title: A new approach to the nazarov reaction via sequential electrocyclic ring opening and ring closure.
abstract: Regioselective dichlorocyclopropanation of 2-silyloxydienes furnishes vinylcyclopropanol silyl ethers in good yield. Treatment with silver(I) at room temperature effects disrotatory electrocyclic opening to a 2-chloro-3-silyloxypentadienyl cation, which then undergoes conrotatory (Nazarov) electrocyclization to provide chlorocyclopentenones. This two-step sequence offers a convenient and mild alternative to the standard Nazarov cyclization protocol via a formal 4+1 construction and furnishes products containing useful halogen functionality. In one case possessing a pendant phenyl group, interrupted Nazarov reaction to give a benzohydrindenone was observed.
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, Alta., Canada T6G 2G2.
authors.forename: Tina N
authors.initials: TN
authors.lastname: Grant
authors.forename: F G
authors.initials: FG
authors.lastname: West