Functionalized Heptahelicene Bidentate Ligands and Chiral Building Blocks

Syntheses of functionalized heptahelicenes 11-13 disubstituted at positions 3 and 16 by hydroxymethyl or bromomethyl functions are described as a new series of bidentate ligands or chiral building blocks. Those functions are flexible enough and properly positioned for a possible chelate effect onto a metal center. Photocyclodehydrogenation, phase-transfer-catalyzed Wittig reaction, and use of THP groups for increasing solubility and further functional group transformations were key elements in this synthetic route.