Intramolecular Diels–Alder reaction leading to tricyclic derivatives as intermediates of natural products synthesis

Tricyclic compounds possessing a bicyclo[4.3.0] moiety, were successfully synthesized by using the intramolecular Diels–Alder reaction. The siloxy- rather than acyloxy-substituents increased the ratio of the endo-cylcoadducts and . The oxygen substitution of influenced conformation of the transition state, which was stereochemically restricted by the butenolide moiety. In addition, carrying a hydroxyl group also produced in a similar ratio to . Compound was the only exo-adduct produced in all of the entries.