The molecular structure of 6, 8, 6 and related systems

Abstract

90.00", /? = 90.38", y = 90.00", Z = 8) have been determined. The first two, which belong to the 6,8,6 ring system, exist in the solid state in the chair conformation, whereas both the chair and the boat forms are present in solution. The central twelve-membered ring of compound 12 exists in the crystal as an almost perfect C, propeller, which is also the only observed conformation in solution.Finally, there are four different molecules of compound 16 in the crystal; however, they roughly correspond to the same conformation (and its enantiomer) [(+-+,-+-,++-,---) and (-+-,+-+, --+,+ + +)I. Partial and complementary to literature NMR ('H and 13C) results agree with previous conformational analyses in solution.

Synthesis of Annulenes via Multiple Wittig Reactions; In‐Situ Dimerization of 1,2;5,6‐Dibenzocyclooctatetraene

“…The physical and spectroscopic properties of 7 are in good agreement with the reported data. [18] Additionally, a mixture of cis/trans isomers of hexabenzo[24]annulene 8 was obtained from the reaction between 1 and 2. Hydrogenation with palladium on activated charcoal confirmed the common [24]annulene substructure of the isomers (Scheme 4).…”

Gas-phase conformations and exciton couplings in 5,6,11,12-tetrahydrodibenzo[a,e]cyclooctene

“…The twist-boat (TB) and chair (C) conformers have been observed in solution using NMR techniques [2,3]. X-ray studies show that only the C conformer is present in the crystal [1]. The gas-phase conformational analysis of THDC which can be readily compared with the results of theoretical computations of the isolated THDC conformations has not yet been reported in the literature.…”

“…The conformations of 5,6,11,12-tetrahydrodibenzo[a,e]cyclooctene (THDC), also known as [2.2]-orthocyclophane, have been extensively investigated by X-ray and NMR techniques [1][2][3]. Previous theoretical studies of THDC were limited to molecular mechanics and density functional theory (DFT) calculations [3,4].…”

Conformational analysis of dibenzo[a,e]cyclooctadiene and three related heterocyclic compounds

“…We were the first to determine its X-ray molecular structure [11] (CSD refcode PAMTUS) [12][13][14]. We have also determined the structures of three heterocyclic analogs 2 (JIZKOS) [15], 3 (BIMZOC) [16], and 4 (PAMVAA) [11]. The conformational analysis of bis(benzocorannuleno) [a,e]cyclooctadiene, an homolog of 1 has been reported recently [17].…”

“…The conformation of dibenzo[a,e]cyclooctadiene (1), also called dibenzo [1,5] cyclooctadiene, dibenzo[a,e]cyclooctane, 5,6,11,12-tetrahydrodibenzo[a,e]cyclooctene, has been studied both experimental (crystallography, dynamic NMR) and theoretically [4][5][6][7][8][9][10]. We were the first to determine its X-ray molecular structure [11] (CSD refcode PAMTUS) [12][13][14]. We have also determined the structures of three heterocyclic analogs 2 (JIZKOS) [15], 3 (BIMZOC) [16], and 4 (PAMVAA) [11].…”