Ene reaction

In organic chemistry, the ene reaction (also known as the Alder-ene reaction by its discoverer Kurt Alder in 1943) is a chemical reaction between an alkene with an allylic hydrogen (the ene) and a compound containing a multiple bond (the enophile), in order to form a new σ-bond with migration of the ene double bond and 1,5 hydrogen shift. The product is a substituted alkene with the double bond shifted to the allylic position.[1]

Figure 1 - the ene reaction
Figure 1 - the ene reaction

This transformation is a group transfer pericyclic reaction,[2] and therefore, usually requires highly activated substrates and/or high temperatures.[3] Nonetheless, the reaction is compatible with a wide variety of functional groups that can be appended to the ene and enophile moieties. Many useful Lewis acid-catalyzed ene reactions have been also developed, which can afford high yields and selectivities at significantly lower temperatures, making the ene reaction a useful C–C forming tool for the synthesis of complex molecules and natural products.

  1. ^ Alder, K.; Pascher, F; Schmitz, A. "Über die Anlagerung von Maleinsäure-anhydrid und Azodicarbonsäure-ester an einfach ungesättigte Kohlenwasserstoffe. Zur Kenntnis von Substitutionsvorgängen in der Allyl-Stellung". Ber. Dtsch. Chem. Ges. 7: 2. doi:10.1002/cber.19430760105.
  2. ^ Mikami, K.; Shimizu, M. (1992). "Asymmetric ene reactions in organic synthesis". Chem. Rev. 92 (5): 1021. doi:10.1021/cr00013a014.
  3. ^ Snider, B. B. (1980). "Lewis-acid catalyzed ene reactions". Acc. Chem. Res. 13 (11): 426. doi:10.1021/ar50155a007.