Prochirality revisited. An approach for restructuring stereochemistry by novel terminology

The importance of orbits (equivalence classes) has been stressed to restructure stereochemistry. The concept of sphericity has been formulated by a new scheme that requires a minimum set of knowledge on point-group theory. The concept of prochirality has been revisited from the viewpoint based on the new formulation of sphericity. A variety of objects such as atoms, ligands, and faces are discussed as the members of such an orbit. In particular, orbits for atoms in tetrahedral molecules and for the faces of carbonyl compounds, ethylene derivatives, and allene derivatives have been examined in terms of the concept of sphericity. The conventional topicity terms of two categories ("topic relationship between two sites" and "topic attribute of a site") have been effectively replaced by the sphericity terms.