A Superior Synthesis of Longitudinally Twisted Acenes

Seven longitudinally twisted acenes (an anthracene, two tetracenes, three pentacenes, and a hexacene) have been synthesized by the addition of aryllithium reagents to the appropriate quinone precursors, followed by SnCl2‐mediated reduction of their diol intermediates, and several of these acenes have been crystallographically characterized. The new syntheses of the three previously reported twisted acenes, decaphenylanthracene (1), 9,10,11,20,21,22‐hexaphenyltetrabenzo[a,c,l,n]pentacene (2), and 9,10,11,12,13,14,15,16‐octaphenyldibenzo[a,c]tetracene (14), resulted in a reduction of the number of synthetic steps. As a consequence their overall yields were increased by factors of 50‐, 24‐, and 66‐fold, respectively. All of the twisted acene syntheses reported here are suitable for the synthesis of at least gram quantities of these remarkable hydrocarbon materials. Let′s twist again: The addition of several aryllithium reagents to a variety of sterically congested polycyclic quinones followed by SnCl2‐mediated reduction allowed relatively easy access to a large number of longitudinally twisted acenes. This facile approach also allows the preparation of these remarkable hydrocarbons in gram‐scale quantities.