Metal-free direct construction of sulfenylated pyrazoles via the NaOH promoted sulfenylation of pyrazolones with aryl thiols

Abstract

A convenient and cost-effective NaOH-promoted direct sulfenylation of pyrazolones with aryl thiols has been developed under mild and metal-free conditions.

Direct construction of sulfenylated pyrazoles catalyzed by I 2 at room temperature

“…Based on these preliminary experiments and previous reports [19,[41][42][43][44][45], a plausible reaction mechanism was proposed, as shown in Scheme 4. Firstly, homolytic cleavage of the disulfide bond occurs, forming thiyl radicals.…”

Sulfenylation of C–H Bonds for C–S Bond Formation under Metal‐Free Conditions

“…In 2016, a convenient and cost‐effective method for NaOH‐promoted direct sulfenylation of pyrazolones with aryl thiols was developed by Wang and co‐workers (Scheme ). [10a] A series of biologically important sulfenylated pyrazoles could be efficiently obtained in good to excellent yields.…”

“…Besides H 2 O 2 and TBHP, O 2 ,, , DTBP,[13b] and DMSO could also be used as oxidants for sulfenylation. In 2016, iodine‐catalyzed regioselective sulfenylation of imidazo heterocycles in dimethyl sulfoxide as both oxidant and solvent was developed by Prabhu et al (Scheme ).…”

Direct Synthesis of Sulfonated or Sulfenylated Pyrazolones Mediated by KIO3 and Their Anti-microbial Activity

“…A tetrabutylammonium iodide (TBAI)-HBr system which mediated the reaction between pyrazolones and benzenesulfonyl chlorides was realized by Yanʼs group. [9] In 2016, Wang's group [10] found that NaOH was good promoter for sulfenylation of pyrazolones. In 2017, Wang et al [11] obtained the sulfenylated pyrazoles via a radical pathway promoted by dimethyl sulfoxide (DMSO).…”