Carbene dimerization

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Reaction in organic chemistr

title: "Carbene dimerization" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["carbenes", "organic-reactions"] description: "Reaction in organic chemistr" topic_path: "general/carbenes" source: "https://en.wikipedia.org/wiki/Carbene_dimerization" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Reaction in organic chemistr ::

Carbene dimerization is a type of organic reaction in which two carbene or carbenoid precursors react in a formal dimerization to an alkene. This reaction is often considered an unwanted side-reaction but it is also investigated as a synthetic tool. In this reaction type either the two carbenic intermediates react or a carbenic intermediate reacts with a carbene precursor. An early pioneer was Christoph Grundmann reporting on a carbene dimerisation in 1938. In the domain of persistent carbenes the Wanzlick equilibrium describes an equilibrium between a carbene and its alkene.

A reoccurring substrate is a diazo compound and more specifically an alpha-carbonyl diazo compound. For example, ethyl diazoacetate is converted to diethyl maleate using the ruthenium catalyst chloro(cyclopentadienyl)bis(triphenylphosphine)ruthenium: :[[File:Carbene dimerization Baratta 1997.svg|Carbene dimerization Baratta 1997]] Grubbs' catalyst is also effective In this reaction type the active intermediate is a transition metal carbene complex. A diazo cross-coupling reaction has also been reported between ethyl diazoacetate and methyl phenyldiazoacetate using the rhodium catalyst [Rh2(OPiv)4].

A direct metal carbene dimerization has been used in the synthesis of novel Polyalkynylethenes

References

References

  1. {{JerryMarch
  2. ''Grundmann, C.'' (1938), ''Über die Zersetzung der Diazoketon''e. Justus Liebigs Annalen der Chemie, 536: 29–36.{{doi. 10.1002/jlac.19385360103
  3. ''Highly stereoselective formation of cis-enediones from α-diazo carbonyl compounds catalysed by [RuCl(η5-C5H5)(PPh3)2]'' Walter Baratta and Alessandro Del Zotto Chem. Commun., 1997, 2163-2164 {{doi. 10.1039/A706459D
  4. ''Maleates from diazoacetates and dilactones from head-to-head dimerisation of alkenyl diazoacetates using Grubbs' 2nd-generation ruthenium carbene catalyst'' David M. Hodgson and Deepshikha Angrish Chem. Commun., 2005, 4902-4904 {{doi. 10.1039/B510829B
  5. (2011). "Rhodium(II)-Catalyzed Cross-Coupling of Diazo Compounds". [[Angewandte Chemie International Edition]].
  6. Barluenga, J., de Sáa, D., Gómez, A., Ballesteros, A., Santamaría, J., de Prado, A., Tomás, M. and Suárez-Sobrino, A. (2008), ''Metal Carbene Dimerization: Versatile Approach to Polyalkynylethenes''. Angewandte Chemie International Edition, 47: 6225–6228. {{doi. 10.1002/anie.200801584

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