Diphenylbenzo phenanthrene

Five-membered ring systems with two adjacent phenyl groups can often be cyclized photochemically to give fused phenanthrene products. This type of reaction is reported for 2,3-diphenylbenzo[6]thiophens (127) if a primary... 

The cascade cyclization reactions of the benzanmilafed enyne-aUenes outlined in Scheme 6 were also adopted for the S3mthesis of the diindeno-fused 1,12-diphenylbenzo [cjphenanthrene 85 (Scheme 17) [76], The X-ray structure of 85 (Rg. 24) shows a twisted structure with a 59.9° acute dihedral angle between the mean planes of rings A and D. Each phenyl substituent is oriented at a 60.8° angle from the benzene ring to which it is attached but is roughly parallel to the opposite side of the twisted benzo[c] phenanthrene framework with a distance of ca. 2.94 A at the closest point. 

Scheme 17 Synthesis of diindeno-fiised l,12-diphenylbenzo[c]phenanthrene 85 [76]...

Figure 3.4 Helical twisted structures of 4,5-diphenylphenanthrenes 3.578-3.580, 1,12-diphenylbenzo [c]phenanthrene 3.581 and l,14-diphenyl[5]helicene 3.582.

Zhang, Y., Petersen, J.L. and Wang, K.K. (2007) Synthesis and structures of diindeno-fused l,12-diphenylbenzo[c]phenanthrene and l,14-diphenyl[5]helicene bearing severe helical twists. Organic Letters, 9(6), 1025-1028. 

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