Diamine nickel catalyst

Scheme 2.3 Conjugate addition of malonates to nitroalkenes with a preformed diamine nickel catalyst.

Scheme 2.7 Conjugate addition of malonates to nitroalkenes with a preformed l,l -bi(tetrahydroisoquinoline)-type diamine nickel catalyst, and an in situ generated nickel catalyst from a biisoindoline ligand.

Chiral p-alkynyl acids constitute an important class of pharmaceutical compounds with diverse biological activities however, their asymmetric synthesis remains a significant challenge. In this context, Peng and Shao have reported the first metal-catalysed asymmetric conjugate addition of malonates to nitroenynes promoted by a simple chiral nickel catalyst, which allowed a novel route to this type of chiral product. As shown in Scheme 2.11 the 1,4-conjugate addition of malonates to nitroenynes catalysed by 2 mol% of preformed diamine nickel catalyst afforded the corre-... 

Scheme 2.12 1,4-Conjugate addition of fert-butyl malonate to a nitrodienyne with an in situ generated diamine nickel catalyst for the synthesis of (+)-lycorine and (+)-lycorane.

Scheme 2.40 Domino Michael/Henry reaction of 1,2-diones with nitroalkenes catalysed by an in situ generated diamine nickel catalyst.

Reduction. Hydrogenation of dimethyl adipate over Raney-promoted copper chromite at 200°C and 10 MPa produces 1,6-hexanediol [629-11-8], an important chemical intermediate (32). Promoted cobalt catalysts (33) and nickel catalysts (34) are examples of other patented processes for this reaction. An eadier process, which is no longer in use, for the manufacture of the 1,6-hexanediamine from adipic acid involved hydrogenation of the acid (as its ester) to the diol, followed by ammonolysis to the diamine (35). 

Kanbara has since generated a family of poly(iminoarene)s by reaction of 1,3-dibromo-benzene, 4,4-dibromodiphenyl ether, 2,6- and 3,5-dibromopyridines, 2,4-dibromothiophene, and l,l -dibromoferrocene with a variety of bifunctional arylamines [229]. In many cases, no polymer was obtained, but for polymerizations involving dibromobenzene and 2,6-dibromopyridine, materials with JVfn values of over 10,000 were obtained. Spectral data were provided for poly(2,6-aminopyridine) and a polymer made from dibromobenzene and a dia-rylamino sulfone. These authors have also investigated nickel catalysts for the polymerization of diamines with dichloroarenes, but the materials generated had molecular weights below 10,000 in most cases [230]. 

Vinylogous Mukaiyama-Michael additions of 2-trimethylsilyloxyfuran to 3-alkenoyl-2-oxazolidinones to provide 7-butenolides were shown to be /7-selective. The reaction could be rendered enantioselective in the presence of a (T symmetric copper-bisoxazoline complex <1997T17015, 1997SL568> or a l,T-binaphthyl-2,2 -diamine-nickel(ii) complex as catalyst, as depicted in Equation (16) <2004CC1414>. 

The hydrogenation reaction takes place in the presence of a Raney nickel catalyst at 120-150°C (250-300°F) and 5000 psig. Nylon properties are sensitive to impurities in the feedstock so the reaction and purification steps for both adiponitrile and hexamethylene diamine are carried out to minimize by-products and impurities in the HMDA product. The hydrogenation of adiponitrile is carried out in a large quantity of ammonia which prevents the formation of hexamethyleneimine by-product. Ammonia also acts as a heat transfer fluid and helps maintain the reaction temperature. The conversion of adiponitrile is nearly 100% and the selectivity to HMDA is 97% giving an overall yield of HMDA from adiponitrile of 96.7%. 

The commercial processes for the manufacture of hexamethylene diamine entail hydrogenation of adiponitrile. It is a continuous liquid-phase process [170] that is usually conducted at 75°C and 3 MPa pressure in the presence of a chromium-containing Raney-nickel catalyst and aqueous sodium hydroxide ... 

Palladium is a relatively high-priced catalyst and it would be preferable if a lower-priced nickel catalyst could be used instead. All attempts, however, to form polymers by nickel-catalyzed carbonylation poly condensations of aromatic diamines with aromatic dibromides failed to yield high molecular weight materials. 

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