Corey-Fuchs reaction

The Corey-Fuchs reaction is a series of chemical reactions designed to transform an aldehyde into an alkyne.Ref|OrigRef|OS2005ARef|OS2005B The reaction is named after its discoverers, American chemists Elias James Corey and Philip L. Fuchs.

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, where the phosphorus ylide is formed from dibromocarbene. This carbene is generated in situ from the reaction of Triphenylphosphine and carbon tetrabromide.

Triphenylphosphine then attacks the nascent carbene to form the reactive ylide. This ylide undergoes a Wittig Reaction when exposed to an aldehyde.

Deprotonation of the weakly acidic olefinic proton with butyllithium gives rise to a lithio-olefinic species which can undergo a beta-elimination to produce the bromoalkyne. Further treatment with butyllithium allows for a lithium-halogen exchange and the intermediate can be quenched with an electrophile, such as water or an alkyl halide, transforming the bromoalkyne to the terminal acetylene, or the internal alkyne, respectively.

References

# Corey, E. J.; Fuchs, P. L. "Tetrahedron Lett." 1972, "36", 3769-3772.
# Mori, M.; Tonogaki, K.; Kinoshita, A. "Organic Syntheses", Vol. 81, p.1 (2005). ( [http://www.orgsyn.org/orgsyn/prep.asp?prep=v81p0001 Article] )
# Marshall, J. A.; Yanik, M. M.; Adams, N. D.; Ellis, K. C.; Chobanian, H. R. "Organic Syntheses", Vol. 81, p.157 (2005). ( [http://www.orgsyn.org/orgsyn/prep.asp?prep=v81p0157 Article] )

ee also

*Fritsch-Buttenberg-Wiechell rearrangement
*Seyferth-Gilbert homologation
*Wittig reaction