Molecular Rearrangement in the Reaction of Cysteine with 1-Fluoro-2,4-Dinitrobenzene

Ultrasensitive colorimetric detection of Cu2+ ion based on catalytic oxidation of l-cysteine

“…As shown in Fig. S2, in HEPES solution (pH 6.8) at 90°C, the reaction between L-cysteine and CDNB was first-order, with a half-time of about 2.2 min and a rate constant k of 0.31, which was consistent with the obtained data by Burchfield (1958). Thus, a simple colorimetric strategy could be established for the sensing of L-cysteine.…”

Studies on the acylation of 4-(2-aminoethylthio)-7-nitrobenzofurazan: the role of bases in promoting the formation of fluorescent S-acyl derivatives through S–N Smiles rearrangement

“…Cysteamine-NDBf 2 was prepared in almost quantitative yield through the reaction of cysteamine hydrochloride (1.1 eq) with NDBf-Cl 1 (1.0 eq) in refluxing ethanol and in the presence of a catalytic amount of KOAc (Scheme 1). [10][11][12][13][14][15][16][17][18] As expected the more nucleophilic sulfur of cysteamine reacts with NDBf-Cl 1 faster than nitrogen atom leading selectively to C4-S derivative 2 while no traces of the C4-N regioisomer were observed. We first decided to react 2 with different bases under mild conditions (DCM, 25 °C), in order to investigate its tendency to give the S-N-Smile rearrangement (Scheme 2, Table 1).…”

“…The influence of the base and of the acyl donors on the outcome of reaction as well as the tendency of the substrate 2 to give the Smiles rearrangement has been highlighted. Smiles rearrangement on NDBfs bearing a cysteamine chain at C4 occurs in the presence of Et 3 N and MeONa and lead to S-or Nacylated NDBfs 18 depending on the nature of the acylating group. In some cases, the unstable S-acylated benzofurazan derivatives can be obtained as the major reaction products.…”

BODIPY-based probes for the fluorescence imaging of biomolecules in living cells

“…In the cases of cysteine and homocysteine, intramolecular replacement of the thiolate group with an amine produced aminated BODIPY 45. 97,98 In contrast, glutathione did not produce the aminated BODIPY, because of the lack of a nucleophilic amine at the appropriate position for intramolecular S to N rearrangement. In addition, thioether 46 showed intense fluorescence at 588 nm, whereas the fluorescence intensity of aminated BODIPY 45 was much lower and/or blue-shifted.…”