Synthesis Of 4H-cyclopenta[c]furan-5(6H)-one Derivatives And 1-oxaspiro[4.5]dec-2-ene-6,10-dione

In this thesis,the synthetic methods of two kinds of heterocyclic compounds,4H-cyclopenta[c]furan-5(6H)-one and 1-oxaspiro[4.5] dec-2-ene-6,10-dione,were studied.On the basis of our theory reported in literature and experimental results,reasonable reaction mechanisms are proposed.The paper is divided into three parts for discussion.In the first chapter,synthesis of furan derivatives and the related reactions of decomposition of diazo compounds have been reviewed.In the second chapter,synthesis of 4H-cyclopenta[c]furan-5(6H)-one is investigated.First,?-yne-?-ketone compound is subjected to cyclization reaction to synthesize a series of diazofuran ring derivatives.The optimized conditions for the synthesis of this diazofuran derivative are as below: 2 mol% Ph3 PAu Cl,2 mol% Ag OTf and 5 mol%p-Ts OH·H2O,toluene as solvent,N2,at 0 o C.Under the optimized reaction conditions,two products,that is,2-diazo-3,6-dioxo-5-propionyl caprylate and diazofuran derivatives,were obtained.The diazofuran derivatives as our target products were obtained only in yield of 0-63%.The 2-diazo-3,6-dioxo-5-propionyl-octanoate compounds can be converted into diazofuran derivative in the presense of 5 mol%p-Ts OH·H2O under these conditions such as toluene as solvent,N2 and at room temperature.At first,Rh2(OAc)4-mediated conversion of the diazo group of the diazofuran derivatives into rhodium carbenoid wasaccomplished,and sequent C-H insertion reaction on the furan ring obtained 4H-cyclopenta[c]furan-5(6H)-one derivatives.This is first C-H insertion reaction of metal carbenoid on the furan ring.The optimum conditions for the C-H insertion reaction on the furan ring are as below:10 mol% Rh2(OAc)4 as catalyst,anhydrous 1,2-dichloroethane as solvent,at 25 o C,N2.Under these optimized conditions,various diazofuran derivatives can be converted to 4H-cyclopenta[c]furan-5(6H)-one,and the yield is 20-83%.The method possesses some advantages such as simple operation,mild reaction conditions and so on.In the third chapter,the synthesis and application of 1-oxaspiro[4.5]dec-2-ene-6,10-dione were investigated.In 5 mol%Rh2(OAc)4/anhydrous 1,2-dichloroethane system,a series of 1-oxaspiro[4.5]dec-2-ene-6,10-dione derivatives were obtained starting from iodine ylide and acetylene ketone(ester).The optimized conditions for the synthesis of the 1-oxaspiro[4.5]dec-2-ene-6,10-dione derivative are as below: 5 mol% Rh2(OAc)4 as catalyst,1.0 equivalent of Et3 N,anhydrous1,2-Dichloroethane as solvent,at 80 °C,N2.This method is unique for the synthesis of 1-oxaspiro[4.5]dec-2-ene-6,10-diones due to mild conditions,simple manipulation,good yield and wide range of substrates.