A New and Selective Method of Oxidation

Kornblum, Nathan; Powers, Jack W.; Anderson, George; Jones, Willard J.; Larson, H. O.; Levand, Oscar; Weaver, William M.

doi:10.1021/ja01581a057

Cited by 381 publications

(131 citation statements)

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“…With hypobromous acid, di- Although the scheme just depicted is intended to represent a working hypothesis rather than a mechanistic proposal, it will be noted that there are formal precedents for it in the wellknown Kornblum (8) and oxidations, and in the conversion of benzylarnines to benzaldehydes upon diazotization in anhydrous DMSO (10). It may also be noted that oxidation of acetylenes to a-diketones has been observed previously: stearolic acid is converted to 9,lO-diketostearic acid by neutral aqueous permanganate (11); and the highly strained acetylenes 3,3,6,6-tetramethyl-1-thiacycloheptyne and cyclooctyne undergo air oxidation to a-diketones (12).…”

mentioning

confidence: 99%

N-Bromosuccinimide-Induced Dimethyl Sulfoxide Oxidation of Acetylenes

Wolfe¹,

Pilgrim²,

Garrard³

et al. 1971

Can. J. Chem.

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The addition of less than 2 mol equiv. of N-bromosuccinimide (NBS) to a solution of diphenylacetylene in anhydrous dimethylsulfoxide (DMSO) leads to the formation of benzil in near-quantitative yield at room temperature. Under the same conditions stilbene gives the dibromo adduct. The conditions for this novel oxidation of an acetylene have been examined in some detail and it has been established that anhydrous DMSO must be employed as the solvent and that NBS is uniquely able to induce the oxidation. Preliminary studies indicate that alkyl aryl, dialkyl, and terminal acetylenes are converted to the corresponding a-dicarbonyl compounds, and that diphenylbutadiyne is oxidized to diphenyltetraketone. Optimum conditions for these latter oxidations have not yet been established. L'addition a la temperature ordinaire de N-bromosuccinimide (NBS), moins de 2 Cquivalents, a une solution de diphCnylacttylene dans du dimethylsulfoxyde (DMSO) conduit a la formation de benzil avec un rendement presque quantitatif. Dans les mimes conditions, le stilbene conduit au dCrivC dibromC. The combination of an N-haloamide or imide and an aqueous medium is often employed to convert an alcohol into a ketone or an olefin into a halohydrin (1). Hypohalous acid, formed in situ by hydrolysis -of the halogen source, is thought to be the oxidizing agent in most of these reactions (2). However, recent work by van Tamelen and Sharpless (3) and by Dalton and co-workers (4) indicates that the intervention of HOX is not obligatory. In aqueous glyme, N-bromosuccinimide (NBS) appears to effect direct transfer of positive bromine to a double bond (3); and, in the reaction of NBS with an olefin in moist dimethyl sulfoxide (DMSO), attack on the brominated cation or bromocarbonium ion is at least 95% by the DMSO (4). The bromohydrin is then produced by hydrolysis of the oxysulfonium intermediate 1.bromoketones are produced (5) and, with Nchlorosuccinimide or NBS in alcoholic solvents, the products are dichloro (6) or dibromoketals (7). In aqueous glyme, NBS effects direct transfer of bromine to a triple bond (7). This similar behavior of olefins and of acetylenes suggested that, in DMSO, a brominated vinyl cation might, like its dihydro analog, be trapped by the solvent to give 2, an unsaturated oxysulfonium cation. In the case of 2, however, competition may now occur between hydrolysis and either unimolecular (2 + 3 ; eq. 1) or bimolecular (2 + DMSO + 4; eq. 2) elimination of dimethyl sulfide. Loss of Br@ and dimethyl sulfide from 4, formed by the reactions of 2 or 3 with DMSO, would then lead, as indicated in eq. 3, to 5, an a-diketone, in what might be described as NBS-induced DMSO oxidation.Acetylenes resemble olefins in a number of respects in their behavior towards these halogenating agents. With hypobromous acid, di- For personal use only.

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mentioning

confidence: 99%

N-Bromosuccinimide-Induced Dimethyl Sulfoxide Oxidation of Acetylenes

Wolfe¹,

Pilgrim²,

Garrard³

et al. 1971

Can. J. Chem.

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“…The use of solvents other than DMSO, such as toluene, CH 3 CN, 1,4-dioxane, DMF, and 1,2-dichloroethane (DCE), resulted in lower yields (Table 1, entries 8-12). A temperature screen revealed that the transformation at 100 8C delivered the highest isolated yield (Table 1, entries [13][14][15]. Interestingly, a compatible yield could be obtained by the use of iodine (50 mol %) in the presence of tert-butylhydroperoxide (TBHP, 1.0 equiv) ( Table 1, entry 16).…”

Section: Resultsmentioning

confidence: 99%

“…Two plausible pathways are proposed (Scheme 2). Phenylglyoxal intermediate A formed in the presence of iodine and DMSO by Kornblum oxidation [13] undergoes condensation with the aniline to form the C-acyl imine intermediate B. Subsequent condensation of intermediate B with N-tosylhydrazine Table 2.…”

Section: Resultsmentioning

confidence: 99%

Metal‐Free CN‐ and NN‐Bond Formation: Synthesis of 1,2,3‐Triazoles from Ketones, N‐Tosylhydrazines, and Amines in One Pot

Chen

Yan

Liu

et al. 2014

Chemistry A European J

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A novel synthetic approach toward 1,4-disubstituted 1,2,3-triazoles by C-N- and N-N-bond formation has been established under transition-metal-free conditions. Complete control of the regioselectivity was successfully achieved. Commercially available anilines, ketones, and N-tosylhydrazine were treated with molecular iodine in one pot to allow the regioselective generation of 1,4-disubstituted 1,2,3-triazoles in high yields without the use of azides.

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“…Eventually, a proton shift and cleavage of the O-S bond yields the benzophenones 3 (Kornblum oxidation). [23] The question can be asked: Why does one obtain a much higher percentage of benzophenone with 1f than with 1c in DMSO/piperidine ( Table 2)? As previously shown, [24] Equation (4) can be used to calculate the rate constants of the reactions of carbocations with a large variety of nucleophiles, including amines, [25] halide ions, [26] and solvents.…”

Section: Reaction Mechanismmentioning

confidence: 99%

Ionizing Power of Aprotic Solvents

Streidl

Mayr

2011

Eur J Org Chem

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Keywords: Kinetics / Reaction mechanisms / Solvent effects / Linear free energy relationships / Ion pairs / Heterolysis reactions Rate constants for the heterolysis reactions (S N 1) of a series of chloro-diarylmethanes in aprotic solvents (dimethyl sulfoxide (DMSO), acetonitrile, carboxamides, etc.) have been determined conductometrically in the presence of amines or triphenylphosphane, which trap the intermediate ion-pairs and suppress ion recombination. The operation of S N 2 mechanisms can be excluded because the observed first-order rate constants become almost independent of the nature of the nucleophilic additive when a certain concentration of nucleophile is exceeded. The heterolysis rate constants are used to

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A New and Selective Method of Oxidation

Cited by 381 publications

References 0 publications

N-Bromosuccinimide-Induced Dimethyl Sulfoxide Oxidation of Acetylenes

N-Bromosuccinimide-Induced Dimethyl Sulfoxide Oxidation of Acetylenes

Metal‐Free CN‐ and NN‐Bond Formation: Synthesis of 1,2,3‐Triazoles from Ketones, N‐Tosylhydrazines, and Amines in One Pot

Ionizing Power of Aprotic Solvents

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