UNUSUAL REACTIVITY OF HIGHLY STRAINED CYCLOPHANES

An essential feature of the concept of aromaticity has been the stabil ity and lack of reactivity of aromatics relative to that of other unsa turated compounds. Contrary to this general experience, high and unusu al reactivity is encountered when simple, monocyclic benzene rings are bent by short bridges into a boat-shaped conformation, as is the case in small [n] paracyclophanes (n less than or equal to 8) and [n]metac yclophanes (n less than or equal to 7). This is illustrated, mostly wi th examples taken from the authors' own work, for thermal and photoche mical behavior and reactions with electrophiles, nucleophiles and dien ophiles. (C) 1998 John Wiley & Sons, Ltd.