Tert-Butylcorannulene

The first evidence for the self-assembly of corannulene tetraanions into a supramolecu-lar dimer, 44, was provided by studies on derivatives of 4371. Owing to their lower symmetry, dimers of monosubstituted corannulene tetraanions are expected to exhibit supramolec-ular stereochemistry, and thus exist in meso and/or as dl dimeric forms (Figure 14a, and b respectively). Reduction of tert-butylcorannulene (45) with excess lithium metal in THF-d i leads to two sets of alkyl groups in almost equal abundance, thus pointing to the presence of tightly bound dimers. Compelling evidence for dimerization comes from the successful detection of a mixed dimer between 434 and 454. In addition, diffusion... 

The reduction of 1,3,5,7,9-penta-tert-butylcorannulene (47) with lithium progresses in four steps, and affords a paratropic dianion and a diatropic tetraanion78. This is reminiscent of the reduction process of 43. In the final stage of the reduction, however, three distinct tetraanionic species could be detected two sandwich-type diastereomers, similar to 44, and another species assigned to a tetraanionic monomer of 47, that slowly disappears. This study showed that the peri derivatization of 43 with bulky alkyl groups has little effect on its dimerization. 

The monosubstituted corannulene derivatives tert-butylcorannulene (3S) and iso-propylcorannulene (36) have lower symmetry than corannulene therefore their reduction provided evidence for the formation of the dimers of corannulene tet-raanion. The dimers of monosubstituted coraimulene tetraanions are expected to exhibit supramolecular stereochemistry, existing in meso and d,l dimeric forms. 

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