The evolution of molecular belts and collars

Abstract

The Diels-Alder reaction has been employed to synthesise a hexaepoxyoctacosahydro[12]cyclacene derivative 6 in a highly efficient manner from the syn-isomer 1 of 1,4:5,8-diepoxy-1,4,5,8-tetrahydroanthracene and 2,3,5,6-tetramethylene-7-oxabicyclo[2.2.1]heptane 2. Each time a new cyclohexene ring is formed in the macropolycyclisation process, which utilises two molar equivalents of both the bisdienophile 1 and the bisdiene 2, the cycloadditions are trebly diastereoselective. A sequence of reactions on compound 6 involving (i) deoxygenation, (ii) dehydration, and (iii) partial hydrogenation have led to the isolation and characterisation of the D6h symmetrical dodecahydro[12]cyclacene derivative 10 containing six benzene rings. The synthetic strategy is new and the macropolycyclic compounds, which can be prepared according to this kind of molecular’LEGO’, are novel. © 1989 IUPAC