title: Intramolecular Nitrone Cycloaddition of α-(Trifluoromethyl)styrenes. Role of the CF3Group in the Regioselectivity.
abstract: The intramolecular 1,3-dipolar cycloaddition of ortho-substituted 1,1,1-trifluoromethylstyrene-derived nitrones is described. Tricyclic fused isoxazolidines were obtained as major or exclusive products, in contrast to the case for nonfluorinated substrates, which rendered the bridged derivatives. This change in the regioselectivity was attributed to the electronic and, particularly, steric requirements of the trifluoromethyl group in comparison to the methyl group. It is worth mentioning that trifluoromethylstyrenes have been employed for the first time as dipolarophiles in a 1,3-dipolar intramolecular cycloaddition reaction, leading to the corresponding isoxazolidines bearing a quaternary trifluoromethyl moiety. Finally, the synthetic utility of the developed methodology has been illustrated with the synthesis of a family of bicyclic fluorinated 1,3-amino alcohols.
authors.affiliation: Departamento de Química Orgánica, Universidad de Valencia , 46100 Burjassot, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Rabasa-Alcañiz
authors.affiliation: Departamento de Química Orgánica, Universidad de Valencia , 46100 Burjassot, Spain.
authors.forename: Amparo
authors.initials: A
authors.lastname: Asensio
authors.affiliation: Departamento de Química Orgánica, Universidad de Valencia , 46100 Burjassot, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Sánchez-Roselló
authors.affiliation: Departamento de Química Orgánica, Universidad de Valencia , 46100 Burjassot, Spain.
authors.forename: Marcos
authors.initials: M
authors.lastname: Escolano
authors.affiliation: Departamento de Química Orgánica, Universidad de Valencia , 46100 Burjassot, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Del Pozo
authors.affiliation: Departamento de Química Orgánica, Universidad de Valencia , 46100 Burjassot, Spain.|Laboratorio de Moléculas Orgánicas, Centro de Investigación Príncipe Felipe , 46012 Valencia, Spain.
authors.forename: Santos
authors.identifier: 0000-0002-7575-9439
authors.initials: S
authors.lastname: Fustero