title: Diastereoselective Synthesis of alpha,alpha-Disubstituted gamma-Carboxypyroglutamates via Sm(III)-Azomethine Ylide Cycloadditions.
abstract: Sm(III)-azomethine ylides 2 have been generated from ketones 1. Cycloaddition of ylides 2 with alpha,beta-unsaturated esters 3 through a transition state chelation-controlled by the metal allowed for the asymmetric synthesis of gamma-carboxypyroglutamates having a quaternary alpha-carbon that are potentially useful in the synthesis of neuroprotective agents.
authors.affiliation: Departamento de Química Orgánica I, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Alvarez-Ibarra
authors.forename: Aurelio G.
authors.initials: AG
authors.lastname: Csákÿ
authors.forename: Isabel
authors.initials: I
authors.lastname: López De Silanes
authors.forename: M. Luz
authors.initials: ML
authors.lastname: Quiroga