title: Two conformers of 10,11-dihydro-5H-dibenzo[a,d]cycloheptene spiro-linked with homobenzoquinone epoxide.
abstract: The crystal structures of the two thermally equilibrated conformational isomers of the epoxide 1',5'-dimethylspiro[10,11-dihydro-5H-dibenzo[a,d]cycloheptene-5,8'-4'-oxatricyclo[5.1.0.0(3,5)]octane]-2',6'-dione, C23H20O3, have been determined by X-ray diffraction. In the tricyclic dione skeleton, the oxirane and cyclopropane rings adopt an anti structure with respect to the conjunct quinone frame. The spiro-linked 10,11-dihydro-5H-dibenzo[a,d]cycloheptene ring of the major isomer has a fairly twisted boat form, folding opposite to the adjoining cyclopropane methyl substituent, whereas the seven-membered ring of the minor isomer has an almost ideal twist-boat form, inversely folding to the side of the relevant methyl group. The conformational structures of these isomers have been compared with those of the corresponding isomers of the unepoxidized homobenzoquinone.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Haruyasu
authors.initials: H
authors.lastname: Asahara
authors.forename: Takuya
authors.initials: T
authors.lastname: Koizumi
authors.forename: Eiko
authors.initials: E
authors.lastname: Mochizuki
authors.forename: Takumi
authors.initials: T
authors.lastname: Oshima
mesh_terms: D002220:Carbamazepine / Q000031:analogs & derivatives* / Q000737:chemistry; D018360:Crystallography, X-Ray; D003508:Cycloheptanes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation
chemical_list: D003508:Cycloheptanes; D002220:Carbamazepine; C004822:10,11-dihydro-10,11-dihydroxy-5H-dibenzazepine-5-carboxamide