The Corey–Fuchs reaction, also known as the Ramirez–Corey–Fuchs reaction, is a series of

chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and break ...

s designed to transform an

aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group ...

into an

alkyne \ce \ce Acetylene \ce \ce \ce Propyne \ce \ce \ce \ce 1-Butyne In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and no ...

. The formation of the 1,1-dibromoolefins via phosphine-dibromomethylenes was originally discovered by Desai, McKelvie and Ramirez. The second step of the reaction to convert dibromoolefins to alkynes is known as

Fritsch–Buttenberg–Wiechell rearrangement The Fritsch–Buttenberg–Wiechell rearrangement, named for Paul Ernst Moritz Fritsch (1859–1913), Wilhelm Paul Buttenberg, and Heinrich G. Wiechell, is a chemical reaction whereby a 1,1-diaryl-2-bromo-alkene rearranges to a 1,2-diaryl-alkyne b ...

. The overall combined transformation of an aldehyde to an alkyne by this method is named after its developers, American chemists

Elias James Corey Elias James Corey (born July 12, 1928) is an American organic chemist. In 1990, he won the Nobel Prize in Chemistry "for his development of the theory and methodology of organic synthesis", specifically retrosynthetic analysis. Regarded by many a ...

and

Philip L. Fuchs Philip, also Phillip, is a male given name, derived from the Greek (''Philippos'', lit. "horse-loving" or "fond of horses"), from a compound of (''philos'', "dear", "loved", "loving") and (''hippos'', "horse"). Prominent Philips who popularize ...

. By suitable choice of base, it is often possible to stop the reaction at the 1-bromoalkyne, a useful functional group for further transformation.

Reaction mechanism

The Corey–Fuchs reaction is based on a special case of the

Wittig reaction The Wittig reaction or Wittig olefination is a chemical reaction of an aldehyde or ketone with a triphenyl phosphonium ylide called a Wittig reagent. Wittig reactions are most commonly used to convert aldehydes and ketones to alkenes. Most ...

, where two equivalents of triphenylphosphine are used with carbon tetrabromide to produce the triphenylphosphine-dibromomethylene ylide. This ylide undergoes a Wittig Reaction when exposed to an aldehyde. Alternatively, using a ketone generates a gem-dibromoalkene. The second part of the reaction converts the isolable gem-dibromoalkene intermediate to the alkyne. Deuterium-labelling studies show that this step proceeds through a carbene mechanism. Lithium-Bromide exchange is followed by α-elimination to afford the carbene. 1,2-shift then affords the deuterium-labelled terminal alkyne. The 50% H-incorporation could be explained by deprotonation of the (acidic) terminal deuterium with excess BuLi. Corey-Fuchs carbene

References

# Corey, E. J.; Fuchs, P. L. '' Tetrahedron Lett.'' 1972, ''13'', 3769–3772. # Mori, M.; Tonogaki, K.; Kinoshita, A. ''

Organic Syntheses ''Organic Syntheses'' is a peer-reviewed scientific journal that was established in 1921. It publishes detailed and checked procedures for the synthesis of organic compounds. A unique feature of the review process is that all of the data and exper ...

'', Vol. 81, p. 1 (2005).
Article
) # Marshall, J. A.; Yanik, M. M.; Adams, N. D.; Ellis, K. C.; Chobanian, H. R. ''

'', Vol. 81, p. 157 (2005).
Article
) # N. B. Desai, N. McKelvie, F. Ramirez '' JACS'', Vol. 84, p. 1745-1747 (1962).

External links

Corey-Fuchs Alkyne Synthesis
{{DEFAULTSORT:Corey-Fuchs Reaction Carbon-carbon bond forming reactions Rearrangement reactions Name reactions

Reaction mechanism

See also

References

External links