Phosphines ligand synthesis

Because of the relatively high loading of functional groups on these hyperbranched PE powders, it was feasible to characterize the products and intermediates in this catalysts synthesis by P CP-MAS NMR spectroscopy, ATR-IR spectroscopy, and XPS analysis. P CP-MAS NMR spectroscopy was especially useful for in distinguishing the phosphinated powder, phosphine-palladium complex, and any adventitiously formed phosphine oxide. Similar NMR analyses were not successfully carried out on hyperbranched grafts on PE films. However, when this same phosphine ligand synthesis and introduction of Pd was carried out on a PE film sample, it was possible to analyze... 

N. Takaishi, H. Imai, C. A. Bertelo, and J. K. Stille (1978), Transition metal catalyzed asymmetric organic synthesis via polymer-attached optically active phosphine ligands. Synthesis of R amino acid and hydratopic acid by hydrogenation. / Amer. Chem. Soc. 100, 264-267. 

Mas 1978 Masuda, T. and Stille, J.K., Transition Metal Catalyzed Asymmetric Organic Syntheses via Polymer-Attached Optically Active Phosphine Ligands. Synthesis of R Amino Acids by Hydrogenation with a Polymer Catalyst Containing Optically Active Alcohol Sites, J. Am. Chem. Soc., 100 (1978) 268-272. 

The benzoic acid derivative 457 is formed by the carbonylation of iodoben-zene in aqueous DMF (1 1) without using a phosphine ligand at room temperature and 1 atm[311]. As optimum conditions for the technical synthesis of the anthranilic acid derivative 458, it has been found that A-acetyl protection, which has a chelating effect, is important[312]. Phase-transfer catalysis is combined with the Pd-catalyzed carbonylation of halides[3l3]. Carbonylation of 1,1-dibromoalkenes in the presence of a phase-transfer catalyst gives the gem-inal dicarboxylic acid 459. Use of a polar solvent is important[314]. Interestingly, addition of trimethylsilyl chloride (2 equiv.) increased yield of the lactone 460 remarkabiy[3l5]. Formate esters as a CO source and NaOR are used for the carbonylation of aryl iodides under a nitrogen atmosphere without using CO[316]. Chlorobenzene coordinated by Cr(CO)j is carbonylated with ethyl formate[3l7]. 

The coupling of the enol triflate 703 with the vinylstannane 704[397] has been applied to the synthesis of glycinoeclepin[576]. The introduction of a (Z)-propenyl group in the / -lactam derivative 705 proceeds by use of tri-2-furylphosphine[577]. However, later a smooth reaction to give the propenyl-iactam in 82% yield was achieved simply by treating with Pd(OAc)2 in NMP or CH2CI2 for 3-5 min without addition of LiCI and the phosphine ligand[578]. 

Borane complexes of P-heterocycles as versatile precursors for the synthesis of chiral phosphine ligands used for asymmetric catalysis 98S1391. 

Synthesis of novel optically active cyclic phosphine ligands and their use in catalytic asymmetric reactions 98YGK511. 

Other sources of Ru(0) can also be used for this synthesis. For example, it was recently demonstrated that [Ru(arene)(diene)] complexes such as 39 undergo double oxidative addition of heterosubstituted dihalo compounds 40 in the presence of phosphine ligands (Eq. 5) [21]. 

Coordination-catalyzed ethylene oligomerization into n-a-olefins. The synthesis of homologous, even-numbered, linear a-olefins can also be performed by oligomerization of ethylene with the aid of homogeneous transition metal complex catalysts [26]. Such a soluble complex catalyst is formed by reaction of, say, a zero-valent nickel compound with a tertiary phosphine ligand. A typical Ni catalyst for the ethylene oligomerization is manufactured from cyclo-octadienyl nickel(O) and diphenylphosphinoacetic ester ... 

A number of excellent reports which deal with synthesis of optically active phosphine ligands are available to date, and have been referenced in this chapter. Therefore it is not the intention here to overlap with them, but rather to describe recent advances in the field. Thus, this chapter is intended to serve as a review to the preparation of some efficient P-chirogenic compounds which have been developed over the past ten years, by either resolution or asymmetric synthesis. Considerable progress has been made in the preparation and use of P-stereogenic compounds. Use of newer methods is stressed here however an at-... 

Thereafter, however, P-chirogenic phosphine ligands were the subject of less investigation since the synthesis of highly enantiomerically enriched P-stereo-genic phosphines often proves difficult. Another reluctance Hes in the fact that this class of phosphines, especially diaryl- and triarylphosphines, is conforma-tionally unstable and gradually racemize at high temperature [57,58]. In contrast, optically active trialkylphosphines are known to be optically stable even at considerably elevated temperature. 

Scheme 19. Example of synthesis of a structurally rigid phosphine ligand...

Crego-Calama M, Reinhoudt DN, ten Cate MGJ (2005) Templation in Noncovalent Synthesis of Hydrogen-Bonded Rosettes. 249 in press Crepy KVL, Imamoto T (2003) New P-Chirogenic Phosphine Ligands and Their Use in Catalytic Asymmetric Reactions. 229 1-40 Cristau H-J, see Taillefer M (2003) 229 41-73... 

It was shown that planar-chiral cyclopentadienyl-phosphine ligands were excellent chirality inducers during the synthesis of chiral-at-metal tetrahedral Ru-phosphine or -phosphite complexes (99% de). 

Table 3.12 surveys current industrial applications of enantioselective homogeneous catalysis in fine chemicals production. Most chiral catalyst in Table 3.12 have chiral phosphine ligands (see Fig. 3.54). The DIP AMP ligand, which is used in the production of L-Dopa, one of the first chiral syntheses, possesses phosphorus chirality, (see also Section 4.5.8.1) A number of commercial processes use the BINAP ligand, which has axial chirality. The PNNP ligand, on the other hand, has its chirality centred on the a-phenethyl groups two atoms removed from the phosphorus atoms, which bind to the rhodium ion. Nevertheless, good enantio.selectivity is obtained with this catalyst in the synthesis of L-phenylalanine. 

Tocopherol can be produced as the pure 2R,4 R,8 R stereoisomer from natural vegetable oils. This is the most biologically active of the stereoisomers. The correct side-chain stereochemistry can be obtained using a process that involves two successive enantioselective hydrogenations.28 The optimum catalyst contains a 6, 6 -dimethoxybiphenyl phosphine ligand. This reaction has not yet been applied to the enantioselective synthesis of a-tocopherol because the cyclization step with the phenol is not enantiospecific. 

Phosphine ligands based on the ferrocene backbone are very efficient in many palladium-catalyzed reactions, e.g., cross-coupling reactions,248 Heck reaction,249 amination reaction,250 and enantioselective synthesis.251 A particularly interesting example of an unusual coordination mode of the l,l -bis(diphenylphosphino)ferrocene (dppf) ligand has been reported. Dicationic palladium(II) complexes, such as [(dppf)Pd(PPh3)]2+[BF4 ]2, were shown to contain a palladium-iron bond.252,253 Palladium-iron bonds occur also in monocationic methyl and acylpalladium(II) complexes.254 A palladium-iron interaction is favored by bulky alkyl substituents on phosphorus and a lower electron density at palladium. 

The synthesis, characterization, and the relative thermodynamic hydricities of hydridoplatinum(II) species-containing bidentate phosphine ligands [PtHL2]+ (L2 = dppe, depe, dmpe, l,3-bis(dimethylphosphino)propane [dmpp]) have been determined, with the best hydride donor found to be [PtH(dmpe)2]+.365... 

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