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.