Synthesis and bioactivity of 10 N-substituted amino coumarins

Under the guidance of substructure combination strategy,10 N-substituted amino coumarins were synthesized,their fungicidal and herbicidal activity was determined as well.6-amino coumarin was prepared from reducing of 6-nitro coumarin by Fe/NH4Cl and condensed with different aldehyde to give the intermediate Schiff base,which was then reduced by sodium borohydride to give N-substituted amino coumarins.Nine of the compounds were not reported in the literature.The structures of the synthesized compounds were confirmed by IR,1H NMR and ESI-MS.All the synthesized compounds showed certain inhibition against Valsa mali,Coniothyrium diplodiella,Fusarium oxysporium and Citrusanthrax bacteria. Compound 4e indicated the most fungicidal activity with EC50 value of 7.53 and 12.93 mg/L against V.mali and C.bacteria respectively,and 50 value of about 11 mg/L against V.mali and C.diplodiella.Furthermore,all the synthesized compounds except 4f have some herbicidal activity against the root and seedling development of Amaranthus retroflexus.The inhibitory rates of compound 4c against A.retroflexus were 99% at 100 mg/L.