Controlled helical senses of twisting in two-, three- and four-layer cyclophanes with planar chirality.

We synthesized planar chiral cyclophanes with multiple pairs of helical conformations that were generated by twisting at the interlayer. Three- and four-layer cyclophanes preferred a homochiral form with a single sense of twisting through intramolecular transmission of planar chirality. Alternatively, a heterochiral form was dominant in a two-layer cyclophane consisting of two achiral planes that were stacked orthogonally.