title: Regioselectivity in the ligand-assisted addition of vinylmagnesium bromide: an experimental and theoretical study on the gamma-alkoxycyclobutenone model.
abstract: Compounds 2 (M = Mg) obtained in the mono addition of vinylmagnesium bromide to squarates are attractive structural models to determine the influence of complexation between magnesium(II) and the alkoxide group on the regioselectivity of the 1,2- versus 1,4-addition of organomagnesium by complex induced proximity effects (CIPE). The 1,4-addition is observed almost exclusively in the case of vinylmagnesium in THF solution with formation of hydroxyketones type 5, which are always side or minor products in the known reaction of alkenyllithium derivatives. A comparative study on the reactivity of alkenyllithium and magnesiun derivatives is reported. The high regioselectivitity observed in the 1,4-addition of vinylmagnesium bromide is fully understood by computational studies of compounds 2 (M = Mg) at the DFT level with the density functional B3LYP.
authors.affiliation: Departamento de Quimica Organica, Universidad de Valencia, Avda. V.A. Estelles s/n 46100-Burjassot, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Varea
authors.forename: Ana
authors.initials: A
authors.lastname: Alcalde
authors.forename: Amparo
authors.initials: A
authors.lastname: Grancha
authors.forename: Julio
authors.initials: J
authors.lastname: Lloret
authors.forename: Gregorio
authors.initials: G
authors.lastname: Asensio
authors.forename: Agusti
authors.initials: A
authors.lastname: Lledos