单嘧磺酯钠盐的合成及除草活性

单嘧磺酯是新型超高效磺酰脲类除草剂,为了寻找生物活性与之相当、环境友好的同类药剂,室温条件下用单嘧磺酯与氢氧化钠在水中反应合成了单嘧磺酯钠盐,其结构经核磁共振氢谱、红外、质谱及元素分析确认。室内生物测定结果显示,单嘧磺酯钠盐与其母体单嘧磺酯对马唐Digitaria ciliaris、稗草Echinochloa crusgalli、苋菜Amaranthus retroflexus和藜Chenopodium aldum的除草活性基本相当。     

Synthesis and herbicidal potential of substituted aurones

BACKGROUND: With the objective of exploring the herbicidal activity of substituted aurones, a series of 4,6‐disubstituted and 4,5,6‐trisubstituted aurones were synthesised, and their herbicidal activities against Brassica campestris L. and Echinochloa crusgalli (L.) Beauv. were evaluated in laboratory bioassays. Effects of some of the compounds were evaluated on seed germination. The most active compounds in the laboratory were evaluated in the greenhouse. RESULTS: The compounds were characterised by ¹H NMR, ¹³C NMR and HRMS; some of them were further identified by IR. A (Z)‐configuration was assigned to the aurones, based on spectroscopic and crystallographic data. Bioassay results of root growth showed that the aurones had a moderate herbicidal activity against the dicotyledonous plant Brassica campestris. (Z)‐2‐Phenylmethylene‐4,6‐dimethoxy‐3(2H)‐benzofuranone(6o) was the most active compound, with 81.3 and 88.5% inhibition at 10 and 100 µg ml^?1 respectively, equal to the activity of mesotrione. Some of the aurones possessed some inhibition of germination on several plant species. For glasshouse tests, the substituted aurones had lower herbicidal activity than metolachlor and mesotrione. CONCLUSION: It is possible that aurone derivatives, which possess structures different from those of the commercial herbicides, may become novel lead compounds for the development of herbicides against dicotyledonous weeds with further structure modification. Copyright © 2012 Society of Chemical Industry     

Synthesis and herbicidal activity of optically active cinmethylin,its enantiomer,and C3-substituted cinmethylin analogs

We investigated the synthesis and herbicidal activity of optically active cinmethylin, its enantiomer, and C3-substituted cinmethylin analogs. Optically active cinmethylin could be obtained in seven steps with the Sharpless asymmetric dihydroxylation of α-terpinene. The synthesized cinmethylin and its enantiomer showed similar herbicidal activity, which was independent of the stereochemistry. Next, we synthesized cinmethylin analogs with various substituents at the C3 position. We found that analogs with methylene, oxime, ketone, or methyl groups at the C3 position show excellent herbicidal activity.     

阿魏酸衍生物的合成及其除草活性测定

为从天然产物中获取新的除草活性成分,通过化学合成的方法对分离自瓜果腐霉Pythium aphanidermatum代谢产物中的阿魏酸进行了结构改造,并采用小杯法,以马唐、马齿苋和播娘蒿为供试杂草对所得化合物进行了除草活性测定。结果显示:所合成的4-羟基-3-甲氧基肉桂酸乙酯、4-羟基-3-甲氧基肉桂酸邻氯苯胺、4-羟基-3-甲氧基肉桂酸酰肼、4-羟基-3-甲氧基肉桂酸叔丁酯和4-乙酰氧基-3-甲氧基肉桂酸5种化合物的回收率分别为96.81%、97.39%、82.20%、75.67%和98.29%。4-羟基-3-甲氧基肉桂酸酰肼和4-乙酰氧基-3-甲氧基肉桂酸对马齿苋胚根的抑制活性最强,IC50分别为87.50 mg/L和74.86 mg/L,其余3种活性相对较弱;4-羟基-3-甲氧基肉桂酸乙酯和4-乙酰氧基-3-甲氧基肉桂酸分别在500 mg/L和1 000 mg/L浓度下可完全抑制播娘蒿和马齿苋胚根、芽的生长,而4-羟基-3-甲氧基肉桂酸邻氯苯胺则在1 000 mg/L浓度下可完全抑制播娘蒿胚根的生长。表明在阿魏酸分子中的不同位点引入适当的基团结构可以提高或者降低阿魏酸分子的除草活性,并获得新的除草活性物质。     

靶标酶在除草剂研究与开发中的应用

大多数除草剂都是通过特殊酶的抑制而产生杀草作用的。因此,以靶标进行分子设计,鉴定化合物分子结构中的活性团,开发能有效杀死杂草、而不伤害作物并对动物及环境安全的除草剂品种有着重要意义。本文着重对各种不同类型靶标酶在除草剂的研究与开发过程中的应用加以阐述。     

Dimethoxypyrimidines as novel herbicides. Part 4. Quantitative structure–activity relationships of dimethoxypyrimidinyl(thio)salicylic acids

The activity of a number of O-(4,6-dimethoxypyrimidin-2-yl)salicylic acids and their thio analogs inhibiting acetolactate synthase (ALS) preparation was measured. The effects of substituents on the salicylic-benzene ring on the inhibitory activity were analyzed quantitatively with physicochemical substituent parameters. For 6-substituted (thio)salicylic acids, the activity was shown to vary parabolically with the ‘intramolecular’ steric parameter ( E_s ). In addition, the higher steric dimension of substituents in terms of the STERIMOL width or length parameter lowered the activity. The field-inductive electron-withdrawing property of the 6-substituents in terms of the Swain–Lupton–Hansch F was favorable for the activity of salicylic acid series. In 5-substituted salicylic acids, the activity was increased by electron-donating substituents with smaller size. The relationships between ALS inhibitory and herbicidal activities were also analyzed with some weed species. Both pre- and post-emergence activities against barnyard grass, Echinochloa crus-galli, were linearly related to the ALS inhibitory activity after allowing for the hydrophobic factor that may contribute to the transport processes. Those against two broad-leaved weed species, Polygonum convolvulus and Abutilon theophrasti were linearly related to the in-vitro activity with no significant participation of the hydrophobic factor. © 1998 SCI     

Sorption and leaching potential of herbicides on Brazilian soils

Sorption of the herbicides alachlor, atrazine, dicamba, hexazinone, imazethapyr, metsulfuron-methyl, nicosulfuron, simazine and sulfometuron-methyl was characterized on six Brazilian soils, using the batch equilibration method. In general, weak acid herbicides (dicamba, imazethapyr, metsulfuron-methyl, nicosulfuron and sulfometuron-methyl) were the least sorbed, whereas weak bases such as triazines and nonionic herbicides (alachlor) were the most sorbed. The Kd values found showed a significant correlation with soil organic carbon content (OC) for all herbicides except imazethapyr and nicosulfuron. Koc values showed a smaller variation among soils than Kd . To estimate the leaching potential, Koc and the ground-water ubiquity score (GUS) were used to calculate half-lives ( t_1/2 ) that would rank these herbicides as leachers or non-leachers. Comparison of calculated values to published values for t_1/2 demonstrated that sulfonylureas and hexazinone are leachers in all soils, alachlor is transitional, and atrazine, simazine and dicamba are leachers or transitional, depending on soil type. Results discussed in this paper provide background to prioritize herbicides or chemical groups that should be evaluated in field conditions with regard to their leaching potential to ground-water in tropical soils.     

吡啶甲酸类除草剂应用研究进展

吡啶甲酸类除草剂属合成激素类, 目前登记使用的有效成分包括氨氯吡啶酸、二氯吡啶酸和氯氨吡啶酸, 分别于1963年、1977年和2005年上市, 主要用于阔叶杂草和灌木的茎叶处理防控, 其中氯氨吡啶酸具有土壤封闭活性。吡啶甲酸类除草剂的作用靶标仍未明确, 有可能来自生长素结合蛋白家族。全世界报道的抗吡啶甲酸类除草剂杂草共涉及7种8个生物型。目前, 我国登记的除草剂品种中共有13个复配剂含氨氯吡啶酸和二氯吡啶酸, 1个含氨氯吡啶酸、氯氨吡啶酸和二氯吡啶酸;国外登记的吡啶甲酸类除草剂复配剂主要为与其他激素型除草剂、ALS(乙酰乳酸合酶)抑制剂、ACCase(乙酰辅酶A羧化酶)抑制剂的组合。该类除草剂仍然具有较好的应用前景, 在主要应用场景下常见杂草对氨氯吡啶酸、二氯吡啶酸、氯氨吡啶酸的敏感性仍需系统研究, 该类除草剂主要靶标杂草种群的抗药性水平也亟须检测。     

Aryl chain analogues of the biotin vitamers as potential herbicides. Part 3

Novel aryl chain isosters and analogues of 7-keto-8-aminopelargonic acid (KAPA) and 7,8-diaminopelargonic acid (DAPA), the vitamer intermediates involved in the biosynthetic pathway of biotin, possessing chain lengths of eight carbon atoms, were prepared and evaluated as potential herbicides. In the greenhouse test the most active compounds were the fluorinated derivative 9d and the selenophenyl/furan mixture 17m/17p, which were most active against Foxtail millet. In the more sensitive Arabidopsis test the most active substances were 9a and 17m, which displayed GR(50) (concentration of active compound causing 50% growth inhibition) values of 0.2 and 0.5 mg kg(-1) respectively (values of < 50 mg kg(-1) are considered herbicidal).     

Synthesis and herbicidal activity of 3-substituted toxoflavin analogs

We investigated the synthesis and herbicidal activity of 23 toxoflavin analogs, 1a–w, in which aromatic rings (R) were introduced into the C-3 position. In paddy field conditions, 1k (R=2-CF₃–C₆H₄) and 1w (R=2-thienyl) showed excellent herbicidal activity. Under upland field conditions, we found that toxoflavin analogs 1a (R=C₆H₅), 1n (R=2-CH₃O–C₆H₄), and 1p (R=4-CH₃O–C₆H₄) exhibited wide herbicidal spectrum against Echinochloa crus-galli (L) var. crus-galli (ECHCG), Chenopodium album, and Amaranthus viridis (AMAVI). The analog with the 2-fluoro group on benzene ring 1b also showed high herbicidal activity against both ECHCG and AMAVI.     

12-(取代苯氧异丁酰氧亚氨基)-1,15-十五内酯的合成及除草活性

通过取代苯氧异丁酸与12-(羟基亚氨基)十五内酯的反应,合成了取代苯氧异丁酰氧亚氨基十五内酯,并测定了其对苋菜的除草活性。所有化合物均经过1H NMR、13C NMR和元素分析确证。初步的生物活性测定结果表明,目标化合物 Ⅲa~Ⅲd 的EC50值分别为34.570、46.492、55.385、50.114 mg/L,其活性比对照药剂2,4-D(117.325 mg/L)高,而比苯磺隆(22.381 mg/L)低。     

5种除草剂对土壤蔗糖酶和脲酶活性的影响

采用室内培养法,研究了土壤中添加5种除草剂(氟磺胺草醚、甲咪唑烟酸、乳氟禾草灵、扑草净和噻吩磺隆)对土壤蔗糖酶和脲酶活性的影响。结果表明:在0.05、0.5和5 mg/kg的甲咪唑烟酸、乳氟禾草灵、扑草净和噻吩磺隆作用下,在3~40 d内对土壤蔗糖酶活性表现为抑制-激活-恢复效应,其中0.5mg/kg的乳氟禾草灵处理,3 d时土壤蔗糖酶被显著抑制,6、9、25和40 d时被激活;而0.05、0.5和5 mg/kg的氟磺胺草醚处理,前9 d土壤蔗糖酶活性被显著抑制,25和40 d时被激活。在用0.05、0.5和5mg/kg的甲咪唑烟酸、噻吩磺隆和5 mg/kg扑草净处理的3~40 d内,对土壤脲酶活性均表现为抑制-激活-抑制效应;0.05和0.5 mg/kg的扑草净及0.05和5 mg/kg的乳氟禾草灵处理,土壤脲酶在3~40 d内虽然也出现上述变化趋势,但到40 d时已恢复到对照水平;低浓度(0.05和0.5 mg/kg)氟磺胺草醚处理对土壤脲酶表现为抑制-激活效应,而高浓度(5 mg/kg)处理则表现为抑制-激活-抑制作用。     

Natural products as sources of herbicides: current status and future trends

Although natural product-based discovery strategies have not been as successful for herbicides as for other pesticides or pharmaceuticals, there have been some notable successes. Phosphinothricin, the biosynthetic version of glufosinate, and bialaphos are phytotoxic microbial products that have yielded commercial herbicides. Cinmethylin, a herbicidal analogue of cineole, has been sold in Europe and Asia. The triketone herbicides are derivatives of the plant-produced phytotoxin leptospermone. These products represent only a small fraction of commercialized herbicides, but they have each introduced a novel molecular target site for herbicides. Analysis of the literature reveals that phytotoxic natural products act on a large number of unexploited herbicide target sites. The pesticide industry's natural product discovery efforts have so far concentrated on microbially derived phytotoxins, primarily from non-pathogenic soil microbes, involving the screening of large numbers of exotic isolates. Plant pathogens usually produce potent phytotoxins, yet they have received relatively little attention. Even less effort has been made to discover plant-derived phytotoxins. Bioassay-directed isolation has been the preferred method of discovery after a producing organism is selected. This laborious approach often leads to rediscovery of known compounds. Modern tandem separation/chemical characterization instrumentation can eliminate much of this problem by identification of compounds before they are bioassayed.     

14种除草剂对野稷的活性测定及田间防效

参照除草剂室内生物测定和田间药效防治试验准则,在温室中测定了14种除草剂对野稷的生物活性,并进行了田间小区药效评价。生测结果表明,土壤处理药剂中,异噁唑草酮、氟噻草胺、乙草胺、精异丙甲草胺、异噁草松对野稷的活性较高,其ED₉₀分别为43.08、47.14、137.09、209.93、583.74 g/hm²(有效成分用量);茎叶处理药剂中,苯唑草酮、高效氟吡甲禾灵、烟嘧磺隆和苯唑氟草酮对野稷的活性较高,其ED₉₀分别为22.21、35.95、95.64、111.43 g/hm²。田间药效试验结果表明,野稷出苗前,土壤喷雾40%氟噻草胺SC (810 g/hm²)、900 g/L乙草胺EC (1 620 g/hm²)和960 g/L精异丙甲草胺EC (2 160 g/hm²)对野稷防效较高,药后40 d对野稷的株防效均在86.0%以上,鲜重防效在88.4%以上,其次是75%异噁唑草酮WG (90 g/hm²),防效...     

嘌呤氧基苯氧丙酸酯的合成及除草活性

以4,6-二氯-5-硝基嘧啶为起始原料,经过还原胺化、取代、醚化等一系列反应,得到11个未见文献报道的嘌呤氧基苯氧丙酸酯类化合物1a~1k,其结构经1H NM R和M S确认。初步生物活性测定表明:在200 mg/L下,所有目标化合物均表现出一定的除草活性,其中化合物1f((R)-2-(4-((9-(4-氯苯)-8-(三氟甲基-9H-嘌呤-6-基)氧)苯氧)丙酸丁酯)和1h((R)-2-(4-((9-(4-氯苯)-8-(三氟甲基-9H-嘌呤-6-基)氧)苯氧)丙酸乙酯)对靶标的抑制率几乎都达到100%。     

手性除草剂喹禾糠酯的合成研究

以L-乳酸乙酯为起始原料,通过磺酰化、醚化得到手性除草剂喹禾糠酯,总收率为73%,含量为95%,该合成路线条件温和,成本较低,易于实现工业化。     

异香豆素噁二唑类化合物的合成及除草活性

为了寻找具有较高除草活性的异香豆素类化合物,设计合成了16个新型异香豆素噁二唑类化合物4a～4p,其结构均经核磁共振氢谱、碳谱及高分辨质谱确证。初步除草活性测定结果表明,部分目标化合物在500 mg/L下对马唐Digitaria sanguinalis L.和反枝苋Amaranthusretroflexus L.具有一定的除草活性,其中化合物4j（4-[5-（4-氯-苯基）-[1,2,4]二唑-3-基]-3-己基-6,7-二甲氧基异香豆素）的活性最好,对马唐和反枝苋的致死率分别为64%和62%。     

嘧啶联吡唑甲酰胺类化合物的合成及除草活性

设计合成了一系列结构新颖的嘧啶联吡唑甲酰胺类化合物5a~5o,其结构均经过1H NM R和MS分析确证。初步生物活性测试结果表明:在有效成分150 g/hm2剂量下苗后茎叶喷雾处理时,化合物(R)-N-[1-(4-氯苯基)乙基]-3-二氟甲基-1-(4,6-二甲氧基嘧啶-2-基)-1H-吡唑-4-甲酰胺(5c)、N-[1-(4-氯苯基)乙基]-1-(4,6-二甲氧基嘧啶-2-基)-N-甲基-3-三氟甲基-1H-吡唑-4-甲酰胺(5i)和N-[1-(4-氯苯基)乙基]-1-(4,6-二甲氧基嘧啶-2-基)-3-三氟甲基-1H-吡唑-4-甲酰胺(5k)对繁缕Stellaria media的抑制率高达90%以上;而同样剂量下苗前土壤喷雾处理时,化合物N-[1-(4-氯苯基)乙基]-3-二氟甲基-1-(4,6-二甲氧基嘧啶-2-基)-1H-吡唑-4-甲酰胺(5b)和5c对繁缕的抑制率达100%。该类结构化合物有望作为除草先导化合物进行开发。     

10种N-取代氨基香豆素的合成及生物活性

基于结构拼接思想,设计合成了10个N-取代氨基香豆素类化合物,并测定了其抑菌及除草活性。6-硝基香豆素经Fe/NH4Cl还原得6-氨基香豆素,再与不同醛缩合得Schiff碱,最后经硼氢化钠还原制得10个N-取代氨基香豆素类化合物(4a~4J),其中9个未见文献报道,其结构均经红外光谱、核磁共振氢谱和质谱确认。抑菌活性测试结果表明,所有化合物对苹果腐烂病菌Valsa mali、葡萄白腐病菌Coniothyrium diplodiella、棉花枯萎病菌Fusarium oxysporium和柑橘炭疽病菌Citrusanthrax bacteria均有一定抑制作用,其中 4e 的抑菌活性最强,对苹果腐烂病菌和柑橘炭疽病菌的EC50值分别为7.53和12.93 mg/L,对其余2种植物病原菌的EC50值均小于25 mg/L;化合物 4f 次之,对苹果腐烂病菌和葡萄白腐病菌的EC50值均约为11 mg/L。除草活性测试结果表明,除 4f 外,所有目标化合物均有一定除草作用,其中 4c 的活性最强,100 mg/L下对反枝苋Amaranthus retroflexus种子根、茎生长的抑制率均为99%。