8种4-甲基香豆素衍生物的合成及其农药活性

香豆素类化合物的生物活性与苯并吡喃环上取代基的种类及其位置密切相关，研究不同取代香豆素的农药生物活性，以期发现有价值的农药先导化合物。以间苯二酚为起始原料，合成了8种4-甲基香豆素衍生物。采用菌丝生长速率法和种子萌发法测定了合成化合物的抑菌及除草活性。结果表明：6种4-甲基香豆素衍生物对4种供试植物病原真菌具有一定抑制作用，其中4-甲基-7-羟基-8-苯甲酰基香豆素的抑菌活性最强，对苹果腐烂病菌的EC50为62.40 mg/L，对葡萄白腐病菌的EC50为69.22 mg/L；4-甲基-7-羟基-8-邻氟苯甲酰基香豆素次之，对葡萄白腐病菌EC50接近100 mg/L。4-甲基-7-丙酰氧基香豆素除草活性较强，1000 mg/L下对反枝苋及生菜种子幼根生长的抑制率均大于43%。由此可见，4-甲基-7-羟基香豆素7位酯化使抑菌作用降低，7位苯甲酰基及邻氟苯甲酰基重排至8位后抑菌活性明显增强；合成化合物的除草活性均较弱。

Synthesis and Pesticidal Activity of 8 Derivatives of 4-Methyl-Coumarin

Abstract: Eight derivatives of 4-methyl-coumarin were synthesized, and their pesticidal activities were determined in this paper. First, 4-methyl-7-hydroxy-coumarin was prepared from ethyl acetoacetate and resorcinol by Pechmann reaction. Then 4 kinds of 4-methyl-7-acyloxy-coumarins were obtained by acylation of 4-methyl-7-hydroxy-coumarin with different chlorides. Finally, 4 kinds of 4-methyl-7-acyloxy-coumarin occurred Fries rearrangement to give 4-methyl-7-hydroxy-8-acyl-coumarin catalyzed by anhydrous AlCl3. The antifungal and herbicidal activities were determined by methods of mycelium growth rate and seed germination respectively. The results indicated that six derivatives of 4-methyl-coumarin had certain antifungal activity against all the 4 kinds of plant pathogens tested. The antifungal activity of 4-methyl-7-hydroxy-8-benzoyl-coumarin was the best of the six chemicals, with EC50 of 62.40 and 69.22 mg/L against Valsa mali and Coniothyrium diplodiella respectively. Followed was 4-methyl-7-hydroxy-8-o-fluorobenzoyl-coumarin. Herbicidal activities of the synthesized compounds against the root and stem development of Amaranthus retroflexus and Lactuca sativa seedlings were weak.