Sulfhydryl arylation

In the presence of sulfide or sulfhydryl anions, the quinonemethide is attacked and a benzyl thiol formed. The P-aryl ether linkage to the next phenylpropane unit is broken down as a result of neighboring-group attack by the sulfur, eliminating the aryloxy group which becomes reactive phenolate ion (eq. 2). If sulfide is not present, a principal reaction is the formation of the stable aryl enol ether, ArCH=CHOAr. A smaller amount of this product also forms in the presence of sulfhydryl anion. 

Although a sulfhydryl group generally is not converted to an 5-phenyl thioether, the conversion can be accomplished through the use of a Pd-catalyzed arylation with an aryl iodide. Thiophenol can be used to introduce sulfur into molecules by simple displacement or by Michael additions, and thus, the phenyl group serves as a suitable protective group that can be removed by electrolysis (—2.7 V, DMF, R N X-). ... 

Warfarin, diphenacoum, bromodiolone, flocoumafen, and brodiphacoum are examples Both alkyl and aryl mercury compounds can bind to sulfhydryl groups Have caused population declines in certain mollusks... 

Aryl halide compounds such as fluorobenzene derivatives can be used to form covalent bonds with amine-containing molecules like proteins. The reactivity of aryl halides, however, is not totally specific for amines. Other nucleophiles such as thiol, imidazolyl, and phenolate groups of amino acid side chains also can react (Zahn and Meinhoffer, 1958). Conjugates formed with sulfhydryl groups are reversible by cleaving with an excess of thiol (Shaltiel, 1967). 

Sulfhydryl Compound Fluorobenzene Derivative Aryl Thioether Bond... 

Although photoreactive aryl azides are relatively inert to thermochemical reactions prior to photolysis, they are not stable in the presence of sulfhydryl compounds which can reduce the... 

Although photoreactive aryl azides are relatively inert to thermochemical reactions prior to photolysis, they are not stable in the presence of sulfhydryl compounds, which can reduce the azide functional group to an amine. Avoid, therefore, the use of reduc-tants such as DTT or 2-mercaptoethanol before the photolyzing step, as these can react with the aryl azide within minutes (Staros et al., 1978). Avoid also amine-containing... 

Thiol esters are reduced at less negative potentials than carboxylic esters and can be cleaved in protic (e.g., methanol) [141] or aprotic [123, 142] media. Aroyl and benzylox-ycarbonyl groups may thus be used for protection of sulfhydryl groups in MeCN the radical anion of an arylthioic 5 -ester is usually cleaved to alkylthiolate and aryl radical if it is relatively stable (minutes) it reacts eventually with oxygen with formation of an arylcarboxylate [43]. 

Although a sulfhydryl group generally is not converted to an 5-phenyl thioether, the conversion can be accomplished through the use of a Pd-catalyzed arylation with an... 

Ethers have two alkyl or aryl groups attacheri to the oxygen atom anri may be thought of as substituted alcohols. The functional group characteristic of an ether is R—O—R. Thiols are a family of compounds that contain the sulfhydryl group (—SH). They, too, have a structure similar to that of alcohols. 

It is known that aryl thiols are more reactive than alkyl thiols due to their lower p a values (5-7) [28]. Aromatic thiols, for example, have already been shown to increase the folding rate of disulfide-cOTitaining proteins more than aUphatic thiols [30, 31]. For a pharmaceutical excipient such as thiolated chitosans, the increased reactivity of the thiol group would further increase its beneficial properties over alkyl thiol chitosan and non-thiolated polymers. Examples of aryl sulfhydryl-bearing compounds covalently attached to chitosan via an amide bond are 6-mercaptonicotinic acid and 4-mercaptobenzoic acid. As mentioned for alkyl thiol chitosan, the amount of free and oxidized thiol groups can be determined by Ellman s method. Examples of developed thiolated chitosans and their degrees of modification are listed in Table 1. 

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