Kinetics and mechanism of the reduction of sulphoxides by hydriodic acid

Landini, Dario; Montanari, Fernando; Hogeveen, H.; Maccagnani, G.

doi:10.1016/s0040-4039(00)71715-1

Cited by 19 publications

(14 citation statements)

References 11 publications

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“…(2) The small change in rate with solvent and ionic strength variation indicates the transition state is not differently charged than the reactants, consistent with a concerted mechanism. (3) Finally, the concerted mechanism is preferred by its analogy to the rearrangement of epoxides19 and the acid-catalyzed rearrangement of the arene oxides.…”

Section: Discussionmentioning

confidence: 99%

Mechanism of the aromatization of arene oxides

Kasperek¹,

Bruice²

1972

J. Am. Chem. Soc.

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The kinetics of the aromatization of arene oxides has been studied at 30' (p = 1 .O) between p H 2.5 and 14.0. The pH-log k&sd profiles for benzene oxide (1) and naphthalene oxide (2) are characterized by a straight line of slope -1 .O in the acid region in agreement with specific acid catalysis, and a plateau in the p H >7 region indicating a spontaneous aromatization. With phenanthrene oxide (3) only the acid-catalyzed portion was detected.For the spontaneous aromatization the entropy of activation (AS * = -25.7), solvent deuterium kinetic isotope

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Section: Discussionmentioning

confidence: 99%

Mechanism of the aromatization of arene oxides

Kasperek¹,

Bruice²

1972

J. Am. Chem. Soc.

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“…A proposed reaction mechanism for reduction of methionine sulphoxide with ammonium iodide is shown in Fig. 3 (16, 21). Dimethylsulphoxide (DMSO) and iodine, both of which have been used to form peptide disulphide bonds (19, 20), are by‐products of the reaction.…”

Section: Resultsmentioning

confidence: 99%

“…Generally, disulphide bonds are formed after isolation of the peptide (3, 19, 20). With Reagent H, however, we have found in situ formation of disulphide bonds by reaction with dimethylsulphoxide and/or I 2 , both of which are products of the reduction of Met(O) (21).…”

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confidence: 81%

A cleavage cocktail for methionine‐containing peptides

Huang

Rabenstein

1999

The Journal of Peptide Research

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A new cocktail has been developed for cleavage and deprotection of methionine-containing peptides synthesized by 9-fluorenylmethoxycarbonyl (Fmoc)-based solid-phase peptide synthesis methodology. The cocktail (trifluoroacetic acid 81%, phenol 5%, thioanisole 5%, 1,2-ethanedithiol 2.5%, water 3%, dimethylsulphide 2%, ammonium iodide 1.5% w/w) was designed to minimize methionine side-chain oxidation. Application of the new cocktail (Reagent H) is demonstrated with the synthesis of a model pentadecapeptide from the active site of DsbC, a periplasmic protein involved in protein disulphide bond formation. The model peptide, which contains one methionine and two cysteine residues, was cleaved with several cleavage cocktails, including Reagent H. The crude peptides obtained with the widely used cocktails K, R and B were found to be 15% to 55% in the methionine sulphoxide form, whereas no methionine sulphoxide was detected in the crude peptide obtained by cleavage and deprotection with Reagent H. Also, no methionine sulphoxide was detected when 1.5% w/w NH4I was added to cocktails K, R and B; however, the yield of the desired peptide was less than with Reagent H. A second 28 amino acid model peptide of the active site of DsbC was also cleaved and deprotected with Reagent H. The reduced dithiol form of the peptide was found to be the major component (51% yield) of the crude peptide obtained by cleavage for 3 h. When the cleavage time was extended to 10 h, the peptide was converted to the intramolecular disulphide form (35% yield). A proposed mechanism for the in situ oxidation of cysteine with Reagent H is presented.

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“…Contribution from the Department of Chemistry and Materials Research Center, Northwestern University, Evanston, Illinois 60201. Received March 30,1971 Abstract: Thian-l-imide (3) has been synthesized and found to have a slight excess (55/45 at -85°) of the imide functionality in the equatorial position, in contrast to the isoelectronic thiane 1-oxide (9), which favors an axial orientation of the oxide functionality. The /V-tosyl-(6) and N-benzenesulfonyl (7) derivatives of 3, however, favor the axial imide conformation.…”

mentioning

confidence: 99%

“…In recent years there has been considerable effort in developing new preparative methods for these functionalities and in defining the stereochemistry of their reactions at sulfur. 3 In this paper we report the fundamental conformational properties of the sulfimide and sulfoximide functionalities incorporated into a sixmembered ring.…”

mentioning

confidence: 99%