Phosphine-free Direct Conversion of Carboxylic Acids into Acyl Isothiocyanates Using Various Electrophilic Halogenation Reagents

In this study, the efficiency of some electrophilic halogen reagents including 2,4,6-trichloro- 1,3,5-triazine, 2,4,4,6-tetrabromo-2,5-cyclohexadienone, 2-chloro-1-methylpyridinium iodide, Nbromosuccinimide, trichloroisocyanuric acid, and 1,3-dibromo-5,5-dimethylhydantoin for the direct phosphine-free conversion of carboxylic acids into the corresponding acyl isothiocyanates was investigated. All of the reagents work well for this transformation, but, the best results were obtained when cyanuric chloride in the presence of pyridine was used at room temperature.