The title annulenes have been synthesized and their 1H n.m.r. spectra indicate that the [28]-and [34]-annulenes as well as the lower-membered ones can sustain a ring current.Although theoretical calculations on monocyclic annulenes predicted that the limit of aromaticity of (4n + 2) x-electron systems would lie between 22-and 24-membered rings ,1 didehydro[26]annulene ,2 tetradehydro[26]annulene,3 and tetrahydro [30]annulene4 have proved to be diatropic. Also, the

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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.