Imine phosphine complexes

The regioselective arylation occurs when the reaction of 2-arylpyridines with aryl halides is conducted with the aid of the ruthenium(ii)-phosphine complex as catalyst (Equation (66)).81 The ortho-position to the 2-pyridyl group is arylated predominantly. The aromatic imines are also arylated with the same catalytic system.82... 

This system also worked well in ionic liquids.518 Li etal. found silver-phosphine complexes to promote aldehyde-alkyne coupling in water. When triphenylphosphinesilver chloride was used as a catalyst in water, the only detected product was the aldehyde addition product instead of the adduct derived from imine (Scheme 111).519... 

It has been demonstrated625 that ytterbium-aromatic imine dianion complexes can act as effective catalysts for the isomerization of terminal alkynes to internal alk-2-ynes. Isomerization of acetylenic pentafluorophenyl esters in the presence of phosphines has been found to give rise to activated dienoic acids, which have been coupled directly with amines (and alcohols) in a simple one-pot procedure626 (see Scheme 124). 

Figure 12 Activation of phenoxy-imine nickel complexes by loss of a phosphine or pyridine ligand.

The metal-catalyzed addition reaction of organoboron compounds have not yet been well developed, but die reaction of NaBPh4 or arylboronic acids with enones in the presence of Pd(OAc)2 and NaOAc or SbCL, was recently reported by Uemura and his coworkers.2 The reaction was proposed to proceed through the oxidative addition of the C-B bond to the Pd(0) species however, another probable process, the transmetalation to transition metals, may allow a similar catalytic transformation by the use of organoboronic acids. We report here the 1,4-addition reaction of organoboronic acids to oc, J-unsaturated ketones or esters and 1,2-addition to aldehydes or imines catalyzed by a (acac)Rh(CHj=CH2)2/phosphine complex, which may involve the B-Rh transmetalation as the key step. 

There are some reports on the asymmetric catalytic hydrogenation of C=N double bonds. Rhodium phosphine complexes do not have high activity, and the stereoselectivity is low. - Homogeneous hydrogenation of oximes, Schiff s bases and cyclic imines " have been reported. A cyano cobalt complex has been used for the homogeneous catalytic hydrogenation of oximes and Schiff s bases but the degree of asymmetric induction is unknown. 

Heteroditopic hgands have been also proposed for the copolymerization reaction. The catalytic activity of systems containing one phosphorus ligating moiety is lower fhan fhat of fhe diphosphines. For fhe imine-phosphine-modified catalyst precursor 30 (Scheme 8.8), a low turnover frequency of 6 mol (mol h) [59] has been reported. Complex 30 was also used to investigate olefin and carbon monoxide insertions [60]. 

Some years ago, Malmstrom etal. synthesized water-soluble metal phosphine complexes based on water-soluble polymers [41], In order to have solubility in both an acidic and a basic medium, they prepared two different water-soluble polymers. For the first, they made methyl [4-(diphenylphosphino)benzyl]amine (PNH) react with poly(acrylic acid) (PAA) using dicydocarbodiimide (DCC) as the coupling agent, under strict exclusion of oxygen (25). For the second, they reacted (4-carboxy-phenyl)diphenylphosphine with polyethylene imine (PEI) at room temperature (26). The reduction by sodium borohydride was made in situ, followed by the addition of methanesulfonic add and diethyl ether. Then, the methanesulfonic salt of phosphinated polyethylenimine was predpitated. 

Poly( ethylene imine) with Rh-phosphine complexes =0.84 H2O Hydroformylation of olefins (gas phase and hiphasic solution) Phase separation [144]... 

Pyridylbenzenes are directly ortfio-arylated with tetra-arylstannanes in the presence of a rhodium(I)-phosphine complex as catalyst [140]. A mechanistic pathway was proposed based on the oxidative addition of a rhodium] I) complex to the ortho position of the phenyl ring directed by the pyridine nitrogen, followed by arylation by the tetra-arylstannane. A somewhat related reaction of arylboronic acids was achieved with a [RhCl(C2H4)2]2/P[p-(CF3)QH4]3 catalyst system [141]. In this instance, the 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) radical was used as a stoichiometric oxidant. Arylboronic acids also arylate benzophenone imines in the presence of Rh(I) catalysts [142]. 

Adducts with Nitrogen Heterocycles, Amines, Imines, Phosphines, and Arsines. The addition of nitrogen heterocycles such as 2,2 -bipyridyl or 1,10-phenanthroline to bis[(trimethylsilyl) methyl]zinc leads to the quantitative formation of orange-red to red adducts which show remarkable stability towards oxygen. The complex with iV,iV,iV, Ai -tetramethylethylenediamine is less stable. ... 

The cycloaddition of alkynes and imines catalyzed by Ni-phosphine complexes developed by Ogoshi et al. also affords (dihydro)pyridine product [16]. In an effort to... 

Organogermanium phosphorous derivatives include phosphines, phosphine imines, tris(trimethylgermyl)phosphine complexes with transition metals and mixed organosilicon and organotin phosphides. The compounds listed in Table 71 are prepared by methods from the following scheme. 

The discussion of the activation of bonds containing a group 15 element is continued in chapter five. D.K. Wicht and D.S. Glueck discuss the addition of phosphines, R2P-H, phosphites, (R0)2P(=0)H, and phosphine oxides R2P(=0)H to unsaturated substrates. Although the addition of P-H bonds can be sometimes achieved directly, the transition metal-catalyzed reaction is usually faster and may proceed with a different stereochemistry. As in hydrosilylations, palladium and platinum complexes are frequently employed as catalyst precursors for P-H additions to unsaturated hydrocarbons, but (chiral) lanthanide complexes were used with great success for the (enantioselective) addition to heteropolar double bond systems, such as aldehydes and imines whereby pharmaceutically valuable a-hydroxy or a-amino phosphonates were obtained efficiently. 

Prochiral imines can be hydrogenated to the corresponding amines with extremely high enan-tioselectivities in H20/ethyl ethanoate biphasic systems, using Rh1 complexes of sulfonated phosphines 342 The cationic rhodium complex [Rh(NBD)(131)]+ was an active catalyst for hydrogenation of 2-ethanamido-propenoic acid in aqueous solution.343... 

In asymmetric reactions, chiral phosphine ligands such as BINAP derivatives are used as effective chiral ligands in silver complexes. In particular, an Agr-BINAP complex activates aldehydes and imines effectively and asymmetric allylations,220-222 aldol reactions 223 and Mannich-type reactions224 proceed in high yield with high selectivity (Scheme 51). 

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