Studies On The Reactions To Construct B-N Bond In Nido-Carborane

Carboranes have three – dimensional aromaticity and high stability.In another side,carboranes have high boron content and low biological toxicity,which makes carboranes exhibit potential commercial value and application prospects in fields such as catalysis,biomedicine and materials.Therefore,post – modification of carboranes is of great significance.Methods including non – directed metal catalysis,directed transition metal catalysis and photocatalysis have been developed for the functionalization of carboranes in the recent years.At present,the research on closo –carborane has been gradually improved,while there are less research on nido –carborane,and it is mostly concentrated on the bare five membered ring plane.This paper introduces the method of using nido – carborane to synthesize charge –compensated neutral carborane compounds.The specific content is divided into the following two parts:1.The coupling reaction between nido – carborane and N – containing heterocycles promoted by DDQIn this chapter,the organic oxidant dichloro-dicyano – benzoquinone(DDQ)was used to achieve the coupling reaction between nido – carborane and N – containing heterocycles.Compared with the reported literature,the reaction condition was mild,the products can be efficiently obtained in a short time.Besides,the reactivity of pyridines,quinolines and azole compounds was explored.According to the calculation from density functional theory and experimental results,a new mechanism involving single electron transfer,hydrogen transfer and nucleophilic attack was proposed.At last,gram amplification reaction was carried out,and the applicability of drug molecules was studied,Then the stability of products and optical properties such as aggregation induced luminescence(AIE)were explored.The facile synthesis has application potential for materials and pharmaceuticals2.Photocatalytic coupling reaction of nido – carborane with aminesIn this chapter,the coupling reaction of nido – carborane and amine catalyzed by visible light was studied.This reaction is applicable to primary and secondary amines,but not to tertiary amines and aniline compounds.Based on the existing literatures,the mechanistic cycle of photocatalytic coupling reaction was proposed: the excited photocatalyst undergoes a single electron transfer reaction with the substrate,and then a hydrogen transfer reaction occurs in the system,eventually two substrates were coupled.