title: An efficient approach to azirino and pyrrolo-fused dibenzazepines. Conformations of substituted dibenzo[c,f]pyrrolo[1,2-a]azepines.
abstract: An effective approach to azepino-fused heterocycles is described. trans-1-Aryl-7,11b-dihydro-1H-azirino[1,2-a]dibenzo[c,f]azepines were synthesised via a domino sequence: isomerization of gem-dichloroaziridine-intramolecular Friedel-Crafts acylation of the tethered benzene ring catalysed by SnCl(4) and subsequent hydride induced intramolecular cyclization. Cycloaddition of dibenzazepinium ylides, generated by heating these aziridines, to activated C[double bond]C, C[triple bond]C dipolarophiles and fullerene C(60), leads to derivatives of dibenzo[c,f]pyrrolo[1,2-a]azepine. The reaction proceeds with complete stereoselectivity via cycloaddition of only W-ylide, which due to the high barrier does not undergo E,Z-isomerization under the reaction conditions. It was found that 2,3,9,13b-tetrahydro-1H-dibenzo[c,f]pyrrolo[1,2-a]azepine systems can exist in conformations of two types depending on the substituents at the pyrrolidine carbons in β-position with respect to nitrogen. Details of cycloaddition reactions and the conformational behavior of cycloadducts were studied by DFT calculations at the B3LYP/6-31G(d) level.
authors.affiliation: Department of Chemistry, Saint Petersburg State University, St. Petersburg, Russia. alexander.khlebnikov@pobox.spbu.ru
authors.forename: Alexander F
authors.initials: AF
authors.lastname: Khlebnikov
authors.forename: Mikhail S
authors.initials: MS
authors.lastname: Novikov
authors.forename: Maria V
authors.initials: MV
authors.lastname: Golovkina
authors.forename: Petr P
authors.initials: PP
authors.lastname: Petrovskii
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Konev
authors.forename: Dmitry S
authors.initials: DS
authors.lastname: Yufit
authors.forename: Helen
authors.initials: H
authors.lastname: Stoeckli-Evans
mesh_terms: D001381:Azepines / Q000737:chemistry*; D003984:Dibenzazepines / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D010077:Oxazepines / Q000737:chemistry; D011758:Pyrroles / Q000737:chemistry*
chemical_list: D001381:Azepines; D003984:Dibenzazepines; D010077:Oxazepines; D011758:Pyrroles; C527817:dibenzazepine