Free‐Energy Profile for a Host‐Accelerated Diels–Alder Reaction: The Sources of <i>exo</i> Selectivity

Abstract

Simultaneous reduction of the activation energy for the exo reaction and increase of that for the endo reaction explain how a cyclic porphyrin trimer that can bind diene 1 and dienophile 2 in its cavity increases the exo selectivity of a Diels–Alder reaction and accelerates it dramatically.