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Search for "1st generation" in Full Text gives 39 result(s) in Beilstein Journal of Organic Chemistry.

Grubbs–Hoveyda type catalysts bearing a dicationic N-heterocyclic carbene for biphasic olefin metathesis reactions in ionic liquids

  • Maximilian Koy,
  • Hagen J. Altmann,
  • Benjamin Autenrieth,
  • Wolfgang Frey and
  • Michael R. Buchmeiser

Beilstein J. Org. Chem. 2015, 11, 1632–1638, doi:10.3762/bjoc.11.178

Graphical Abstract
  • orange suspension formed. The 1st-generation Grubbs–Hoveyda catalyst (400 mg, 0.67 mmol) dissolved in hexane (6 mL) was added to the reaction mixture. The reaction mixture was removed from the glovebox and was heated to 60 °C for 4 h. The formation of a green solid was observed. After cooling to room
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Published 15 Sep 2015

Ruthenium indenylidene “1st generation” olefin metathesis catalysts containing triisopropyl phosphite

  • Stefano Guidone,
  • Fady Nahra,
  • Alexandra M. Z. Slawin and
  • Catherine S. J. Cazin

Beilstein J. Org. Chem. 2015, 11, 1520–1527, doi:10.3762/bjoc.11.166

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  • Stefano Guidone Fady Nahra Alexandra M. Z. Slawin Catherine S. J. Cazin EaStCHEM School of Chemistry, University of St Andrews, St Andrews, UK, KY16 9ST, UK 10.3762/bjoc.11.166 Abstract The reaction of triisopropyl phosphite with phosphine-based indenylidene pre-catalysts affords “1st generation
  • -type ligands. Keywords: 1st generation; indenylidene; metathesis; phosphite; ruthenium; Introduction The olefin metathesis reaction is a powerful tool for C–C bond formation in the synthesis of highly valuable organic compounds [1][2][3][4]. Protocols involving W-, Mo- and Ru-based pre-catalysts can
  • halides. The apex of the pyramid is occupied by an alkylidene moiety, such as a benzylidene or an indenylidene. Mixed NHC/phosphine complexes (G-II and Ind-II) known as “2nd generation” pre-catalysts generally display higher catalytic activity than “1st generation” complexes (G-I and Ind-I) containing two
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Published 01 Sep 2015

Hybrid macrocycle formation and spiro annulation on cis-syn-cis-tricyclo[6.3.0.02,6]undeca-3,11-dione and its congeners via ring-closing metathesis

  • Sambasivarao Kotha,
  • Ajay Kumar Chinnam and
  • Rashid Ali

Beilstein J. Org. Chem. 2015, 11, 1123–1128, doi:10.3762/bjoc.11.126

Graphical Abstract
  • , the cis-syn-cis-triquinane dione 2 was treated with an excess amount of allyl bromide in the presence of NaH to generate the hexaallyl derivative 12 in 59% yield. Later, it was subjected to RCM with Grubbs’ 1st generation catalyst to deliver the three-fold RCM product 13 in 80% yield. Furthermore
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Published 06 Jul 2015

Redox active dendronized polystyrenes equipped with peripheral triarylamines

  • Toshiki Nokami,
  • Naoki Musya,
  • Tatsuya Morofuji,
  • Keiji Takeda,
  • Masahiro Takumi,
  • Akihiro Shimizu and
  • Jun-ichi Yoshida

Beilstein J. Org. Chem. 2014, 10, 3097–3103, doi:10.3762/bjoc.10.326

Graphical Abstract
  • scan rate was 100 mV/s. Two synthetic approaches toward the peripherally functionalized dendronized polystyrenes (blue dotted line = polystyrene, orange sector = dendron of the 1st generation, dark orange sector = dendron of the 2nd generation). (a) Peripheral functionalization of the dendronized
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Published 22 Dec 2014

Why a diaminopyrrolic tripodal receptor binds mannosides in acetonitrile but not in water?

  • Diogo Vila-Viçosa,
  • Oscar Francesconi and
  • Miguel Machuqueiro

Beilstein J. Org. Chem. 2014, 10, 1513–1523, doi:10.3762/bjoc.10.156

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  • of the 1st generation amino groups (Wq3b and Wq4) induces a higher solvent exposure which destabilizes the mentioned hydrophobic interaction. As a result, these systems behave like ACN where there is no significant interaction. These observations are illustrated with two typical conformations in Wq0
  • responsible for the intermolecular interaction. In water, hydrophobic effects may play an important role, rendering the interactions between the carbon chain and the phenyl group a structural determinant when all 1st generation amino groups are neutral. Conclusion In this work, we performed a full pH
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Published 03 Jul 2014

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

  • Gijs Koopmanschap,
  • Eelco Ruijter and
  • Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

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Published 04 Mar 2014

Synthesis of the B-seco limonoid core scaffold

  • Hanna Bruss,
  • Hannah Schuster,
  • Rémi Martinez,
  • Markus Kaiser,
  • Andrey P. Antonchick and
  • Herbert Waldmann

Beilstein J. Org. Chem. 2014, 10, 194–208, doi:10.3762/bjoc.10.15

Graphical Abstract
  • directing effect of the β-hydroxy group. Bicyclic system 65 could be obtained by ring-closing metathesis using Grubbs 1st generation catalyst and subsequent selective deprotection of the primary silyl ether. After esterification with 4-oxocyclohexanecarboxylic acid (25) and protection of the remaining two
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Published 16 Jan 2014

Aldol elaboration of 4,5,6,7-tetrahydroisoxazolo[4,3-c]pyridin-4-ones, masked precursors to acylpyridones

  • Raymond C. F. Jones,
  • Abdul K. Choudhury,
  • James N. Iley,
  • Mark E. Light,
  • Georgia Loizou and
  • Terence A. Pillainayagam

Beilstein J. Org. Chem. 2012, 8, 308–312, doi:10.3762/bjoc.8.33

Graphical Abstract
  • -cycloaddition strategies to access the isoxazolo[4,3-c]pyridin-4-one 4 as 2nd-generation masked nonpolar scaffolds for the 3-acyl-4-hydroxypyridin-2-one nucleus [12]; our 1st-generation approach had employed the [4,5-c] isomer 5 [13][14][15]. We have recently reported on elaboration of isoxazolopyridone 4 at C
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Published 27 Feb 2012

Metathesis access to monocyclic iminocyclitol-based therapeutic agents

  • Ileana Dragutan,
  • Valerian Dragutan,
  • Carmen Mitan,
  • Hermanus C.M. Vosloo,
  • Lionel Delaude and
  • Albert Demonceau

Beilstein J. Org. Chem. 2011, 7, 699–716, doi:10.3762/bjoc.7.81

Graphical Abstract
  • resolution in the ester reduction step, enantiopure (+)-21 was obtained. 1st-generation Grubbs catalyst was used for the RCM of (+)-21. It should be noted that the yield of (+)-22 in RCM (10 mol % 2, in benzene) was temperature dependent (88% at room temperature and 98% at 80 °C). Further stereocontrolled
  • diastereomer. The nitrogen atom in 25 was then Boc-protected, debenzylated, and allylated to give the diene 26. RCM of the latter with 1st-generation Grubbs catalyst (10 mol % 2, in dichloromethane, at room temperature) provided the pyrrole scaffold 27. Subsequent stereoselective dihydroxylation (OsO4 and 4
  • moderate inhibition of β-galactosidase, and α-galacto- and α-mannosidases, respectively. It should be noted that diene 38 did not cyclize in the presence of 1st-generation Grubbs catalyst, even in refluxing toluene, whereas 2nd-generation Grubbs catalyst afforded (in toluene, at 60 °C) the cyclic products
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Published 27 May 2011

The cross-metathesis of methyl oleate with cis-2-butene-1,4-diyl diacetate and the influence of protecting groups

  • Arno Behr and
  • Jessica Pérez Gomes

Beilstein J. Org. Chem. 2011, 7, 1–8, doi:10.3762/bjoc.7.1

Graphical Abstract
  • research only the tungsten catalysed cross-metathesis of methyl 10-undecenoate with 2 has been described [28]. The highest yield of the resulting cross-metathesis product was 51% after 2 h at 125 °C. With Grubbs 1st generation catalyst [Ru]-1, the reaction temperature could be lowered to 45 °C
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Published 03 Jan 2011

About the activity and selectivity of less well-known metathesis catalysts during ADMET polymerizations

  • Hatice Mutlu,
  • Lucas Montero de Espinosa,
  • Oĝuz Türünç and
  • Michael A. R. Meier

Beilstein J. Org. Chem. 2010, 6, 1149–1158, doi:10.3762/bjoc.6.131

Graphical Abstract
  • ]. Later it was demonstrated that the degradation product of Grubbs 1st generation catalyst was capable of catalyzing olefin isomerization [12]. Double bond isomerization was also observed with 2nd generation catalysts on a broad variety of substrates competitively and sometimes prior to olefin metathesis
  • demonstrated that, while Grubbs 1st generation and Schrock's molybdenum alkylidene catalysts did not produce appreciable double bond isomerization, Grubbs 2nd generation catalyst presented significant isomerization activity, which was greatly reduced at temperatures below 30 ºC [17][28]. These studies were
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Published 03 Dec 2010

Backbone tuning in indenylidene–ruthenium complexes bearing an unsaturated N-heterocyclic carbene

  • César A. Urbina-Blanco,
  • Xavier Bantreil,
  • Hervé Clavier,
  • Alexandra M. Z. Slawin and
  • Steven P. Nolan

Beilstein J. Org. Chem. 2010, 6, 1120–1126, doi:10.3762/bjoc.6.128

Graphical Abstract
  • in this field [1][2][3][4][5][6][7][8]. Mixed complexes bearing both a phosphane and a NHC ligand, so-called 2nd generation catalysts, typically display better thermal stability and activities compared to 1st generation catalysts [9][10]. Key to the success and research activity involving 2nd
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Published 23 Nov 2010

Cross-metathesis of allylcarboranes with O-allylcyclodextrins

  • Ivan Šnajdr,
  • Zbyněk Janoušek,
  • Jindřich Jindřich and
  • Martin Kotora

Beilstein J. Org. Chem. 2010, 6, 1099–1105, doi:10.3762/bjoc.6.126

Graphical Abstract
  • reaction was carried out in the presence of any of the following catalysts, Grubbs 1st, Grubbs 2nd, or Hoveyda–Grubbs 1st generation, no cross-metathesis products were obtained. Only catalysis by Hoveyda–Grubbs 2nd generation catalyst gave the desired product 3 in 14% yield. The suitability of Hoveyda
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Published 23 Nov 2010

A short stereoselective synthesis of (+)-(6R,2′S)-cryptocaryalactone via ring- closing metathesis

  • Palakodety Radha Krishna,
  • Krishnarao Lopinti and
  • K. L. N. Reddy

Beilstein J. Org. Chem. 2009, 5, No. 14, doi:10.3762/bjoc.5.14

Graphical Abstract
  • %) without promoting the migration of the acetyl group. Finally, 16 was acrylated with acryloyl chloride/Et3N/CH2Cl2/0 °C to furnish the required bis-olefin 6 in 82% yield. Ring-closing metathesis of bis-olefin 6 with Grubbs’ 1st generation catalyst (I; 10 mol%) [45] gave the required (+)-(6R,2′S
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Published 24 Apr 2009
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