σ N–C Bond Difunctionalization in Bridged Twisted Amides: Sew-and-Cut Activation Approach to Functionalized Isoquinolines

A rare example of highly selective σ N–C bond difunctionalization in bridged twisted lactams through N–C cleavage has been achieved. In combination with the intramolecular Heck cyclization, this method affords a two-step bond reorganization event (“sew-and-cut”) to access functionalized isoquinoline ring systems directly with high atom economy. C–H bond functionalizations directed by a weakly coordinating bridged amide bond increase scaffold diversity. Preliminary mechanistic studies on the effect of amide distortion and the role of electrophile in this unusual σ N–C amide difunctionalization are described.