Martin Hennum
University of Oslo
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Featured researches published by Martin Hennum.
Angewandte Chemie | 2015
Vitthal N. Yadav; Angiolina Comotti; Piero Sozzani; Silvia Bracco; Tore Bonge-Hansen; Martin Hennum; Carl Henrik Görbitz
Dipeptides with two hydrophobic side chains have proved to be an exceptional source of microporous organic materials, but since previous structures were limited to the incorporation of only proteinogenic residues, their full potential as adsorbents has remained unexplored. Single-crystal XRD data for ten new compounds with non-proteinogenic L-2-aminobutanoic acid and/or L-2-amino-pentanoic acid are presented. The gas-phase accessibility of their crystal pores, with cross-sections of 2.3 to 5.1 Å, was monitored by CO2 and CH4 adsorption isotherms. Included CO2 was also detected spectroscopically by 2D MAS NMR. An extensive conformational analysis reveals that the use of linear rather than branched side chains (such as L-valine and L-isoleucine) affords peptides with a greater degree of conformational freedom and yields more-flexible channel surfaces that may easily adapt to a series of potential guest molecules.
Journal of Organic Chemistry | 2014
Martin Hennum; Heike Fliegl; Lise-Lotte Gundersen; Odile Eisenstein
The asymmetric nucleophilic 1,2-addition of (S)-N-benzylidene-2-methylpropane-2-sulfinamide with methylmagnesium bromide and methyllithium has been investigated using DFT(B3LYP) computations. The calculated ratio of the two diastereomers agrees with experimental observations, and the factors that determine the diastereomeric ratio are discussed. The preference for the E isomer and the rapid equilibrium between the E and Z isomers of N-tert-butanesulfinyl imine are two key features for understanding the mechanism of this reaction. Methylmagnesium bromide and methyllithium have bifunctional roles, acting as both Lewis acid and nucleophile, and the Lewis acid character plays a determining role in the stereoselectivity of the reaction.
Journal of Organic Chemistry | 2013
Christian Schnaars; Martin Hennum; Tore Bonge-Hansen
Three new protocols for the nucleophilic halogenations of diazoesters, diazophosphonates, and diazopiperidinylamides as complementary methods to our previously reported electrophilic halogenations are presented for the first time. On the basis of hypervalent α-aryliodonio diazo triflate salts 1A, 2A, and 3A, the corresponding halodiazo compounds are generated via nucleophilic halogenations with tetrabutylammonium halides or potassium halides. The products from subsequent catalytic intermolecular cyclopropanations of the halodiazoesters and halodiazophosphonates and thermal intramolecular C-H insertion of the brominated diazopiperidinylamide are obtained in moderate to good yields after two steps. DFT calculations are presented for the diazoesters to give insight into the mechanism and transition states of the nucleophilic substitutions with the neutral nucleophiles dimethyl sulfide and triethylamine and the bromination with Br(-).
Beilstein Journal of Organic Chemistry | 2015
Magnus Mortén; Martin Hennum; Tore Bonge-Hansen
Summary In this letter, we report a novel synthesis of ethyl quinoline-3-carboxylates from reactions between a series of indoles and halodiazoacetates. The formation of the quinoline structure is probably the result of a cyclopropanation at the 2- and 3-positions of the indole followed by ring-opening of the cyclopropane and elimination of H–X.
Beilstein Journal of Organic Chemistry | 2016
Magnus Mortén; Martin Hennum; Tore Bonge-Hansen
Summary Rates for the thermal decomposition of ethyl halodiazoacetates (halo = Cl, Br, I) have been obtained, and reported herein are their half-lives. The experimental results are supported by DFT calculations, and we provide a possible explanation for the reduced thermal stability of ethyl halodiazoacetates compared to ethyl diazoacetate and for the relative decomposition rates between the chloro, bromo and iodo analogs. We have also briefly studied the thermal, non-catalytic cyclopropanation of styrenes and compared the results to the analogous Rh(II)-catalyzed reactions.
Angewandte Chemie | 2015
Vitthal N. Yadav; Angiolina Comotti; Piero Sozzani; Silvia Bracco; Tore Bonge-Hansen; Martin Hennum; Carl Henrik Görbitz
Microporous Materials In their Communication on page 15684 ff., C. H. Görbitz and co-workers report that dipeptides containing non-proteinogenic residues form crystals with open channels, the diameter of which is tuned by the bulk of the non-proteinogenic units.
Acta Crystallographica Section E-structure Reports Online | 2008
Åsmund Kaupang; Marianne Bolsønes; Thywill Gamadeku; Tore Hansen; Martin Hennum; Carl Henrik Görbitz
In the racemic hydrochloride salt of the title ester, C19H22Cl2NO2 +·Cl−, the pentanoic acid chain shows a mixture of trans and gauche orientations to give an overall helical conformation. The dihedral angle between the two aromatic rings is 26.11 (10)°. The charged secondary amine function participates in two N—H⋯Cl hydrogen bonds.
Tetrahedron Letters | 2013
Victor H.R. Marzouk; Martin Hennum; Lise-Lotte Gundersen
Tetrahedron Letters | 2014
Thomas Ihle Aarhus; Urs Fabian Fritze; Martin Hennum; Lise-Lotte Gundersen
European Journal of Organic Chemistry | 2014
Haakon Saetren Gulbrandsen; Martin Hennum; Maksim Osheka; Matthew Lovell Read; Lise-Lotte Gundersen