Theoretical investigation of the Diels–Alder reactions of unsaturated boronates

Abstract

The Diels–Alder reactions of simple unsaturated boronates have been investigated using computational methods and the results were compared with those for the analogue dihalo- and dialkylboranes. Our results indicate that the activating effect of the boronate moiety is small. All the studied reactions are concerted normal electron-demand Diels–Alder reactions with asynchronous transition structures and weak [4 + 3] C–B secondary orbital interactions, which explains the low experimental reactivity. Both electronic and steric effects contribute to give the observed low stereo- and regioselectivities.