Reductions nickel

The Raney nickel reduction of cyanothiazoles leads to the corresponding amino compounds (96). 

Pyrazolopyridines isomeric to those described previously have been obtained by other methods. Thus, the derivative (558) was formed by Raney nickel reduction of the 4-nitrosopyrazole (557) (7UHC1035), and the pyrazolo[3,4-c]pyridine derivative (560) was prepared from the azide (559) (79CC627). 

ANILINES, BENZYL AMINES, AND ANALOGUES An orally active local anesthetic agent that can be used as an (intiarrhythmic agent is meobenti ne (57). Its patented synthesis starts with -hydroxyphenyl nitrile and proceeds by dimethyl sulfate etherification and Raney nickel reduction to Alkylation of -methyl-dimethylthiourea with completes l.he synthesis of meobenti ne (57). ... 

Enzymic syntheses are considered next. Xylitol is a substrate for sheep-liver L-iditol dehydrogenase, a NAD-linked enzyme. 1-Deoxy-D-xylitol, prepared by Raney nickel reduction of D-xylose diethyl dithioacetal in a 27% overall yield from D-xylose, was also reported31 to be a substrate, although with a higher Km and lower Vmax. The product was assumed to be l-deoxy-D-f/ireo-pentulose because of the appearance of a yellowish fluorescent spot when a chromatogram was sprayed with acidic 3,5-aminobenzoic acid, resembling that formed from 1 -deoxyfructose. There was no more-rigorous characterization. 

Raney nickel reduction of 4(5)-nitroimidazole (27 R = H) in a mixture of acetic anhydride and acetic acid gave a diacetylated compound (35%) that was identified as 1- (or 3-) acetyl-4-acetamidoimidazole (57JA2188). 

For a brief review of the use of Raney nickel reductive desulfurization in organic chemistry in general see J. F. W. McOmie, Ann. Repts. on Progress Chem. (Chem. Soc. London), 40, 198 (1948). 

Another method is to proceed after the Raney Nickel reduction like this filter the catalyst off and purify as above. React the product with CH2O and hydrogen or HCO2H to get the 2-Me derivative, which is heated with H3PO4 at 140-150° for 70 hours. Note HCO2H is a strange way to say formic acid. 

Figure 1. Structure of the Isobacterlochlorln obtained by the Raney nickel reduction of nickel (II) methyl mesopyropheophorblde a.

Hoping to improve or to shorten our total synthesis of L-daunosamine, we explored the following reactions with 112 and 113, the adducts of the racemic 7-oxanorbomene derivative 47 + 48 to PhSeCl and PhSCl, respectively. Saponification of 112 and 113, followed by treatment with formalin, afforded ketones 114 and 115, respectively. Treatment of with tributyltin hydride in toluene/benzene (AIBN 1 - 2%, 80 °C) gave the key intermediate ( )-I03 in 69 % yield. Under the same conditions, 115 was reduced to ( )-I03 in 40 - 45 % yield. Raney nickel reduction of 115 afforded ( )-103 in 50 % yield together with 40 % of ( )-7-oxabicyclo[2.2.1]heptan-2-one. However, we found the multistep procedure 32 100 101 102 103 easier to scale up. Several intermediates in our synthesis do not have to be isolated. For instance, transfomation of 32 into 102 can be carried out in the same pot in 94 % yield. 

The second of these hypotheses (more facile reduction of nickel on zeolitic particles) is contradicted by the results of our TPR experiments. In fact, the TPR results on both nickel contaminated zeolitic and non-zeolitic particles suggest that none of the nickel on these materials is reduced under normal MAT testing conditions, since the onset temperature of nickel reduction (1100-1150°F) is considerably higher than the operating temperature of the MAT (910op). 

Scott Denmark of the University of Illinois reports (J. Org. Chem. 68 8015,2003) a hetero intramolecular Diel-Alder reaction of a nitro alkene 5, followed by intramolecular dipolar cycloaddition of the resulting nitronate 6, to give the tricycle 7. Raney nickel reduction effected cleavage of the N-0 bonds and reductive amination of the liberated aldehyde, to give, after acetylation, the angularly substituted cis-decalin 8. 

Deoxy-l,2 5,6-di-0-i sopropy1idene-a-D-ri bo-hexofuranose has been prepared by a variety of other methods, the most widely used of which is the Raney nickel reduction of the 3-S-[(methylthio)carbonyl1-3-thioglucofurunose... 

Table I. Dependence of the Degree of Nickel Reduction to Metal and the Size of Crystallites on the Nature of a Catalyst Support (45)...

Raney nickel reduction of 2-benzyl-5-ethylselenophene (71) yields 1-phenylheptane (72), a conversion analogous to the much used reductive desulfurization of thiophenes (73JGU871). The electrochemical reduction of selenophene-2-carboxylic acid gives a mixture of dimeric products the major product is compound (73). This is in contrast to the 2,5-dihydro derivatives obtained by electrochemical reduction of thiophene and furan carboxylic acids (82CS( 19)95). Wolff-Kishner reduction of 2-selenienyl 2 -thienyl ketone gives, in addition to the expected methylene derivative, 2-(pentenyl)thiophene (72ZOB1780). 

Raney nickel reduction yields a homologous series of bicyclic terpenoid hydrocarbons of basic structure... 

These hydrocarbons are generated from the Raney nickel reduction of the sulfides, and the most abundant member of the sulfides is also the C23 compound. Finally, three deuterium-exchangeable hydrogen atoms were observed for the sulfone derivative of the C23 sulfide, Figure 11. The structure established for the C40 member of the series is ... 

The rest of the cyclic terpenoid sulfides are complex mixtures of partially degraded and isomerized derivatives of the terpenoid sulfides which elute on the capillary GC column as a broad, unresolved hump. On Raney nickel reduction this fraction yields a complex mixture of naphthenic hydrocarbons which cannot be resolved further by GC analysis. 

The sulfide fraction of non-biodegraded petroleums usually contains a complement of n-alkyl substituted sulfides, thiolanes and thianes, in addition to the terpenoid class. In the biodegraded Alberta oil sand bitumens, however, n-alkyl substituted sulfides are absent. The two classes of sulfides can be separated by thiourea adduction, the n-alkyl-containing molecules being adducted. Raney nickel reduction of the Bellshill Lake sulfides (1 11 yielded a series of n-alkanes showing a distribution quite similar to that of the n-alkanes in the saturate fraction of this oil. In some oils the thiolane and thiane concentrations are commensurate, e.g. Houmann, Figure 13 in others, the concentration of thianes may be small compared to thiolanes. 

Ortho-thioquinones are also accessible by this route [238, 239]. They were treated with glycals as dienophiles with success (Table 5, entry 2). These reactions were designed [240] to offer an original glycosyl transfer, by achieving a Diels-Alder reaction with the appropriate a,adioxothione (Table 5, entry 4), and a simple Raney nickel reductive desulfurisation of the cycloadduct. 

Hydroxydec-2-enoic acid 397 was identified in the fodder juice of the Weisel cells (gelee royale) of honey bees. One of the synthesis of 397 starts from suberic acid ethylester 393 222) which was first converted into the hydroxyacid 394 and then into the thiol ester 395. Raney nickel reduction of the latter yields an intermediate aldehyde which, in statu nascendi, reacts with the phosphorane 67 to give 396. Subsequent hydrolysis of396affords the ( )-a,0-unsaturated hydroxy acid 397 222) (Scheme 70). 

Treatment of the 2-pyrrolyl allyl thioether (498) with acetic anhydride and quinoline at 170 °C (or in A jV-dimethylaniline at ca. 100 °C) results in a thio-Claisen rearrangement to give the 5-(3-allyl-2-pyrrolyl) thioacetate (499), whilst peracid oxidation of (498) produces the non-rearranged sulfone in low yield and Raney nickel reduction of (498) yields 3-propylpyrrole (78CJC221). The polyphosphoric acid-catalyzed cyclization of (2-pyrrolylthio) acetic acid (501 R = R = H) somewhat unexpectedly yields (502) via the Spiro intermediate, instead of forming the expected oxothiolane (500), which can be obtained by a Dieckmann cyclization of ethyl (3-ethoxycarbonyl-2-pyrrolylthio) acetate (501 R = Et, R = C02Et) (B-77MI30506). 

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