Bridged aromatics are the largest group of molecules possessing chiral planes. For example:

The plane of the benzene ring is the chiral plane. Attachment of the Br in that plane in this instance destroys two perpendicular symmetry planes. That is, if the Br were not there, the plane of the page would be a symmetry plane, as would a vertical plane perpendicular to the page.

To assign a configuration:

• Choose a pilot atom (= P), not in the chiral plane, but attached to an atom that is in the plane.

• Create a path from the attached atom (a), using the sequence rules to choose the next atom in the path. That is, move along bonds from one atom to the next. Wherever a choice must be made of which is the "next" atom, choose the one of higher priority.

• Continue this process until a path has been laid out long enough that a clockwise or anticlockwise direction can be discerned.

• View the path from the pilot atom toward the chiral plane. If the path a .... d turns clockwise, the structure is R. If anticlockwise, S.

Thus, the example molecule above has the R configuration.

In the next example, a biphenylene structure is made dissymmetric by placement of a carboxyl on one ring. Following the rules above leads to the assignment of S configuration.

The last example demonstrates choice of a pilot atom when two seem possible, by selecting the one that leads to a shorter path to the higher priority substituent on the aromatic ring, the chlorine atom.