title: Torquoselectivity in the Nazarov reactions of allenyl vinyl ketones.
abstract: Nazarov reactions mediated by BF3-etherate of a series of carbon-substituted allenyl vinyl ketones provided intermediates in which substituents on the termini of the allenes had rotated away from the vinyl moieties, and these intermediates were trapped by (4 + 3)-cyclizations. A computational examination of the torquoselectivity of these Nazarov reactions confirmed a kinetic preference for the observed isomers and pointed to steric interactions and the degree of allene deformation as significant factors in determining the torquoselectivity. The study also suggested that the high proportion of one geometrical isomer in the Nazarov products might also be due to some preferential trapping of the major Nazarov intermediate.
authors.affiliation: Department of Chemistry, Dalhousie University , P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada.
authors.forename: Timothy D R
authors.initials: TD
authors.lastname: Morgan
authors.forename: Luc M
authors.initials: LM
authors.lastname: LeBlanc
authors.forename: Giselle H
authors.initials: GH
authors.lastname: Ardagh
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Boyd
authors.forename: D Jean
authors.initials: DJ
authors.lastname: Burnell