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  • 1.
    Andersson, Samir
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Zou, Dapeng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Zhang, Rong
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Sun, Shiguo
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Åkermark, Björn
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Selective Positioning of CB 8 on Two Linked Viologens and Electrochemically Driven Movement of the Host Molecule2009Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 8, s. 1163-1172Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The binding interactions between cucurbit[8]uril (CB[8]) and a dicationic guest N,N-dimethyl-3,3'-dimethyl-4,4'-bipyridinium (DMV2+) have been investigated by various experimental techniques including NMR, ESI-MS, and UV/Vis and fluorescence spectroscopy. In a three-component system consisting of CB[81, N,N-dimethyl-4,4'-bipyridinium (MV2+) and DMV2+, CB[8] was found to exhibit a higher binding affinity to DMV2+ than to MV2+, When DMV2+ was connected to MV2+ by an alkyl chain, the first equiv. of CB[8] could be selectively positioned on the DMV2+ moiety, and then a second equiv. of CB[8] was positioned on the MV2+ moiety. Spectroelectrochemical studies showed that upon the reduction of this system at -0.6 V vs. AgCl, the CB[8] could move from the DMV2+ moiety to the MV+center dot radical, which formed a dimer inside the CB[8] cavity. Molecular oxygen quenched the dimer, and the CB[8] moved back to the DMV2+ moiety, indicating it molecular movement driven by electrochemistry. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

  • 2. Angelin, Marcus
    et al.
    Hermansson, Magnus
    Dong, Hai
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Direct, mild, and selective synthesis of unprotected dialdo-glycosides2006Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 19, s. 4323-4326Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A direct and highly convenient organocatalytic method for the preparation of 1,5-dialdo-pyranosides and 1,4-dialdo-furanosides is presented. The method relies on the chemoselective properties of TEMPO in combination with trichloroisocyanuric acid under very mild, basic conditions. Unprotected glycosides are prepared in a single step in high yields and are efficiently purified with the use of solid-phase imine capture. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006).

  • 3.
    Angelin, Marcus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Vongvilai, Pornrapee
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Fischer, Andreas
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Crystallization Driven Asymmetric Synthesis of Pyridine β-Nitroalcoholsvia Discovery-Oriented Self-Resolution of a Dynamic System2010Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 33, s. 6315-6318Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The study of dynamic nitroaldol systems aided the discovery of a diastereoselective crystallization process through amplification of 2-nitro-1-(pyridine-4-yl)propan-1-ol. The phenomenon was further developed into an effective procedure for asymmetic synthesis of pyridine-nitroalcohols and several substrates were screened to this end. These results demonstrate how work with larger dynamic systems facilitates and increases the likelihood of serendipitous discoveries.

  • 4. Chen, Long
    et al.
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ying, Weijiang
    Zhang, Xiaoyu
    Guo, Fuling
    Li, Jing
    Hua, Jianli
    5,6-Bis(octyloxy)benzo[c][1,2,5]thiadiazole-Bridged Dyes for Dye-Sensitized Solar Cells with High Open-Circuit Voltage Performance2013Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 9, s. 1770-1780Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three new metal-free dyes with a 5,6-bis(octyloxy) benzo[c][1,2,5] thiadiazole core (DOBT-I-III) have been designed and synthesized for use as DSSCs. Their absorption properties and electrochemical and photovoltaic performances have been investigated systematically. The DSSCs based on DOBT-I-III show high open-circuit voltages (V-oc) of 829, 818, and 784 mV, respectively. Of the three dyes, DOBT-III, which contains a thiophene-bridging linker, exhibits the best photovoltaic performance: a short-circuit photocurrent density (J(sc)) of 12.74 mA cm(-2) and a fill factor (FF) of 0.73, which corresponds to an overall conversion efficiency of 7.29% under standard global AM 1.5 solar conditions.

  • 5.
    Danielsson, Jakob
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Toom, Lauri
    Institute of Technology, University of Tartu, Tartu, Estonia.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    1,3-Dipolar Cycloaddition of Azomethine Ylides to Aldehydes: Synthesis of anti alpha-Amino-beta-Hydroxy Esters2011Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 3, s. 607-613Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 1,3-dipolar cycloaddition reaction of azomethine ylides to aldehydes is described. The azomethine ylides, generated by thermal electrocyclic ring opening of aziridines, adds to aldehydes in good yields with moderate to good selectivities to furnish oxazolidines. The oxazolidines were subsequently hydrolyzed to the corresponding amino alcohols, giving the anti diastereomer as the major product.

  • 6. Del Litto, Raffaella
    et al.
    Benessere, Vincenzo
    Ruffo, Francesco
    Moberg, Christina
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Carbohydrate-Based Pyridine-2-carboxamides for Mo-Catalyzed Asymmetric Allylic Alkylations2009Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 9, s. 1352-1356Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bis(pyridine-2-carboxamides) were prepared from 1,2-diamines obtained from alpha-D-ghlcose and alpha-D-mannose. The ligands were assessed in molybdenum-catalyzed asymmetric allylic alkylations (AAA) by using both methyl (E)-3-phenyl-2-propenyl and methyl rac-1-phenyl-2-propenyl carbonates and dimethyl malonate as nucleophile under microwave irradiation. High enantioselectivity (99 % ee) and high regioselectivity (49:1 in favour of the branched isomer) were observed in reactions of the linear achiral substrate in the presence of 10 mol-% of a catalyst prepared from a ligand derived from glucose. Somewhat lower enantioselectivity (up to 96 % ee) was observed in reactions with the branched racemic carbonate by using the same ligand. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

  • 7. Dyrager, Christine
    et al.
    Börjesson, Karl
    Dinér, Peter
    University of Gothenburg.
    Elf, A.
    Albinsson, Bo
    Wilhelmsson, Marcus
    Grøtli, Morten
    Synthesis and Photophysical Characterisation of Fluorescent 8-(1H-1,2,3-Triazol-4-yl)adenosine Derivatives2009Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 10, s. 1515-1521Artikkel i tidsskrift (Fagfellevurdert)
  • 8.
    El Remaily, Mahmoud Abd El Aleem Ali Ali
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. Sohag University, Egypt.
    Naidu, Veluru Ramesh
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ni, Shengjun
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Franzén, Johan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Carbocation Catalysis: Oxa-Diels-Alder Reactions of Unactivated Aldehydes and Simple Dienes2015Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 30, s. 6610-6614Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The versatility of the trityl cation (TrBF<inf>4</inf>) as a highly efficient Lewis acid organocatalyst is demonstrated in the oxa-Diels-Alder reaction of various unactivated aromatic and aliphatic aldehydes and simple unactivated dienes, such as isoprene and 2,3-dimethylbutadiene. The transformation proceeds smoothly to give 3,6-dihydropyrane adducts in high to moderate yields with catalyst loadings down to 1.0 mol-% under mild reaction conditions. In contrast to most previously reported strategies, this protocol does not require substrate functional group activation, neither by electron-deficient aldehydes (2-oxo aldehydes) or electron-rich dienes (methoxy or amino-butadiene).

  • 9. Eriksson, P.
    et al.
    Engman, L.
    Lind, Johan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Merenyi, Gabor
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Aqueous phase one-electron reduction of sulfonium, selenonium and telluronium salts2005Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 4, s. 701-705Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Triorganylsulfonium, -selenonium and -telluronium salts were reduced by carbon dioxide radical anions/solvated electrons produced in aqueous solution by radiolysis. The radical expulsion accompanying reduction occurred with the expected leaving group propensities (benzyl > secondary alkyl > primary alkyl > methyl > phenyl), although greater than expected loss of the phenyl group was often observed. Diorganyl chalcogenides formed in the reductions were conveniently isolated by extraction with an organic solvent. Product yields based on the amount of reducing radicals obtained from the T-source were often higher than stoichiometric (up to 1800 %) in the reduction of selenonium and telluronium compounds; it is likely that this result can be accounted for in terms of a chain reaction with carbon-centred radicals/formate serving as the chain transfer agent. The product distribution was essentially independent of the reducing species for diphenyl alkyl telluronium salts, whereas significant variations were seen for some of the corresponding selenonium salts. This would suggest the intermediacy of telluranyl radicals in the one-electron reduction of telluronium salts. However, pulse radiolysis experiments indicated that the lifetimes of such a species (the triphenyltelluranyl radical) would have to be less than 1 mus.

  • 10.
    Hellberg, Jonas
    et al.
    KTH, Tidigare Institutioner, Kemi.
    Dahlstedt, Emma
    KTH, Tidigare Institutioner, Kemi.
    Woldegiorgis, Andreas
    KTH, Tidigare Institutioner, Kemi.
    Umpolung of the 5-alkyl-2-dimethylamino-1,3-dithiolium-4-thiolate mesoion and its application in the synthesis of some new tetrathiafulvalenes2004Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 7, s. 1455-1463Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The 5-alkyl-2-dimethylamino-1,3-dithiolium-4-thiolate mesoion could be umpoled with sulfuryl chloride to yield a dicationic electrophile 3 that reacted with various electron-rich aromatic substrates to yield arylthio-substituted 1,3-dithiolium salts 13-25. Two of these compounds have been transformed to the corresponding symmetrical tetrathiafulvalenes 43 and 44, and their cyclovoltammetric behaviour recorded.

  • 11.
    Hirner, Sebastian
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Kirchner, Donata Katharina
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Synthesis of alpha-Amino Acids by Umpolung of Weinreb Amide Enolates2008Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 33, s. 5583-5589Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient and diastereoselective synthesis of alpha-amino acids from readily available starting materials has been developed. The key feature of this reaction is an umpolung of a glycine-derived enolate, providing an alternative approach for the synthesis of alpha-amino acids.

  • 12. Koch, Daniel
    et al.
    Koch, Eva
    Desarbre, Eric
    Stensland, Birgitta
    Svensson, Per H.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi. SP Process Development, Sweden.
    Bergman, Jan
    2,2 '-Biindolyl Reactions with Aldehydes2016Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 7, s. 1389-1396Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    2,2'-Biindolyl has been condensed with aromatic and aliphatic aldehydes and products featuring 10-membered rings have been obtained. Thus, benzaldehyde gave compound 24a as the primary product, which readily underwent transannular oxidative coupling to 25a. The structures of both compounds were confirmed by X-ray crystallography. The product from 2,2'-biindolyl and formaldehyde under strongly acidic conditions was slightly different leading to compound 11, whose structure also was confirmed by X-ray crystallography. In this case, two molecules of 2,2'-biindolyl reacted with six molecules of formaldehyde.

  • 13. Lake, F.
    et al.
    Moberg, Christina
    KTH, Tidigare Institutioner                               , Kemi.
    Sulfonamide ligands from chiral aziridines - Application to the titanium-mediated addition of diethylzinc to benzaldehyde2002Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 18, s. 3179-3188Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A modular approach was developed for the preparation of chiral, enantiopure sulfonamide ligands with C-1, C-2, and C-3 symmetry by ring opening of chiral N-sulfonylaziridines with ammonia, primary amines, and diamines. The new ligands were assessed in the titanium-mediated addition of diethylzinc to benzaldehyde, giving the product with selectivities up to 76% ee. ((C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).

  • 14.
    Larsson, Michael
    et al.
    Mittuniversitetet i Sundsvall.
    Nguyen, Ba - Vu
    Mittuniversitetet i Sundsvall.
    Högberg, Hans -Erik
    Mittuniversitetet i Sundsvall.
    Hedenström, Erik
    Mittuniversitetet i Sundsvall.
    Syntheses of the sixteen stereoisomers of 3,7,11-trimethyl-2-tridecanol, including the (2S,3S,7S,11R) and (2S,3S,7S,11S) stereoisomers identified as pheromone precursors in females of the pine sawfly Microdiprion pallipes (Hymenoptera : Diprionidae).: Diprionidae)2001Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 2, s. 353-363Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    All sixteen stereoisomers of 3,7,11-trimethyl-2-tridecanol were synthesised in high stereoisomerical purities (> 95%), for use in the identification of the stereoisomers present in females of the pine sawfly Microdiprion pallipes (Fallen) (Hymenoptera: Diprionidae) as the precursor of the actual sex pheromone (which is the propionate), and also for investigation of the biological activities of the esters. The key step in the syntheses was the coupling of each of the enantiomers of cis-3,4-dimethyl-gamma -butyrolactone with each of the four pure stereoisomers of 1-lithio-2,6-dimethyloctanes. The four corresponding alcohols were obtained by lipase-catalysed (Amano PS) kinetic separation, based on selective acylation of either (2R/S,6S)- or (2R/S,GR)-2,6-dimethyl-1-octanol (obtained from the optically pure enantiomers of citronellal). Additionally, a mixture of the 16 possible stereoisomers of 3,7,11-trimethyl-2-tridecanol was also prepared.

  • 15.
    Larsson, Rikard
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Dynamic Combinatorial Thiolester Libraries for Efficient Catalytic Self-Screening of Hydrolase Substrates2006Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 1, s. 285-291Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dynamic combinatorial thiolester libraries were efficiently generated from pools of thiols and acyl functionalities through reversible transthiolesterification in aqueous media at neutral pH. The dynamic features of the library generation were investigated, and the libraries were screened against acetylcholinesterase, clearly demonstrating the catalytic self-screening of its substrates from the constituents. Acetyl- and propionylthiocholine were easily identified as the best substrates for the enzyme, whereas other constituents showed lower efficiency or were inactive. A range of hydrolases was furthermore screened for rapid substrate identification, clearly demonstrating the differences in selectivity. The results show that transthiolesterification is a useful method to generate dynamic libraries, and that the catalytic self -screening concept is highly valuable for substrate identification.

  • 16.
    Laurell, Anna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Moberg, Christina
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Opposite Enantiomers from Minor Enantiomer Recycling and Dynamic Kinetic Resolution Using a Single Biocatalyst2011Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 20-21, s. 3980-3984Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A one-pot recycling procedure comprising Lewis acid catalyzed enantioselective addition of acetyl cyanide to (E)-2-butenal to give the O-acetylated cyanohydrin and enzyme-catalyzed conversion of the minor product enantiomer back to (E)-2-butenal provided essentially enantiopure (2R,3E)-2-acetoxy-3-pentenenitrile in close to quantitative yield. The opposite enantiomer was obtained, albeit in lower yield and with lower enantiomeric purity than that observed from the minor enantiomer recycling, by dynamic kinetic resolution consisting of reversible addition of HCN to the aldehyde coupled to enzyme-catalyzed acetylation of the cyanohydrin.

  • 17.
    Li, Fei
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Wingstrand, Erica
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Widyan, Khalid
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Moberg, Christina
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Chiral Lewis base catalyzed enantioselective acetylcyanation of α-oxo esters2009Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 23, s. 3917-3922Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Acetyl cyanide adds to alkyl benzoylformates and to 2-oxoalkanoates to yield enantioenriched acylated cyanohydrins in one step in the presence of a catalytic amount of a chiral base. The reaction is accelerated by Lewis acids and by the addition of a catalytic amount of methanol. Under optimized conditions, 94% of a 94:6 mixture of the O-acetylated and non-protected cyanohydrins was formed from, methyl benzoylformate in the presence of cinchonidine; from, this mixture the acylated compound with 66% ee was isolated in 77% yield. Ethyl pyruvate and ierf-butyl 2-oxobutanoate were more reactive, and essentially full conversion to the products with 69 and 82% ee, respectively, was achieved. The reaction proceeds by a non-selective addition of cyanide ion to give the non-protected cyanohydrin followed by a dynamic kinetic resolution to provide the enantioenriched acetylated product.

  • 18. Marcelli, Tommaso
    et al.
    Himo, Fahmi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Reaction of carboxylic acids with isocyanides: A mechanistic DFT study2008Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 28, s. 4751-4754Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a computational investigation of the reaction between isocyanides and carboxylic acids. Our results indicate that this reaction begins with a stereoselective concerted alpha-addition of the acid to the isocyanide, leading exclusively to a Z-acyl imidate. Isomerization to the E isomer and successive rate-limiting 1,3 O -> N acyl migration yields an N-formyl imide. The calculated barriers are in good agreement with the experimental reaction conditions. Our results might provide an explanation for the peculiar reactivity observed when this reaction is carried out in a self-assembled capsule. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).

  • 19.
    Naidu, Veluru Ramesh
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Bah, Juho
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Franzén, Johan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Direct Organocatalytic Oxo-Metathesis, a trans-Selective Carbocation-Catalyzed Olefination of Aldehydes2015Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 8, s. 1834-1839Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A direct organocatalytic carbonyl/olefin oxo-metathesis has been developed. The reaction is catalyzed by trityl tetrafluoroborate (TrBF4) and utilizes unactivated alkenes for the olefination of aromatic aldehydes to give trans -alkylstyrenes in yields of 44-85% with only acetone as the byproduct. The pronounced Lewis acidity of the carbocation results in unusual reactivity that is proposed to catalyze a stepwise [2+2] cycloaddition to give an oxetane intermediate. Fragmentation of the latter in a formal retro [2+2] reaction gives the oxo-metathesis product.

  • 20. Nakhai, Azadeh
    et al.
    Stensland, Birgitta
    Svensson, Per H.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    Bergman, Jan
    Synthesis of Benzotriazine and Aryltriazene Derivatives Starting from 2-Azidobenzonitrile Derivatives2010Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 34, s. 6588-6599Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    3-Substituted 3,4-dihydro-4-imino-1,2,3-benzotriazine derivatives 7 were formed from 2-azidobenzonitriles 4 as starting materials on treatment with Grignard or lithium organic reagents. In some cases these procedures gave aryltriazenes 10 and 11 as products. All compounds were identified by NMR spectroscopy and the structures of three products, namely 7a, 10a and 11i, were corroborated by X-ray crystallography.

  • 21.
    Neimert-Andersson, Kristina
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    A Metathesis Approach for the Preparation of Polyhydroxylated Compounds as Head Groups in Surfactant Synthesis2006Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 4, s. 978-985Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Starting from methyl-a-D-glucopyranoside, an efficient protocol for the preparation of polyhydroxylated surfactant head-groups is demonstrated and applied in the synthesis of a typical surfactant. The key transformation is a metathesis reaction between two monosaccharide residues to afford an octahydroxydecen. The importance of a strategic protecting-group constellation for a successful metathesis reaction is also investigated.

  • 22.
    Ni, Shengjun
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Naidu, Veluru Ramesh
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Franzen, Johan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Chiral Anion Directed Asymmetric Carbocation-Catalyzed Diels-Alder Reactions2016Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 9, s. 1708-1713Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In recent years the carbocation has re-emerged as a highly efficient Lewis acid catalyst for a variety of organic transformations. However, the goal of asymmetric carbocation catalysis has so far been out of reach mainly as a result of difficulties associated with the preparation of stable chiral carbocations. Here, we describe developments towards asymmetric carbocation catalysis based on the concept of chiral-anion-directed catalysis. Chiral tritylium salts can be conveniently prepared in situ by mixing trityl chloride derivatives with chiral phosphonate, phosphoramide, bis(sulfonyl) amide, and bis(sulfuryl) amide silver or sodium salts. It is shown that the bis(sulfuryl) amide/tritylium ion salt catalyzes the Diels-Alder reaction with an up to 53 % enantiomeric excess.

  • 23. Pei, Y. X.
    et al.
    Brade, K.
    Brule, E.
    Hagberg, L.
    Lake, F.
    Moberg, Christina
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    A general method for the preparation of chiral TREN derivatives2005Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 13, s. 2835-2840Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A general procedure for the preparation of C-3-symmetric TREN derivatives with backbone chirality has been developed. Stereo- and regioselective ring opening by ammonia of (S)-N-tosyl-2-isopropylaziridine, obtained starting from either the corresponding amino alcohol or amino acid, followed by deprotection of the amino groups afforded the parent chiral TREN compound in high overall yield. In addition to TREN compounds with primary amino groups, the synthetic method employed provides easy access to a variety of N,N',N-substituted derivatives. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).

  • 24.
    Pei, Zhichao
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Dong, Hai
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Caraballo, Rémi
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Synthesis of Positional Thiol Analogs of β-D-Galactopyranose2007Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 29, s. 4927-4934Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Approaches toward the synthesis of thio- beta -D -galactose derivatives are described. These compounds were prepared from the parent carbohydrates: D-galactose, methyl P-D-galactoside and methyl P-D-glucoside, respectively. It was found that not only the strategies of protecting group introduction and selective deprotection, but also the choices of solvent and nucleophilic reagent concentration were crucial to allow the efficient introduction of sulfur at different positions of the galactose ring. The effects from the solvent, the nucleophilic reagent concentration, and the protecting group patterns have been investigated. The results clearly show that ester protecting groups play highly important roles for the synthesis of thio-containing carbohydrates, requiring nonpolar solvents to suppress the neighboring group participation. For the Lattrell-Dax (nitrite -mediated) inversion reaction, employed in the synthetic route to the 2-thio-beta-D-galactoside, intramolecular nucleophilic attack, as well as stronger stereospecific ester activation, are necessary to overcome hindrance from 4,6-O-benzylidene protection.

  • 25. Rahm, F.
    et al.
    Fischer, Andreas
    KTH, Tidigare Institutioner                               , Kemi.
    Moberg, Christina
    KTH, Tidigare Institutioner                               , Kemi.
    Pyridyl phosphinites and pyridyl phosphites from chiral pyridyl alcohols - A modular approach2003Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 21, s. 4205-4215Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Chiral arylated pyridyl alcohols, pyridyl phosphinites and pyridyl phosphites were prepared by Suzuki arylation and/or O-functionalization with a chlorodiarylphosphane or a chloro-diarylphosphite of chiral 2-bromo-6-(1-hydroxyalkyl)pyridines or 2-(1-hydroxyalkyl) pyridines, with the chirality originating from the chiral pool. The pyridyl alcohols were assessed as catalysts for the addition of diethylzinc to benzaldehyde and the P,N-ligands were employed in the palladium-catalysed substitutions of rac-1,3-diphenyl-2-propenyl acetate and rac-2-cyclohexenyl acetate with dimethyl malonate. Moderate enantioselectivities were observed in the catalytic reactions. We observed kinetic resolution of the racemic acetate when using one of the phosphite ligands. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).

  • 26. Rahm, Fredrik
    et al.
    Fischer, Andreas
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    Moberg, Christina
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Pyridyl phosphinites and pyridyl phosphites from chiral pyridyl alcohols - A modular approach (pg 4205, 2003)2008Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 10, s. 1817-1817Artikkel i tidsskrift (Fagfellevurdert)
  • 27.
    Restorp, Per
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Regioselective and Divergent Opening of Vinyl Epoxides with Alkyne Nucleophiles2005Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 18, s. 3946-3951Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A divergent procedure for nucleophilic ring-opening of vinyl epoxides with alkynes has been developed, The combination of lithium acetylides and BF(3)center dot OEt2 afforded the S(N)2 products, whereas alkynylalanes gave S(N)2' addition. The regioselectivity of these processes is affected by the alkyne substituent. Ethoxyacetylene added with complete regiocontrol under both SN2 and SN2' conditions, and the SN2 isomeric adducts could he rearranged into gamma-butyrolactones. The synthetic utility of the process is demonstrated by a short synthesis of gamma-butyrolactone 24, a key intermediate in the synthesis of prostaglandin PGF(20).

  • 28.
    Santangelo, Ellen M.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Liblikas, Ilme
    Mudalige, Anoma
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Törnroos, Karl W.
    Norrby, Per-Ola
    Unelius, C. Rikard
    Asymmetric Synthesis of Iridoid Derivatives Using Resolved 2-Phenylindoline as a Chiral Auxiliary2008Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 35, s. 5915-5921Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An asymmetric synthetic route to cis,cis-nepetalactol (component of the sex pheromone for the hop aphid, Phorodon humuli) is presented. 2-Phenylindoline was resolved to provide a chiral auxiliary for the cycloaddition of oxocitral. The resolution was made by chromatographic separation of the diastereomers of the urea derivative made from 2-phenylindoline and with (R)-(+)-alpha-methylbenzyl isocyanate, followed by reductive cleavage of the isolated diasteromers using diborane. The cycloaddition of oxocitral using (S)-2-phenylindoline yielded an enantiopure product after chromatography. Hydrolysis of the cycloaddition adduct yielded gastrolactol (3). As gastrolactol is a versatile synthon for the synthesis of iridoids, the overall procedure provides a general asymmetric route to elaborated iridoids.

  • 29.
    Seashore-Ludlow, Brinton
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Torssell, Staffan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Addition of Azomethine Ylides to Aldehydes: Mechanistic Dichotomy of Differentially Substituted alpha-Imino Esters2010Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 20, s. 3927-3933Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The formal 1,3-dipolar cycloaddition of azomethine ylides and aldehydes is explored, as hydrolysis of the resulting oxazolidine product gives facile access to valuable syn-beta-aryl-beta-hydroxy-alpha-amino esters. The use of using benzaldehyde-derived imines as the ylide precursor results in 1,3-dipolar cycloaddition with high conversions but low diastereoselectivity. In contrast, the employment of benzophenone-derived imines as the ylide precursor results in an aldol reaction, which gives the intermediate oxazolidine in high diastereoselectivity and requires a weak acid catalyst to achieve higher conversions.

  • 30.
    Sebelius, Sara
    et al.
    Stockholms universitet.
    Szabó, Kálmán J.
    Stockholms universitet.
    Allylation of Aldehyde and Imine Substrates with In Situ Generated Allylboronates – A Simple Route to Enatioenriched Homoallyl Alcohols2005Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 12, s. 2539-2547Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Allylation of aldehyde and imine substrates was achieved using easily available allylacetates and diboronate reagents in the presence of catalytic amounts of palladium. This operationally simple one-pot reaction has a broad synthetic scope, as many functionalities including, acetate, carbethoxy, amido and nitro groups are tolerated. The allylation reactions proceed with excellent regio- and stereoselectivity affording the branched allylic isomer. By employment of commercially available chiral diboronates enantioenriched homoallyl alcohols (up to 53% ee) could be obtained. The mechanistic studies revealed that the in situ generated allylboronates react directly with the aldehyde substrates, however the allylation of the sulfonylimine substrate requires palladium catalysis.

  • 31. Stranne, R.
    et al.
    Moberg, Christina
    KTH, Tidigare Institutioner                               , Kemi.
    Pyrrolidinopyridines in palladium-catalyzed allylic substitutions - Conformation of the ligand2001Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 11, s. 2191-2195Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The (R,R)-2-[(2,5-dimethylpyrrolidin-1-yl)methyl]pyridines 4, 5, and 6 carrying a 2-hydroxyalkyl, 2-alkoxyalkyl or 2-siloxyalkyl substituent in the 6-position of the pyridine ring were prepared and assessed in palladium-catalyzed allylations of 1,3-diphenylpropenyl acetate with malonate. All ligands having g-substituents with an S absolute configuration afforded the product with an R configuration in 80-84% ee, whereas those having substituents with an R absolute configuration gave the opposite product with a selectivity depending on the nature of the substituent (8-74% ee). It is believed that the enantioselectivity is dependent on the conformation of that substituent.

  • 32.
    Svedendahl Humble, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi (stängd 20130101).
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi (stängd 20130101).
    Biocatalytic Promiscuity2011Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 19, s. 3391-3401Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Enzymes are attractive catalysts because of their promiscuity and their ability to perform highly regio-, chemo- and stereo-selective transformations. Enzyme promiscuity allows optimisation of industrial processes that require reaction conditions different from those in nature. Many enzymes can be used in reactions completely different from the reaction the enzyme originally evolved to perform. Such catalytically promiscuous reactions can be secondary activities hidden behind a native activity and might be discovered either in screening for that particular activity or, alternatively, by chance. Recently, researchers have designed enzymes to show catalytic promiscuity. It is also possible to design new enzymes from scratch by computer modelling (de novo design), but most work published to date starts from a known enzyme backbone. Promiscuous activity might also be induced or enhanced by rational design or directed evolution (or combinations thereof). Enzyme catalytic promiscuity provides fundamental knowledge about enzyme/substrate interactions and the evolution of new enzymes. New enzymes are required by industry, which needs to optimise chemical processes in an environmentally sustainable way. In this review various aspects of enzyme catalytic promiscuity are considered from a biocatalytic perspective.

  • 33. Veld, Martijn A. J.
    et al.
    Hult, Karl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Palmans, Anja R. A.
    Meijer, E. W.
    Fast DKR of amines using isopropyl 2-methoxyacetate as acyl donor2007Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 32, s. 5416-5421Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dynamic kinetic resolution (DKR) of various primary amine substrates was performed using a modified version of the Backvall system. A single equivalent of isopropyl 2-methoxyacetate was used as acyl donor in combination with p-MeO Shvo complex as the racemization catalyst and Novozym 435 as the acylation catalyst. A reaction temperature of 100 degrees C was employed to ensure a high racemization rate. Adding 2,4-dimethyl-3-pentanol (DMP) as hydrogen donor at a concentration of 0.5 m successfully suppressed side product formation. Under these modified DKR conditions, complete conversion was observed for most substrates within 26 It showing both high ee values and good chemoselectivity, whereas the original system required a reaction time of 72 h. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007).

  • 34.
    Zalubovskis, Raivis
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Fjellander, Ester
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Szabó, Zoltán
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Moberg, Christina
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Stereochemical Control of Chirally Flexible Phosphepines2007Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 2007, nr 1, s. 108-115Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The barriers to interconversion of the two enantiomeric atropisomers of 6-methoxy-6,7-dihydro-5H-dibenzo[c,e]phosphepine and that of the diastereomeric forms of 6-(-)menthoxy-6,7-dihydro-3H-dibenzo[c,e]phosphepine were determined by NMR spectroscopical methods to be 19.3 and 18.5 kcalmol(-1), respectively, at 298 K. The ratio of the atropisomers was shown to depend on the group bound to phosphorus. Only complexes with two homochiral ligands bound to the each metal center were obtained upon reaction with [Rh(COD)(2)](+) BF4-. The Rh complexes catalyzed the hydrogenation of alpha-acetamidocinnamate. The major isomer of 6-(-)-menthoxy-6,7-dihydro-5H-dibenzo[c,e]phosphepine was found to exhibit higher activity but to afford a product with lower ee than its diastereomer.

1 - 34 of 34
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