Synthesis And Characterization Of Nitrogenous Derivatives Of Coumarin

Coumarin and its derivatives are widely found in natural products and have a variety of biological activities,such as anti-tumor,anti-inflammatory,anti-malaria,anti-bacterial and anti-oxidative activities.The benzopyran ring in the coumarin is an excellent fluorescent group,because of its strong and stable fluorescence emission,and good structural flexibility.It has many applications in the field of fluorescent materials,fluorescent probes,etc,such as the detection of metal ions,has the characteristics of good selectivity and high sensitivity.Metformin is one of the most extensive and effective drugs for the treatment of diabetes,and it is also one of the common precursors for the synthesis of heterocyclic compounds such as triazine and pyrimidine.Triazine compounds are used as herbicides,anti-tuberculosis,antibacterial,anti-inflammatory,anti-cancer and the treatment of diabetes.Pyrimidine is an important pharmaceutical intermediate,a pharmacophore for some anti-tumor,anti-HIV,and antibacterial drugs;it is also a precursor of common photosensitizers.The hydrazide,acylhydrazone and nitrogen-containing heterocyclic product oxadiazole used as a precursor for the synthesis of nitrogen-containing heterocyclic rings are often used as anionic and cationic fluorescent probes,and have good biological activities,such as antibacterial,herbicidal,insecticidal,etc.In this paper,a series of triazine,pyrimidine,pyrazole,acylhydrazone,dihydrazide,oxadiazole compounds containing coumarin ring were synthesized,and related fluorescence properties were determined.The substituted coumarin-3-ethyl carboxylate or 3-acetyl coumarin compounds were prepared from salicylaldehyde derivatives,diethyl malonate or ethyl acetoacetate using piperidine as catalysts.Coumarin-based triazine and pyrimidones were synthesized by reacting coumarin-3-ethyl carboxylate with metformin hydrochloride under alkaline conditions.3-acetyl coumarin combines with phenylhydrazine and then reacts with metformin hydrochloride to form coumarin-based pyrazole triazine compounds.The ?,?-unsaturated ketones were the produces of 3-acetyl coumarin and substituent benzene formaldehyde.Which reacts with metformin to form pyrimidine derivatives of coumarin.These products were characteried by ¹H-NMR,¹³C-NMR,FT-IR,and single crystal diffraction.The reaction conditions were discussed and the possible reaction mechanism was proposed.Coumarin-3-formaldehyde and coumarin-3-formyl chloride were synthesized from coumarin-3-ethyl carboxylate.Coumarin oxadiazole was obtained by dehydration of Coumarin hydrazone or bisylhydrazine which came from reacting benzoyl hydrazine with Coumarin-3-formaldehyde or coumarin-3-formyl chloride.The products were determined by ¹H-NMR,¹³C-NMR,FT-IR,elemental analysis and single crystal diffraction.At the same time,the product was tested for fluorescence,and its performance as a metal ion fluorescent probe was studied.