One century of aryne chemistry

Arynes, which are formally derived from aromatic rings by abstraction of two hydrogen atoms, have been a focus of organic chemistry for 100 years. In contrast to ortho-benzyne, which is mentioned in almost every introductory textbook on organic reaction mechanisms as a reactive intermediate of nucleophilic aromatic substitution, the meta and para isomers were regarded as rather exotic until recently. This situation has changed dramatically with the discovery of the enediyne antibiotics, a promising new class of antitumor drugs, and has aroused the interest of research groups from all branches of chemistry. Nowadays, arynes and related compounds are among the most intensively studied systems in chemistry. However, many aspects of the chemistry of these reactive intermediates are not well understood yet. In this review we outline the historical developement with an emphasis on recent progress in this challenging field of research.