Palladium-Catalyzed Aryne Insertion/Arene Dearomatization Domino Reaction: A Highly Chemoselective Route to Spirofluorenes

A palladium(0)-catalyzed
dearomatizing [3+2] spiroannulation of
naphthalene-based biaryls with arynes has been developed for the rapid
construction of spirofluorene architectures. This reaction was realized
by carbopalladation of aryne to generate an arylpalladium species,
followed by termination with naphthalene dearomatization, which is
a sharp contrast to the conventional C–H functionalization
approach. Mechanistic studies revealed that the arene dearomatization
might take place through a 5-exo-trig spiroannulation and distal-hydride
elimination Heck-type pathway.