Highly Regioselective C–H Alkylation of Alkenes Through an Aryl to Vinyl 1,4-Palladium Migration/C–C Cleavage Cascade

Palladium-catalyzed C−H alkylation of gem-disubstituted ethylenes has been efficiently achieved
with cyclobutanols
as the coupling partners through an aryl to vinyl 1,4-palladium migration/ring-opening
C–C cleavage cascade, giving trisubstituted alkenes in high
yields. The protocol features good regioselectivity, high yields,
broad substrate scopes, and good functional group tolerance. The mechanistic
studies implicate that the cross-coupling reaction occurs via oxidative
addition, 1,4-palladium migration, ring-opening C–C cleavage,
and reductive elimination. DFT calculations have revealed that the
high efficiency of the protocol is attributed to the thermodynamically
favored 1,4-palladium migration assisted by 2-fluorophenol.