Synthesis Of Cyclobutene And Fluorenone Derivatives By Palladium Catalyzed Tandem [2+2] And [4+2] Cycloaddition

Tandem reactions are often used to synthesize various compounds because they have high reaction efficiency and can synthesize complex structures with fewer reaction steps.During the decades,the chemistry of allenes has been extensively studied.They have shown interesting reactivities and selectivities while making complex structures.In particular,the [2+2] cycloaddition of allenes represents an important strategy for the preparation of cyclic compounds.However,the [2+2]cycloaddition of most allenes has some problems,such as isolation of allene compounds,high reaction temperature and long reaction time.The first section of this thesis was the synthesis of cyclobutane derivatives using iodoheptynones via a tandem reaction under Pd catalysis,which did not require isolation of allene intermediates,the reaction temperature was lower and the reaction time was also shorter,providing a highly efficient way to synthesize cyclobutenoid derivatives.The second section of this thesis is the production of fluorenone derivatives using [4+2] cycloaddition reaction between allenes and iodoalkynones catalyzed by palladium catalyst.Fluorenones are an important class of organic compounds that have attracted extensive attention due to their important applications in biomedicine and optoelectronic materials.Most of the methods for synthesizing fluorenone derivatives require high temperature,high pressure and long reaction time.However,the substrates synthesized in this work could be obtained efficiently by one step using tandem reaction under mild conditions.