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  • 1.
    Blid, J
    et al.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Somfai, P
    KTH, Superseded Departments (pre-2005), Chemistry.
    Brandt, P
    KTH, Superseded Departments (pre-2005), Chemistry.
    Asymmetric Lewis acid-mediated [2,3]-sigmatropic rearrangement of allylic alpha-amino amides.2004In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 228, p. U60-U60Article in journal (Other academic)
  • 2.
    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    KTH, Superseded Departments, Chemistry.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    KTH, Superseded Departments, Chemistry.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.

  • 3.
    Blid, Jan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Asymmetric [2,3]-Sigmatropic Rearrangement of Allylic Ammonium Ylides: Scope and Mechanistic InvestigationManuscript (Other academic)
  • 4.
    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.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Asymmetric [2,3]-sigmatropic rearrangement of allylic ammonium ylides2005In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 127, no 26, p. 9352-9353Article in journal (Refereed)
    Abstract [en]

    An asymmetric Lewis acid-mediated [2,3]-sigmatropic rearrangement of allylic amines has been developed, affording the corresponding homoallylic amines in good yield and excellent enantioselectivities. The rearrangement proceeds by complexation of the chiral Lewis acid to the amine followed by deprotonation and rearrangement.

  • 5.
    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.

  • 6.
    Blid, Jan
    et al.
    KTH, Superseded Departments, Chemistry.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Lewis Acid Mediated [2,3]-Sigmatropic Rearrangement of Allylic Ammonium Ylides2003In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 44, no 15, p. 3159-3162Article in journal (Refereed)
    Abstract [en]

    An investigation of the Lewis acid mediated [2,3]-sigmatropic rearrangement of allylic ammonium ylides has been conducted by employing various bases and boron Lewis acids. Using BBr3 together with the phosphazene base 6, various allylic amines could be rearranged in good yields with low to excellent diastereoselectivity.

  • 7.
    Borg, Tessie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Danielsson, Jakob
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Mohiti, Maziar
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Restorp, Per
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Diastereoselective Nucleophilic Addition to Aldehydes with Polar alpha- and alpha,beta-Substituents2011In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 353, no 11-12, p. 2022-2036Article in journal (Refereed)
    Abstract [en]

    The stereoselectivities obtained in Lewis acid-promoted Mukaiyama aldol additions and Sakurai allylations of mono-, and syn- and anti-disubstituted aldehydes possessing various polar alpha- and beta-substituents under non-chelating conditions are presented. The stereochemical outcome in the nucleophilic addition to alpha-substituted aldehydes containing an alpha-benzyloxy, alpha-fluoro or alpha-sulfonamide substituent are accurately predicted by current stereoinduction models. In contrast, the selectivitites obtained from addition of sterically demanding nucleophiles to alpha-chloro-substituted aldehydes cannot be rationalized by the same models and an alternative is discussed. The stereochemichal outcome in the additions to alpha, beta-disubstituted aldehydes is more complex and cannot be predicted using current models.

  • 8.
    Borg, Tessie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Danielsson, Jakob
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Mukaiyama aldol addition to α-chloro-substituted aldehydes. Origin of the unexpected syn selectivity.2010In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 46, no 8, p. 1281-1283Article in journal (Refereed)
    Abstract [en]

    The addition of sterically demanding enolsilanes to alpha-chloro aldehydes results unexpectedly in preferential formation of the anti-PFA product (1,2-syn), while the addition of the corresponding boron enolate furnishes the expected polar Felkin-Anh product (1,2-anti). A stereoinduction model explaining these observations is proposed.

  • 9.
    Borg, Tessie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Restorp, Per
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    ORGN 988-Diastereoselective addition of nucleophiles to aldehydes having polar - and -substituents2007In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 234Article in journal (Other academic)
  • 10.
    Borg, Tessie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Timmer, Brian
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Diastereoselective formation of 2,3,4,5-tetrasubstituted tetrahydrofurans by a Lewis acid promoted addition of C3-substituted 1,3-bis(silyl)propenes to aldehydes2010Manuscript (preprint) (Other academic)
  • 11.
    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.

  • 12.
    Danielsson, Jakob
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Toom, Lauri
    Institute of Technology, University of Tartu, Tartu, Estonia.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    1,3-Dipolar Cycloaddition of Azomethine Ylides to Aldehydes: Synthesis of anti alpha-Amino-beta-Hydroxy Esters2011In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 3, p. 607-613Article in journal (Refereed)
    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.

  • 13. Dressel, Martina
    et al.
    Restorp, Per
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Total synthesis of (+)-alexine by utilizing a highly stereoselective 3+2 annulation reaction of an N-tosyl-alpha-amino aldehyde and a 1,3-bis(silyl)propene2008In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, no 10, p. 3072-3077Article in journal (Refereed)
    Abstract [en]

    A novel route towards the polyhydroxylated pyrrolizidine alkaloid (+)-alexine has been developed. A key step in this synthesis is a highly stereoselective [3+2] annulation reaction of N-Ts-alpha-amino aldehyde 7a (Ts=tosyl) and 1,3-bis(silyl)propene 8a for the construction of the polyhydroxylated pyrrolidine subunit of the target molecule. Previous synthetic strategies rely on carbohydrates that require several protecting-group manipulations, thereby making the total number of steps relatively high. The [3+2] annulation strategy compares favorably with carbohydrate-based syntheses and constitutes a highly efficient entry to polyhydroxylated alkaloids.

  • 14.
    Hirner, Sebastian
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kirchner, Donata Katharina
    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 Acids by Umpolung of Weinreb Amide Enolates2008In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 33, p. 5583-5589Article in journal (Refereed)
    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.

  • 15.
    Hirner, Sebastian
    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.
    Edefuhr, Magnus
    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 aryl glycines by the alpha arylation of Weinreb amides2008In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 47, no 10, p. 1907-1909Article in journal (Refereed)
  • 16.
    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.
    Microwave-Assisted Rearrangement of Vinylaziridines to 3-Pyrrolines: Formal Synthesis of (-)-Anisomycin2005In: Synlett: Accounts and Rapid Communications in Synthetic Organic Chemistry, ISSN 0936-5214, E-ISSN 1437-2096, no 20, p. 3099-3102Article in journal (Refereed)
    Abstract [en]

    An efficient microwave-assisted rearrangement of activated vinylaziridines to 3-pyrrolines is described. The rearrangement proceeds in good to excellent yields and is mediated by NaI or LiI in MeCN at elevated temperatures. The synthetic utility of this reaction is shown in an efficient formal total synthesis of the antibiotic (-)-anisomycin.

  • 17.
    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.

  • 18. Lindquist, C.
    et al.
    Ersoy, O.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Parallel synthesis of an indole-based library via an iterative Mannich reaction sequence2006In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 62, no 14, p. 3439-3445Article in journal (Refereed)
    Abstract [en]

    A library of 1,3-disubstituted indoles has been prepared via an iterative Mannich reaction sequence. The first Mannich reaction with secondary amines and formaldehyde preferentially yields 3-aminomethyl indoles, while the second Mannich reaction introduces an additional aminomethyl group at the N1-position of the indole ring. A library of 25 substituted indoles has thus been prepared in moderate to good yields with purity.

  • 19. Lindquist, C.
    et al.
    Tedebark, U.
    Ersoy, O.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Microwave-assisted coupling of carboxylic acids to a polymer bound hydrazine linker2003In: Synthetic Communications, ISSN 0039-7911, E-ISSN 1532-2432, Vol. 33, no 13, p. 2257-2262Article in journal (Refereed)
    Abstract [en]

    A set of carboxylic acids, all being potential scaffolds for combinatorial chemistry or peptide synthesis, were coupled to a polymer bound aryl hydrazine linker using microwave irradiation in good yields. Improved yields and reduced reaction times were achieved by using microwave-assisted heating compared to conventional heating.

  • 20. Lindström, U. M.
    et al.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Aza- 3,3 -claisen enolate rearrangement in vinylaziridines: Stereoselective synthesis of mono-, di-, and trisubstituted seven-membered lactams2001In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 7, no 1, p. 94-98Article in journal (Refereed)
    Abstract [en]

    Several 2,3-disubstituted vinylaziridines have been N-acylated and subjected to LiHMDS in THF at - 78 degreesC. Upon warming to room temperature, the resulting amide enolates underwent a highly stereoselective [3,3]-sigmatropic rearrangement to give mono-, di-, and trisubstituted seven-membered lactams in good yields. The scope and limitations of the process have been investigated by using variously substituted vinylaziridines. A kinetically controlled process proceeding through a six-membered boatlike transition state assembly has been invoked to explain the stereochemical outcome of the reaction.

  • 21.
    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.

  • 22.
    Neimert-Andersson, Kristina
    et al.
    KTH, Superseded Departments, Chemistry.
    Blomberg, Eva
    KTH, Superseded Departments, Chemistry.
    Vollhardt, Dieter
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Influence of Surfactant Stereochemistry on Intermolecular Forces in Langmuir MonolayersManuscript (Other academic)
  • 23.
    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.

  • 24.
    Neimert-Andersson, Kristina
    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.
    A Metathesis Approach for the Preparation of Polyhydroxylated Compounds as Head Groups in Surfactant Synthesis2006In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 4, p. 978-985Article in journal (Refereed)
    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.

  • 25. 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.

  • 26. Olofsson, B.
    et al.
    Khamrai, U.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    A regio- and stereodivergent synthesis of vic-amino alcohols2000In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 2, no 25, p. 4087-4089Article in journal (Refereed)
    Abstract [en]

    [GRAPHICS] A regio- and stereodivergent synthesis of vic-amino alcohols starting from vinylepoxides is described. The developed strategy focuses on the propensity of vinylepoxides and vinylaziridines to be ring-opened at the allylic position by suitable nucleophiles and makes use of reactions that perform such tasks selectively with either retention or inversion of configuration.

  • 27. 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.

  • 28. Olofsson, B.
    et al.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Determination of the relative configuration of vic-amino alcohols2003In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 44, no 6, p. 1279-1281Article in journal (Refereed)
    Abstract [en]

    A large set of syn- and anti-1,2-amino alcohols has been synthesized. Upon comparison of the CHO and CHN H-1 NMR shifts a general trend has been observed, making it possible to determine the relative configuration of 1,2-amino alcohols without derivatization or shift reagents.

  • 29. Olofsson, B.
    et al.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Vinylepoxides in Organic Synthesis2006In: Aziridines and Epoxides in Organic Synthesis, John Wiley & Sons, 2006, p. 315-347Chapter in book (Refereed)
  • 30. Olofsson, B.
    et al.
    Wijtmans, R.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Synthesis of N-H vinylaziridines: a comparative study2002In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 58, no 30, p. 5979-5982Article in journal (Refereed)
    Abstract [en]

    Vinylaziridines are useful and versatile synthetic intermediates, as the relief of ring-strain provides a driving force for efficient ring-opening or ring-expansion reactions. Furthermore, the vinyl group can be derivatized into interesting functionalities. The ring-closure of vicinal amino alcohols constitutes a straightforward route to aziridines. Several methods exist for this transformation, although many cannot be applied to vinylaziridines due to their acid lability. This comparative study describes the most effective sequences for the formation of N-H vinylaziridines.

  • 31. Ray, C. A.
    et al.
    Risberg, E.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Diastereoselective Lewis acid-catalysed 4+2 cycloadditions of 3-alkyl-, 3-aryl- and 3-carboxyl-2H-azirines: a route to aziridine containing azabicyclo 4.1.0 heptanes and azatricyclo 2.2.1.0 nonanes2002In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 58, no 30, p. 5983-5987Article in journal (Refereed)
    Abstract [en]

    3-Substituted-2H-azirines have been employed as 2pi components in Lewis acid-catalysed hetero Diels-Alder reactions with a variety of diene systems. A series of Lewis acids were screened for catalytic behaviour in the reaction between Danishefsky's diene and 3-phenyl-2H-azirine to give the cycloaddition adduct, and in most cases elevated temperature were required to effect cycloaddition. A noteworthy exception was a BF3.Et2O-catalysed cycloaddition which proceeded in less than I h between -70degreesC and -60degreesC. The cycloadditions were found to proceed with endo selectivity providing a single diastereoisomeric product. Benzyl 2H-azirine-3-carboxylates were found to be activated by Lewis acids and participate in endo selective cycloadditions at -20degreesC.

  • 32. Ray, C. A.
    et al.
    Risberg, E.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Lewis acid-catalyzed hetero Diels-Alder cycloadditions of 3-alkyl, 3-phenyl and 3-carboxylated 2H-azirines2001In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 42, no 52, p. 9289-9291Article in journal (Refereed)
    Abstract [en]

    Activation by Lewis acids of 3-alkyl and 3-phenyl 2H-azirines promotes their participation in hetero Diels-Alder reactions with a variety of dienes. This methodology circumvents the previous requirement of an electron-withdrawing carboxyl moiety at the 3-position of the 2H-azirine.

  • 33.
    Restorp, P
    et al.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Somfai, P
    KTH, Superseded Departments (pre-2005), Chemistry.
    Regioselective and divergent opening of vinyl epoxides with ethoxyacetylene.2004In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 228, p. U60-U60Article in journal (Other academic)
  • 34. Restorp, Per
    et al.
    Dressel, Martina
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Synthesis of functionalized pyrrolidines by a highly stereoselective 3+2 -annulation reaction of N-tosyl-alpha-amino aldehydes and 1,3-bis(silyl)propenes2007In: Synthesis (Stuttgart), ISSN 0039-7881, E-ISSN 1437-210X, no 10, p. 1576-1583Article in journal (Refereed)
    Abstract [en]

    An efficient protocol for stereoselective construction of densely functionalized pyrrolidines by a [3+2]-annulation reaction of N-tosyl-alpha-amino aldehydes and 1,3-bis(silyl)propenes is described. This methodology is also applied as a key step in the synthesis of the polyhydroxylated pyrrolidine alkaloid 2,5-dideoxy-2,5-imino-D-glucitol (DGDP)

  • 35.
    Restorp, Per
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Stereoselective Synthesis of Functionalized Pyrrolidines via a [3 + 2]- Annulation of N-Ts-α-Amino Aldehydes and 1,3-Bis(silyl)propenes2006In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Journal of the American Chemical Society, Vol. 128, p. 12646-12647Article in journal (Refereed)
  • 36.
    Restorp, Per
    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.
    Diastereoselective Aldol Additions to α-Amino-β-Silyloxy Aldehydes. Divergent Synthesis of Aminodiols2005In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 7, no 5, p. 893-895Article in journal (Refereed)
    Abstract [en]

    A divergent protocol for substrate-controlled diastereoselective synthesis of aminodiols has been developed using nucleophilic Mukaiyama aldol additions to alpha-amino-beta-silyloxy aldehydes. The merged stereochemical impact on the diastereoselectivity of the polar alpha- and beta-substituents is highlighted.

  • 37.
    Restorp, Per
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    ORGN 72-Studies toward the total synthesis of (+)-alexine2006In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 232Article in journal (Other academic)
  • 38.
    Restorp, Per
    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.
    Regioselective and Divergent Opening of Vinyl Epoxides with Alkyne Nucleophiles2005In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 18, p. 3946-3951Article in journal (Refereed)
    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).

  • 39.
    Restorp, Per
    et al.
    KTH, Superseded Departments, Chemistry.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Regioselective and Divergent Opening of Vinyl Epoxides with Ethoxyacetylene2004In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 18, p. 2086-2087Article in journal (Refereed)
    Abstract [en]

    A divergent protocol for nucleophilic opening of vinyl epoxides with ethoxyacetylide has been developed and demonstrated to give complete regioselectivity depending on reaction conditions.

  • 40.
    Restorp, Per
    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.
    Synthetic Studies Toward the Polyhydroxylated Alkaloids DGDP and (+)-Alexine utilizing a [3 + 2]-Annulation Reaction of N-Ts-α-Amino Aldehydes and 1,3-Bis(silyl)propenesManuscript (Other academic)
  • 41. Risberg, E.
    et al.
    Fischer, A.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lewis acid-catalyzed asymmetric radical additions of trialkyl-boranes to (1R,2S,5R)-2-(1-methyl-1-phenylethyl)-5-methylcyclohexyl-2H-azirine-3-carboxylate2005In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 61, no 35, p. 8443-8450Article in journal (Refereed)
    Abstract [en]

    The asymmetric addition of alkyl radicals to (IR,2S,5R)-2-(l-methyl-l-phenylethyl)-5-methylcyclohexyl-2H-azirine-3-carboxylate (1) yielding the corresponding 2-alkylaziridine-2-carboxylates has been investigated. High diastereoselectivities and good yields were obtained in the addition of primary alkyl radicals to azirine 1, while secondary radicals gave a lower dr. The influence of Lewis acids was also investigated, 10 mol% of CuCl were found to increase the dr.

  • 42. Risberg, E.
    et al.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Enantioselective addition of organolithium reagents to a 2H-azirine2002In: Tetrahedron: asymmetry, ISSN 0957-4166, E-ISSN 1362-511X, Vol. 13, no 18, p. 1957-1959Article in journal (Refereed)
    Abstract [en]

    3-(2-Naphthyl)-2H-azirine was used as a model substrate in the first enantioselective addition of organolithium reagents to an azirine. Various organolithium reagents have been used together with different chiral ligands.

  • 43.
    Risberg, Erik
    et al.
    KTH, Superseded Departments, Chemistry.
    Fischer, Andreas
    KTH, Superseded Departments, Chemistry.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Asymmetric radical additions of trialkylboranes to 2H-azirine-3-carboxylates2004In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 10, no 18, p. 2088-2089Article in journal (Refereed)
    Abstract [en]

    Asymmetric additions of alkyl radicals, generated from R3B, to chiral 2H-azirine-3-carboxylates offer a new entry to enantio-enriched aziridines, and proceed with high diastereoselectivity when using 8-phenylmenthol as chiral auxiliary.

  • 44. Roth, P.
    et al.
    Anderson, P. G.
    Somfai, Peter
    KTH, Superseded Departments, Chemistry.
    Asymmetric reduction of azirines; a new route to chiral aziridines2002In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 16, p. 1752-1753Article in journal (Refereed)
    Abstract [en]

    The first enantioselective reduction of aromatic 2H-azirines yields aziridines in up to 70% ee, using the aminoalcohol[RuCl2(p-cymene)](2) catalyzed asymmetric transfer hydrogenation reaction.

  • 45.
    Seashore-Ludlow, Brinton
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Danielsson, Jakob
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Domino Carbopalladation-Carbonylation: Investigation of Substrate Scope2012In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 354, no 1, p. 205-216Article in journal (Refereed)
    Abstract [en]

    This work gives an in depth account of our domino carbopalladation-carbonylation method for substrates possessing beta-hydrogens. The scope of the method is examined for allylic amines containing trisubstituted olefins and we detail our attempts toward the diastereospecific synthesis of contiguous quaternary centers using this technology. The results give key insights into the relative rates of the competing reactions of the alkyl palladium intermediates, which is crucial for the understanding and development of new domino processes.

  • 46.
    Seashore-Ludlow, Brinton
    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.
    1,3-Bis(silyl)propenes2011In: E-EROS ENCYCLOPEDIA OF REAGENTS FOR ORGANIC SYNTHESISArticle, review/survey (Other academic)
  • 47.
    Seashore-Ludlow, Brinton
    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.
    Domino carbopalladation-cross-coupling for the synthesis of 3,3-disubstituted oxindoles2012In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 14, no 15, p. 3858-3861Article in journal (Refereed)
    Abstract [en]

    This study examines a domino carbopalladation-cross-coupling reaction for the formation of valuable oxindole scaffolds. Furthermore, the reaction sequence forges vicinal stereocenters in a stereospecific manner through the formation of two carbon-carbon bonds and, thereby, rapidly generates complexity. The reaction gives high yields for a variety of acrylamide substrates, and various organoboranes have also been evaluated for the cross-coupling. This work offers insight into the relative rates determining a successful carbopalladation-cross- coupling reaction and how to favor the desired reaction pathway.

  • 48.
    Seashore-Ludlow, Brinton
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Torssell, Staffan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Addition of Azomethine Ylides to Aldehydes: Mechanistic Dichotomy of Differentially Substituted alpha-Imino Esters2010In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 20, p. 3927-3933Article in journal (Refereed)
    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.

  • 49.
    Seashore-Ludlow, Brinton
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Villo, Piret
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Häcker, Christine
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Enantioselective Synthesis of anti-beta-Hydroxy-alpha-amido Esters via Transfer Hydrogenation2010In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 12, no 22, p. 5274-5277Article in journal (Refereed)
    Abstract [en]

    The asymmetric transfer hydrogenation of alpha-amido-beta-keto esters to provide the corresponding anti-beta-hydroxy-alpha-amido esters in good to excellent yields, diastereoselectivity, and enantioselectivity is reported. The procedure is operationally simple, and delicate handling of the catalyst is not necessary.

  • 50.
    Seashore-Ludlow, Brinton
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Villo, Piret
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Enantioselective Synthesis of anti-β-Hydroxy-α-Amido Esters by Asymmetric Transfer Hydrogenation in Emulsions2012In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, no 23, p. 2719-2723Article in journal (Refereed)
    Abstract [en]

    Herein, we present two methods for an asymmetric transfer hydrogenation through the dynamic kinetic resolution of α-amido-β-ketoesters. These procedures yield the corresponding anti-β-hydroxy-α-amido esters in good yields and with good diastereo- and enantioselectivities. First, the scope of the reduction of α-amido-β-ketoesters by using triethylammonium formate azeotrope is examined. Then, an emulsion technology with sodium formate is explored, which allows for broader substrate scope, faster reaction times, and lower catalyst loading. Furthermore, these reactions are operationally simple and can be set up in air.

12 1 - 50 of 69
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