Displacement thiol group

In many cases, a thiol group is introduced into a substrate through the use of a thiol (e.g., monoprotected H2S), by a simple displacement or an addition reaction. ... 

Displacement of the nitro group in pentachloronitrobenzene by hydroxyl and thiol groups (Bahig et al. 1981) (Figure 2.16) in golden orfs Idas idus). 

Penicillamine reacts with pyridoxal-5-phosphate to form a thiazolidine derivative, and is able to displace many amino acids from their Schiff base complexes, forming stable compounds of this type. The reactivity of the thiol group of penicillamine is less than that of cysteine, probably because of steric hindrance by the adjacent methyl groups of penicillamine, which in consequence is less rapidly oxidized in vivo [7]. 

The thiol group was displaced from 3-mercapto-l,2,4-triazoles 59 using oxidation to yield the corresponding 3-unsubstituted compounds 60a-d in good yield (Equation 19) (Table 5) <2006S156>. 

In one synthesis of this drug, L-proline (11-2) is acylated with the acid chloride (11-1) obtained from the addition of hydrogen chloride to the double bond in methacrylic acid followed by reaction with thionyl chloride to give amide (11-3) as a mixture of diastereomers. The pure 2S isomer is then isolated from the mixture by fractionation as the dicyclohexylamine salt. Treatment of that compound with ammonium hydrosulfide leads to the displacement of chlorine by a thiol group and the formation of captopril (11-4) [13]. 

A preliminary investigation of the spectra of thiophenols and their methyl ethers has given no clear indication for the formation of an external hydrogen bond between the thiol group and ethanol which, if present, can only be weak. This is illustrated in Table 2 foF the K-bands of thiophenol and p-nitrothiophenol and their methyl ethers which show displacements attributable to any possible hydrogen bond formation (D, H-bond) of +9 and —20 A as compared with +75 and +140 A respectively in the case of the corresponding phenols. 

The metallation of neither 1,3-selenazoles nor l-benzo-l,3-selenazoles has been reported. Nucleophilic reagents replace some substituents present at the 2-position. Displacement of the 2-thiol group of 2-thiol-l-benzo-l,3-selenazole to prepare 2-aminoderivative is an example [3], The 2-chlorine atom is easily substituted by an amino group when treated with propargylamine [75],... 

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