Reactivity Of Osmacyclopropene-fused Osmapentalenes With Aldehydes Or Allenes

Metallaaromatic chemistry,which has drawn increasing attention,is a very important branch of organometallic chemistry.Our group has carried out a series of researches in the field of Metallaaromatic chemistry and has achieved certain achievement in recent years.In 2015,our group reported the synthesis of metallacyclopropene within osmapentalene derivate.Preliminary studies sh ow that the compound is susceptible to ring-opening,ring-expanding and ring-enhancing reactions with unsaturated substrates due to its ring strain.In addition,the metallacyclopropene unit of the compound has a certain nucleophilic properties.Based on this,the reactions of metallacyclopropene within osmapentalene derivate were investigated.a series of metallapentalynes and metallapentalenes were constructed.The applications of metallapentalyne in molecular oxygen activation and transformation was investigated based on the reactivity of metal carbyne.The dissertation consists of the following five chapters:In chapter 1,the general conception and criteria of aromaticity were briefly introduced.In addition,the reactivity of metal carbenes and small molecule activation mediated by transition-metal complexes were also summarized.In chapter 2,the reactions of metallacyclopropene with aldehydes were investigated.Utilizing the nucleophilicity of the metallacyclopropene.a series of metallapentalynes and metallapentalenes were constructed.Besides,an oxygen coordinated metallapentalene was synthesized by the reaction of metallapentalyne with oxygen in the presence of sodium methoxide..and its application in the activation and transformation of molecular oxygen was also investigated.In chapter 3,the reactions of metallacyclopropene within osmapentalene derivate with alkynes were investigated.By controlling the addition of different reagents,the opening/closing/expansion control of the metallacyclopropene unit is achieved.In this chapter,a new method for preparing planar MCPP compounds starting from metallapentalynes were disclosed.All above lay the foundation for the subsequent expansion and enrichment of carbonlong chemistry.In chapter 4,the activation and transformation of molecular oxygen catalyzed by a osmium peroxo complexes were investigated.Experiments have suggested that in addition to catalyzing the oxidation of alcohols to aldehydes,peroxo complexes can also catalyze the oxidation of aldehydes to nitriles in the presence of ammonium source.The reaction exhibited a good functional group tolerance and substrate application range.This discovery expands the application range of carbonlong compounds and provides a new way for the synthesis of nitrile compounds.In chapter 5,the summary of this dissertation was concluded and the prospect of this research was also presented.