柠檬醛基1,2,3-三唑化合物的合成及抑菌活性

Synthesis and antifungal activity of citral-based 1,2,3-triazole compounds

摘要:

分别将橙花醇和香叶醇（Ⅰ）（柠檬醛两个立体异构体的前体）氧化为相应的醛（Ⅱ），进一步氧化为酸（Ⅲ），然后与溴丙炔发生亲核取代反应得到末端炔酯（Ⅳ），最后与系列取代叠氮化合物发生Husigen环加成反应，得到26个(Z)-、(E)-柠檬醛基1,2,3-三唑化合物（Ⅴa～m）。采用FTIR、1HNMR、13CNMR和ESI-MS对目标化合物结构进行了表征，并测试了目标化合物的抑菌活性。结果表明：在目标化合物质量浓度为50 mg/L时，对西瓜炭疽病菌、黄瓜枯萎病菌、花生褐斑病菌、苹果轮纹病菌、小麦赤霉病菌、番茄早疫病菌、玉米小斑病菌和水稻纹枯病菌8种植物病原菌均显示出一定的抑菌活性，其中(E)-柠檬醛基对-溴苄基1,2,3-三唑[(E)-Ⅴm]、(E)-柠檬醛基邻-甲基苄基1,2,3-三唑[(E)-Ⅴb]和(Z)–柠檬醛基间-甲基苄基1,2,3-三唑[(Z)-Ⅴc]对西瓜炭疽病菌的抑制率分别为95.2%（A级活性水平，优于阳性对照百菌清）、81.0%（B级活性水平）和81.0%（B级活性水平）。此外，目标化合物(E)-Ⅴm对玉米小斑病菌的抑制率高达95.2%（A级活性水平，优于阳性对照百菌清）。因此，目标化合物(E)-Ⅴm值得进一步研究，有望成为新的候选抑菌剂。

Abstract:

Nerol and geraniol（Ⅰ）, which are precursors of the two stereoisomers of citral, were first oxidized to their corresponding aldehydes（Ⅱ）, respectively, and the aldehydes were further oxidized to their corresponding acids（Ⅲ）. Then, terminal alkynyl esters（Ⅳ） were prepared by nucleophilic substitution reaction of the acids（Ⅲ） with bromopropyne, followed by Husigen cycloaddition reaction of the terminal alkynyl esters（Ⅳ） with a series of substituted azide compounds to yield twenty-six (Z)- and (E)-citral-based 1,2,3-triazole compounds(Ⅴa ～ m). All the target compounds were characterized by FTIR, 1HNMR, 13CNMR, and ESI-MS, and also evaluated for their antifungal activity. It was found that, at 50 μg/mL, the target compounds Ⅴa ～ m showed certain antifungal activity against the eight tested plant pathogens, including Colletotrichum lagenarium, Fusarium oxysporum f.sp.cucumerinum, Cercospora arachidicola, Physalospora piricola, Gibberella zeae, Alternaria solani, Helminthosporium maydis, and Rhizoctonia solani, in which (E)-citral-based p-bromobenzyl 1,2,3-triazole [(E)-Ⅴm], (E)-citral-based o-methylbenzyl 1,2,3-triazole [(E)-Ⅴb], and (Z)-citral-based m-methylbenzyl 1,2,3-triazole [(Z)-Ⅴc] had inhibition rates of 95.2% (A-class activity level, better than that of the positive control chlorothanil), 81.0% (B-class activity level), and 81.0% (B-class activity level), respectively, against Colleetotrichum lagenarium. Besides, compound (E)-Ⅴm had inhibition rate of up to 95.2% against Helminthosporium maydis (A-class activity level, better than that of the positive control chlorothanil). Therefore, the target compound (E)-Ⅴm is worthy of further investigation and expected to become a new candidate antifungal agent.