Esters with potassium permanganate

Oxidation of 3-hydroxyfurazan-4-acetic acid with potassium permanganate under alkaline conditions gave 3-hydroxy-4-furazancarboxylic acid (1895CB753). The acid yielded an ester when heated in ethanol saturated with dry HCl. The ester... 

Ueno and coworkers49 have developed a procedure for the synthesis of chiral sulfinic acids. Treatment of (R)-( + )-23 with disulfide 24 and tributylphosphine in THF gave (S)-( — )-25. Compound 25 was oxidized with potassium permanganate to the sulfone, which was then reduced to the sulfinic acid, (S)-( — )-26, by treatment with sodium borohydride. Conversion of 26 or an analog to an ester would lead to diastereomers. If these epimers could be separated, then they would offer a path to homochiral sulfoxides with stereogenic carbon and sulfur atoms. 

The constitution of the new compound was proved22 by the isolation of an acid XX after oxidation at low temperature with potassium permanganate in alkaline solution. This acid was converted to its diethyl ester (XXI), the melting point and other properties of which coincide with those of a compound synthesized by Fischer and Hussong.23... 

Methoxylation of the ester (132) by electrolysis gave a mixture of the two isomers (133) and (134) (73CCC455). ds-Hydroxylation of these compounds with potassium permanganate in aqueous methanol afforded the isomeric 2,5-dimethoxy-3,4-dihydroxy-2-benzoyloxy-methyltetrahydrofurans (135) and (136). Debenzoylation of (135) with sodium methoxide in methanol and cleavage of the acetal groups with Dowex W-50 yielded erythro-pentopyranos-4-ulose (137) in the form of its hydrate (Scheme 30). 

Oxidation of methyl 3,4-isopropylidene-2-desoxy-a-D-galactoside with potassium permanganate in the presence of potassium hydroxide afforded methyl 3,4-isopropylidene-2-desoxy-a-D-galacturonoside (LXXXIV) as its potassium salt. This could readily be converted into methyl 2-desoxy-a-D-galacturonoside (LXXXV) and both LXXXIV and LXXXV afforded crystalline esters and amides.230 The uronic acid derivative could be reduced by lithium aluminum hydride in ethereal solution to give methyl 3,4-isopropylidene-2-desoxy-a-D-galactoside.230 Although 2-des-... 

Acetyl-n-valeric acid has been prepared by the oxidation of 1-methylcyclohexene with potassium permanganate 5 by the oxidation of 2-methylcyclohexanone with chromic oxide and sulfuric acid 6 by the reaction of methylzinc iodide on the ethyl ester of adipic acid chloride and saponification of the ethyl ester of 5-acetyl-w-valeric acid so obtained 7 by the saponification of the ethyl ester of diacetylvaleric acid 2 and through the hydrolysis of ethyl a-acetyl-6-cyanovalerate with boiling 20% hydrochloric acid.3... 

Fig.6.3.2. Major carboxylic acid methyl esters formed in the oxidation of lignin with potassium permanganate (Compounds 3, 6 and 9 are from hardwood lignin)...

A -Acetyltryptophan ethyl ester on reaction with Lawesson s reagent afforded the thioamide 9, which with methyl iodide in acetone yielded the methylthioiminium salt 10 which cyclized spontaneously to the quaternary salt 11 (24). BC 12 on condensation with benzaldehyde gave stilbene 13, which oh oxidation with potassium permanganate afforded... 

The popularity of the Nef reaction is due in part to the ready availability of nitro compounds. Primary and secondary halides react with sodium nitrite in dimeAyl sulfoxide (DMSO) or dimethylform-amide (DMF) to give useful yields of nitro compounds. Primary amines can be oxidized to nitro compounds with potassium permanganate, m-chloroperbenzoic acitP or ozone. Chlorination of oximes with hypochlorous acid and reduction with magnesium, zinc or hydrogen/lpalladium gives secondary nitro compounds. Stabilized carbanions can be nitrated by treauitent with a nitrate ester, and enol acetates are nitrated by acetyl nitrate to give nitro ketones. ... 

Tridecylic acid has been prepared by the malonic ester 33 1-thesisfrom imdecyl iodide, by the oxidation of a-hydroxymyristic add in acetone with potassium permanganate, by the action of dodecyl bromide on potassium cyanide and subsequent hydrolysis, and from imdecyl iodide and ethyl cyanoacetate. The present method is an adaptation of that of Ruzicka, Stoll, and Schinz. ... 

For the synthesis of (69), the enol ether (71) from the indanone (70) was carboxylated with COa-n-butyl-Iithium in THF at —70 C to yield (72). The methyl ester (73) was converted into (75) via the maleic anhydride adduct (74), essentially as described in earlier work. Lithium aluminium hydride reduction followed by oxidation with dicyclohexylcarbodi-imide afforded the aldehyde (76). This was condensed with excess (77) to yield a mixture of the diastereomers (78). Oxidation with chromium trioxide-pyridine in methylene dichloride gave (79), which could be converted into the diketone (80) by treatment with excess benzenesulphonylazide. The diketo-lactam (81) was prepared from (80) as described for the synthesis of the analogous intermediate used in the synthesis of napelline. Reduction of (81) with lithium tri-t butoxyaluminohydride gave the desired dihydroxy-lactam (82). Methylation of (82) with methyl iodide-sodium hydride gave (83). Reduction of this lactam to the amine (84) with lithium aluminium hydride, followed by oxidation with potassium permanganate in acetic acid, gave (69). 

Ludwig. This compound has an empirical formula corresponding to structure (1) and shows the ultraviolet and infrared" absorptions of a pyrrole-3-carboxylic ester. Its acetylation gives a tetra-O-acetyl derivative." Oxidation with lead tetraacetate yields ethyl 5-formyl-2-methyl-pyrrole-3-carboxylate (4), identical with the compound prepared in a different way. Oxidation with potassium permanganate in alkaline solution at low temperature yields 3-(ethoxycarbonyl)-2-methylpyrrole-5-carboxylic acid (7) which can be transformed " into the diethyl ester (8), identical... 

Quinoxaline-2-carboxaldehyde has been converted into the 2-carboxylic acid by oxidation with potassium permanganate in acetone and reduced to the 2-hydroxymethyl compound by treatment with formalin and potassium hydroxide. It also undergoes other typical reactions of aromatic aldehydes such as benzoin formation on reaction with potassium cyanide - and condensation reactions with malonic acid and its diethyl ester and Schiff base formation. Acid-catalyzed reaction of quinoxaline-2-carboxaldehyde with ethylene glycol gives the cyclic acetal the diethylacetal has been prepared by reaction of 2-dibromomethylquinoxaline with sodium ethoxide. " An indirect preparation of the oxime 11 is achieved by treatment of 2-nitromethyl-quinoxaline (10) with diazomethane followed by thermolysis of the resulting nitronic ester. 

In our laboratory we have used two methods, both of which involve saponification with alkali to yield methanol. The released methanol can be analyzed colorimetrically after oxidation to formaldehyde with potassium permanganate, and reaction of the formaldehyde with pentan-2,4-dione, to yield a chromophore with Amax 412 nm (Wood and Siddiqui, 1971). Alternatively, the methanol produced can be converted to its nitrite ester by reaction with sodium nitrite and analyzed by GLC (Litchman and Upton, 1972 Versteeg, 1979). For the latter procedure to be reliable, careful timing of the reactions is required (Litchman and Upton, 1972). 

Sulphinic acid esters have also been oxidized, to the sulphonic acid ester, with hydrogen peroxide although the reaction usually proceeds in poor yield345,346. This resistance to oxidation is also evident when other oxidants are used233,347. A much improved procedure for the oxidation of aromatic sulphinate esters uses potassium permanganate in aqueous solution, as oxidant345,348,349, as shown in equation 79. Mefa-chloroperbenzoic acid has also been used with success for the oxidative preparation of sulphonate esters. Indeed, it has resulted in the preparation of unstable sulphonate esters that are hard to form by other means350. 

Controlled oxidation of the a-pinenes with potassium permanganate leads to the enantiomeric 2-hydroxy-3-pinanones 38 29-31, while under forcing conditions, ring cleavage occurs, leading to cyclobutane derivatives 39. The hydroxy ketones 38 are useful auxiliaries forming imines with benzylic amines or glycine esters which can be alkylated enantioselectively via the enolates (Sections D.l. 1.1.1.3.2., D. 1.1.1.4.1. and D.I.5.2.4.). 

Oxidation of 34 b and 35 b with potassium permanganate afforded the tetraacids 36 and 38 in 76 % and 80% yields, respectively (Eq. 13 and 14). The acids 36 and 38 were able to react with diazomethane to afford their corresponding esters 37 and 39 in quantitative yields On the other hand, the inseparable mixture of 34a and 35a could be converted to their adds -/O and 41 which were also difficult to separate (Eq. 15)... 

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