View source for Fujimoto–Belleau reaction

The '''Fujimoto–Belleau reaction''' is a [[chemical reaction]] that forms cyclic α-substituted [[α,β-Unsaturated carbonyl compound|α,β-unsaturated]] [[ketone]]s from [[enol]] [[lactone]]s. The reaction was discovered in 1951 by [[George I. Fujimoto]] and [[Bernard Belleau]]. Belleau used this reaction to synthesize 1-methyl-3-keto-1,2,3,9,10,10a-hexahydrophenanthrene from a ketoacid starting material and Fujimoto demonstrated that steroids could be synthesized from naturally occurring lactone species using this method as well.
[[File:Fujimoto-Belleau Reaction Scheme.png|center|500px|The Fujimoto-Belleau reaction]]
The reaction starts with opening the ring by the attack of the Grignard reagent, forming an [[enolate]]. A [[Acid–base reaction|proton transfer]] occurs, forming another enolate via deprotonation of the carbon atom attached to the R group. Using the enolate, an [[aldol condensation]] then occurs with aqueous or acidic workup—i.e., [[aldol addition]] followed by an [[E1cB-elimination reaction|E1cB elimination]] of [[hydroxide]] occurs.<ref>{{Cite book|chapter-url=https://onlinelibrary.wiley.com/doi/10.1002/9780470638859.conrr253|title=Comprehensive Organic Name Reactions and Reagents|chapter=Fujimoto-Belleau Reaction|last=Wang|first=Zerong|date=September 15, 2010|isbn=9780470638859|doi=10.1002/9780470638859}}</ref>
[[File:Fujimoto-Belleau reaction mechanism.svg|center|550px|mechanism of the reaction]]
== Applications of the Fujimoto-Belleau reaction ==
=== Steroid synthesis ===
The Fujimoto–Belleau reaction is used in commonly used in steroid synthesis. The reaction can be employed in the syntheses of steroids such as cholestenone, testosterone, and cortisone. Below is a scheme for the Fujimoto–Belleau reaction invoked in steroid synthesis. Note that this pathway is not the true total syntheses for these steroids.
==References==
{{Reflist}}
* {{cite journal
| title = Labeling of Steroids in the 4-Position
| author = [[George I. Fujimoto]]
| journal = [[J. Am. Chem. Soc.]]
| volume = 73
| issue = 4
| pages = 1856
| year = 1951
| url =
| doi = 10.1021/ja01148a518   }}
* {{cite journal
| title = The Reaction of Methylmagnesium Iodide with β-(1-Hydroxy-3,4-dihydro-2-naphthyl)-butyric Acid Lactone
| author = [[Bernard Belleau]]
| journal = [[J. Am. Chem. Soc.]]
| volume = 73
| issue = 11
| pages = 5441–5443
| year = 1951
| url =
| doi = 10.1021/ja01155a504   }}
* Weill-Raynal, J. ''Synthesis'' '''1969''', 49.
{{DEFAULTSORT:Fujimoto-Belleau reaction}}
[[Category:Addition reactions]]
[[Category:Carbon-carbon bond forming reactions]]
[[Category:Condensation reactions]]
[[Category:Name reactions]]