Study On Oxidative Coupling Reaction Of Spin - 2 Hydrogen - Bonding Based On Nitrogen And Oxygen Coordination

Transition-metal-catalyzed C-H bond activation/functionalization has constituted an expedient carbon-carbon and carbon-heteroatom bond formation protocol with features of step economy and green chemistry primarily, and therefore, laborious arene prefunctionalization like that required for traditional palladium(0)-catalyzed cross-coupling reactions such as the Mizoroki-Heck reaction would be or is now no longer required in many cases. This thesis introduced two novel synthetic methods via directing C-H functionalizations:palladium-catalyzed alkenylation via sp2 C-H bond activation using phenolic hydroxyl as the directing group and palladium-catalyzed direct C(sp2)-H alkoxylation of 2-aryloxypyridines using 2-pyridyloxyl as the directing group.Hydroxyl is a very important functional group in organic chemistry, and also, it exhibits weak coordination to transition metals. This characteristic enables it to play an important role in several transition-metal-catalyzed transformations. We have developed a new Pd-based catalytic system that successfully effects C-H alkenylation of 2-arylphenols to produce 2-(2’-alkenylphenyl)phenols selectively in moderate to good yields. The reaction proceeds in an atmosphere of air under relatively mild reaction conditions which can tolerate a series of functional groups and provides the alkenylation products regio-and stereoselectively in moderate to good yields.Compared with the transition-metal-catalyzed direct aromatic C-C bond formation reaction, the alkoxylation of inert C-H is more difficult and still needed to be studied more adequately. On the other hand,2-phenoxypyridine series compounds have interesting bioactivities and have aroused much attention in the pharmaceutical field. Therefore, an efficient and highly regioselective palladium catalyzed ortho-C(sp2)-H bond alkoxylation of 2-aryloxypyridines was developed using 2-pyridyloxyl as the directing group and alcohols as alkoxylation reagents. This technology was available for both primary and secondary alcohols. The reaction could proceed smoothly in an air atmosphere under mild reaction conditions, making the method highly applicable.