Synthesis of a basket-shaped C56H38 hydrocarbon as a precursor toward an end-cap template for (6,6) carbon nanotubes

A basket-shaped C56H38 hydrocarbon (70) possessing a 30-carbon difluorenonaphthacenyl core that can be mapped onto the surface of C78 was synthesized from 4-bromo-1-indanone. The first stage of the synthesis involved the preparation of tetraketone 3 as a key intermediate.;The use of cascade cyclization reactions of benzannulated enyne-allenes as key features in the next stage of the synthetic sequence provides an efficient route to 70 from 4-bromo-1-indanone in 12 steps. The all- cis relationship among the methyl groups and the methine hydrogens causes the two benzofluorenyl units in 70 to be in an essentially perpendicular orientation to each other. Hydrocarbon 70 and its derivatives could serve as attractive precursors leading to a geodesic C68H26 end-cap template for (6,6) carbon nanotubes