Photochemical Rearrangements and Fragmentations of Benzene Derivatives and Annelated Arenes

Abstract

AbstractIn this article the numerous intramolecular reactions of electronically excited benezene derivatives, which in many instances are only mentioned in original papers, are systematically analyzed and arranged according to reaction types. All known reaction types can be classified, and subdivided into reactions of the benzene ring (ionization, ring opening, ring alteration), reactions with participation of side chains (α‐, β‐, γ‐cleavage, homolysis, heterolysis), reactions of substituents with side chains (cyclization, dealkylation, cleavage of protective groups), and reactions of side chains with the aromatic ring (substitution, addition, dearomatization, cyclization). The selectivity of the energetically feasible competing reactions is primarily determined by geometric factors. Applications of the empirical effects are numerous and varied in preparative organic chemistry. Many of the reactions under discussion are already utilized industrially (e.g. in photochromism, UV stabilization, photography, information storage, printing, coating and polymer technology, and pharmacy).