title: Enantioselective cycloadditions of 2-alkenoylpyridine-N-oxides catalysed by a bis(oxazoline)/Cu(II) complex: structure of the reactive intermediate.
abstract: Diels-Alder and 1,3-dipolar cycloadditions involving (E)-3-aryl-1-(pyridin-2-yl-N-oxide)prop-2-en-1-ones as the 2π components are efficiently catalysed by bis(oxazoline)-Cu(II) complexes. The cycloadducts are obtained in quantitative yields with up to 98 % ee; absolute configurations were determined by X-ray analysis. The structure of the reactive complex, determined by X-ray analysis, is fully consistent with the stereochemical outcome of the catalysed process (approach of the diene or nitrone to the less hindered face of the coordinated pyridine-N-oxide derivative).
authors.affiliation: Department of Organic Chemistry, University of Pavia, V.le Taramelli, 10, 27100 Pavia, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Livieri
authors.forename: Massimo
authors.initials: M
authors.lastname: Boiocchi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Desimoni
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Faita