Preparation of tricyclic nitrogen heterocycle via Intramolecular Diels-Alder reaction

Preparation of rigid tricyclic nitrogen heterocycles under radicalic condition has been studied. Cyclisation is performed by Diels-Alder ring closure after radicalic hydrogenation. We did not observe any radicalic Cycloaddition / Fragmentation product 12. Tri-n-butyltin hydride (TBTH) and azobisisobutyronitrile were used in toluene or benzene to generate radicalic condition. Intramolecular Diels-Alder (IMDA) reaction on substituted furan species gave tricyclic heterocycle.