Palladium-Catalyzed Aryl C–H Olefination with Unactivated, Aliphatic Alkenes

Palladium-catalyzed
coupling between aryl halides and alkenes (Mizoroki–Heck
reaction) is one of the most popular reactions for synthesizing complex
organic molecules. The limited availability, problematic synthesis,
and higher cost of aryl halide precursors (or their equivalents) have
encouraged exploration of direct olefination of aryl carbon–hydrogen
(C–H) bonds (Fujiwara–Moritani reaction). Despite significant
progress, the restricted substrate scope, in particular noncompliance
of unactivated aliphatic olefins, has discouraged the use of this
greener alternative. Overcoming this serious limitation, we report
here a palladium-catalyzed chelation-assisted ortho C–H bond
olefination of phenylacetic acid derivatives with unactivated, aliphatic
alkenes in good to excellent yields with high regio- and stereoselectivities.
The versatility of this operationally simple method has been demonstrated
through drug diversification and sequential C–H olefination
for synthesizing divinylbenzene derivatives.