title: Formation of substituted oxa- and azarhodacyclobutanes.
abstract: The preparation of substituted oxa- and azarhodacyclobutanes is reported. After exchange of ethylene with a variety of unsymmetrically and symmetrically substituted alkenes, the corresponding rhodium-olefin complexes were oxidized with H2O2 and PhINTs (Ts=p-toluenesulfonyl) to yield the substituted oxa- and azarhodacyclobutanes, respectively. Oxarhodacyclobutanes could be prepared with excellent selectivity for incorporation of the oxygen atom on the more substituted carbon atom of the alkene. At the same time, azarhodacyclobutanes showed good-to-excellent selectivity for heteroatom incorporation on the less substituted carbon. Furthermore, it was shown that steric modifications of the ancillary ligand have a significant influence on the selectivity of Rh-olefin complex formation as well as formation of the substituted azametallacycles.
authors.affiliation: Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T1Z1 (Canada).
authors.forename: Alexander
authors.initials: A
authors.lastname: Dauth
authors.forename: Carla
authors.initials: C
authors.lastname: Rigling
authors.forename: Jennifer
authors.initials: J
authors.lastname: Tsoung
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Love
keywords: alkene complexes; metallacycle; oxidation; regioselectivity; rhodium