Search results

Search for "[2 2] cycloaddition" in Full Text gives 106 result(s) in Beilstein Journal of Organic Chemistry.

Heavy atom effects in the Paternò–Büchi reaction of pyrimidine derivatives with 4,4’-disubstituted benzophenones

  • Feng-Feng Kong,
  • Jian-Bo Wang and
  • Qin-Hua Song

Beilstein J. Org. Chem. 2011, 7, 113–118, doi:10.3762/bjoc.7.16

Graphical Abstract
  • ; Introduction The regio- and stereoselectivity in the Paternò–Büchi reaction, which is a photochemical [2 + 2] cycloaddition of a carbonyl compound with an olefin, has been extensively studied [1][2][3][4]. The ene–carbonyl photocycloaddition generally proceeds through attack of the excited carbonyl state
PDF
Album
Full Research Paper
Published 26 Jan 2011

Recent advances in the development of alkyne metathesis catalysts

  • Xian Wu and
  • Matthias Tamm

Beilstein J. Org. Chem. 2011, 7, 82–93, doi:10.3762/bjoc.7.12

Graphical Abstract
  • the reaction of 5 with an excess of 3-hexyne confirmed that the [2 + 2]-cycloaddition (Katz) mechanism is operative [73][74]. The prototype 5 of our new catalyst system was used for the ACM of 1-phenylpropyne (7) and was shown to be significantly more active than the classic Schrock alkylidyne complex
  • formation of deprotonated, inactive metallacyclobutadienes [96]. Hence, future efforts should also re-address this issue, e. g., by adjusting the properties of the metallacyclobutadiene key intermediates [97] in order to prevent their degeneration and therefore ineffectiveness in undergoing the Katz [2 + 2
  • ]cycloaddition/cycloreversion mechanism (Scheme 1). Alkylidyne complexes 9 and 10. Alkyne metathesis based on the Katz mechanism. Reaction patterns of alkyne metathesis. Typical examples from traditional catalyst systems. Ligand synthesis and catalyst design. Catalysts synthesis using high- and low-oxidation
PDF
Album
Review
Published 18 Jan 2011

Stereoselectivity of supported alkene metathesis catalysts: a goal and a tool to characterize active sites

  • Christophe Copéret

Beilstein J. Org. Chem. 2011, 7, 13–21, doi:10.3762/bjoc.7.3

Graphical Abstract
  • steps: alkene coordination, [2 + 2]-cycloaddition generating metallacyclobutanes and the corresponding reverse steps, i.e., cycloreversion and alkene dissociation (Scheme 1b). The approach of an alkene of a given configuration towards a metal–alkylidene intermediate in a given configuration will
PDF
Album
Review
Published 05 Jan 2011

Synthesis of 2a,8b-Dihydrocyclobuta[a]naphthalene-3,4-diones

  • Kerstin Schmidt and
  • Paul Margaretha

Beilstein J. Org. Chem. 2010, 6, No. 76, doi:10.3762/bjoc.6.76

Graphical Abstract
  • ; quinone monoacetals; Introduction The behaviour of excited 1,2- and 1,4-quinones towards ground-state molecules differs greatly. Whereas the former typically react via H-abstraction by an excited carbonyl group [1], the latter smoothly undergo [2 + 2] cycloaddition to alkenes to afford cyclobutane-type
PDF
Album
Full Research Paper
Published 13 Jul 2010
Graphical Abstract
  • are readily available materials, prepared by [2 + 2] cycloaddition of vinyl ethers with hexafluoroacetone [1][2][3] or hexafluorothioacetone [4][5], respectively. Although both groups of compounds have been known for over 40 years, reports on their chemical transformations are limited. Among the
PDF
Album
Supp Info
Full Research Paper
Published 10 May 2010

A thermally-induced, tandem [3,3]-sigmatropic rearrangement/[2 + 2] cycloaddition approach to carbocyclic spirooxindoles

  • Kay M. Brummond and
  • Joshua M. Osbourn

Beilstein J. Org. Chem. 2010, 6, No. 33, doi:10.3762/bjoc.6.33

Graphical Abstract
  • Kay M. Brummond Joshua M. Osbourn Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, U.S.A 10.3762/bjoc.6.33 Abstract The synthesis of C3-carbocyclic spirooxindoles was realized by way of an intramolecular [2 + 2] cycloaddition reaction between a vinylidene indolin
  • observed, but are likely intermediates of an infrequently encountered thermal [3,3]-sigmatropic rearrangement of a propargylic acetate. Keywords: allene; propargylic acetate; spirooxindole; thermal [2 + 2] cycloaddition; thermal [3,3]-sigmatropic rearrangement; vinylidene indolin-2-one; Introduction
  • discovery of new biological probes and pharmaceuticals [8]. We recently disclosed a thermal [2 + 2] cycloaddition reaction of allene-ynes to provide a variety of alkylidene cyclobutenes in good yields [9][10][11][12][13][14][15][16][17][18]. Notable features of this reaction were the stability of the
PDF
Album
Supp Info
Preliminary Communication
Published 08 Apr 2010
Other Beilstein-Institut Open Science Activities