Studies On The Reductive Oxy-Nazarov Electrocyclization Reaction:New Method For The Synthesis Of 4-Hydroxy-2-cyclopentenone And Exploration Of Constructing Cycloheptenone Via 6?-Electrocyclization

In the first chapter of this paper,Nazarov electrocyclization is summarized,the development of chemical selectivity and stereoselectivity controlled Nazarov electrocyclization is systematically introduced.The reductive oxy-Nazarov electrocyclization developed by our research group is highlighted.Reductive oxy-Nazarov electrocyclization is a new type of Nazarov electrocyclization(Scheme 1),which has the characteristics of stereospecificity and wide adaptability of substituents.It has been applied to the total synthesis of homoharringtonine,a natural drug.In the second chapter,the synthesis methods of 4-hydroxy-2-cyclopentenone are described.We design 4-ethoxypentadienyl ester as a new precursor of cyclization,and construct 4-hydroxy-2-cyclopentenone based on reductive oxy-Nazarov electocyclization(Scheme 2),which extended the range of substrates for reductive oxy-Nazarov electrocyclization and developed a new method for synthesis of 4-hydroxy-2-cyclopentenone.In Chapter 3,the construction methods of cycloheptenone structural units from simple cycloheptenone compounds to complex natural products are systematically introduced.Based on reductive oxy-Nazarov electrocyclization,we design heptantrienyl ester as precursor compound for cyclization,and intend to explore the constructon of cycloheptenone via 6? electrocyclization by reduction of Dibal-H.Although the construction of cycloheptenone has not yet been realized in the present experimental studies,six-membered cyclization products were unexpectedly found in the process of exploration,and the cyclopentenone product was obtained in the reduction process of Dibal-H(Scheme 3).