The Synthesis of Dibenzo-Annelated Annulenes Using Reductive Coupling. Bisdehydrodibenzo[14]-, -[16]-, -[18]-, -[20]-, and -[22]annulene

Bisdehydrodibenzo[14]-, -[16]-, -[18]-, -[20]-, and -[22]annulene were synthesized by intramolecular reductive couplings using a low-valent titanium reagent. These bisdehydrodibenzo-annulenes proved to be atropic from an examination of the 1H NMR spectra.