Cyclo-octatetraene is a compound of fundamental importance to theoretical chemists and has played an outstanding role in many aspects of organic and organometallic chemistry. As [8]annulene, the next higher vinylogue of benzene, it is essential to the understanding of cyclic alternating pi systems. As a medium-ring polyene, it undergoes a wide variety of reactions that are often accompanied by skeletal transformations, and it is the progenitor of a large number of interesting species, ranging in complexity from cyclobutadiene to triamantane. It also forms an exceptional variety of complexes with transition metals, important from the viewpoint of bonding theory, and increasingly useful in providing routes to systems that are not readily available by the conventional transformations of organic chemistry. The recent rapid developments and growth of interest in the study of cyclo-octatetraenes and its derivatives make this comprehensive review especially timely.
