Study On The Hypervalent Iodine Reagent Mediated Oxidative Cascade Reactions And Related Transformations Of Diarylalkynes

In this dissertation,we focused on the novel cascade reactions mediated by hypervalent iodine reagents.Generally,five kinds of new cascade reactions with high efficiency have been developed as follows:?1?Firstly,the reaction of 1,2-darylalkynes with phenyliodine?III?bis?trifluoroacetate??PIFA?resulted in 35 structurally novel spiro[indoline-2,1'-isoindoline]-3,3'-diones.This unprecedented process encompasses not only two sequential C-N/C-O bond formations,but also the insertion of a carbonyl oxygen,all in one pot under metal-free conditions.Two reasonable mechanisms were proposed after further investigation on the insight of the effective transformation.?2?Secondly,it was discolosed that an exclusive trans-aminocarboxylation and oxoaminocarboxylation of 2-??2-?sulfonamido?phenyl?ethynyl?benzoic acid can be converted to 17 fused and 12 spiro polycyclic heterocycles in the presence of lewis acid and phenyliodine?III?diacetate?PIDA?.This novel protocol features not only a BF₃·Et₂O-catalyzed selective lactonization but also an intramolecular oxidative C-N bond formation process.Notably,both of the products could be obtained through a“one-pot”strategy.?3?Then the isochromenoindolones obtained above can undergo a ring-contraction process involving saponification?or amidation?,disproportionation and spirocyclization to give N-unsubstituted spiro[indoline-2,1?-isobenzofuran]-3,3?-diones and spiro[indoline-2,1?-isoindoline]-3,3?-diones.The advantage of this method includes one-pot,mild conditions,simple operation,transition-metal-and oxidant-free,excellent yields at gram-scale with no column chromatography purification necessary.18 N-H polycyclic products further improved the compound library of spiroindolones.?4?Further study on the aboved mentioned BF₃·Et₂O-catalyzed selective lactonization shows various readily available 2-alkynyl benzoic acids are of high efficiency,affording 21 isochromenone derivatives.In this project,we can control the electronic effect to selectively form the five-membered and six-membered products.?5?In addition,it was found that enamines can be transferred to2-aryl-indole-3-carboxamides,which could realize the final oxidative C–N bond formation to give 16 cytotoxic bioactive molecules indoloquinolinones.