PHOSPHINE-NICKEL CATALYZED

Phenylurefbanes, 58, 10 Phosgene, 57, 46 Phosphine, diphenyl-, 56,45 Phosphine-mckcl catalyst, 58, 129 PHOSPHINE-NICKEL CATALYZED COMPLEX CROSS-COUPLING OF GRIG-NARD REAGENTS WITH ARYL AND ALKENYL HALIDES, 58, 127 Phosphine, phenyl-, bis(3-dimethylamino-piopyl)-, 55, 128 Phosphine, triphenyl-, 56, 81 Phosphomum, [ 4-(4-rne thoxy phenyl)-2-butenyl) triphenyl, iodide, 56, 81 Phosphomum, 2-octadecenyltnphenyl-, iodide, 56, 81... 

Other dichloro(ditertiary phosphine)nickel(II) complexes (see Table VI) catalyze both hydrosilylation and H/Cl exchange, but analogous complexes containing monodentate phosphine ligands or bidentate amine groups are essentially inactive (173). 

A number of chiral monodentate phosphines have been examined in asymmetric nickel-catalyzed reductive couplings of aldehydes and alkynes. The best results to date have been obtained with (+)-NMDPP (16) [33]. Aromatic internal alkynes and branched aldehydes participate with excellent enantiose-lectivity (Scheme 15), although yields and enantioselectivities were somewhat lower with other combinations of aldehydes and alkynes. In a complemen-... 

Although more hydrolytically sensitive than the phosphine boranes, diorganochlorophosphines can be more accessible than diorganophosphines and are not pyrophoric. Thus, the reaction of a chlorophosphine with an aryl halide or aryl triflate in the presence of zinc as a reducing agent and (DPPE)NiCl2 as catalyst provides a convenient procedure for P—C coupling (Equation (49)).150 A related nickel-catalyzed process driven by electrochemical reduction has also been reported 151... 

The catalyst efficiency of these hydroalumination varies from a turnover number (TON) of 20-91. It is possible that the catalyst is deactivated by the presence of oxygen and water. Examination of the 31P NMR spectrum of the catalyst indicates that the phosphine monoxide and dioxide are formed in the presence of nickel prior to the addition of the substrate. Rigorous exclusion of oxygen and water is necessary in all these reactions. The enantioselective nickel-catalyzed hydroalumination route to dihydronaphthalenols may prove to be particularly important. Only one other method has been reported for the enantioselective syntheses of these compounds microbial oxidation of dihydronaphthalene by Pseudomonas putida UV4 generates the dihydronaphthalenol in 60% yield and >95% ee.1... 

K. Tamao, S. Kodama, I. Nakajima, M. Kumada, A. Minato, and K. Suzuki, Nickel-phosphine complex-catalyzed Grignard coupling — II Grignard coupling of heterocyclic compounds, Tetrahedron, 38 3347-3354, 1982. 

Asymmetric Grignard Cross-Coupling Catalyzed by Chiral Phosphine-Nickel Complexes 73)... 

More recent review Hayashi, T. Asymmetric Grignard Cross-Coupling Catalyzed by Chiral Phosphine-Nickel and Phosphine-Palladium Complexes, in Asymmetric Reactions and Processes in Chemistry (Eliel, E. L., Otsuka, S. ed.), American Chemical Soc. Symp. Series Vol. 185, p. 177 (1982)... 

Similarly, decreasing the electron density on the metal will enhance its willingness to undergo reductive elimination and become more electron rich. A typical demonstration of this tendency is the nickel catalyzed coupling of sp3 hybridized carbon atoms. Here, if a nickel-phosphine catalyst is used, the catalytic cycle is very slow, due to disfavoured reductive elimination. The use of additives that deplete the electron density of the nickel atom through coordination (e.g. fluorostyrenes) leads to a marked increase of the turnover frequency.18... 

An analogous nickel catalyzed coupling was also reported recently, where 3-, and 4-cyanopyridine were coupled with different ethynylzinc derivatives in the presence of a nickel-phosphine catalyst system (7.43.),61 Although this reaction is not a Sonogashira coupling, it constitutes an efficient alternative approach to ethynylpyridines. It is also interesting to... 

PHOSPHINE-NICKEL COMPLEX CATALYZED CROSSCOUPLING OF GRIGNARD REAGENTS WITH ARYL AND ALKENYL HALIDES 1,2-DIBUTYLBENZENE... 

Organometallic reagents and catalysts continue to be of considerable importance, as illustrated in several procedures CAR-BENE GENERATION BY a-ELIMINATION WITH LITHIUM 2,2,6,6-TETRAMETHYLPIPERIDIDE l-ETHOXY-2-p-TOL-YLCYCLOPROPANE CATALYTIC OSMIUM TETROXIDE OXIDATION OF OLEFINS PREPARATION OF cis-1,2-CYCLOHEXANEDIOL COPPER CATALYZED ARYLA-TION OF /3-DICARBONYL COMPOUNDS 2-(l-ACETYL-2-OXOPROPYL)BENZOIC ACID and PHOSPHINE-NICKEL COMPLEX CATALYZED CROSS-COUPLING OF GRIG-NARD REAGENTS WITH ARYL AND ALKENYL HALIDES 1,2-DIBUTYLBENZENE. 

Among the catalysts used are Lewis acids991 and phosphine-nickel complexes.992 Certain of the reverse cyclobutane ring openings can also be catalytically induced (8-40). The role of the catalyst is not certain and may be different in each case. One possibility is that the presence of the catalyst causes a forbidden reaction to become allowed, through coordination of the catalyst to the -it or a bonds of the substrate.993 In such a case the reaction would of course be a concerted 2S + 2S process. However, the available evidence is more consistent with nonconcerted mechanisms involving metal-carbon a-bonded intermediates, at least in most cases.994 For example, such an intermediate was isolated in the dimerization of nor-bornadiene, catalyzed by iridium complexes.995... 

Fontaine and Zargarian reported in 2004 a seminal catalytic study involving an ambiphilic derivative. The dimeric phosphine-alane (Me2PCH2AlMe2)2 2 was used as a bifunctional cocatalyst for the nickel-catalyzed... 

Formation of the DVCB derivatives is complicated by the nickel-catalyzed isomerization of m-piperylene into traw.v-piperylene which proceeds through the formation of the cyclobutane (LIII). The rate of isomerization is dependent on the nature of the ligand attached to the metal, and increases in the series tri(o-phenylphenyl)phosphite < triphenyl-phosphine < tricyclohexylphosphine. In the case of the nickel-tricyclo-hexylphosphine catalyst, the rate of isomerization is faster than the cyclization reaction. 

The reaction achieved considerable attention over the years, and various alterations have been reported. Behr also reported the combination of carbon dioxide, butadiene and ethylene oxide to give the hydroxyester of the acids depicted in Scheme 19. A nickel-catalyzed analogous system using triphenylphosphine or triisopropylphosphite takes a different route as cyclopentanecarboxylic acids are reported as the main product [126]. A palladium catalyst immobilized on a phosphine-decorated polystyrene polymer [127] or on silica also proved to be active [128]. 

There is a substantial body of literature on the palladium- and nickel-catalyzed formation of aryl sulfides, selenides, and phosphines from aromatic and heteroaromatic halides. Progress on these reactions has continued with several recent contributions [47-50]. A review in 1997 covered the types of transformations that can be conducted and the types of catalysts used [51]. Particularly useful examples are the conversions ofbinaphthol to binaphthylphosphines... 

Fig. 12) [91 ]. This phosphine-carbene ligand has been used in the nickel catalyzed hydroamination of acrylonitrile derivatives [92]. 

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