Rhodium(â…¢)-Catalyzed Direct Functionalization Of Pyridines And Vinylation Of Arenes

In the past seven years, Rh-Catalyzed C-H activation has got stupendous progress and shows powerful catalysis efficiency since more and more publications about chelation assistance have been reported, especially on coupling with alkenes and alkynes. The pyridine ring is a common motif found in nature and have extensive application in pharmaceuticals, agrochemicals, as well as material science. Consequently, tremendous efforts have been made to construct these scaffolds. There are quite a few reports on C2-H functionalization of pyridines, however, there are still few reports on C3-H. Hence, we try to apply Rh to C3-H functionalization of pyridines and explore much more reaction types on Rh Catalysis. The main content of this dissertation is summarize as follows:1. Rhodium(â…¢)-Catalyzed Oxidative Olefination of Pyridines and Quinolineswe have achieved the effective oxidative olefination of both pyridine pivalamides and quinoline pivalamides at the ortho-position of the directing group, which involves a rhodium(â…¢)-catalyzed C-H activation pathway using Cu(OAc)2as a convenient oxidant as well as Lewis acid. The pivalamide not only serves as a directing group, but also could be considered as a protecting group. This protocol was operationally simple and could be successfully applied to an expeditious, multigram-scale synthesis of naphthyridinone with low catalyst loading.2. Rh(â…¢)-Catalyzed Oxidative Olefination of Picolinamides:Convenient Synthesis of3-Alkeny lpicolinamidesWe have developed an efficient Rh(â…¢)-catalyzed oxidative olefination of picolinamides with carboxamides as directing groups. The reaction protocol provides an expedient route to the functionalization of pyridine derivatives with several advantages, including low catalyst loading (0.5mol%in most cases), high yield and good functional group tolerance. When secondary piconilamides were coupled to ethyl acrylate, the olefination-cyclization products were obtained in good yields. The E configuration of the exocyclic double bond was confirmed by NOESY.3. Rh(III)-Catalyzed C-H Activation of Arenes via chelation assistance:Access to Terminal AlkenesWe have found that arenes could couple with vinytriethoxysilane to form terminal alkenes, which undergoes Rh(III)-catalyzed C-H activation of arenes via chelation assistance. The directing groups can be pyrrolidones, pivalamides, benzamides as well as aryl ketones, which are weakly directing groups. The reaction proceeded with moderate yields due to the unbalanced materials.