Concise Route to 3-Arylisoquinoline Skeleton by Lewis Acid Catalyzed C(sp3)–H Bond Functionalization and Its Application to Formal Synthesis of (±)-Tetrahydropalmatine

An expeditious route to furnish an isoquinoline skeleton via hydride shift mediated C–H bond functionalization was developed. In this process, an unusual [1,5]-H shift without the assistance of the adjacent heteroatom took place to produce tetrahydroisoquinoline derivatives in good to excellent chemical yields. The formal synthesis of (±)-tetrahydropalmatine was achieved by exploiting this new transformation.