Tribromo Phloroglucinol as a Novel and Highly Efficient Reagent for the Conversion of Benzothioamides to the Corresponding 1,2,4-Thiadiazoles

2,4,6-Tribromo-1,3,5-trihydroxybenzene (TBTHB) as a reagent was efficiently reacted with 6 molar equivalents of benzothioamides in dimethyl sulfoxide (DMSO), and the corresponding 3,5-diaryl-1,2,4-thiadiazoles were obtained in almost quantitative yields (91–98%) and in short times (15–20 min) with the formation of hexahydroxybenzene as a rather valuable by-product.