Pd(0)-Catalyzed Intermolecular Dearomatizing [3+2] Spiroannulation Of Phenol-Based Biaryls With Allenes

Cyclohexenones are a class of important structural motifs with broad distribution in biologically active natural products and pharmaceuticals.The featuring of cyclic skeleton and active ketene functionality renders them key intermediate in organic synthesis.As a result,developing highly efficient and convenient synthetic methods to this skeleton is of great significance.Among the various methods,the transition-metal-catalyzed dearomatization of phenols has drawn great attention due to their atom economy and step-economy.In this thesis,we intend to describe a palladium(0)-catalyzed intermolecular dearomatizing [3 + 2] spiroannulation of phenol-based biaryls with allenes,leading to the formation of a series of spirocyclic molecules containing a highly valuable terminal olefin moiety.And the detailed contents can be divided into the following two chapters:In the first chapter,we summarized the transition metal-catalyzed intra-and intermolecular dearomatizing cyclization based on phenol-based biaryls.Some conventional transition metal,such as palladium-,iridium-,gold-,rhodium-etc,catalyzed intramolecular dearomatization has been discussed in detail.Additionally,we have also introduced the development of intermolecular dearomatization reactions under oxidation and non-oxidative reaction conditions,respectively.In the second chapter,Readily available phenol-derived biaryls reacted with allenes under palladium catalysis to provide a variety of highly valuable spiro[cyclohexane-1,1?-indene]-2,5-dien-4-ones.In the presence of palladium(0)catalyst,the reaction successively undergoes the steps of oxidation addition,migration insertion and reductive elimination to build target compouds.Preliminary asymmetric studies showed that high enantioselectivity(80% ee)could be realized by using a commercially available PHOX ligand.Moreover,the potential application of this method was exemplified by several further transformations,including oxidation,isomerization and epoxidation.