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Anomalin. A Dihydropyranocoumarin Derivative from the Plant Lingusticum elatum

Padha, N and Goswami, KN and Yadava, VS and Nethaji, M (1995) Anomalin. A Dihydropyranocoumarin Derivative from the Plant Lingusticum elatum. In: Acta Crystallographica Section C, 51 (part12). pp. 2710-2712.

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The title compound, 9,10-dihydro-8,8-dimethyl-2-oxo-2H,8H-benzo[1,2-b:3,4-b']dipyran-9,10-diyl 2-methyl-2-butenoate, C24H26O7, contains a highly planar coumarin nucleus and a substituted dihydropyran ring (C), which has a distorted half-chair conformation, with an 8 alpha,9 beta orientation. The conformation of ring C is further supported by the two angelyloxy (2-methyl-2-butenoyloxy) substituents at positions C9 and C10, which are cis oriented and thus cannot both occupy equatorial positions with respect to the plane of ring C. The conformations of the two angelyloxy substituents are different, as indicated by their endocyclic torsion angles. The most striking of these angles are O1'-C2'-C4'=C6' and O1'-C2'-C4'-C5' [-137.7 (5) and 43.7 (5)degrees, respectively, in the chain at C10 and 155.8 (5) and -24.7 (9)degrees, respectively in the chain at C9]. These variations are due to two intramolecular hydrogen bonds, namely, C16-H161 ... O1' [C16 ... O1' 3.056 (7) Angstrom] and C7''-H7Y ... O3'' [C7'' ... O3'' 2.955 (12) Angstrom]. The methyl substituents, C15 and C16, at position C8 are alpha and beta oriented, respectively. The crystal structure is stabilized by a weak C4-H41 ... O3' hydrogen bond [C4 ... O3' 3.297 (6) Angstrom] between the screw-related molecules.

Item Type: Journal Article
Publication: Acta Crystallographica Section C
Publisher: International Union of Crystallography
Additional Information: Copyright of this article belongs to International Union of Crystallography.
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 26 Apr 2011 06:35
Last Modified: 05 Nov 2018 09:27
URI: http://eprints.iisc.ac.in/id/eprint/36909

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