Catalytic, selective, and stereocontrolled construction of C4 quaternary and homobenzylic dihydroisoquinolones by sp(3) C–H benzylation

C1 benzylated isoquinoline derivatives constitute the core of benzylisoquinoline alkaloids (BIAs). However, their C4 congeners remain elusive. Here, we describe a diastereoselective, catalytic, and modular C(sp(3))–C(sp(3)) coupling protocol wherein β-amino sp(3) C–H bonds of readily affordable vicinally functionalized dihydroisoquinolones are replaced by sp(3) C–benzyl bonds. The method provides expedient access to C4 quaternary and homobenzylic dihydroisoquinolones, which are attractive fragments for potential drug discovery.