Author : James W. Harris
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (136 download)
Book Synopsis Development of Modular Synthetic Pathways Towards Novel P-Unsymmetric Bidentate Ligands by : James W. Harris
Download or read book Development of Modular Synthetic Pathways Towards Novel P-Unsymmetric Bidentate Ligands written by James W. Harris and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Late transition metal catalyzed transformations have become one of the most widely used protocols for carbon carbon and carbon heteroatom bond formation. The use of ancillary ligands is essential for successful reaction outcomes for a multitude of catalytic transformations. Tertiary phosphine ligands and N heterocyclic carbene ligands represent the most successful ligand classes for late transition metal catalyzed reactions. Modern ligand design focuses on the role each half of a chelate has towards the activity of a catalyst. There is a continuing need for the controlled synthesis of bidentate ligands with independent control of the coordinating groups. A modular synthesis of P unsymmetric diphosphine ligands has been developed through sequential nucleophilic substitutions. Key to the developed synthesis is the air stability of intermediates for much of the procedure. Purifications can be conducted in air, without risk of pyrophoric oxidation. Functionalizable synthetic intermediates allow the rapid generation of P unsymmetrical diphosphine ligands, in which the electron donor and steric parameters can be easily altered. A library of novel ligands has been developed utilizing the synthetic method developed. New examples of the corresponding phosphonium salts are also reported, providing facile entry for catalytic protocols requiring an external base. Palladium(II) chloride complexes of these ligands are reported and structurally characterized. Recent ligand development has focused on the combination of strong/weak ϳ donor hybrid bidentate ligands. Ligands of this type have been shown to form extremely active palladium catalysts for polymerization of alkenes. Reported is a synthetic alternative for the formation of phosphonate ester and phosphine oxide intermediates formed through the classical Michaelis Arbuzov reaction of phosphites and phosphinites with dihaloalkanes. This method provides chemoselective control in the synthesis of BPMO ligands in which the phosphorus centers are differentially substituted. A library of N heterocyclic carbene phosphine oxide and BPMO ligand precursors was synthesized to display the practicality of this method. The high yielding, limited step synthetic process is an attractive alternative to contemporary methods. Selected examples of N heterocyclic carbene phosphine oxide silver complexes, and corresponding transmetalation reactions with palladium are reported. Interesting examples of trans syn and trans anti rotational isomerism is reported for palladium(II) dimers and bis(NHC)palladium(II) chloride complexes.