Reduction with Raney nickel

With polyhalogen derivatives the amount of the potassium hydroxide must be equivalent to the number of halogens to be replaced by hydrogen. 

DESULFURIZATION WITH RANEY NICKEL Preparation of Aldehydes from Thiol Esters [1101] 

A solution of 10 g (0.06 mol) of ethyl thiolbenzoate in 200 ml of 70% ethanol is refluxed for 6 hours with 50 g of Raney nickel. After the removal of the catalyst the filtrate is distilled and the aldehyde is isolated from the distillate by treatment with a saturated (40%) solution of sodium bisulfite. The yield of benzaldehyde-sodium bisulfite addition complex is 8.0 g (62%). 

For desulfurization of compounds containing reducible functions the Raney nickel (20 g) is deactivated prior to the desulfurization by stirring and refluxing with 60 ml of acetone for 2 hours. This removes the hydrogen which is adsorbed in Raney nickel. 

To a stirred suspension of 1.24 g (5 mmol) of powdered nickel acetate in 50 ml of 95% ethanol in a 250 ml flask is added 5 ml of 1 m solution of sodium borohydride in 95% ethanol at room temperature. Stirring is continued until the evolution of gas has ceased, usually within 30 minutes. The flask with the colloidal material is used directly in the hydrogenation. 

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From 13.1 g of N-pmethanol-ethyl acetate at normal pressure and at about 40°C with combination of the theoretical quantity of hydrogen, 12.2 g are obtained of o-emino-N-pfrom aqueous methanol hasaMPof90°C. 

Partial reduction of the acetylenes 1 over 10 % palladium on barium sulfate yields the ra-alkenes 2 which ring close spontaneously to the 3//-2-benzazepines 3.78 Reduction with Raney nickel is less successful and produces mixtures of the 3-benzazepines and their 4,5-dihydro derivatives. 

It is interesting to note that some 1,5-benzodiazepines such as 29 also possess CNS depressant activity. Treatment of substituted diphenylamine 26 with methyl malonyl chloride and reduction with Raney nickel led to orthophenylenediamine analogue 27. Sodium alkoxide treatment led to lactam formation (28), and alkylation in the usual way with NaH and methyl iodide produced clobazam (29). °... 

R. Schroter, Reductions with Raney nickel catalysts, in Newer Methods of Preparative Organic Chemistry, Interscience Publishers Inc., New York, 1965, pp. 61-101. 

On the other hand, reduction with Raney nickel led to a 1 1 mixture of diols. Since one of them was identical to the diol obtained before, the second diol should be the corresponding isomer in which the angular methyl and the hydroxyl group are ds (3a, X = OH). 

Moderate to good enantioselectivities were obtained for nearly all examples, but the products from 83a-c could be recrystallized to higher enantiomeric purity. Addition of iodine was critical for catalysis as was the use of a ligand with electron-poor para-fluorophenyl groups on the phosphorous atom. Substitution at the 3 position of the pyridine ring was described as being difficult for both the quinolines and pyridine systems. The resulting hydrazine derivatives could be easily converted to piperdines by reduction with Raney nickel or under Birch conditions. 

Cyclododecene may be prepared from 1,5,9-cyclododecatriene by the catalytic reduction with Raney nickel and hydrogen diluted with nitrogen, with nickel sulfide on alumina, with cobalt, iron, or nickel in the presence of thiophene, with palladium on charcoal, with palladimn chloride in the presence of water, with palladium on barium sulfate, with cobalt acetate in the presence of cobalt carbonyl, and with cobalt carbonyl and tri- -butyl phosphine. It may also be obtained from the triene by reduction with lithium and ethylamine, by disproportionation, - by epoxidation followed by isomerization to a ketone and WoliT-Kishner reduction, and from cyclododecanone by the reaction of its hydrazone with sodium hydride. ... 

Cyanoanthracene, 50,55 p-Cyanobenzenesulfonamide, reduction with Raney nickel alloy to p-for-mylbenzenesulfonamide, 51,20 p-Cyano-N,N-diethylaniline, 50, S4 Cyanohydrins, formation by use of alkyl-aluminum cyanides, 52, 96... 

Cyanoanthracene, 50, 55 p-Cyanobenzenesulfonamide, reduction with Raney nickel alloy to p-formylbenzenesulfonamide, 51, 20... 

The P-cyanodiester 4 was prepared by condensation of isovaleraldehyde with diethyl malonate followed by the addihon of potassium cyanide. The cyanodiester 4 was hydrolyzed and decarboxylated to give the P-cyano acid 5. Reduction with Raney nickel gave racemic pregabalin (6), which was resolved with (S)-mandelic acid. The diastereomeric salt was split with wet TH F under neutral conditions to give pregabalin, which was recrystallized from isopropanol (IPA) to give the final Active Pharmaceutical Ingredient (API). 

Aliphatic nitro compounds are reduced to various products, in all the published examples, only C-F bonds at a-positions are reduced, while the nitro group can be reduced in two steps. Catalytic hydrogenation of primary nitro compounds over palladium transforms them to the corresponding isonitroso compounds, i. e. oximes, while secondary nitro groups are converted into amines (Table 4). The reduction with Raney nickel alloy converts all types of nitro compounds into the corresponding amines, e. g. formation of 14.136... 

Desulfuration.2 Vinyl sulfides arc reduced to the corresponding alkene by isopropylmagnesium bromide in the presence ol [(C6H5)3P]2NiCl2. No overreduction in observed, as frequently noted in reductions with Raney nickel. 

The manno thioglycoside 55 on treatment with DAST give the 2-deoxy-2-phenyl-thio-glucosyl fluoride as anomeric mixture 56. On glycosylation with the 6-hydroxy-glucoside 57 in dichloromethane and the presence of SnCl2, the ot,l- 6 disaccharide 58 is obtained exclusively (92%), which on reduction with Raney-Nickel yields the 2 -deoxy derivative 59. 

Isocolchicine (33) (only ring C is shown in Fig. 12), when reacted with sodium methane thiolate in aqueous methanol, was reported to give two reaction products, with the isothiocolchicine structure 34 assigned to the minor one (55). It has been shown on the basis of a detailed H-NMR analysis that the major reaction product is the pseudothiocolchicine (35) (56). Addition of the methyl sulfide occurred on either side of the carbonyl group. Both compounds, 34 and 35 shown in Fig. 12, afforded on reduction with Raney nickel the same isocolchicide (36). 

Application of this reaction to 2, 2-anhydrouridine (LXXXVII) led to a 3-substituted nucleoside (CIV) which, upon acylation followed by reduction with Raney nickel, yielded 3-deoxyuridine (CV, R = uracilyl). Reductive cleavage of CV, by the sodium-liquid ammonia procedure,72 afforded 3-deoxy-D-en/fAro-pentose ( 3-deoxy-D-ribose ), a result which establishes position 3 as the site originally containing the ethylthio function. The authors suggest,248 as a plausible route to CIV, the initial formation of the anion CII, followed by formation of the 2,3-anhydride structure. The anhydride (CIII) is then attacked, at C3, by the ethanethiol ion, to yield... 

Methyl-D-fucose has been prepared by two methods.68 In the first, methyl a-D-galactopyranoside was converted into the 6-tosyl derivative, from which by condensation with acetone methyl 3,4-isopropylidene-6-tosyl-a-D-galactopyranoside (LXIV) was obtained. Methylation gave the corresponding 2-methyl ether which was converted into the 6-deoxy iodide (LXV) by heating with sodium iodide in acetone solution at 140°. Reduction with Raney nickel gave sirupy methyl 2-methyl-3,4-isopro-pylidene-a-D-fucopyranoside (LXVI) from which 2-methyl-D-fucose was obtained on hydrolysis. 

N-Nitrosoamines are highly versatile substrates for a-lithiation, because while the N=0 group has activating and coordinating properties similar to the carbonyl group, it lacks the carbonyl group s electrophilicity. The nitroso group will direct lithiation even to a tertiary position (90 -> 91), and can be removed by reduction with Raney nickel.60 The drawback is the toxicity of N-nitrosoamines. 

Finally, this interconversion may also be done by photoassisted reaction with amide ion194,195 or by reaction with hydrazine followed by reduction with Raney nickel in water160,172. The reaction with amide ion may proceed via an aryne mechanism and thus cme-substitution may result this may be used to synthetic advantage (equation 23)196. 

The thiadiazole ring was employed as a diamine protecting group in a synthesis which led to the unambiguous formation of the 9-substituted adenine arprinocid (24) (78JOC960). The thiadiazole (23) readily underwent amine replacement, formylation, and reduction with Raney nickel to produce (24 Scheme 5). 

Blout and Silverman (57) have reported a good example of selective reduction with Raney nickel. It was found that Raney nickel effectively catalyzes the hydrogenation of aromatic nitro compounds in... 

Catalytic Reductions with Raney Nickel in the Presence of Various Types of Hydrogen... 

Also purine-fused diazocine 25a, deazapurine-fused diazocine 25b, and azapurine-fused diazocine 25c underwent several of the above reactions. Thus, 25a-c underwent deisopropylidenation in acid medium to give the corresponding dihydroxy derivative 26a-c. Treatment of 25a and 25b with Lawesson s reagent produced the thio derivatives 27a and 27b. The thio derivative 27a, upon reduction with Raney nickel, afforded 28, while 27b reacted with ammonia to give the amino derivative 29. Diazocine 25a could be alkylated to give the corresponding alkyl derivatives 30 (Scheme 3) <2004W0013300>. 

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