title: Application of an S --> O Allylic Transposition in the Context of a Bridgehead Olefinic System. New Opportunities for the Structural Modification of Bicyclo[6.2.1]undecanes via Transannular Ring Closure.
abstract: A practical route is described for the preparation of allylic sulfide 8, whose double bond resides at a bridgehead site. Following hydride reduction of the ketone carbonyl and sulfoxidation, exposure to trifluoroacetic anhydride results in the operation of an intermolecular S --> O allylic transposition. This central step leads to 14a, an intermediate useful for probing the consequences associated with epoxidation of its cis-cyclononene double bond. A total of three different transannular cyclizations are described in order to demonstrate the ease with which ring closures can operate in a medium-ring setting of this type. Represented are transformations that generate tetrahydrofuran, oxetane, and cyclopropane subunits. The kinetic biases favoring these transformations are highlighted.
authors.affiliation: Evans Chemical Laboratories, The Ohio State University, Columbus, Ohio 43210.
authors.forename: Jeffrey N.
authors.initials: JN
authors.lastname: Johnston
authors.forename: Hon-Chung
authors.initials: HC
authors.lastname: Tsui
authors.forename: Leo A.
authors.initials: LA
authors.lastname: Paquette