Construction of a tube-like molecule via sequential cyclopropylidene dimerisation and intramolecular [π2s+π2s] cycloaddition reactions

The syn-cyclopropylidene dimer 5, obtained by reaction of compound 4 with methyllithium, is readily elaborated to the bis-p-benzoquinone 7 which undergoes intramolecular [π2s+π2s] cycloaddition to give the tube-like molecule 8.