Cobalt-Catalyzed One-Step Access to Pyroquilon and C-7 Alkenylation of Indoline with Activated Alkenes Using Weakly Coordinating Functional Groups.

A new strategy for the C(7)-H functionalization of indoline derivatives using first-row transition-metal cobalt has been demonstrated wherein the pivaloyl group acts as a weakly coordinating directing group. Biologically important pyroquilon (tetrahydropyroquinolinone) derivatives have been synthesized in a one-pot manner through selective C(7)-H functionalization and concomitant cyclization. In this process, aromatic C-H and amidic C-N bonds are cleaved, and new C-C and C-N bonds are formed in a step-economical fashion. Further, selective C(7)-H alkenylation of indoline derivatives has also been accomplished using activated alkenes by varying the reaction conditions.