Study On The New Organic Reactions By Employing Aryne Insertion Strategy

Arynes,as important organic synthesis intermediates,have been widely used in the efficient synthesis of natural products,alkaloids,and functional materials.Generally,aryne intermediates possess high reactivity even under mild condition,thus undergoing easily electrical attacks by nucleophiles to construct new C–C bond and C–X bond in high regioselectivity,which have considerable practical value in the organic synthesis.At the current stage,study on the formation of new chemical bonds by aryne chemistry has been one of the new topics.However,the traditional methods for synthesizing arynes are dramatically limited by harsh conditions and narrow substrate scope,which hampered the further application of arynes.In recent years,much advancement has been made in the development of aryne chemistry.Particularly,the aryne precursor,2-?trimethylsilyl?pheny trifluoromethanesulfonate,was found to be a competing alternative to the other conventional ones,which features high efficiency and easy handling.This thesis contains two sections involving the aryne insertion,which is listed as follows:?1?2-?Trimethylsilyl?pheny trifluoromethanesulfonate can react with a series of3-phenyl-1,2,4-oxadiazol-5?4H?-one in the presence of CsF in CH₃CN to proceed toward O-arylation and N-arylation,respectively.It was found that only a catalytic amount of AgNO₃ absolutely control the O-arylation orientation.Inversely,N-arylation occurred in absence of silver salts,producing N-arylated products in high selectivity.It should be noted that excellent group tolerance was present in the both arylations,and which provides an efficient and convenient method for synthesis of aryl ether compounds.?2?A new cycladdition of azobenzene react with O-trimethylsilylphenyl triflates?3?has been developed in the presence of cesium fluoride as base in acetonitrile at 80 ^oC for 8 h.The results showed that a synergistic[2+2+2]cycladdition may be involved in the process,including the cleavage of N=N bond and dimerization of arynes.The rare cycloaddition can proceed well in open air without any transition metals or additives,giving a number of complex N-containing molecules in moderate yields.This cyclization further expand the reaction types of azobenzenes.