Concepts for stereoselective acrylate insertion

Handle URI:
http://hdl.handle.net/10754/562615
Title:
Concepts for stereoselective acrylate insertion
Authors:
Neuwald, Boris; Caporaso, Lucia; Cavallo, Luigi ( 0000-0002-1398-338X ) ; Mecking, Stefan
Abstract:
Various phosphinesulfonato ligands and the corresponding palladium complexes [{((PaO)PdMeCl)-μ-M}n] ([{( X1-Cl)-μ-M}n], (PaO) = κ2- P,O-Ar2PC6H4SO2O) with symmetric (Ar = 2-MeOC6H4, 2-CF3C6H4, 2,6-(MeO)2C6H3, 2,6-(iPrO)2C 6H3, 2-(2′,6′-(MeO)2C 6H3)C6H4) and asymmetric substituted phosphorus atoms (Ar1 = 2,6-(MeO)2C6H 3, Ar2 = 2′-(2,6-(MeO)2C 6H3)C6H4; Ar1 = 2,6-(MeO)2C6H3, Ar2 = 2-cHexOC 6H4) were synthesized. Analyses of molecular motions and dynamics by variable temperature NMR studies and line shape analysis were performed for the free ligands and the complexes. The highest barriers of ΔGa = 44-64 kJ/mol were assigned to an aryl rotation process, and the flexibility of the ligand framework was found to be a key obstacle to a more effective stereocontrol. An increase of steric bulk at the aryl substituents raises the motional barriers but diminishes insertion rates and regioselectivity. The stereoselectivity of the first and the second methyl acrylate (MA) insertion into the Pd-Me bond of in situ generated complexes X1 was investigated by NMR and DFT methods. The substitution pattern of the ligand clearly affects the first MA insertion, resulting in a stereoselectivity of up to 6:1 for complexes with an asymmetric substituted phosphorus. In the consecutive insertion, the stereoselectivity is diminished in all cases. DFT analysis of the corresponding insertion transition states revealed that a selectivity for the first insertion with asymmetric (P aO) complexes is diminished in the consecutive insertions due to uncooperatively working enantiomorphic and chain end stereocontrol. From these observations, further concepts are developed. © 2012 American Chemical Society.
KAUST Department:
KAUST Catalysis Center (KCC); Physical Sciences and Engineering (PSE) Division; Chemical Science Program
Publisher:
American Chemical Society
Journal:
Journal of the American Chemical Society
Issue Date:
23-Jan-2013
DOI:
10.1021/ja3101787
PubMed ID:
23256526
Type:
Article
ISSN:
00027863
Is Supplemented By:
Neuwald, B., Caporaso, L., Cavallo, L., & Mecking, S. (2013). CCDC 896036: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/ccz2ddt; DOI:10.5517/ccz2ddt; HANDLE:http://hdl.handle.net/10754/624743; Neuwald, B., Caporaso, L., Cavallo, L., & Mecking, S. (2013). CCDC 896035: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/ccz2dcs; DOI:10.5517/ccz2dcs; HANDLE:http://hdl.handle.net/10754/624742
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Chemical Science Program; KAUST Catalysis Center (KCC)

Full metadata record

DC FieldValue Language
dc.contributor.authorNeuwald, Borisen
dc.contributor.authorCaporaso, Luciaen
dc.contributor.authorCavallo, Luigien
dc.contributor.authorMecking, Stefanen
dc.date.accessioned2015-08-03T10:58:28Zen
dc.date.available2015-08-03T10:58:28Zen
dc.date.issued2013-01-23en
dc.identifier.issn00027863en
dc.identifier.pmid23256526en
dc.identifier.doi10.1021/ja3101787en
dc.identifier.urihttp://hdl.handle.net/10754/562615en
dc.description.abstractVarious phosphinesulfonato ligands and the corresponding palladium complexes [{((PaO)PdMeCl)-μ-M}n] ([{( X1-Cl)-μ-M}n], (PaO) = κ2- P,O-Ar2PC6H4SO2O) with symmetric (Ar = 2-MeOC6H4, 2-CF3C6H4, 2,6-(MeO)2C6H3, 2,6-(iPrO)2C 6H3, 2-(2′,6′-(MeO)2C 6H3)C6H4) and asymmetric substituted phosphorus atoms (Ar1 = 2,6-(MeO)2C6H 3, Ar2 = 2′-(2,6-(MeO)2C 6H3)C6H4; Ar1 = 2,6-(MeO)2C6H3, Ar2 = 2-cHexOC 6H4) were synthesized. Analyses of molecular motions and dynamics by variable temperature NMR studies and line shape analysis were performed for the free ligands and the complexes. The highest barriers of ΔGa = 44-64 kJ/mol were assigned to an aryl rotation process, and the flexibility of the ligand framework was found to be a key obstacle to a more effective stereocontrol. An increase of steric bulk at the aryl substituents raises the motional barriers but diminishes insertion rates and regioselectivity. The stereoselectivity of the first and the second methyl acrylate (MA) insertion into the Pd-Me bond of in situ generated complexes X1 was investigated by NMR and DFT methods. The substitution pattern of the ligand clearly affects the first MA insertion, resulting in a stereoselectivity of up to 6:1 for complexes with an asymmetric substituted phosphorus. In the consecutive insertion, the stereoselectivity is diminished in all cases. DFT analysis of the corresponding insertion transition states revealed that a selectivity for the first insertion with asymmetric (P aO) complexes is diminished in the consecutive insertions due to uncooperatively working enantiomorphic and chain end stereocontrol. From these observations, further concepts are developed. © 2012 American Chemical Society.en
dc.publisherAmerican Chemical Societyen
dc.titleConcepts for stereoselective acrylate insertionen
dc.typeArticleen
dc.contributor.departmentKAUST Catalysis Center (KCC)en
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentChemical Science Programen
dc.identifier.journalJournal of the American Chemical Societyen
dc.contributor.institutionDepartment of Chemical Materials Science, Department of Chemistry, University of Konstanz, 78464 Konstanz, Germanyen
dc.contributor.institutionDepartment of Chemistry and Biology, University of Salerno, Via Ponte Don Melillo, 84084-Fisciano (SA), Italyen
kaust.authorCavallo, Luigien
dc.relation.isSupplementedByNeuwald, B., Caporaso, L., Cavallo, L., & Mecking, S. (2013). CCDC 896036: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/ccz2ddten
dc.relation.isSupplementedByDOI:10.5517/ccz2ddten
dc.relation.isSupplementedByHANDLE:http://hdl.handle.net/10754/624743en
dc.relation.isSupplementedByNeuwald, B., Caporaso, L., Cavallo, L., & Mecking, S. (2013). CCDC 896035: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/ccz2dcsen
dc.relation.isSupplementedByDOI:10.5517/ccz2dcsen
dc.relation.isSupplementedByHANDLE:http://hdl.handle.net/10754/624742en

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