Fig. 1: Transformations of Azulenes.
From: Selective ring expansion and C−H functionalization of azulenes
A Dipolar properties of azulenes and general azulene functionalizations. B Silver(I)-catalyzed C(sp2)–C(sp3) coupling of azulenes in this work. C Ring expansion reaction of benzenoid aromatic compounds (Buchner reaction). D Selective ring expansion and C–H alkylation of azulene, which is non-benzenoid aromatic compound.
