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- Bergman_cyclization abstract "The Bergman cyclization or Bergman reaction or Bergman cycloaromatization is an organic reaction and more specifically a rearrangement reaction taking place when an enediyne is heated in presence of a suitable hydrogen donor (Scheme 1). It is the most famous and well-studied member of the general class of cycloaromatization reactions. It is named for the American chemist Robert George Bergman (b. 1942). The reaction product is a derivative of benzene.The reaction proceeds by a thermal reaction or pyrolysis (above 200 °C) forming a short-lived and very reactive para-benzyne biradical species. It will react with any hydrogen donor such as 1,4-cyclohexadiene which converts to benzene. When quenched by tetrachloromethane the reaction product is a 1,4-dichlorobenzene and with methanol the reaction product is benzyl alcohol.When the enyne moiety is incorporated into a 10-membered hydrocarbon ring (e.g. cyclodeca-3-ene-1,5-diyne in scheme 2) the reaction, taking advantage of increased ring strain in the reactant, is possible at the much lower temperature of 37 °C. Naturally occurring compounds such as calicheamicin contain the same 10-membered ring and are found to be cytotoxic. These compounds generate the diradical intermediate described above which can cause single and double stranded DNA cuts. There are novel drugs which attempt to make use of this property, including monoclonal antibodies such as mylotarg.A biradical mechanism is also proposed for the formation of certain biomolecules found in marine sporolides that have a chlorobenzene unit as part of their structure. In this mechanism a halide salt provides the halogen. A model reaction with the enediyene cyclodeca-1,5-diyn-3-ene, lithium bromide as halogen source and acetic acid as hydrogen source in DMSO at 37 °C supports the theory:The reaction is found to be first-order in enediyne with the formation of p-benzyne A as the rate-limiting step. The halide ion then donates its two electrons in the formation of a new Br-C bond and radical electron involved is believed to shuttle over a transient C1-C4 bond forming the anion intermediate B. The anion is a powerful base, stripping protons even from DMSO to final product. The dibromide or dihydrogen product (tetralin) never form.".
- Bergman_cyclization thumbnail Bergman_cyclization_revised.png?width=300.
- Bergman_cyclization wikiPageExternalLink frame.htm.
- Bergman_cyclization wikiPageID "4098482".
- Bergman_cyclization wikiPageRevisionID "605058709".
- Bergman_cyclization hasPhotoCollection Bergman_cyclization.
- Bergman_cyclization subject Category:Name_reactions.
- Bergman_cyclization subject Category:Rearrangement_reactions.
- Bergman_cyclization type ChemicalProcess113446390.
- Bergman_cyclization type ChemicalReaction113447361.
- Bergman_cyclization type NameReactions.
- Bergman_cyclization type NaturalProcess113518963.
- Bergman_cyclization type PhysicalEntity100001930.
- Bergman_cyclization type Process100029677.
- Bergman_cyclization type RearrangementReactions.
- Bergman_cyclization type Agent.
- Bergman_cyclization type Person.
- Bergman_cyclization type Scientist.
- Bergman_cyclization type Person.
- Bergman_cyclization type Q215627.
- Bergman_cyclization type Q5.
- Bergman_cyclization type Agent.
- Bergman_cyclization type NaturalPerson.
- Bergman_cyclization type Thing.
- Bergman_cyclization type Person.
- Bergman_cyclization comment "The Bergman cyclization or Bergman reaction or Bergman cycloaromatization is an organic reaction and more specifically a rearrangement reaction taking place when an enediyne is heated in presence of a suitable hydrogen donor (Scheme 1). It is the most famous and well-studied member of the general class of cycloaromatization reactions. It is named for the American chemist Robert George Bergman (b. 1942).".
- Bergman_cyclization label "Bergman cyclization".
- Bergman_cyclization label "Bergman-Cyclisierung".
- Bergman_cyclization label "Ciclación de Bergman".
- Bergman_cyclization label "Réaction de Bergman".
- Bergman_cyclization label "伯格曼环化反应".
- Bergman_cyclization label "正宗・バーグマン環化".
- Bergman_cyclization sameAs Bergman-Cyclisierung.
- Bergman_cyclization sameAs Ciclación_de_Bergman.
- Bergman_cyclization sameAs Réaction_de_Bergman.
- Bergman_cyclization sameAs 正宗・バーグマン環化.
- Bergman_cyclization sameAs m.0bhxj8.
- Bergman_cyclization sameAs Q819992.
- Bergman_cyclization sameAs Q819992.
- Bergman_cyclization sameAs Bergman_cyclization.
- Bergman_cyclization wasDerivedFrom Bergman_cyclization?oldid=605058709.
- Bergman_cyclization depiction Bergman_cyclization_revised.png.
- Bergman_cyclization isPrimaryTopicOf Bergman_cyclization.