title: A novel photochemical vinylcyclopropane rearrangement yielding 6,7-dihydro-5H-benzocycloheptene derivatives
abstract: [reaction: see text] 1-Substituted 1-(2,2-diphenylvinyl)cyclopropanes with electron-accepting groups at C1 undergo a novel rearrangement to benzocycloheptenes on triplet-sensitized irradiation. In some instances competition between rearrangement to cyclopentenes and formation of cycloheptenes takes place. When electron-acceptor groups are not present at C1, conventional ring opening to cyclopentenes occurs exclusively. A mechanism involving intramolecular SET from the diphenylvinyl unit to the electron-acceptor group is proposed for this novel photoreaction.
authors.affiliation: Departamento de Quimica Organica I, Facultad de Ciencias Quimicas, Universidad Complutense, Madrid, Spain. darmesto@eucmos.sim.ucm.es
authors.initials: D
authors.lastname: Armesto
authors.initials: A
authors.lastname: Ramos
authors.initials: EP
authors.lastname: Mayoral
authors.initials: MJ
authors.lastname: Ortiz
authors.initials: AR
authors.lastname: Agarrabeitia