Science of Synthesis

Chiu, P.; Lam, S. K., Science of Synthesis, (2010) 47, 737.

General Introduction

The classical Alder-ene, or ene reaction, involves the transfer of an allylic hydrogen from the “ene” to an unsaturated “enophile” to form a new C—H bond, concomitantly with C—C bond formation and double-bond migration (‌Scheme 1‌).[‌1‌–‌7‌] It is a pericyclic reaction related to the Diels–Alder reaction, also involving a six-electron cyclic transition state. A concerted pathway is one limiting mechanism; biradical and zwitterionic pathways for highly polarized ene/enophile combinations are also known.[‌8‌] Compared with the Diels–Alder reaction, the activation energy for the ene reaction is much higher; thus, the temperatures required for such reactions are also generally very high.

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References

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• 8.Meeeee-Meee, (8888) 88/8, 888.