THE STRUCTURE-DIRECTED SYNTHESIS OF CYCLACENE AND POLYACENE DERIVATIVES

The treble diastereoselectivities exhibited by Diels-Alder reactions which occur between diene and dienophilic components associated with bicyclic systems have been employed in the stepwise construction of compounds with molecular architectures that resemble cups and cages. These macropolycyclic compounds are potential synthetic precursors of novel hydrocarbons composed of [a,d]-fused and [a,c]-fused six-membered rings. The hydrocarbons themselves are of considerable importance in investigating the behaviour of pi-electrons in highly-conjugated cyclic systems and in understanding the influence upon the aromaticity and antiaromaticity of benzenoid and fused benzenoid rings that are obliged to become bent.