Synthesis and characterization of a new hexacyclic helicene

A new helically chiral hexacyclic system, bearing an acetoxymethyl group, was prepared from a simple naphthalene building block in good yield and purity, via a four-step sequence involving palladium-catalysed Heck couplings and oxidative photocyclizations. Suitable crystals of the latter indicate that its conformation closely resembles that of unsubstituted [6]helicene, whose idealized symmetry is C2. The optical properties of the hexacyclic helicene were investigated and show interesting behaviour.