## 1 Introduction  
Cancer, a disease of the cell cycles, has remained the largest cause of mortality and morbidity for several decades now. In spite of rapid development in diagnostic and therapeutic protocols, according to the World Health Organization (WHO), cancer holds second place after cardiovascular disease as a cause of death in the world [1]. Among all the available therapeutic methods, chemotherapy still remains a significant option for the treatment of cancer, which has emerged as a new era of molecularly targeted therapeutics [2]. However, the major drawback of successful cancer treatment is the emergence of multi-drug resistance (MDR) in various cancer cell lines due to mutations in the cell, which limit the successful outcomes in most of the cases. Consequently, there is a requirement of novel advances that are exclusively designed to overcome the menace of drug resistance. Thus, the development of novel, potent, and selective anticancer agents is still one of the most significant areas of modern cancer research and turns out to be the main objective of organic and medicinal chemists across the world. Among the various organic molecules, the nitrogen-containing heterocycles are important building blocks for many bioactive natural products and commercially available drugs. Indazole and its derivatives belong to an enormously important family of nitrogen-containing heterocyclic systems (Figure 1), often allied with a wide range of biological activities [3, 4, 5, 6, 7]. Many of indazole derivatives have been reportedly found to possess potent pharmacological activity such as anti-tumor [8, 9], anti-platelet [10], antiviral [11], antioxidant [12], anti-spermatogenic activity [13], anti-tubercular [14, 15], anti-inflammatory and anti-microbial [16], neuroprotection [17], and COX inhibition activity [18]. Moreover, some indazoles were reported as protein kinase C-B/AKt inhibitors [19], potent IDO1/TDO dual inhibitors [20], and also as 5-HT2, 5-HT3, and 5-HT4 receptor antagonists [21, 22]. Furthermore, many of the synthetic and natural indazole based heterocycles with a sundry mechanism of action have been reported as lead anticancer agents [23; 24; 25]. Importantly, a number of indazole based anticancer drugs (Figure 2) were used clinically. For example, niraparib has been widely used as an anticancer drug for the treatment of recurrent epithelial ovarian, fallopian tube, breast, and prostate cancer [26], pazopanib [27] and axitinib [28] are tyrosine kinase inhibitors approved by the FDA for renal cell carcinoma; these are some of the present-day anticancer drugs possessing a privileged indazole skeleton. These interesting therapeutic properties of indazole derivatives have made them attractive target molecules in organic synthesis. Considering this wide range of pharmacological activities of indazole scaffolds, various methodologies have been developed by the researchers for the synthesis of these moieties, of which many employed transition metal-based catalytic systems. The various metal catalysts that have been employed are [Ir(OMe)(COD)]\({}_{2}\)[29], [Cp*RHCl\({}_{2}\)]\({}_{2}\)[30; 31], CuCl [32], [Cp*CoCl\({}_{2}\)]\({}_{2}\)[33], Pd(OAc)\({}_{2}\)[34], Pd(dba)\({}_{2}\)[35], ZnBr [36], FeBr\({}_{3}\)[37], and NiCl\({}_{2}\)[38]. Very recently, our group developed efficient methodologies towards the construction of various heterocyclic compounds using Cu catalyst [39; 40; 41; 42; 43]. Inspired by the above facts, and in continuation of our efforts towards the development of new heterocyclic moieties of therapeutic importance [44; 45; 46], in the present investigation, we report the synthesis of a series of 3-aryl-1\(H\)- indazoles and \(N\)-methyl-3-arylindazol  
Figure 1: Some biologically active molecules of indazoles. Figure 2: Indazoles containing anticancer drugs. as shown in Scheme 1.