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.