Ene Reaction

Definition:

The addition of a compound with a double bond having an allylic hydrogen (the "ene") to a compound with a multiple bond (the "enophile")

 

Frequency of appearance:

        This bar graph represents all of the online articles that were found to contain this specific name reaction in the title of the article. Tetrahedron letters, Tetrahedron, Synthetic letters, Synthesis, Journal of Organic Chemistry and Journal of the American Chemical Society are represented here. This table by no means represents the periodicity of the name reaction found in the literature.

 

Original references:

1. K. Alder et al., Ber. 76, 27 (1943).

Recent academic references: Click here for more references

2. Novel Synthesis of Cyclic a-Amino Acid Esters via Ene Reaction and Ruthenium-catalyzed Ring Rearrangement

• Osipov, Sergey N.; et al., Synlett; 05, 2001

3. Practical total synthesis of (+)-camptothecin: The full story

• Ciufolini, M. A.; Roschangar, F. Tetrahedron 53, 11049 (1997).

4. Synthesis of (+-)-3-epi-6-protoilludene by intramolecular magnesium-ene and ketene/alkene addition reactions

• Oppolzer, W., Nakao, A., Tetrahedron Lett., 27, 5471-5474 (1986).

Recent process references:

                                                    N/A

Mechanism: http://www.hut.fi/Yksikot/Orgaaninen/opetus/perisykliset_reaktiot/ene_reactions.pdf

Scope and Limitations:

• Enophiles: carbonyl and thiocarbonyl compounds, imines, alkenes, alkynes.
• Ene reactivity: 1⁰ > 2⁰ > 3⁰ B
• Lewis acids: BF₃-O(CH₂CH₃)₂, SnCl₄, Al(CH₂CH₃)Cl₂, Al(CH₃)₂Cl, FeCl₃. ^B
• Regioisomers may form with substituted enophiles. ^B
• Sometimes may be facilitated at high pressures. ^B
• Reverse of the reaction is called the retro-ene. ^B

Synonyms: