Lanthanum-pyBOX complexes as catalysts for the enantioselective conjugate addition of malonate esters to β,γ-unsaturated α-ketimino esters
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Lanthanum-pyBOX complexes as catalysts for the enantioselective conjugate addition of malonate esters to β,γ-unsaturated α-ketimino esters

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Lanthanum-pyBOX complexes as catalysts for the enantioselective conjugate addition of malonate esters to β,γ-unsaturated α-ketimino esters

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dc.contributor.author Espinosa López, Miguel
dc.contributor.author Blay Llinares, Gonzalo
dc.contributor.author Cardona Prósper, María Luz
dc.contributor.author Fernández Picot, Isabel
dc.contributor.author Muñoz, M. Carmen
dc.contributor.author Pedro, José Ramón
dc.date.accessioned 2020-09-29T14:18:53Z
dc.date.available 2020-09-29T14:18:53Z
dc.date.issued 2018
dc.identifier.uri https://hdl.handle.net/10550/75684
dc.description.abstract In this paper, we report the application of chiral complexes of La(III) with pyBOX ligands as Lewis acid catalysts in the conjugate addition of malonic esters to N-tosyl imines derived from β,γ-unsaturated α-keto esters to give the corresponding chiral α,β-dehydroamino esters. pyBOX complexes with La(III), Yb(III), Sc(III), and In(III) triflates were assessed in this reaction but only La(III) showed good activity and enantioselectivity, while Yb(III) provided the expected product with low yield and stereoselectivity, and the Sc(III) and In(III) complexes were completely inactive. The complex of La(OTf )3 with the diphenylpyBOX ligand prepared in situ provided the best results and allowed obtaining chiral α,β-dehydroamino esters 3 with excellent yields, E:Z diastereomeric ratios (29:71-99:1) and high enantiomeric excesses (20-95%). The reaction could be applied to imines having a substituted aromatic ring or a heterocycle attached to the double bond, although the presence of electron-withdrawing groups on the aromatic ring was detrimental for stereoselectivity. The reaction products were obtained with the S configuration at the stereogenic center and the Z configuration at the enamine double bond as determined by NOESY experiments and X-ray analysis. Based on the experimental results a stereochemical model involving a nine- coordinate La(III) species has been proposed.
dc.language.iso eng
dc.relation.ispartof Journal of Coordination Chemistry, 2018, vol. 71, num. 6, p. 864-873
dc.rights.uri info:eu-repo/semantics/openAccess
dc.source Espinosa López, Miguel Blay Llinares, Gonzalo Cardona Prósper, María Luz Fernández Picot, Isabel Muñoz, M. Carmen Pedro, José Ramón 2018 Lanthanum-pyBOX complexes as catalysts for the enantioselective conjugate addition of malonate esters to β,γ-unsaturated α-ketimino esters Journal of Coordination Chemistry 71 6 864 873
dc.subject Química orgànica
dc.subject Catàlisi
dc.title Lanthanum-pyBOX complexes as catalysts for the enantioselective conjugate addition of malonate esters to β,γ-unsaturated α-ketimino esters
dc.type info:eu-repo/semantics/article
dc.date.updated 2020-09-29T14:18:53Z
dc.identifier.doi https://doi.org/10.1080/00958972.2018.1437422
dc.identifier.idgrec 126269

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