interactions with the coordinating acetate catalyst.

  • 48. Stenlid, Joakim H.
    et al.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Nucleophilic Aromatic Substitution Reactions Described by the Local Electron Attachment Energy2017In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, no 6, p. 3072-3083Article in journal (Refereed)
    Abstract [en]

    A local multiorbital electrophilicity descriptor, the local electron attachment energy [E(r)], is used to study the nucleophilic aromatic substitution reactions of SNAr and VNS (vicarious nucleophilic substitution). E(r) considers all virtual orbitals below the free electron limit and is determined on the molecular isodensity contour of 0.004 atomic units. Good (R-2 = 0.83) to excellent (R-2 = 0.98) correlations are found between descriptor values and experimental reactivity data for six series of electron deficient arenes. These include homo- and heteroarenes, rings of five to six atoms, and a variety of fluorine, bromine, and hydride leaving groups. The solvent, temperature, and nucleophile are in addition varied across the series. The surface E(r) [E-s(r)] is shown to provide reactivity predictions better than those of transition-state calculations for a concerted SNAr reaction with a bromine substantially stronger than those of LUMO energies, and is overall more reliable than the molecular electrostatic potential. With the use of E-s(r), one can identify the various electrophilic sites within a molecule and correctly predict isomeric distributions. Since the calculations of E-s(r) are computationally inexpensive, the descriptor offers fast but accurate reactivity predictions for the important nucleophilic aromatic substitution class of reactions. Applications in, e.g., drug discovery, synthesis, and toxicology studies are envisaged.

  • 49.
    Strand, Daniel
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Norrby, Per-Ola
    Rein, Tobias
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Divergence en Route to Nonclassical Annonaceous Acetogenins. Synthesis of Pyranicin and Pyragonicin2006In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, no 5, p. 1879-1891Article in journal (Refereed)
    Abstract [en]

    Syntheses of the nonclassical annonaceous acetogenins, pyranicin, and pyragonicin from common late-stage intermediates are presented. The construction of key elements relies on asymmetric HWE reactions, including the desymmetrization of a meso-dialdehyde and a parallel kinetic resolution of a racemic aldehyde. A stereoconvergent Pd-catalyzed substitution serves to install the C4 stereocenter in protected form with different orthogonal protective groups. A divergent strategy to form 1.4- and 1.6-diols, employing stereoselective Zn-mediated alkynylations, is used for completion of the core structures. Notably, the stereoselective coupling reaction toward pyragonicin proceeds with highly functionalized fragments. The methodology is further expanded by a divergent synthesis of all stereoisomers of the 2,3,6-trisubstituted tetrahydropyran subunit.

  • 50.
    Syrén, Per-Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Protein Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Enzymatic Hydrolysis of Tertiary Amide Bonds by anti Nucleophilic Attack and Protonation2018In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 83, no 21, p. 13543-13548Article in journal (Refereed)
    Abstract [en]

    The molecular mechanisms conferring high resistance of planar tertiary amide bonds to hydrolysis by most enzymes have remained elusive. To provide a chemical explanation to this unresolved puzzle, UB3LYP calculations were performed on an active site model of Xaa-Pro peptidases. The calculated reaction mechanism demonstrates that biocatalysts capable of tertiary amide bond hydrolysis capitalize on anti nucleophilic attack and protonation of the amide nitrogen, in contrast to the traditional syn displayed by amidases and proteases acting on secondary amide bonds.

12 1 - 50 of 58
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