Synthesis of Fused Tricyclic Hydantoins of Homotriquinane Type

Synthesis of tricyclic hydantoins with angularly fused rings was performed in three-step reaction sequence. Spiro-bicyclic hydantoins with alkenyl moiety, prepared from 2-alkenylcyclohexanones using Bucherer-Bergs reaction, were subjected to amidoselenylation reaction. This selenium-induced intramolecular cyclization is a key step of this sequence. The cyclization is regiospecific and formation of sole regioisomer proceeds via favorable 5-exo-trig ring closure process giving only homotriquinane type tricyclic hydantoins.