A novel and concise synthesis of spirodienone alkaloids using hypervalent iodine(III) reagents

Intramolecular oxidative coupling reaction of N-protected benzyltetrahydroisoquinoline derivatives using hypervalent iodine(III) reagents was investigated. The use of remarkable combination of phenyliodine bis (trifluoroacetate) (PIFA) and heteropoly acid (HPA) in wet acetonitrile smoothly afforded morphinandienone alkaloids, while neospirinedienone alkaloids were obtained in high yield under anhydrous conditions.