Solution-phase synthesis of bowl- and basket-shaped fullerene fragments via benzannulated enyne-allenes

Abstract

Benzannulated enyne-allenes bearing an aryl substituent at both the alkynyl and allenyl termini are excellent precursors of 5-aryl-11H-benzo[b]fluorenyl derivatives having the carbon frameworks of fullerene fragments. The mildness of the reaction conditions and the availability of several synthetic methods for benzannulated enyne-allenes allow the design of new synthetic pathways leading to bowl- and basket-shaped fullerene fragments. Specifically, a bowl-shaped C 28H 18 hydrocarbon bearing a 27-carbon framework of C 60 and a basket-shaped C 56H 40 hydrocarbon bearing a 54-carbon framework of C 60 were synthesized. The interior 30-carbon core of the C 56H 40 hydrocarbon can be regarded as a partially hydrogenated [5,5]circulene, a C 30H 12 semibuckminsterfullerene. In addition, a basketshaped C 56H 38 hydrocarbon was also constructed to serve as a precursor toward an end-cap template for (6,6) carbon nanotubes. © 2012 IUPAC.