[4
+ 3] annulation of primary and secondary benzamide and cinnamamide
derivatives using allyl alcohol as a coupling partner catalyzed by
Rh(III) is reported, where Rh(III) is playing a dual role of an oxidant
and a catalyst for C–H activation. The Rh-catalyst oxidizes
allyl alcohol to its carbonyl derivative, and the in situ-generated
carbonyl compound reacts with benzamide in the presence of the Rh-catalyst,
forming the corresponding alkylated products. Mechanistic studies
show that AgSbF6 is also playing a dual role. Apart from
being a halide scavenger, AgSbF6 catalyzes the cyclization
of the alkylated product, forming the desired lactam. The current
method has good synthetic application and is useful for synthesizing
a few biologically active compounds that can act as the dopamine D3 receptor ligand, including berberine-like analogues. The
deuteration study and control experiments helped us to propose the
mechanism.