Copper-activated C-B/C-H Coupling Reaction

Metal catalytic organic chemistry is one of the frontier subjects of modern chemical research.Currently,the Transition Metal-catalyzed cross coupling reaction is one of the most effective way to build carton-carton bond and carton heteroatomic bond.In particular,the noble metal palladium,which have excellent catalytic activity,high stereoselectivity and chemical selectivity,offers simple access to elusive chemical reactions.In recent years,low-cost and low-toxicity copper catalyst are markedly developed to replace palladium catalyst.However,due to its complexity,the catalytic active compound which participates in reaction is usually hard to get,and unraveled mechanism makes it a challenge to systematically explore this kind of reaction,which is,on the other hand,an opportunity for future studies.This paper first summarizes the metal catalyst and its application,then according to the development of green chemistry and the early Ullmann condensation reaction,leads to the copper catalyzed coupling reaction.At the same time,it emphatically introduces the research and the developing status of copper catalyzed C-B/C-H coupling reaction.In these two classic coupling reaction,copper generally participates in the reaction as co-catalyst,while its independent participation in reaction is limited to active substrates.Mechanism studies prove that the activation methods of copper catalyst and palladium catalyst are different and complementary.This projectuses copper as catalyst/co-catalyst,and through the system filter design,mild-condition copper catalyzed/assisted coupling reaction are achieved.Details are as follows:(1)The second chapter of this paper listed the reported copper-catalyzed homocoupling of arylboronic acids and the effects of all kinds of substrates and additives on the reaction.In order to explore the general method of copper-catalyzed arylboronic acids homocoupling,we comprehensively evaluated different copper species and additives,and finally concluded that products could be afforded in high yields in 15 minutes at room temperature with catalytic amounts of alkali as additives,CuCl2·2H2O,which is cheap and easy to store,as catalyst,and methyl alcohol as solvent.Of note,the reaction were conducted in the presence of air and have a wide range of substrate adaptability.(2)In the third chapter of this paper,we summarized the activation process of aryl chloride substrates,and the development process of the C-H coupling of azole and chlorinated substrates.Then found that multi-metal catalysis is the effective strategy which makes this kind of coupling mild,controllable and selective According to the optimal screening of different catalyst and reaction system,we chose Pd(OAc)2(2 mol%)/NiXantPhos(3 mol%)and CuI(1mol%)/NiXantPhos(1.1 mol%)as double catalytic system,and successfully made effective use of a wide range of aryl(aromatic heterocycte)chlorinated substrates under mild and controllable conditions.What's more,this catalytic system selectively catalyzes heterocyclic unactivated substrates with larger steric hindrance.