C-H, N-H Bond Activation And Polymerization Based On The Later Stage Of Transition Metal

The development of C-H activation faster and faster in recent decades, the new catalyst, the reaction system constant, a lot of reaction has been applied in industrial production. C-H activation products can not be achieved in many organic reactions can be simplified reaction steps. Therefore, chemists search new catalysts and the design of new catalysts to achieve the ultimate solution to global energy issues, green energy for sustainable development and make unremitting efforts. In this paper, the former on the basis of the following aspects:Part I:Herein, we wish to report on the development of a silver-mediated tandem protocol for the synthesis of quinolines involving the oxidative coupling/cyclization of N-arylimines and alkynes. We hypothesized and demonstrated that scenario-dependent metalation could occur either at the ortho C-H bond of an N-arylimine through protonation-driven enhancement of acidity or at the terminal C-H bond of alkynes by virtue of the carbophilic π-acidity of silver. The diverse set of mechanistic manifolds implemented with a single type of experimental protocol points toward the importance of stringent reactivity analysis of each individual potentially reactive molecular site. Importantly, the direct arene C-H bond activation provides a unique and distinct mechanistic handle for the expansion of reactivity paradigms for silver. As expected, the protocol allows for the incorporation of both internal and terminal alkynes into the products and in addition, both electron-withdrawing and-donating groups are tolerated on N-arylimines, thus enabling the vast expansion of substituent architectures on the heterocyclic quinoline framework. Further, an intriguing phenomenon of chemical bond shift and cleavage has been observed for aliphatic internal alkynes. Part II:We have developed a facile and economic method for the fully regio-selective andhigh-yielding protocol for the hydroamination of unsymmetrical internal alkynes represented by ynamides with anilines under mild reaction conditions with AgNTf2. The materials are easily available from commercial vendors, to give synthetically useful enamine derivatives efficiently. This strategy is efficient to build complex structures from simple starting materials in an environmentally compatible fashion. Part III:We have turned our attention to the merger of a late transition metal complex anda Bronsted acid. Our research endeavor into the combination of these two types of chemical structures takes into account the following two considerations:1) The late transition metals enable the creation of a plethora of mechanistically distinct, potentially polymerization-relevant reaction pathways.2) The organometallic reactivity and Lewis acidity of a late transition metal can be tuned through the adjustment of coordination environment and oxidation state of the metal.3) The late transition metals are less oxophilic compared to early transition metals and are therefore more functional group tolerant.4) The Bronsted acids can either serve as potentially viable initiators for cationic polymerization or enter into the coordination sphere of a metal complex through oxidative addition. Herein, we report on the utility of palladium/CF3COOH (TFA) initiating systems for polymerization. Prior to this work, only a couple of sporadic examples of polymerization schemes based on the late metal/Bronsted acid combinations have been briefly mentioned and no systematic study has been documented.The polymerization mechanism could be either cationic or coordination, depending on the oxidation state of the starting metal species (PdⅡ: cationic; Pd0:coordination). No induction period was observed for both of the polymerization systems, indicating the quick formation of propagating center. Block copolymers could be synthesized with the PdⅡ system. We expect that the polymerization results reported herein would contribute to the understanding of chemical reactivity of late metal/Bronsted acid systems.