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Synthesis of new phosphino amino alcohol ligands via ortho-alkyllithiation reactions. Versatile coordination behavior toward copper(I) and palladium(II)

Andrieu, J., Steele, B. R., Screttas, C. G., Cardin, C. and Fornies, J. (1998) Synthesis of new phosphino amino alcohol ligands via ortho-alkyllithiation reactions. Versatile coordination behavior toward copper(I) and palladium(II). Organometallics, 17 (5). pp. 839-845. ISSN 0276-7333

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To link to this article DOI: 10.1021/OM970550E

Abstract/Summary

2-[Methyl(2-methylphenyl)amino]ethanol undergoes an ortho-alkyllithiation reaction with n-butyllithium to lead to a new mixed benzyllithium−lithium alkoxide. This organolithium species reacts with PPh2Cl, with selective P−C bond formation, to afford the ligand 2-[methyl(2-((diphenylphosphino)methyl)phenyl)amino]ethanol L1. The coordination of the ligand L1 to copper(I) leads to the complex [Cu(L1)2](BF4), whose structure has been determined by an X-ray diffraction study. In the solid state, one of the ligands acts as a monodentate phosphine while the other adopts a tridentate P,N,O coordination mode. A variable-temperature 31P NMR study demonstrated the existence of an equilibrium between the two modes in solution, with a coalescence temperature of ca. 0 °C, indicating a double-hemilabile behavior for the nitrogen and the oxygen functions. L1 reacts with [Pd(Me)(Cl)(COD)] to give a dinuclear complex in which the ligand appears to behave as a bridging anionic P,O ligand. Such a complex could serve as a model for a key intermediate in the proposed mechanism for the homogeneous catalysis of the methoxycarbonylation of propyne by certain palladium(II) complexes containing P,N ligands. L1 can undergo a second ortho-alkylmetalation reaction with n-butyllithium which, after addition of PPh2Cl, provides the new ligand 2-{methyl[2-(bis(diphenylphosphino)methyl)phenyl]amino}ethanol (L2) in high yield.

Item Type:Article
Refereed:Yes
Divisions:Faculty of Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
ID Code:23762
Publisher:ACS Publications

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