Regioselectivity and stereoselectivity of Diels-Alder reaction: a DFT study on the functionalization of organic semiconductor crystals

Abstract

Diels–Alder (DA) reaction is one of the most commonly tools in functionalizing organic semiconductor crystals. The DA reactions of two organic semiconductors, i.e. tetracene () and rubrene (), to several dienophiles ( to ) were performed experimentally recently. But the kinetics and mechanism of stereoselectivity and regioselectivity remain unknown. In the current study, all related 20 DA reactions (totally 32 possible pathways) were investigated by density functional theory. It was found that the reaction of and a–b position of is the most favorable one. The c–d position of is more reactive than its a–b position when combines with , but is less reactive when combines with to . The endo and exo pathways have similar activation barriers in each reaction. The rate coefficients were calculated using the canonical variational transition state theory and their Arrhenius expressions were fitted. The theoretical conclusion agrees with the experimental observations and is of general importance for similar reactions. Solvent has a slight effect on these reactions. Copyright © 2016 John Wiley & Sons, Ltd.