Doering–LaFlamme allene synthesis

In organic chemistry, the Doering–LaFlamme allene synthesis is a reaction of alkenes that converts them to allenes by insertion of a carbon atom.[1] This name reaction is named for William von Eggers Doering and a co-worker, who first reported it.[2]

The reaction is a two-stage process, in which first the alkene is reacted with dichlorocarbene or dibromocarbene to form a dihalocyclopropane. This intermediate is then reacted with a reducing metal, such as sodium or magnesium, or with an organolithium reagent. Either approach converts the dihalogenated carbon to a carbene or carbenoid-like structure. The resulting cyclopropylcarbene rearranges to form the allene product.[1] The electronic nature of the carbene intermediate is not entirely understood. Several different mechanisms for its electrocyclic rearrangement have been studied.[3]

References

  1. 1 2 Li, Jie Jack, ed. (2003). "Doering–LaFlamme allene synthesis". Name Reactions: A Collection of Detailed Reaction Mechanisms. Springer. p. 119. doi:10.1007/978-3-662-05336-2_92.
  2. ↑ Doering, W. von E.; LaFlamme, P. M. (1958). "A two-step of synthesis of allenes from olefins". Tetrahedron. 2 (1-2): 75–79. doi:10.1016/0040-4020(58)88025-4.
  3. ↑ Marvell, Elliot (2012). "Chapter 4: Four-Electron Three-Atom Systems. Section I: The Allene–Cyclopropyl Carbene Electrocyclization". Thermal Electrocyclic Reactions. Elsevier. pp. 67–81. ISBN 9780323150453.
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