Syntheses of sulfinic acids

Zoller, Uri

doi:10.1002/9780470772270.ch7

Cited by 7 publications

(3 citation statements)

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“…Hence, there is a need to develop a general, mild, and efficient one-pot synthesis of sulfonamides, which could tolerate the presence of heterosubstituted aryl moieties or reactive functional groups. We therefore sought to reinvestigate the preparation of sulfonamides from aryl halides by reaction of the derived Grignard reagents with sulfur dioxide, sulfuryl chloride, and an amine.…”

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Facile One-Pot Synthesis of Aromatic and Heteroaromatic Sulfonamides

et al. 2003

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Facile One-Pot Synthesis of Aromatic and Heteroaromatic Sulfonamides

et al. 2003

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“…A fourth approach for favoring the deconjugation reaction in microcystins is to convert the sulfide group into a better leaving group, such as a sulfone, which would also be expected to make the hydrogen atom α-to the carbonyl group more acidic. The deconjugation reaction would thus become the well-known base-catalyzed β-sulfone elimination reaction. , For example, the rate of base-catalyzed cleavage of a thiol–maleimide conjugate was markedly increased after oxidation to the sulfone, and deconjugation occurred at a measurable rate even at physiological pH . Oxidation of sulfides to sulfoxides has been shown to facilitate thermal elimination of the thiol moiety to form didehydroamino acids and peptides, but this approach does not appear to have been widely used for natural samples because the reaction conditions are not compatible with proteins nor with many natural products …”

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Rapid and Convenient Oxidative Release of Thiol-Conjugated Forms of Microcystins for Chemical Analysis

Miles

2017

Chem. Res. Toxicol.

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Microcystins are potent cyclic heptapeptide toxins found in some cyanobacteria, and usually contain an α,β-unsaturated carbonyl group that is readily conjugated to thiol-containing amino acids, peptides, and proteins in vivo and in vitro. Methods for deconjugating these types of adducts have recently been reported, but the reactions are slow or result in derivatized microcystins. Mercaptoethanol derivatives of a range of microcystins were therefore used as model compounds to develop deconjugation procedures in which the dialkyl sulfide linkage was oxidized to a sulfoxide or sulfone that, when treated with base, rapidly eliminated the adducted thiol as its sulfenate or sulfinate via β-elimination to afford free microcystins with the α,β-unsaturated carbonyl group intact. These free microcystins can be analyzed by LC/MS to determine the toxin profile of bound microcystins. The method was tested on Cys- and GSH-derivatives of [Dha]MC-LR. In solution, the deconjugation reactions were complete within minutes at pH 10.7 and within a few hours at pH 9.2. Oxidation of sulfides to sulfoxides is easier and more rapid than oxidation to sulfones, allowing the use of milder oxidants and shorter reaction times. Oxidation of any methionine residues present in the microcystins occurs inevitably during these procedures, and interpretation of the microcystin profile obtained by LC/MS analysis needs to take this into account. Oxidation of tryptophan residues and degradation of microcystins by excess oxidant were circumvented by the addition of MeSO as a sacrificial reducing agent. These methods may be useful for other compounds that undergo conjugation via thia-Michael addition, such as acrylamide and deoxynivalenol. Oxidation of sulfides to sulfoxides can occur in vivo and could affect the bioavailability of toxins and drugs conjugated via thia-Michael addition, potentially exacerbating oxidative stress by catalytically converting GSH to its sulfenate via conjugation, oxidation, and elimination to regenerate the free toxin.

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“…The conversion of sulfonyl chlorides to sulfones had been studied extensively prior to the1960s. It was traditionally accomplished via reduction of a sulfonyl chloride, with zinc or sodium sulfite; the resulting sulfinic acid salt was then alkylated to form the sulfone . The procedures usually required two pots, with the sulfinic acid salt as the lone isolated intermediate.…”

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confidence: 99%