Copper Catalysis Of Methylene Cyclopropane With Potassium Benzyl Trifluoroborate

Dihydronaphthalene derivatives are an important family of organic compounds with significant biological activity in various pharmaceuticals and natural products,which are used as lipoxygenase inhibitors,anti-HIV and anti-cancer active substances and fluorescent ligands for estrogen receptors.Several synthetic methods have been reported for the preparation of dihydronaphthalene derivatives,but most of these methods require expensive catalysts.Therefore,it is important to develop a more simple and efficient catalytic system to construct the dihydronaphthalene skeleton.Methylenecyclopropanes are a class of compounds with high ring tension,which have been used in many transformations due to its structural properties of ternary rings and double bond directly linked to each other.This thesis summarizes the structural properties,preparation methods and reaction types of MCP,which mainly include transition metal-catalyzed,lewis acid-catalyzed,free radical-initiated and photoredox-catalyzed reactions.However,the preparation of benzyl-substituted dihydronaphthalene derivatives is less studied by the opening of ternary rings initiated by the addition of benzyl radicals to double bonds and subsequnce intramolecular cyclization of radicals.In this thesis,a series of dihydronaphthalene derivatives were synthesized by using bisphenyl-substituted MCPs and potassium benzyltrifluoroborate via a tandem ring-opening and ring-closing pathway,CuI as the catalyst,1,10-phenanthroline as the ligand and DTBP as the oxidant.(Scheme 1)The catalytic system has potential applications in the synthesis of drug molecules due to the easy availability of raw materials,high reaction efficiency and a wide range of substrates.In addition,the reaction may undergo a free radical process,which has been confirmed by TEMPO and BHT trapping experiments.