title: Expedient synthesis of fused azepine derivatives using a sequential rhodium(II)-catalyzed cyclopropanation/1-aza-Cope rearrangement of dienyltriazoles.
abstract: A general method for the formation of fused dihydroazepine derivatives from 1-sulfonyl-1,2,3-triazoles bearing a tethered diene is reported. The process involves an intramolecular cyclopropanation of an α-imino rhodium(II) carbenoid, leading to a transient 1-imino-2-vinylcyclopropane intermediate which rapidly undergoes a 1-aza-Cope rearrangement to generate fused dihydroazepine derivatives in moderate to excellent yields. The reaction proceeds with similar efficiency on gram scale. The use of catalyst-free conditions leads to the formation of a novel [4.4.0] bicyclic heterocycle.
authors.affiliation: Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720 (USA).
authors.forename: Erica E
authors.initials: EE
authors.lastname: Schultz
authors.forename: Vincent N G
authors.initials: VN
authors.lastname: Lindsay
authors.forename: Richmond
authors.initials: R
authors.lastname: Sarpong
mesh_terms: D001381:Azepines / Q000138:chemical synthesis*; D002384:Catalysis; D003521:Cyclopropanes / Q000737:chemistry*; D015394:Molecular Structure; D012238:Rhodium / Q000737:chemistry*; D014230:Triazoles / Q000138:chemical synthesis*
chemical_list: D001381:Azepines; D003521:Cyclopropanes; D014230:Triazoles; D012238:Rhodium
keywords: azavinylcarbene; dihydroazepine; heterocycles; rearrangements; rhodium