Henning Hopf is Director of the Institute for Organic Chemistry at the TU Braunschweig, Germany. His main areas of research concern hydrocarbon chemistry (alkines, allenes, cumulenes, aromats, cyclophanes, polyolefines, etc.) and mechanistic investigations of high-temperature reactions. Michael Sherburn is Professor of Chemistry at the Research School of Chemistry at the Australian National University in Canberra, Australia. His research interests focus on the development of efficient synthetic methods, strategies and tactics for the synthesis of natural and unnatural structures.