Photocatalytic Hydrogen-Evolving Cross-Coupling Of Arenes With Primary Amines

The aryl structures are one of the most common structures in complex molecules.Aromatic reactions have a wide range of applications in both organic and chemical industry.Due to its importance,chemical researchers have developed a variety of strategies for construct of aryl C-C bonds and C-X bonds.Prefunctionalization of the starting materials is usually required for transition-metal-catalyzed cross-coupling reactions.The direct functionalization of aryl C-H bonds has attracted tremendous attention since this method circumvents the need for prefunctionalization of either coupling partner.However,the requirements of expensive sacrificial oxidants hamper the widespread application of this method.Photocatalytic C-H activation can achieve cross-coupling hydrogen evolution reaction without any sacrificial oxidants under mild conditions,which has a widespread application,and has attracted tremendous attention and research.In this paper,we focus on the latest development of photocatalytic hydrogen-evolution cross-coupling reaction,and expands the method of constructing C-N bond between arenes and primary amine with the shortcomings in development.The paper will be introduced by two parts:Part ?.Review of the strategies of oxidative cross-coupling and dehydrogenative cross-coupling in recent years.Part ?.Introduction of the work.We have developed a strategy for the direct C-H amination of arenes and primary amine by combining an photoredox catalyst with a proton-reduction catalyst under mild reaction conditions,hydrogen is generated as the only side product.A series of arenes and primary amines smoothly underwent the reaction.This protocol has wide substrate scope,functional group tolerance,and high regioselectivity.The sensitive functional group,such as methyl substituent and ethyl substituent,are also tolerated in these oxidant-free conditions.We have also found that the chiral amine afforded the secondary amine in good yield with retention of stereochemistry.Stern-Volmer quenching experiments and light on/off experiment are conducted to exploring the mechanism of reaction.A proposed mechanism is proposed.