Reactions of nitroso hetero-Diels -Alder cycloadducts with azides: Stereoselective formation of triazolines and aziridines

Exo-triazolines are prepared by adding azides to acylnitroso hetero-Diels-Alder cycloadducts that are derived from cyclopentadiene. The steric bulk of the azide has no significant role in the course of reaction, but the reactivity of the alkene is diminished significantly in cycloadducts derived from larger cyclic dienes or in monocyclic alkenes.