Transition metal-free C-H activation of heteroarenes: an overview (2018-2022)

Heteroarene derivatives are one of the most important moieties in organic and medicinal chemistry as they are the core structures of various bioactive molecules. Therefore, development of efficient and practical methods for the synthesis of heteroarene derivatives has always been an important topic in organic and medicinal chemistry. For the synthesis of heteroarene derivatives, metal catalyzed C-H activation reactions became one of the most highlighted areas of research for over a past few decades. But transition metal-catalyzed C-H activations require harsh condition and they are hazardous for bio-organisms. For these reasons metal-free C-H activation reactions were found to be a good alternative. These modern approaches mostly obey the fundamentals of green chemistry which means the reactions occur under very mild conditions and the products are less hazardous for bio-organisms. Here in this review, we have discussed about some articles, published over past five years, regarding metal-free C-H activation processes along with their scopes of reactants and proposed mechanisms.