Synthesis And Biological Activities Of 3-(1'-Alkyloxycarbonylmethylimino) Ethyl-4-Hydroxypyrroline-2-One Derivatives

Tenuazonic acid (TA,3-Acetyl-4-hydroxy-5-see-butylpyrroline-2-one) was an important mycotoxin from Alternaria alternate. Originally, it was found that TA exhibited good medical activities against gram-positive bacteria and leukemia tumor cells and was used to research new antibacterial, antifungal and antineoplastic drugs. In recent years, people also founded that TA presented obvious and extensive herbicidal activities. As a kind of natural product, TA can be degraded rapidly by the soil microorganisms, and is friendly with the environment. During these years, more and more compounds possessing the structures of amino acid ester and Schiff base, which displayed the activities of plant growth regulator, herbicide and fungicide were synthesized. In order to find novel, degradable and low-toxic compounds with better biological activities, and provide more valuable information concerning the structure-activity relationships of TA derivatives. Twenty-two compounds possessing the structures of pyrroline-2-one, amino acid ester and Schiff base were designed and synthesized, and their herbicidal and fungicidal activities were also evaluated.Amino acid ester hydrochlorides were synthesized with natural amino acids and thionyl chloride, and N-arylglycine ethyl esters were prepared with anilines and ethyl chloroacetate. The N-arylglycine ethyl esters and amino acid ester hydrochlorides were reacted with diketen, MeONa, respectively, to give 5 intermediates 3-acetyl-4-hydroxypyrroline-2-one derivatives. Then, these intermediates were reacted with 8 different amino acid ester hydrochlorides to obtain 22 novel 3-(1'-alkyloxycarbonylmethylimino)ethyl-4-hydroxylpyrroline-2-one derivatives. Structures of the target compounds were confirmed by 1H NMR, MS, IR spectra and elemental analysis.The herbicidal activities of the target compounds were evaluated by the petri dish test method with Brassica napus (as a sample of annual dicotyledonous plant) and Echinochloa crusgalli (as a sample of annual monocotyledonous plant). The tested results indicated that the compounds 4b,4g,4h,4j and 4o against Brassica napus, and 4g,4h against Echinochloa crusgalli all exhibited over 80% of inhibition rates at the concentration of 100 mg/L. The antifungal activities of the target compounds were tested by the mycelial growth petri dish test method against 3 kinds of plant fungi Rhizoctonia cerealis, Colletotrichum orbiculare and Fusarium graminearum. The results indicated that the compounds 4b,4g,4h,4j,4m and 4o showed selective inhibition rates over 60% against Colletotrichum orbiculare at the concentration of 100 mg/L, the antifungal activities is obviously better than that of TA.