Synlett 2016; 27(14): 2105-2112
DOI: 10.1055/s-0035-1562720
© Georg Thieme Verlag Stuttgart · New York

Aromatic Rings and Aromatic Rods: Nonplanar Character of an Indeno-dehydro[14]annulene

Kévin Cocq
a   CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP44099, 31077 Toulouse Cedex 4, France   Email:   Email:
b   Université de Toulouse, UPS, ICT-FR 2599, 31062 Toulouse Cedex 9, France
Nathalie Saffon-Merceron
c   Université de Toulouse, UPS, Institut de Chimie de Toulouse ICT-FR-2599, 118 Route de Narbonne, 31062 Toulouse Cedex 9, France
Albert Poater
d   Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Campus Montilivi, 17003 Girona, Catalonia, Spain
Valérie Maraval*
a   CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP44099, 31077 Toulouse Cedex 4, France   Email:   Email:
b   Université de Toulouse, UPS, ICT-FR 2599, 31062 Toulouse Cedex 9, France
Remi Chauvin*
a   CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP44099, 31077 Toulouse Cedex 4, France   Email:   Email:
b   Université de Toulouse, UPS, ICT-FR 2599, 31062 Toulouse Cedex 9, France
› Author Affiliations
Further Information

Publication History

Received: 11 May 2016

Accepted after revision: 04 July 2016

Publication Date:
20 July 2016 (online)


Since the concept of aromaticity has been proposed to be generalizable to acetylenic rods (‘linear ring’ of [2]annulene), p-diisopropyl-tetraphenyl-carbo-benzene (C48H34) and an indenone-fused isopropyl-triphenyloctadehydro[14]annulene (C42H26O) can be regarded as based on heptacyclic aromatic cores. The formation and X-ray crystal structures of both products are described. The latter has been obtained as a reductive rearrangement product of a transient isopropyl-pentaoxy[5]pericyclyne devised as a putative precursor of a carbo-fulvene target. A mechanism accounting for this peculiar transformation is proposed. Deviation from global planarity is measured by a 6° angle between the mean plane of the indenone bicycle and that of 13 atoms of the [14]annulenic macrocycle, forming dihedral angles with the local plane of the isopropyl-substituted sp2 vertex of 16° and 15°, respectively. The magnetic aromaticity of the carbo-benzene and indeno-octadehydro[14]annulene products is evaluated by NICS calculations.

Supporting Information

  • References and Notes

  • 1 The larger the number of atoms prone to undergo slight strains vs. the ideal VSEPR configuration (Gillespies’ valence shell electron pair repulsion model), the larger the allowed global out-of-plane deformation of the ring, the angular strain being spread out over all the endocyclic atoms.

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