Research On The Synthesis And Fluorescent Properties Of Novel Coumarins

Coumarins and its derivatives are important classes of organic compounds and existwidely in plant. They not only play a significant role in pharmacological activity such asantibacterial, anti-HIV and anticancer activity, but also use in laser dyes, fluorescent probes，fluorescent whiteners due to their outstanding optical properties. In this thesis, we report thesynthesis and spectroscopic characteristics of a several of3-benzylsulfinyl and3-benzylsulfonyl coumarin derivatives，Moreover, the synthesis of two benzimidazolylcoumarins. The thesis consists of the following three parts:In the first part, we reviewed the application of coumarin derivatives in the field ofbiological activities and functional materials, as well as the fluorescent characteristics of thecoumarins. Furthermore, the synthetic methods of coumarins such as Perkin reaction,Knoevenagel reaction, Pechmann reaction and Wittig reaction are introduced.In the second part, the synthesis of several3-benzylsulfinyl and3-benzylsulfonylcoumarin derivatives was studied. Firstly, thiobenzyl alcohol and ethyl chloroacetate was usedas raw material and reacted catalyzed by NaH to afford the corresponding sulfide. Then, thesulfide was oxidized to ethyl benzylsulfinylacetate and ethyl benzylsulfonylacetate by30%H2O2at room temperature and60°C, respectively. Subsequently, these two active methylenecompounds were subjected to Knoevenagel reaction with4-(diethylamino)salicylaldehydecatalyze by piperidine under solvent-free conditions to afford the corresponding3-benzylsulfinyl-7-diethylaminocoumarin (6) and3-benzylsulfonyl-7-diethylaminocoumarin(7), respectively. Moreover, four coumarin derivatives were obtained in this way using2,4-dihydroxybenzaldehyde and2-hydroxy-1-naphthaldehyde as starting materials. Thesynthetic compounds are characterized by1H NMR,13C NMR and HRMS. Typically, thecrystal structure of3-benzylsulfonyl-7-diethylaminocoumarin (7) was determined by X-raycrystal analysis. Futhermore, the UV–vis absorption spectra and fluorescence spectra of thesecoumarins were tested.In the third part, the synthesis of two benzimidazolylcoumarins was studied. Firstly,using4-(diethylamino)salicylaldehyde as starting material,7-diethylaminocoumarin wasobtained through the Wittig reaction. Then the coumarin was formylated by POCl3/DMF toafford the corresponding3-aldehyde-7-diethylaminocoumarin. Meanwhile, starting from3-diethylaminophenol,4-methyl-7-diethylaminocoumarin was obtained via Pechmannreaction, which was oxidized by SeO2to afford4-aldehyde-7-diethylaminocoumarin.Subsequently, these two formylcoumarins were reacted with o-phenylenediamine in thepresence of NaHSO3to afford3-(2-benzimidazolyl)-7-diethylaminocoumarin (20) and 4-(2-benzimidazolyl)-7-diethylaminocoumarin (25). These two benzimidazolylcoumarinswere characterized by1H NMR,13C NMR and HRMS spectra.