Distortion, Tether, and Entropy Effects on Transannular Diels–Alder Cycloaddition Reactions of 10–18-Membered Rings

Abstract

Density functional theory calculations were performed on a set of 13 transannular Diels-Alder (TADA) reactions with 10-18-membered rings. The results were compared with those for bimolecular and intramolecular Diels-Alder reactions in order to investigate the controlling factors of the high TADA reactivities. The effects of tether length, heteroatoms, and alkynyl dienophiles on reactivity were analyzed. We found a correlation between tether length and reactivity, specifically with 12-membered macrocycles undergoing cycloaddition most readily. Furthermore, modifying 12-membered macrocycles by heteroatom substitution and utilizing alkynyl dienophiles enhances the reaction rates up to 10(5)-fold.