title: Highly diastereoselective 1,3-dipolar cycloadditions of chiral non-racemic nitrones to 1,2-diaza-1,3-dienes: an experimental and computational investigation.
abstract: Asymmetric 1,3-dipolar cycloadditions between 1,2-diaza-1,3-dienes and chiral non-racemic nitrones to give 3-substituted-5-diazenyl isoxazolidines were studied both experimentally and theoretically. Whereas cyclic nitrones provide complete selectivity for the cycloaddition reaction (only one isomer is obtained), acyclic nitrones derived from D-glyceraldehyde and D-galactose lead to 1 : 1 mixtures of two isomers. A DFT analysis based on reactivity indices correctly predicts the regiochemistry of the reaction in agreement with the high electron-withdrawing character of the diazenyl group. The same theoretical studies considering solvent effects (PCM model) based on transition state theory are in qualitative agreement with the observed experimental results.
authors.affiliation: Laboratorio de Síntesis Asimétrica, Departamento de Síntesis y Estructura de Biomoléculas, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza, CSIC, E-50009 Zaragoza, Aragón, Spain. pmerino@unizar.es.
authors.forename: Roberta
authors.initials: R
authors.lastname: Majer
authors.forename: Olga
authors.initials: O
authors.lastname: Konechnaya
authors.forename: Ignacio
authors.initials: I
authors.lastname: Delso
authors.forename: Tomas
authors.initials: T
authors.lastname: Tejero
authors.forename: Orazio A
authors.initials: OA
authors.lastname: Attanasi
authors.forename: Stefania
authors.initials: S
authors.lastname: Santeusanio
authors.forename: Pedro
authors.initials: P
authors.lastname: Merino
mesh_terms: D003500:Cyclization; D006834:Hydrazines / Q000737:chemistry*; D007555:Isoxazoles / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009589:Nitrogen Oxides / Q000737:chemistry*; D011789:Quantum Theory; D013237:Stereoisomerism
chemical_list: D006834:Hydrazines; D007555:Isoxazoles; D009589:Nitrogen Oxides; C015388:nitrones