Boron‐substituted 1,3‐dienes participate in enereactions to afford new functionalized synthetic intermediates. After evaluating several enophiles as partners, the resulting products have been engaged in multistep sequences involving first a Diels Alder/allyboration process. A variety of skeletally diverse and complex polycyclic heterocycles were thus synthesized, such as tetrahydro‐ 1H ‐isoindole‐1