Study On Synthesis Of Aryl Difluoromethyl Selenyl Ether From Aryl Boric Acid

Fluorine containing organic compound is nearly non-existent in nature,which provides unlimited opportunities for organic chemists to prepare them.Incorporation fluorine atoms to the molecules will greatly change their properties due to the special character.Hence,fluorine containing molecules are widely used in materials,medicine,pesticides and other fields.Since Fluorouracil come into the market,there is a growing interest in the research of fluorinated drugs.Up to now 30 percent of the drugs in the market are fluorinated drugs.The introduction of fluorine-containing groups especially trifluoromethyl group,trifluoromethylthio group,difluoromethyl group and difluoromethylthio group is a hot topic for organic chemists and medicinal chemists.However,the research for the introduction of trifluoromethylselenyl group and difluoromethylselenyl group is rare.Therefore,the development of new fluoromethylselenyl reagents is one of the hot topics for organic chemists.As we all know,aromatic boric acids,which are commercial available reagents,are widely used in organic synthesis and drug synthesis.Based on the literature and previous research of our group,a novel method to transfer aromatic boric acids to difluoroseleno ether was developed.In this thesis,difluoroselenolation of aromatic boric acid was realized by using Se-(difluoromethyl)4-methylbenzenesulfonoselenoate as difluoroselenolation reagent under copper catalysis at room temperature.First,the reaction condition was screening by using different catalyst,ligand,base,solvent and temperature and the optimized reaction condition was determined.Then the generality of this reaction was investigated.The substrate scope of this reaction is broad and the most of the desired products were obtained in good yield.Finally,the mechanism of this transformation was investigate and found that 1,2-bis(difluoromethyl)diselane was generated from Se-(difluoromethyl)4-methylbenzenesulfonoselenoate in the present of copper catalyst,which reacted with aromatic boric acid to give the desired product.This paper uses TsSeCF2H to develop the method of preparing aromatic difluoroselbente.Optimal reaction conditions:aromatic boric acid(1.2 eq),TsseCF2H(1.0 eq),copper acetate(0.1 eq),potassium carbonate(1.0 eq),4,4’-dimethyl-2,2’-eq(L2)(0.1 eq),acetylene(0.24 mol/L),at room temperature,get target compounds.Forty desired products were synthesized and twenty seven of them are new compound.The structure of the new compound was confirmed by 1H NMR,13C NMR,19F NMR and high resolution mass spectrum.