Methodological Study Of Organic Boron Compounds As Reducing Agents In Organic Synthesis

Compounds contained carbon-nitrogen?C-N?bonds skeletons are one of the important synthetic skeletons and organic intermediates in the field of organic synthesis.They are also the most basic in a wide range of natural products,pharmaceutical molecules and agricultural products.The structure of C-N bonds has become a hot area of research by researchers,especially by organic synthesis scholars.Although there are various methods to construct C-N bonds,the method of constructing C-N bonds by reducing is also faced with the problem of selection of hydrogen sources and reducing agents.The organoboron compounds have a certain degree of reducibility by means of hydrogen sources.H₂O is a hydrogen source in the reduction reaction,and its advantages are self-evident.In addition,D₂O has obvious advantages as a source of helium.Therefore,the application of organoboron compounds as reducing agents in organic synthesis is the research direction,and a novel efficient method to construct the formation of C-N bonds has been realized.The application of a novel organoboron reagent in hydrogen transfer reaction has been carried out.On the one hand,the application of B-B/H₂O system in reductive amination is studied.According to the investigation and application of B-B/H₂O system,this paper proposes a convenient and mild Ru-catalyzed reductive amination reaction between aldehyde and primary amine using B₂?OH?₄/H₂O system.The method can accomplish the reductive amination reaction of aldehydes simply and efficiently,and exhibits excellent chemical selectivity to unsaturated and heteroaromatic aldehydes.In the B₂?OH?₄/D₂O system,a high yield,high deuteration rate of?-carbon deuterated secondary amine compounds are obtained.On the other hand,a reaction study on the participation of carboxylic acid in which H₃B·NH₃ involved as an N-alkylating agent is carried out.In this part,a convenient,mild,metal-free reaction study of an amine with a hydrogen source of H₃B·NH₃ and carboxylic acid as N-alkylating agent is investigated.The reaction confirms that the amide is the main intermediate by a control experiment.Both primary and secondary amines can be alkylated with carboxylic acid.In the case of primary amines,single and dialkylated products can be selectively obtained.This reaction shows excellent functional group compatibility,an aliphatic,aromatic and unsaturated carboxylic acid can perform N-alkylation reaction well.Under this catalytic system,a series of secondary and tertiary amines are successfully obtained.In addition,a method for synthesizing a class of fluorine-containing amine compounds and drug molecules can be performed,and some drug molecules or natural products can also be characterized.In this thesis,a class of secondary amines,?-carbon secondary secondary amine compounds,tertiary amine compounds are gained by organoboron compounds as reducing agent.The compounds are simple in preparation,high in reaction and stable in chemical properties.Simple drug molecule as well as potential natural product,drug molecular skeleton precursor structure compounds can be synthesized.The use of this system to explore the synthesis of such compounds has important scientific significance and potential application values.