Novel loop-like aromatic compounds: a further step on the road to nanobelts and nanotubes

The synthesis and crystal structural characterization of new compounds 2-6 were accomplished. As a common synthetic methodology, the Diels-Alder reaction was applied to 9,9',10,10'-tetradehydrodianthracene (TDDA) (7) to furnish the [12]annulenes 2 and 3 [16]annulene 6 and adduct 5.