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Raney nickel carbonyl compounds

The zwitterion (6) can react with protic solvents to produce a variety of products. Reaction with water yields a transient hydroperoxy alcohol (10) that can dehydrate to a carboxyUc acid or spHt out H2O2 to form a carbonyl compound (aldehyde or ketone, R2CO). In alcohoHc media, the product is an isolable hydroperoxy ether (11) that can be hydrolyzed or reduced (with (CH O) or (CH2)2S) to a carbonyl compound. Reductive amination of (11) over Raney nickel produces amides and amines (64). Reaction of the zwitterion with a carboxyUc acid to form a hydroperoxy ester (12) is commercially important because it can be oxidized to other acids, RCOOH and R COOH. Reaction of zwitterion with HCN produces a-hydroxy nitriles that can be hydrolyzed to a-hydroxy carboxyUc acids. Carboxylates are obtained with H2O2/OH (65). The zwitterion can be reduced during the course of the reaction by tetracyanoethylene to produce its epoxide (66). [Pg.494]

Thiazoles are desulfurized by Raney nickel, a reaction probably initiated by coordination of the sulfur at Ni. The products are generally anions and carbonyl compounds (see Section 4.02.1.8.4). [Pg.61]

Two techniques, electrochemical reduction (section IIl-C) and Clem-mensen reduction (section ITI-D), have previously been recommended for the direct reduction of isolated ketones to hydrocarbons. Since the applicability of these methods is limited to compounds which can withstand strongly acidic reaction conditions or to cases where isotope scrambling is not a problem, it is desirable to provide milder alternative procedures. Two of the methods discussed in this section, desulfurization of mercaptal derivatives with deuterated Raney nickel (section IV-A) and metal deuteride reduction of tosylhydrazone derivatives (section IV-B), permit the replacement of a carbonyl oxygen by deuterium under neutral or alkaline conditions. [Pg.171]

Ruthenium is excellent for hydrogenation of aliphatic carbonyl compounds (92), and it, as well as nickel, is used industrially for conversion of glucose to sorbitol (14,15,29,75,100). Nickel usually requires vigorous conditions unless large amounts of catalyst are used (11,20,27,37,60), or the catalyst is very active, such as W-6 Raney nickel (6). Copper chromite is always used at elevated temperatures and pressures and may be useful if aromatic-ring saturation is to be avoided. Rhodium has given excellent results under mild conditions when other catalysts have failed (4,5,66). It is useful in reduction of aliphatic carbonyls in molecules susceptible to hydrogenolysis. [Pg.67]

In order to synthesize quinolizidine compounds, some authors have used the Parsons method (Bu3SnH/AIBN) to cleave the iV-tosyl group of 2-piperidones such as 144 (AIBN = 2,2 -azobisisobutyronitrile). After detosylation to 145, the intramolecular cyclization of the lactam promoted by sodium hydride gave quinolizidinone 146. T reatment of this compound with Raney nickel both cleaved the C-S bond and reduced the C=C bond to give quinazolinone 147, while the lactam carbonyl was reduced with LiAlH4 to give 148 (Scheme 23) <2005TL8551>. [Pg.25]

Consequently, by choosing proper conditions, especially the ratios of the carbonyl compound to the amino compound, very good yields of the desired amines can be obtained [322, 953]. In catalytic hydrogenations alkylation of amines was also achieved by alcohols under the conditions when they may be dehydrogenated to the carbonyl compounds [803]. The reaction of aldehydes and ketones with ammonia and amines in the presence of hydrogen is carried out on catalysts platinum oxide [957], nickel [803, 958] or Raney nickel [956, 959,960]. Yields range from low (23-35%) to very high (93%). An alternative route is the use of complex borohydrides sodium borohydride [954], lithium cyanoborohydride [955] and sodium cyanoborohydride [103] in aqueous-alcoholic solutions of pH 5-8. [Pg.135]

Nitro compounds in presence of carbonyl group are selectively reduced to amines in the presence of Raney nickel catalyst. Hydrazine reduces nitrdes yielding hydrazones. Under controlled reaction conditions other functional groups, including nitroso and oxime, may be reduced. Many partially hydrogenated derivatives, such as azo-, hydrazo-, and azoxy compounds may be obtained by partial reduction with hydrazine. Reaction with chlorobenzene yields benzene. [Pg.347]

The diphenyl derivative 388, R = R = Ph, has an absorption band at 1495 cm S which has been assigned to the carbonyl group. This assignment could be questioned. The following chemical reactions of the compound 388, R = R = Ph, may be noted (a) Raney nickel desulfurization followed by oxidation with manganese dioxide yields dibenzyl ketone,(b) hydrazine yields 3,5-diphenyl-4-hydroxypyrazole (390), (c) phenylhydrazine yields PhCH2COCPh=NNHPh," (d)... [Pg.80]

Scheme 1.64). The Ag(I)-mediated cyclization afforded dipole 306 for 1,3-dipolar cycloaddition with methyl vinyl ketone to yield adducts 307 and the C(2) epimer as a 1 1 mixture (48%). Hydrogenolytic N—O cleavage and simultaneous intramolecular reductive amination of the pendant ketone of the former dipolarophile afforded a mixture of alcohol 308 and the C(6) epimer. Oxidation to a single ketone was followed by carbonyl removal by conversion to the dithiolane and desulfurization with Raney nickel to afford the target compound 305 (299). By this methodology, a seven-membered nitrone (309) was prepared for a dipolar cycloaddition reaction with Al-methyl maleimide or styrene (301). [Pg.54]

An excellent review of the problems of the enantioselective heterocatalytic hydrogenation of prochiral double bonds, covering the literature up to 1970, has been compiled by Izumi57). Raney nickel catalysts modified with chiral amino acids or dipeptides gave only very moderate enantiomeric excesses of between 0 and 10% in the hydrogenation of olefins, carbonyl compounds or oximes 57). Only Raney nickel modified with (S)-tyrosine furnished a higher enantiomeric excess in the products58). [Pg.174]

Redaction of aryl carbonyl compounds.2 This reduction has been conducted traditionally by the Clemmenson or Wolff-Kishner method or by reduction of dithioketals. Actually it can be conducted in high yield with W-7 Raney nickel in 50% aqueous ethanol (2-5 hours). Nitro, halo, and cyano groups are also reduced. Examples ... [Pg.339]

Many other uses of a-sulfinyl carbanions are found in the literature, and in the recent past the trend has been to take advantage of the chirality of the sulfoxide group in asymmetric synthesis. Various ways of preparation of enantiopure sulfoxides have been devised (see Section 2.6.2) the carbanions derived from these compounds were added to carbonyl compounds, nitriles, imines or Michael acceptors to yield, ultimately, with high e.e. values, optically active alcohols, amines, ethers, epoxides, lactones, after elimination at an appropriate stage of the sulfoxide group. Such an elimination could be achieved by pyrolysis, Raney nickel or nickel boride desulfurization, reduction, or displacement of the C-S bond, as in the lactone synthesis reported by Casey [388]. [Pg.176]

When the carbonyl compound is sensitive to both acids and bases, or for other reasons gives poor yields in both the Clemmensen and Wolff-Kishner reductions, a recourse may be reduction of the corresponding thioacetal or thioketal with hydrogen-saturated Raney nickel (Section 11-2B) ... [Pg.712]

The reduction is usually effected catalytically in ethanol solution using hydrogen under pressure in the presence of Raney nickel. As in the reduction of nitriles (Section 5.16.1, p. 771), which also involves the intermediate imine, ammonia or the amines should be present in considerable excess to minimise the occurrence of undesirable side reactions leading to the formation of secondary and tertiary amines. These arise from the further reaction of the carbonyl compound with the initially formed amine product. Selected experimental conditions for these reductive alkylation procedures have been well reviewed.210 Sodium borohydride has also been used as an in situ reducing agent and is particularly effective with mixtures of primary amines and aliphatic aldehydes and ketones.211... [Pg.777]

Secondary amines can be prepared from the primary amine and carbonyl compounds by way of the reduction of the derived Schiff bases, with or without the isolation of these intermediates. This procedure represents one aspect of the general method of reductive alkylation discussed in Section 5.16.3, p. 776. With aromatic primary amines and aromatic aldehydes the Schiff bases are usually readily isolable in the crystalline state and can then be subsequently subjected to a suitable reduction procedure, often by hydrogenation over a Raney nickel catalyst at moderate temperatures and pressures. A convenient procedure, which is illustrated in Expt 6.58, uses sodium borohydride in methanol, a reagent which owing to its selective reducing properties (Section 5.4.1, p. 519) does not affect other reducible functional groups (particularly the nitro group) which may be present in the Schiff base contrast the use of sodium borohydride in the presence of palladium-on-carbon, p. 894. [Pg.902]

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). [Pg.148]

The N—O bond of isoxazolines can easily be cleaved via reduction. It is for this reason that isoxazolines are interesting synthetic intermediates. y-Amino alcohols are formed by reduction with LiAlH4 (for an example, see Figure 15.46, left). Hydrogenolysis of isoxazolines catalyzed by Raney nickel yields /j-hydroxy imines, which undergo hydrolysis to / -hydroxy-carbonyl compounds in the presence of boric acid (Figure 15.46, right). [Pg.682]

Catalytic hydrogenation of the ketone (160) in the presence of Raney nickel resulted in reduction of the carbonyl function affording the alcohol (161) (57%) <88CPB168>. Treatment of the same ketone (160) with potassium hydroxide in aqueous ethanol at reflux opened the oxazole ring and gave compound (162) (63%) (Scheme 11). [Pg.301]


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See also in sourсe #XX -- [ Pg.320 ]

See also in sourсe #XX -- [ Pg.8 , Pg.320 ]

See also in sourсe #XX -- [ Pg.8 , Pg.320 ]




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