M. Lakshman, P. Kole, S. Chaturvedi
Dec 27, 2000
Citations
0
Influential Citations
48
Citations
Journal
Journal of the American Chemical Society
Abstract
1,4-Dimethylbenzo[c]phenanthrene (1,4-DMBcPh) is the dimethylated analogue of the benzo[c]phenanthrene (BcPh), where one of its two methyl groups resides in the highly congested fjord-region. A comparative X-ray crystallographic analysis, described herein, shows that BcPh is distorted out-of-plane so that there is an angle of 27° between the outermost rings. The additional methyl groups in 1,4-DMBcPh increase this nonplanarity to an angle of 37°. This methyl group-induced disruption of planarity results in P and M enantiomers of 1,4-DMBcPh, and this helicity is observed in a pronounced manner in its putative metabolites, the dihydrodiol and diol epoxide. Synthetically, photochemical cyclization offers convenient access to 1,4-DMBcPh as well as its metabolites. For this, Wittig reaction of 2,5-dimethylbenzyltriphenylphosphonium chloride and 2-naphthaldehyde provided a cis/trans mixture of alkenes which, when subjected to photolysis, provided 1,4-DMBcPh. Despite the high steric congestion in the fjord-regio...