The chemistry of bisallenes Henning Hopf* and Georgios Markopoulos Review Open Access Address: Beilstein J. Org. Chem. 2012, 8, 1936–1998. Institute of Organic Chemistry, Technical University of Braunschweig, doi:10.3762/bjoc.8.225 Hagenring 30, D-38106 Braunschweig, Germany, fax: +49-(0)531-391-5388 Received: 01 August 2012 Accepted: 13 October 2012 Email: Published: 15 November 2012 Henning Hopf* -
[email protected] Dedicated to Professor Roald Hoffmann on the occasion of his 75th * Corresponding author birthday. Keywords: Associate Editor: J. A. Murphy alicyclic; bisallenes; cyclic; cycloadditions; cycloisomerization; isomerization; molecular complexity; step economy © 2012 Hopf and Markopoulos; licensee Beilstein-Institut. License and terms: see end of document. Abstract This review describes the preparation, structural properties and the use of bisallenes in organic synthesis for the first time. All classes of compounds containing at least two allene moieties are considered, starting from simple conjugated bisallenes and ending with allenes in which the two cumulenic units are connected by complex polycyclic ring systems, heteroatoms and/or heteroatom-containing tethers. Preparatively the bisallenes are especially useful in isomerization and cycloaddition reactions of all kinds leading to the respective target molecules with high atom economy and often in high yield. Bisallenes are hence substrates for generating molecular complexity in a small number of steps (high step economy). Table of Contents Introduction 2. Acyclic nonconjugated bisallenes 2.1 1,2,5,6-Heptatetraene and its derivatives Review 2.2 1,2,6,7-Octatetraene and its derivatives 2.3 Higher acyclic α,ω-bisallenes 1. Acyclic conjugated bisallenes 2.4 The chemical behavior of nonconjugated, acyclic 1.1 Synthesis of hydrocarbons α,ω-bisallenes 1.2 Synthesis of functionalized systems 3.