Synthesis And Pesticidal Activities Of N-(m-fluoro-benzyl)-6-amino-coumarin Derivatives

Coumarin is a widespread natural product,it has been valued in many fields,but little research has been done on the agricultural field,especially on herbicidal and anti-pathogenic activities.At the same time,the synthesis of amide fungicides and herbicides has also been a hotspot in the field of pesticide research.Therefore,a series of N-?m-fluoro-benzyl?-6-amino-coumarin derivatives were designed and synthesized through the principle of bioactive substructure combination.And the herbicidal and anti-pathogenic activities were evaluated.Firstly,N-?m-fluoro-benzyl?-6-amino-coumarin?b1?was synthesized by coumarin,and the optimal reaction conditions were obtained by the control variate method:for the synthesis of 6-nitro-coumarin,the best nitrating agent was cerium nitrate and concentrated sulfuric acid,the molar ratio of n₁?cerium nitrate?:n₂?coumarin?=1.5:1.0,reaction temperature 15?,reaction time 4 h,the yield of the product was 97.5%;for the6-amino-coumarin,the molar ratio of n₁?80%hydrated hydrazine?:n₂?6-nitro-coumarin?=2.5:1.0,reaction time 3.5 h,reaction temperature 78?,1.6 g FeCl₃,0.4 g activated carbon,the yield of product was 85.0%;for b1,the optimal reaction conditions were the molar ratio of n₁?m-fluorobenzaldehyde?:n₂?6-amino-coumarin?=1.2:1.0,reaction temperature 78?,reaction time 4 h,1.1 g NaBH₄,reduction temperature 0⁵?,reduction time 2 h,the yield of the product was 73.5%.Secondly,twenty three kinds of N-?m-fluoro-benzyl?-6-amino-coumarin derivatives were obtained through acylation with b1.And the structure of the derivatives were confirmed by ¹H NMR?¹³C NMR and LC-MS.The anti-pathogenic activity showed that most compounds had a certain inhibitory effect on the four pathogens?Fusarium oxysporium,Citrusanthrax bacteria,Valsa mali,Botrytis cinerea?,especially on the Botrytis cinerea.All compounds exhibited marked inhibition against Botrytis cinerea than Carbendazim at 20 ppm,but parts of the compounds?e1,e4,e6,et al?had higher inhibition rates than Carbendazim at 100 ppm.The herbicidal activity indicated that compounds of e11,e12 and e1,e2,e14,e22exhibited marked inhibition against the roots and stems of Amaranth and Crabgrass at 20mg/L and 100 mg/L.