Directors extend their reach

Abstract

The root of the regioselectivity problem is taught to chemistry students in their first organic chemistry course at university, in studies of classical electrophilic aromatic-substitution reactions - the most widely used reactions for attaching groups to benzene rings. In a benzene ring, the carbon atoms on either side of the point of attachment of a chemical group are said to be in the ortho-positions; the next two around the ring are in the meta-positions; and the carbon atom on the other side of the ring from the attached group is in the para-position (Fig. 1a).