SYNTHESES AND PROPERTIES OF TRIMETHYLBISDEHYDRO[15]ANNULENONE AND ITS BENZANNELATED DERIVATIVES

Syntheses of 5,10,15-trimethyl- 6,10,15-dimethylbenzo[d]-6,8-bisdehydro[15]annulenone 7,2,12-dimethylbenzo[f]-8,10-bisdehydro[15]annulenone 8, and 15-methyldibenzo[d,j]-6,8-bisdehydro[15]annulenone 9 are described. As observed for the corresponding[17]annulenone, the 1H-NMR spectra of these annulenones suggest that the skeleton of the bisdehydro[15]annulenone of this type is more planar and less strained than that of [13]annulenone.