Reaction of 1,2,3,4,5,6,7-(heptamethoxycarbonyl)cyclohepta-2,4,6-trien-1-yl potassium with tropylium tetrafluoroborate to form cage structures

A new original route to the construction of cage structures containing seven or more electron-withdrawing groups in a molecule was elaborated. This method is based on the reaction of a tropylium cation with a cycloheptatrienyl anion totally substituted with methoxycarbonyl groups. After the formation of a C–C bond between two different seven-membered carbocycles, some further transformations take place to give 2,3,4,5,6,7,8-hepta(methoxycarbonyl)pentacyclo[7.5.0.02.4.03.8.05.14]tetradeca-7,10,12-triene (6). Low temperature NMR experiments for the formation of this compound and some of its reactions were also studied.