The Development Of New Dearomatization Strategies And Their Application In The Synthesis Of Complex Molecular Scaffolds

The dearomatization reaction of arenes has drawn tremendous interests from synthetic and pharmaceutical chemists due to both the readily available and cheap starting materials as well as the versatile dearomatized products.The great practicability of this transformation has been elegantly highlighted by their successful application in the synthesis of numerous natural products.Despite great efforts have been made,there is still a lack of efficient and reliable methodologies,especially in a direct catalytic asymmetric manner,to disrupt the aromatic ?-system systematically.Therefore,development of more novel and general dearomative methodologies is of great significance and urgently needed.This dissertation focuses mainly on the development of new methodologies for the dearomatization of phenols and indoles.In our works,a dearomative Diels-Alder reaction was developed and successfully applied to a continuous dearomatization process of phenols.Besides,we also realized asymmetric construction of vicinal all-carbon quaternary stereocenters and synthesis of a variety of polycyclic compounds of medicinal value by utilizing dearomatization strategies.The dissertation includes five chapters.The first chapter reviews the recent developments in catalytic asymmetric dearomatization reactions of phenols and indoles.In chapter 2,we developed an organocatalyzed asymmetric dearomatization reaction of ?-naphthols with 3-bromooxindoles under mild reaction conditions.This protocol,to the best of our knowledge,is the first example of constructing vicinal all-carbon quaternary stereocenters via a dearomatization process of ?-naphthols.In chapter 3,we realized chiral phosphoric acid catalyzed continuous dearomatization processes of phenols by employing a newly developed dearomative Diels-Alder reaction.The dearomative 1,8-addition and subsequent intramolecular cycloaddition made the current process especially intriguing.In chapter 4,we reported a catalyst-free 1,3-dipolar cycloaddition of C,N-cyclic azomethine imines and 3-nitroindoles.The current methodology is of vital significance by virtue of the mild and facile reaction conditions and also the efficient incorporation of the two intriguing skeletons(tetrahydroisoquinoline and indoline)of medicinal value.The last chapter is a brief summary of our works and prospect about this research field.