Collective Syntheses of 8‑Oxoprotoberberines via Sequential In(OTf)3‑Catalyzed Cyclization and Pd(OAc)2‑Catalyzed Heck Coupling

Six 8-oxoprotoberberines were synthesized collectively in four steps with acceptable yields (14–19%), of which the products 8-oxopalmatine, 8-oxopseudopalmatine, 8-oxoberberine, and 8-oxopseudoberberine come from nature. The synthetic route was featured with the In­(OTf)3-catalyzed cyclization and Heck coupling. Moreover, the syntheses of the natural products berberine, canadine, and iambertine were achieved via various reductions from 8-oxoberberine, which provided a concise approach to the syntheses of this kind of alkaloids.