Studies On Copper(Selenium)/Selectfluor System Mediated Tandem Cyclization Reactions

Cyclic structure is an important structural unit in many pharmaceutical molecules and natural products.Many complicated molecules even include two or more cyclic units.Copper-catalyzed tandem cyclization reactions can provide concise and efficient methods for the construction of C-C bond and the C-X bond(X = N,O,S,etc.),thereby providing an effective approach for the synthesis of complicated cyclic compounds.The cascade annulation reaction is widely used in the synthesis of natural products,pharmaceutical molecules and new materials,and become one of the indispensable synthetic tools in modern organic synthesis.In recent years,more and more copper-catalyzed tandem cyclization reactions have been reported.In order to enrich the diversity of copper-catalyzed organic reactions and provide more convenient routes for the synthesis of cyclic compounds,we attempted to study the Cu/Selectfluor systemcatalyzed tandem cyclization with hope to develop more concise and efficient methods for the synthesis of cyclic compounds.This dissertation is divided into six chapters:In the first chapter,firstly,we briefly reviewed the recent progress of copper-catalyzed tandem annulation reactions based on different reaction types,including coupling reaction,C-H bond activation reaction,and free radical reaction.Then we introduced the background of this research.In the second chapter,we investigated the Cu/Selectfluor system catalyzed tandem cyclization reaction of 1,6-enynes to access 5-arylbenzofluorenones and 5-fluorobenzofluorenones with high selectivity.In my opinion,this tranformation is an interesting transformation,exhibiting a good chemical selectivity and a range wide scope of the substrats,and the highest yield was up to 90% and 82%,respectively.Several control experiments were carried out to probe the reaction mechanism involves tandem oxycupration and annulation followed by aromatization to give the final products.This method can be used as a general method for the synthesis of a series of benzofluorenone derivatives.In the third chapter,we investigated the Cu/Selectfluor system-catalyzed double C-H activation/oxygen insertion of 2-arylbenzaldehydes or 5-arylpyrazole-4-carbaldehydes.This reaction has advantages of easy availability of the starting materials,simple operation and good compatibility of the substrates,and the highest yield was up to 87%,and could be provided a simple and high efficient route for the synthesis of heterocyclobenzopyranones.Simultaneously,Several control experiments were carried out to probe the reaction mechanism involves oxycupration and C-H Functionalization.In the fourth chapter,we investigated the Cu/Selectfluor system-catalyzed intramolecular cross-dehydrogenative coupling of aldehyde C-H and aromatic sp2 C-H bond.This reaction exhibits a good scope with respect to various o-aryloxy benzaldehydes in synthetically useful yields of xanthone derivatives,and the highest yield was up to 95%.It could be used to synthesize phenanthridinones and thioxanthenone 10,10-dioxides.In the fifth chapter,we investigated the Se/Selectfluor system-catalyzed tandem annulation/oxidative reaction of o-aryl acetophenones to construct a variety of 9,10-phenanthrenequinones.This reaction has advantages of easy availability of the starting materials,simple operation and eco-friendly,and the highest yield was up to 76%.In addition,this method could also be applied in the synthesis of plant growth regulators.In the sixth chapter,we summarized the research contents of this dissertation,and prospected the future development trend of Cu/Selectfluor system and pointed out the necessity of developing other zero-valent metal or nonmetal/Selectfluor combined systems.