It is well-known that indazole usually bears a benzo
five-membered heterocycle unit, which has been broadly
studied for its unique biological activity in medicinal
chemistry (Figure 1).13 Pursuing our interests in CH
activation,14 herein we first report a novel approach to
the acylated azobenzenes through Pd-catalyzed acylation
of azobenzenes with aldehydes via azo-directed CH
activation. It is important to note that the obtained
acylated azobenzenes can easily be converted into the
corresponding indazoles via an intramolecular reductive
cyclization process in nearly quantitative yields