Acetic acid reduction

Other preparations of succinic acid mentioned in the Hterature are electrochemical reduction of maleic or fumaric acid (153,154), ultrasound-promoted Zn—acetic acid reduction of maleic or fumaric acid (155), reduction of maleic acid with H2PO2 at room temperature (156),... 

Mercury-sensitized irradiation of 1,2,3-triphenylisoindole (65) in the presence of oxygen gives a peroxide (103). This peroxide is relatively stable compared with the peroxide (104) derived from similar oxidation of 1,3-diphenylisobenzofuran and can be reconverted to the isoindole (65) by pyrolysis or by treatment with zinc and acetic acid. Reduction of 103 under mild conditions affords o-dibenzoylbenzene (46) and aniline. Aerial oxidation of 47 gives 46 and methylamine, presumably via a peroxide intermediate similar to 103. °... 

An interesting comparison between a catalytic hydrogenation and a zinc and acetic acid reduction is observed in the case of the oximino acid (49). The cw-fused hydroxamic acid (50) was the sole... 

Solvents may have an important influence on the reduction. No reaction occurred on attempted hydrogenolysis of the azetidine (7) over 5% Pd-on-C in ethanol, but in acetic acid reduction proceeded smoothly to give the 1-hydroxyazctidine (8) (137). 

The first synthesis of stable 3-hydroperoxy-sultams (24) which are a new class of sultam with oxidising properties, was reported. The synthesis involved oxidation of the isothiazolium salts (23) with hydrogen peroxide in acetic acid. Reduction of (24) with aqueous sodium bisulphite afforded the corresponding novel 3-hydroxysultams whereas thermolysis in ethanol resulted in the elimination of water to give 3-ketone derivatives, which are versatile as dieneophiles <96T783>. 

The residues from zinc dust-acetic acid reduction operations may ignite after a long delay if discarded into waste-bins with paper. Small amounts appear to ignite more rapidly than larger portions. 

Other synthetic routes to benzazepines involving ring expansion of six-membered heterocycles include the action of diazomethane (77CPB321), sulfonium ylides (77H(7)37> or acyl halides (75T1991) on quaternary 3,4-dihydroisoquinolines that of sulfoxonium ylides on quaternary quinolines (74IJC(B)1238) and the zinc-acetic acid reduction of quaternary 1-acyltetrahydroisoquinolines (77BSF893). Photoaddition of acyl- or aryl-nitrenes to the exocyclic alkene bond of 2-methylene-1,2-dihydroquinolines results in ring expansion to... 

Halogenomethylpyrroles have been oxidized with lead(IV) salts or by chromium trioxide to yield the formylpyrroles, whilst catalytic hydrogenolysis or zinc-acetic acid reduction produces the 2-methylpyrroles (B-77MI30504). The methyl derivatives are also obtained by hydride reduction of trifluoromethyl-pyrroles and -indoles, and trifluoromethylindoles are converted into the carboxylic esters by ethanol under basic conditions (74JOC1836). 

Provided that supporting electrolytes of wide electrochemical windows are used (e.g., TBA salts), the cathodic limit for acetic acid reduction is around -1.7... 

Yellow deoxyvomicine gives the greatest number of hydrogenation products, five in all, A-E. The primary product A is dihydrodeoxy vomicine II (CCLXX), also obtained in very poor yield by the electrolytic reduction of yellow deoxyvomicine or by the zinc and acetic acid reduction of the iodo compound obtained as a minor product in the preparation of yellow deoxyvomicine. Product B (CCLXXI) simply arises by reduction of the 21,22-double bond further reduction of B does... 

Thallium trifluoroacetate has not enjoyed widespread use as a reagent for quinone synthesis, possibly because it is still a relatively new reagent but more probably because of its toxicity. One example of its use lies in the synthesis of metacyclophanes and related compounds as reported by Tashiro et al Thus the r-butylphenol (59) gave the bisquinone (61), while the phenol (60) afforded the monoquinone (62). An alternative and more practical synthesis of the bisquinone (61) for large scale work involved dealkylation to afford the bisphenol (63) which was then treated with sodium nitrite to give the bisoxime (64). Hydrolysis of the bisoxime did not give the quinone (61), but it could be obtained by zinc/acetic acid reduction of the bisoxime followed by oxidation with nitric acid (Scheme 13). 

Still another scheme is concerned with the zinc-acetic acid reduction of an aliphatic nitro olefin, which is readily prepared by the condensation of an aldehyde with the nitroparaffin (method 37). ... 

A number of metals salts can be used as the source of electrophiles in reactions with alkenes. One of the most interesting of these involves the attack of mercury(II) acetate in acetic acid. Reductive cleavage of the organomercury compound with sodium borohydride leads to the overall hydration of the alkene in a Markownikoff sense. There are a number of preparative advantages, such as a reduced tendency to rearrange, associated with this and similar relatively mild procedures when compared to the direct protonation of a double bond (Scheme 3.14)... 

Synthesis and Reaction of 2-(Acyloxy) and 2-(Benzoyloxy) vinyl ethers of (R)-(-)-DCP. 2-(Acyloxy)vinyl ethers (13) of DCP have been prepared (eq 7). Allylation of 1 followed by ozonolysis with a zinc/acetic acid reductive work-up affords the corresponding chiral aldehyde. Heating this aldehyde with the appropriate anhydride and sodium salt of the carboxylic acid gives the desired 2-(acyloxy)vinyl ethers. 

Nitro-4 -anisoyl-4-aminophenyIarsinic acid results in 48 per cent, yield. It crystallises in woolly needles from boiling acetic acid. Reduction in the usual manner gives a 95 per cent, yield of the amino-add, which forms the following salts hyd/rochloride, wedge-shaped crystals sulphate, sphsero-crystals nitrate, woolly needles. The acdyl derivative is prepared by dissolving the amino-aeid in normal sodium hydroxide and adding an excess of acetic anhydride. From dilute formic acid it separates in anisotropic sphsero-crystals. 

In a typical preparation, 2 xl of 0.5 M TCEP was added to 500 pg of GDNF (16.0 nmol) in 200 pi of 0.17 M acetic acid. Reduction was allowed to proceed at 45°C for 2 hours before the sample was chromatographed through a Vydac C4 column (0.46 x 25 cm) using a Hewlett Packard 1090 M liquid chromatograph. Solvent A was 0.1% TFA in water and solvent B was 0.1% TFA in 90% acetonitrile. The column was equilibrated in 10% solvent B and a flow rate of 0.7 ml per min was used. After sample application, the column was washed isocratically with 10% solvent B for 5 min. Protein elution was accomplished by a linear gradient in 2 steps 10 to 30% solvent B over 5... 

In the second stage of our reduction process the oxime obtained in the first stage is further reduced to the amine. Any suitable means for reducing the oxime without undue hydrolysis may be employed for this purpose. Among these methods may be mentioned reduction with sodium amalgam and acetic acid, reduction with metallic sodium in alcohol solution, and hydrogenation with a platinum, palladium or nickel catalyst. We prefer to employ hydrogenation with a nickel catalyst, and this process is illustrated in the example below ... 

Zinc dust-acetic acid. Reduction. N-Nitroso-N-methylaniline is reduced to a-... 

A hydroxycodeine has been prepared by the zinc and acetic acid reduction of 14-hydroxycodeinone [xxxm] [312-14], but its structure is uncertain, as on further reduction it gives hydroxydihydrocodeine-A, which is not identical with either 14-hydroxydihydrocodeine-B or C [xxxiv] obtained by the catalytic hydrogenation of [xxxm] [315] (see Chap. XVIII). 

An attempt to prepare 1-bromodesoxycodeine-A by the zinc-dust and acetic acid reduction of 1-bromo-a-chlorocodide gave instead, 1-bromodesoxycodeine-C (q.v.) [5]. 

The open-chain tautomers 24b and 25 of precursor incipient imidazolidine and perhydropyrimidine derivatives, which bear a six carbon transferable fragment, on acid-catalyzed reactions with tryptamine formed the diester 85. A similar reaction of 24a leads to quantitative formation of 86 and the reaction of 25 with tryptamine is appreciably faster than that of 24b. Sodium cyanoborohydride/acetic acid reduction of 85 was accompanied by intramolecular aminolysis to form piperidone 87. Its Bischler-Napieralski cyclization followed by borohydride reduction gave cis- and trara-isomers of indoloquinolizine ester 88, which on hydrolysis to acid and subsequent methylene lactam rearrangement gave methylene lactam 89. Its DIBAL reduction gave 18- or-deplancheine 84a (88T6187). 

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