(E)-3,3',4,4',7,7',8,8'-Octa-methyl-2H,2'H-1,1'-bi(cyclo-penta-[fg]acenaphthyl-enyl-idene)-2,2',5,5',6,6'-hexa-one dichloro-methane monosolvate.

The title compound, C(36)H(24)O(6)·CH(2)Cl(2), is a dimer of two essentially planar (r.m.s., deviations of fitted plane of 14 pyracene C atoms = 0.0539 and 0.0543 Å) tetra-cyclic pyracene frameworks (each with four methyl groups and three carbonyl groups on the peripheral carbon atoms) twisted along a central C=C bond with an angle of 50.78 (3)° at 90 K. There are notably long Csp(2)-Csp(2) bonds associated with the carbonyl groups, the longest being 1.601 (3) Šbetween two carbonyl C atoms. There are also intermolecular carbonyl⋯carbonyl interactions of both parallel and antiparallel types, with C⋯O distances in the range 3.041 (3) to 3.431 (2) Å. This compound is of inter-est with respect to the synthesis of fullerene fragments, such as corannulene and semibuckminsterfullerene derivatives (or 'buckybowls'), and is a side product of the previously reported oxidation reaction. Structural details, such as planarity analysis of fused rings, out-of-plane deviation of substituents, inter-molecular inter-actions, and longer than typical bond lengths, will be discussed as well as comparisons to structurally related compounds.

Isocorannulenofuran: a versatile building block for the synthesis of large buckybowls.

Isocorannulenofuran, synthesized in two steps from accessible bromocorannulene, gives Diels-Alder adducts with benzynes which can be deoxygenated to produce large polycyclic aromatic hydrocarbons (PAHs) combining the bowl-shaped corannulene subunit with planar fragments. [reaction: see text]

The first buckybowl aryne. Corannulyne: a nonplanar benzyne.

[reaction: see text] Treatment of bromocorannulene with NaNH(2)/tBuOK in THF in the presence of furans or amines leads to formation of addition products in good yields, presumably through formation of 1,2-didehydrocorannulene (corannulyne). HDFT calculations predict that corannulyne exists as a bowl-shaped entity and that the didehydrogenation energy of corannulene is slightly lower than that of benzene.

Novel twin corannulene: synthesis and crystal structure determination of a dicorannulenobarrelene dicarboxylate.

[reaction: see text] The dicorannulenobarrelene 1 was synthesized with the final step achieved by a nickel-mediated fourfold intramolecular coupling of dibromomethyl with bromomethyl groups. Low-temperature (1)H NMR spectra of 1 show a presence of three conformers with approximate populations of 0.82:0.13:0.05, in good agreement with theoretical predictions. In the crystal, 1 incorporates two CCl(4) molecules and adopts the bis-exo conformation.

Formation of the corannulene core by nickel-mediated intramolecular coupling of benzyl and benzylidene bromides: a versatile synthesis of dimethyl 1,2-corannulene dicarboxylate.

[reaction: see text] A practical synthesis of dimethyl 1,2-corannulene dicarboxylate (5) is reported, with the final ring-forming step achieved by the double intramolecular nickel powder mediated coupling of benzyl and benzylidene bromide groups with 60% isolated yield.

Addition of organolithium reagents to corannulene and conformational preferences in 1-alkyl-1,2-dihydrocorannulenes.

Addition of organolithium reagents to corannulene (1) produces 1-R-1,2-dihydrocorannulenes (2), which can be easily converted to 1-R-corannulenes (3). Molecular mechanics (MM) calculations predict a slight pseudoequatorial preference for the small substituents in both exo and endo arrangements of 2, whereas bulky substituents are expected to favor strongly the exo-pseudoaxial location. X-ray diffraction studies show the exo-pseudoaxial conformation in the solid state for both i-Pr and t-Bu-2. In solution, a gradual increase in the contribution of pseudoequatorial conformations with decreasing size of the substituent is demonstrated by analysis of the (3)J H-H coupling constants within the reduced ring.

Synthesis of a new C(32)H(12) bowl-shaped aromatic hydrocarbon: acenaphtho[3,2,1,8-ijklm]diindeno[4,3,2,1-cdef:1',2',3',4'-pqra]triphenylene.

The flash vacuum pyrolysis (FVP) of 1,2-bis(2-bromophenyl)-4,9-dibromocorannulene leads to a new C(32)H(12) buckybowl.