Treatment of substituted octa-2,6-dien-4-yne-1,8-dial derivatives with CF3COOH gave cyclopentadiene, thiophene, or isobenzothiophene derivatives. Formation of an 18-membered cyclic ether was observed in the case of octa-2,7-dien-4-yne-1,6-diol derivative.
A bisdehydro[14]annuleno[c]furan and a tetrakisdehydro[14]annuleno[14]annulene have been synthesized; their properties and effects of annelation on annulene rings are discussed on the basis of 1H NMR and electronic spectra. Attempts to synthesize the related [14]annuleno[16]annuleno[14]annulene are also described.
A bisdehydro[14]annuleno[c]furan, an isoannelated diatropic annulene, has been synthesized. Cyclic glycol, a precursor of the annuleno[c]furan, could be converted into bisdehydro[14]annulene derivatives under mild acidic conditions.