Quinolines nickel catalysts

Table II shows that, at least for the reactions with quinoline and with 4-methylquinoline (lepidine), nickel-alumina and degassed Raney nickel catalysts are of similar efficiency but better yields have been obtained with degassed Raney nickel, and only this catalyst produces the biaryl from 7-methyIquinoIine.

Sufficient data are not yet available to allow evaluation of the relative merits of palladium-on-carbon and degassed Raney nickel catalysts. Comparable yields of 2,2 -biquinolines have been obtained by both methods under suitable conditions but the percentage conversions with degassed Raney nickel have been found to be much lower, reflecting the extent of side reactions with this catalyst. However, work in this laboratory has shown that the reaction of quinoline with palladium-on-carbon is not free from complications for example, at least three products in addition to 2,2 -biquinoline have been detected by paper chromatography. 

In acetylenes containing double bonds the triple bond was selectively reduced by controlled treatment with hydrogen over special catalysts such as palladium deactivated with quinoline [565] or lead acetate [56], or with triethylam-monium formate in the presence of palladium [72]. 1-Ethynylcyclohexene was hydrogenated to 1-vinylcyclohexene over a special nickel catalyst (Nic) in 84% isolated yield [49]. 

When the hydrochloride salt of 2,3,4,4a,5,6-hexahydro-l//-pyridazino [1,6-a]quinoline was subjected to catalytic hydrogenation in ethanol over Pt02, 3-[2-(l,2,3,4-tetrahydroquinolyl)]propylamine was obtained (66YZ608). Catalytic reduction of perhydropyrido[l,2-ft]pyridazine over a skeletal nickel catalyst in ethanol at 30 atm gave ring-opened 2-(3-aminopropyl)piperidine (66KGS91). 

Pyridine is converted by a modified Raney nickel catalyst into 2,2 -bipyridyl, and the reaction has been extended to many substituted pyridines and quinolines. 2-Substituted pyridines give the 6,6 -bipyridyls. 3-Methylpyridine gives 5,5 -dimethyl-2,2 -bipyridyl, but none of the other isomers. 

A mixture of 114.0 g (0.587 m) of N-methyl-4-nitroacetanilide and 800 ml of ethanol was shaken with hydrogen over one teaspoon of Raney active nickel catalyst in water. A pressure drop of 127 psi was recorded (calc. 118 psi). The catalyst was removed by filtration and the ethanol filtrate refluxed overnight with 127.0 g (0.587 m) of the 9-chloro-7-methylimidazo[4,5-f]quinolone. The mixture was chilled, filtered, washed with ether and air-dried to give 75.5 g of 9-[p-(N-methylacetamido)anilino]-7-methyl-l-H-imidazo[4,5-f] quinoline... 

Hydrogenation of an alkyne can be stopped at the alkene stage by using a poisoned (partially deactivated) catalyst made by treating a good catalyst with a compound that makes the catalyst less effective. Lindlar s catalyst is a poisoned palladium catalyst, composed of powdered barium sulfate coated with palladium, poisoned with quinoline. Nickel boride (Ni2B) is a newer alternative to Lindlar s catalyst that is more easily made and often gives better yields. 

Alternative catalysts such as palladium-on-barium sulfate (poisoned by synthetic quinoline) (24), "P-2" nickel boride (with ethylenediamine) (25), and other nickel catalysts (19c) can be used in place of Lindlar catalyst. However, in our hands selective hydrogenation of triple bonds to Z olefins proceeds with the greatest stereoselectivity with Lindlar catalyst. Palladium-on-barium sulfate (in ethanol with quinoline) can give considerable over-reduction and isomerization to the E isomer (22a). Use of "P-2" nickel boride as the catalyst at room temperature usually gives a. 2% of the J5 isomer (e.g. 23). 

In more recent work, pyridine, quinoline, and their derivatives have been dimerized with the aid of specially prepared Raney nickel catalyst.301... 

Palladium and nickel catalysts can also be used to effect arylation of quinoline at the 2-position. Using Pd(OAc)2 and AgN03/02 as an oxidant system results in an oxidative arylation (eq 21). Similarly, using Ni(cod)2 and diarylzinc nucleophiles, it is possible to selectively arylate the 2-position (eq 22). ... 

Several products other than 2,2 -biaryls have been isolated following reaction of pyridines with metal catalysts. From the reaction of a-picoline with nickel-alumina, Willink and Wibaut isolated three dimethylbipyridines in addition to the 6,6 -dimethyl-2,2 -bipyridine but their structures have not been elucidated. From the reaction of quinaldine with palladium-on-carbon, Rapoport and his co-workers " obtained a by-product which they regarded as l,2-di(2-quinolyl)-ethane. From the reactions of pyridines and quinolines with degassed Raney nickel several different types of by-product have been identified. The structures and modes of formation of these compounds are of interest as they lead to a better insight into the processes occurring when pyridines interact with metal catalysts. 

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