Studies On Radical Cyclization Of Para-Qumone Methides For The Synthesis Of Cyano-containing Benzofuran-2-ones

para-Quinone methides(p-QMs),which are chemically defined as neutral and zwitterionic resonance entities,are used extensively with its high reactive species in organic chemistry.Benzofuranones usually occur in a wide variety of natural products and medicines.The developent of new synthetic methods toward these molecule skeletons are one of the hot spots in the organic synthetic community.The thesis focused on the synthesis of cyano-containing benzofuran-2-ones via radical cyclization of para-quinone methides.The main contents are as follows:First,reviewing the progress on 1,6-conjugate addition of p-QMs,as well as the synthesis and modification of benzofuranone skeletons.Secondly,using the dipropylamine as the catalyst,the condensation reaction of arylaldehyde and 2,6-disubstituted phenol proceeds smoothly,thereby affording 23p-QMs compounds.Thirdly,we develop a new method for the construction of benzofuranones and derivatives via a radical cascades of p-QMs with AIBN by Cu catalysis.In the presence of CuI(20 mol%),this cascade proceeds smoothly through 1,6-conjugate addition,aromatization,?-cyanoalkylation by C(aryl)-C(~tbutyl)bond cleavage,and downstream cyano-insertion/cyclization/hydrolysis,which leads to cyano-containing benzofuran-2(3H)-ones.Moreover,the cyclization reaction enables a gram-scale syntheis of benzofuran-2(3H)-ones.Apparently,the protocol provides new access to cyano-containing benzofuran-2(3H)-one scaffolds,as well as the new concept for the difunctionalization of p-QMs.The last part,based on the experimental results and documented papers,a possible mechanism was proposed.In addition,computational studies using unrestricted density-functional theory(DFT)revealed that the mechanism is reasonable and scientifical.Then,benzofuran-2(3H)-ones can be transformed into pharmaceutically important benzofurans by a reduction and treatment of Lewis acid sequence.