SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF TETRADEHYDROBENZO[A]PHENANTHRO[9,10-E]CYCLOOCTENE, C24H12

A benzo-phenanthro-fused planar cyclooctatetraene derivative, namely, -tetradehydrobenzo[a]phenanthro[9,10-e]cyclooctene (5) was synthesized in two steps from the known benzo[a]phenanthro[9,10-e]cyclooctene (6) . Compound 5 crystallizes in space group Pbam with a = 9.828(2), b = 1 9.466(4), c = 15.901(3) Angstrom, and Z = 8. X-Ray analysis (MoK alpha radiation, R = 0.060 for 1233 observed data) has shown that both inde pendent molecules have the same planar C-2v configuration with average d bond lengths of 1.381(7) and 1.208(7) Angstrom for the phenanthrene C-6a-C-14b bond and the acetylenic C drop C bond, respectively. H-1 an d C-13 NMR spectral results of 5 and 16-tetrahydrobenzo[a]phenanthro[9 ,10-e]cyclooctene (7) are also presented.