Aryl thiocyanate compounds are important building blocks for the synthesis of bioactive compounds and intermediates for several functional groups. Reported thiocyanation reactions via C−H functionalization have limited substrate scope and low RME. The ball-milling method reported here uses ammonium persulfate and ammonium thiocyanate as reagents and silica as a grinding auxiliary. It afforded aryl thiocyanates with moderate to excellent yields for a wide variety of aryl compounds (36 examples, 8−96% yield), such as anilines, phenols, anisoles, thioanisole, and indole, thus tolerating substrates with sensitive functional groups. New products such as benzo [d][1,3]oxathiol-2-ones were obtained with C-4 substituted phenols. Thus, to our knowledge, we report, for the first time, aryl thiocyanation reaction by ball-milling at room temperature and solvent-free conditions, with short reaction times and no workup. Analysis of several mass-based green metrics indicates that it is an efficient greener method.
The chemistry of quinoxalines has attracted great attention due to the potential applications of this class of nitrogen‐based heterocycle in many areas. In this paper, heteroaromatic nucleophilic substitution of the quinoxaline substrate 2,3‐dichloro‐6,7‐dinitroquinoxaline (DCDNQX) with anilines and phenols is reported. Reactions using this reagent were proven to proceed under mild and metal‐free conditions for selectively obtaining mono and disubstituted products in good to excellent yields.
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