Nickel complexes ester

CgH, N, Benzenamine, lV,lV-dimethyl-, chromium complex, 28 139 CgHyO P, Phosphonous acid, phenyl-, dimethyl ester, nickel complex 28 101 CgH,P, Phosphine, dimethylphenyl-, iron complex 26 61,28 171 molybdenum complex, 27 11 osmium complex 27 27 osmium-rhodium complex 27 29 osmium-zirconium complex, 27 27 ruthenium complex 26 273,278,28 223, 224,228... 

PCgH,, Phosphonous acid, phenyl-, dimethyl ester, nickel complex, 28 101 OjPCijH, , Phosphinic acid, diphenyl-, tin complex, 29 25... 

A proline derived chiral nickel complex 1 may be used instead of oe,/J-unsaturated esters of lactones modified with a chiral alcohol as the Michael acceptor. The a,(9-unsaturated acid moiety in 1 reacts with various enolates to afford complexes 2 with diastereomcric ratios of 85 15 to 95 5. Hydrolysis of the imine moiety yields the optically active /(-substituted r-alanines. A typical example is shown296. 

A related stereoselective route to glutamic acid derivatives consists of the addition of the nickel complex 5 to various activated olefins, i.e., 2-propenonitrile, 2-propenal and a,/ -unsaturated esters. 

Salmonella typhimurium, 6,582 esters, nickel(II) complexes hydrolysis, 6, 424... 

Baker has also reported the reaction of butadiene with phenylhydra-zones leading to azoalkenes (example 14, Table IV). This is also a Grig-nard-type reaction which is catalytic. Analogous results were obtained with methylhydrazones (136). A wider scope was recently attained by causing allylic esters to react with phenylhydrazones in the presence of zero-valent nickel complexes having trialkyl phosphites (example 15, Table IV). 

P.Y.153 is a nickel complex which was introduced to the market in the late 1960s. It produces slightly dull reddish shades of yellow. Although not fast to acids, the pigment may safely be exposed to alkali. It is fast to mineral spirits and alcohols, but only moderately so to aromatic solvents, such as xylene, and to esters, such as ethyl acetate. 

C4H602, 2-Propenoic acid, methyl ester platinum complex, 26 138 C4H7NO, 3-Butenamide nickel complex, 26 206 C4HsO, Furan, tetrahydro-iron complex, 26 232 magnesium complex, 26 147 neodymium and samarium complexes, 26 20... 

Thioethers (sulfides) can be prepared by treatment of alkyl halides with salts of thiols (thiolate ions).7S2 R may be alkyl or aryl. As in 0-35, RX cannot be a tertiary halide, and sulfuric and sulfonic esters can be used instead of halides. As in the Williamson reaction (0-12), yields are improved by phase-transfer catalysis.753 Instead of RS ions, thiols themselves can be used, if the reaction is run in benzene in the presence of DBU (p. 1023).754 Neopentyl bromide was converted to Me3CCH2SPh in good yield by treatment with PhS in liquid NH3 at -33°C under the influence of light.755 This probably takes place by an SrnI mechanism (see p. 648). Vinylic sulfides can be prepared by treating vinylic bromides with PhS in the presence of a nickel complex,756 and with R3SnPh in the presence of Pd(PPh3)4.757 R can be tertiary if an alcohol is the substrate, e.g,758... 

More numerous by far are the nickel complexes with organophosphorus oxoanions such as phosphate and phosphite esters (R0)2P02 and (RO)2PO , phosphonates (RO)R P02, phosphinates R2P02 and phosphinites R2PO-.1707... 

Aryl halides may also be electrochemically coupled with a-halo esters, when catalyzed by nickel complexes (equation 146)833,834. 

Although in most instances CO2 is an inert solvent, it is also the ideal mediiun in which to carry out reactions of CO2 itself. 3-Hexyne in SC CO2 has been shown to react in the presence of Ni(COD)2PPh2(CH2)4PPh2 (COD = cyclooctadiene) to afford the cyclic ester shown (Scheme 1) with the nickel complex acting as a template [51]. The hydrogenation of CO2 catalysed by a ruthenium complex and NEta can be advantageously carried out in SC CO2, where the high concentration of H2 makes enhanced activity possible [52]. 

Bailar and co-workers have used several complexes as catalysts for reduction of linolenic ester to linoleic or oleic ester without any reduction to the saturated stearic ester. A considerable portion of this work was carried out using a mixed catalyst consisting of tin(II) chloride and a platinum(II) complex. However, catalytic work has also been carried out using palladium and nickel complexes, the former again being used along with tin(II) chloride J91). The experimental details have been recently reviewed (f90) so that this article is concerned with the conclusions and mechanistic aspects rather than with the direct results. 

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