Synthesis of optically active bihelicenols

All six stereoisomers of dimethyl 5,5'-dihydroxy-1,1',12,12'-tetramethyl-[6,6']bi(benzo[c]phenanthrenyl)-8,8'-dicarboxylate (bihelicenol) were synthesized by the oxidative coupling of methyl 8-hydroxy-1,12-dimethylbenzo[c]phenanthrene-5-carboxylate (helicenol), and their structures were determined by X-ray analysis. (C) 2003 Elsevier Science Ltd. All rights reserved.