Metal-Free Regioselective Thiocyanation of (Hetero) Aromatic C-H Bonds using Ammonium Thiocyanate: An Overview

(Hetero)aryl thiocyanates have been extensively used as dyes, insecticides, vulcanization accelerators, and building blocks in the synthesis of diverse organosulfur compounds. Therefore, development of novel, efficient, and practical methods for their synthesis has always been the important topic in organic synthesis. Recently, direct thiocyanation of (hetero)aromatic C-H bonds using inexpensive and easily available ammonium thiocyanate has attracted considerable attention from the organic synthesis community, because no prefunctionalization of the starting materials is required and therefore the hazardous waste streams are significantly reduced. In this review, we summarize the recent discoveries and developments in this interesting field by hoping it will inspire and stimulate further research on the topic.