Ortho-Amidation And Meta-Nitration Of 2-Arylbenzothiazole Derivatives And Their Applications

Nitrogenous compounds are widely found in natural products and synthetic compounds.The construction of C-N bond has always been a very important reaction in synthetic chemistry,and has always been one of the research focuses of organic synthetic chemistry.C-H bond is one of the most abundant chemical bonds in nature,and the direct formation of C-H bond through C-H bond activation is one of the most rapidly developed research fields in recent years.Compared with the trad itional method of C-N bond construction,the transition metal catalyzed C-H bond activation and direct functionalization to form C-N bond has many advantages,such as simple synthesis steps,good atomic economy and in line with the concept of green chemistry.Benzo[d]thiazole derivatives are versatile motifs in synthetic chemistry,material chemistry,and the areas related to therapeutic agents,pharmaceuticals,due to their remarkable biological activities and fluorescent properties.2-arylbenzo[d]thiazole compounds have good pharmacological effects,such as anticancer,antibacterial,anti-inflammatory,anticonvulsive and antioxidant.At the same time,these compounds are also important intermediate fragments in drug synthesis.Therefore,the synthesis of benzo[d]thiazole compounds has always been a research focus for organic synthesis workers.Based on the reported of transition-metal-catalyzed ortho-functionalization of2-arylbenzo[d]thiazole by our research group and other research groups,this paper focuses on the functionalization and application of 2-arylbenzo[d]thiazole derivatives.In the first chapter,the research progress of transition metal catalyze C-H bond nitrification and amideation is introduced.In the second chapter,we developed the Rh-catalyzed direct C-H amidation of 2-arylbenzo[d]thiazoles.The transformation is characterized by its efficiency,external oxidant-free conditions,and the avoidance of a traditional three-step process consisting of nitration,ammoniation,and amidation.Furthermore,several of the prepared molecules exhibit bright white-light emission in the solid state.In third chapter,we studied a Ru-catalyzed meta-selective C-H nitration of 2-arylbenzo[d]thiazoles and 2-arylthiazoles.A wide range of functional groups are tolerated,providing the meta-nitrated products in good to excellent yields by using Cu?NO₃?₂·3H₂O as the nitro source.The nitration could be carried out on gram-scale and used to the synthesis of promising therapeutic leads for Human African Trypanosomiasis.In addition,mechanistic studies demonstrated that the reaction may involve the Ru-C?sp²??-bond assisted electrophilic aromatic substitution and a silver-mediated radical process.