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Diene nickel acetylacetonate

Conjugate methylation of A -3-oxo-steroids to give 5/8-methyl-3-ketones can be achieved in moderate yield by the action of either trimethylaluminium-nickel acetylacetonate or lithium dimethylcuprate. Steroidal 4,6-dien-3-ones react with lithium dimethylcuprate to give the 7a- and 7/8-methyl-5-en-3-ones, which may be... [Pg.249]

The complex Ni(7r-l,5-CgHi2)2, presumably a tetrahedral complex of Ni(0), has been obtained as air-sensitive, yellow crystals by ligand displacement from Ni(cyclododecatriene), or by reducing nickel acetylacetonate with alkyl aluminums in the presence of the diene 133). Derivatives such as CgHi2Ni(acac) and CsHi2Ni(PPh3)2 have also been mentioned 134). This work is summarized elsewhere 124). [Pg.375]

Some olefin complexes may conveniently be obtained by electrochemical reduction methods. Cyclooctadiene and cyclododecatriene nickel(O) complexes such as Ni(COD)2 and Ni(CDT) may be prepared by electrochemical reduction of nickel acetylacetonate in the presence of butadiene in acetonitrile, dimethoxymethane, or DMF solutions. Complexes [Fe(CO)4 (alkene)] are reduced electrochemically to lie compounds [Fe(CO)3 (alkene)] . In the case of complexes [Fe(CO)3 (f/Miene)] (diene = BD, cyclohexadiene), during reduction, lie anions [Fe(CO)3 (diene)] are formed in which one olefin bond is decomplexed. ... [Pg.351]

The nickel catalyst is obtained by reduction of a nickel(II) compound such as the acetylacetonate in the presence of butadiene, or simply by exchange of butadiene and bis( -allyl)nickel or bis(cycloocta-l, 5-diene)nickel. In the absence of added ligands, butadiene is rapidly and catalytically converted at low temperatures into 1,5,9-cyclododecatriene, mainly the trans, trans, trans isomer. The trimerization bears the mark of a template process, three butadiene molecules linking very specifically around a naked nickel centre. Detailed studies show that the process is not synchronous but occurs in a stepwise fashion (Fig. 12.5). [Pg.367]

The thermal polymerization of butadiene yields, according to Ziegler et al., a mixture of vinylcyclohexene with at most 15% of cyclooctadiene (95, 96). In 1954 Reed (97) discovered the catalytic cyclodimerization of butadiene to cycloocta-1,5-diene with Reppe catalysts, with a 30-40% conversion at 120-130° C. Wilke et al. recently synthesized a very efficient class of catalyst. If nickel-acetylacetonate is treated with metal alkyls (especially aluminum alkyls) in the presence of electron-donating compounds (mainly cycloolefins), new tt complexes of nickel are obtained which catalyze the cyclo-oligomerization of butadiene (98, 99). Using cycloocta-1,5-diene as the olefinic component, the well-crystallized, faintly yellow bis(cycloocta-... [Pg.38]

Treatment of buca-l,3-diene with titaniumfiv) chloride and diethylaluminium chloride gave a mixture of cis,rrans,rran cyclododeca-l,5,9-triene and all-trons-cyclohexadeca-l,5,9,13-tetraene. The co-dimerization of buta-1,3-diene and iso-prene or trons-1-piperylene by nickel acetylacetonate in the presence of triphenyl-phosphite and perhydro-9b-alumophenalene to give 1- or 3-methylcyclo-octa-1,5-diene, has been studied. Buta-1,3-diene has been cyclo-oligomerized in the presence of a nickel catalyst to give a mixture all-rrans-cyclododeca-l,5,9-triene, all trans-cyclohexadeca-1,5,9,13-tetraene and 11-vinyl-all-trans-cyclotetradeca-1,4,8-triene, in the ratio of 80 15 5, respectively, in 90% combined yield. The catalytic... [Pg.239]

Unsaturated compounds such as monoolefins, dienes and acetylenes readily react with nickel halides or nickel acetylacetonates to afford their Ti-complexes. For example, the reactions shown in eqs. (19.9)-(19.12) give the rr-complexes of an olefin, cyclodiene or cyclotriene [20,23-28]. [Pg.414]

The cyclo-octenyl complex, 1.6a, which is prepared from bis-cyclo-octa 1, S-diene nickel and acetylacetone has a rather similar structure [726] with the ligand forming both a a-, and a n-bond to the metaLf... [Pg.24]

The activity of Ziegler-type systems such as M(acac) -AlEt3 (M = Cr, Mn, Fe, Co, or Ni acac = acetylacetonate) was examined with 1-olefins and triethyl- or triethoxysilanes (55). Systems with nickel or cobalt showed low activity for hydrosilation but isomerized the olefin and were reduced to the metal. The study was extended to dienes and acetylenes (56). Isoprene gave the same products with these catalysts as are made with chloroplatinic acid. Penta-1,3-diene with Pt gave l-methylbut-2-en-ylsilanes. The Ziegler catalysts gave mainly penta-2-enylsilanes... [Pg.430]

An interesting alternative is the synthesis of 3-unsaturated dehy-dropyrones starting from carbon dioxide and 1,3-dienes [45] (Figure 17). The products are formed in yields of about 80 % related to the nickel. By work-up with acetylacetone the nickel can be recovered via the unsoluble complex (bipy)Ni(acac). ... [Pg.74]

The nickel(o)-catalysed oligomerization of butadiene has been further studied. Cyclo-octa-1,5-diene is a major product in hydroxylic solvents, and a minor product in the presence of secondary amines." The oligomerization of butadiene in the presence of nickel(ii)acetylacetonate, triethylamine, alkyl cyanamides, and miscellaneous heterocycles has also been studied, and catalyst systems causing an almost quantitative conversion into trans,trans,trans-, cis,trans,trans-, or cis,cis,trans-cyclododeca-l,5,9-triene were found." The ability of some hydrides, trans-MHX-(PR3)2 (M = Ni or Pd), to act as catalysts for butadiene oligomerization has been found to depend upon the substituent, X, and the solvent the reactions of some cationic palladium hydrides with butadiene was also examined. Unlike other organo-cobalt catalyst systems, CoCUPPhjjj has been found to catalyse the dimerization... [Pg.284]

As mentioned earlier, nickel forms tetrahedral olefin complexes, viz. [Ni(COD)2]. It is obtained by reduction of nickel(II) acetylacetonate by means of trialkylaluminum in the presence of 1,5-cyclooctadiehe. Analogous nickel complexes containing other dienes are also known. [Pg.371]


See other pages where Diene nickel acetylacetonate is mentioned: [Pg.1029]    [Pg.801]    [Pg.1117]    [Pg.40]    [Pg.21]    [Pg.866]    [Pg.485]    [Pg.162]    [Pg.241]   
See also in sourсe #XX -- [ Pg.554 ]




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