Catalyst-Controlled Divergent C–H Functionalization of Unsymmetrical 2‑Aryl Cyclic 1,3-Dicarbonyl Compounds with Alkynes and Alkenes

Achieving
site-selective, switchable C–H functionalizations of substrates
that contain several different types of reactive C–H bonds
is an attractive objective to enable the generation of different products
from the same starting materials. Herein, we demonstrate the divergent
C–H functionalization of unsymmetrical 2-aryl cyclic 1,3-dicarbonyl
compounds that contain two distinct, nonadjacent sites for initial
C–H functionalization, where product selectivity is achieved
through catalyst control. By use of a palladium–N-heterocyclic
carbene complex as the precatalyst, these substrates undergo oxidative
annulation with alkynes to provide spiroindenes exclusively. In contrast,
a ruthenium-based catalyst system gives benzopyrans as the major products.
Examples of divergent, oxidative C–H alkenylations of the same
substrates are also provided.