The structure and properties of O-ethyl O-isopropyl O-(5-methoxy-1-methyl-6-oxo-1H-pyridazin-4-yl) phosphorothioate and by-products in the technical product

The structure and some chemical and physical properties of a new insecticide O-ethyl O-isopropyl O-(5-methoxy-1-methyl-6-oxo-1H-pyridazin-4-yl) phosphorothioate ( I ) and by-products present in the technical product are described. The structures of I and the by-products were proved by infrared, ultraviolet, ¹H-n.m.r., Raman and mass spectrometry.     

Synthesis,spectral properties and insecticidal,acaricidal and ovicidal activities of some O-(1,5-disubstituted- 6-oxo-12H-pyridazin-4-yl) phosphorothioates

A synthesis of O,O-dialkyl, O-alkyl O-2-chloroethyl (or O-2-ethoxyethyl) O-(1,5-disubstituted-6-oxo-1H-pyridazin-4-yl) phosphorothioates is described. Infrared, Raman and ultraviolet spectra of the compounds prepared are interpreted. The wave-numbers of the v(C? C) bands were correlated with substituent constants. Good linear correlations of v(C? O) with σ, σ^F, σ_I and σ_R were observed for compounds containing various substituents in the neighbourhood of the keto group of the pyridazinone ring. The insecticidal, acaricidal and ovicidal activities of O-(ethyl or isopropyl), O-(alkyl, 2-chloroethyl, or 2-ethoxyethyl) O-(5-methoxy-1-methyl-6-oxo-1H- pyridazin-4-yl) phosphorothioates, O-ethyl O-isopropyl O-(5-methoxy-1-substituted-6-oxo-1H-pyridazin-4-yl) phosphorothioates and O-ethyl O-isopropyl O-(1-methyl-5-substitutedd-oxo-1H-pyridazin-4-yl) phosphorothioates are reported together with the toxicity of some of these compounds to rats.     

O-ethyl O-isopropyl O-(5-methoxy-1-methyl-6-oxo-1H-pyridazin-4-yl) phosphorothioate,a new experimental insecticide and acaricide

The insecticidal and acaricidal action, anti-cholinesterase activity and toxicity to rats of a new experimental pesticide, O-ethyl O-isopropyl O-(5-methoxy-1-methyl-6-oxo-1H-pyridazin-4-yl) phosphorothioate ( I ), and those of some by-products found in the technical material, are described. High insecticidal and acaricidal effectiveness of I was found in laboratory and field trials. The activity as a soil insecticide in field trials was equal to, or greater than, that of other chemicals used at present.     

Synthesis,insecticidal and acaricidal properties of some 5-alkoxy-, 5-alkylthio-6-oxo-1-phenyl-1H-pyridazin-4-yl and 6-oxo-5-phenoxy-1-phenyl-1H-pyridazinyl phosphorus esters. II

A series of novel 5-alkoxy-, 5-alkylthio-6-oxo-1-phenyl-1H-pyridazin-4-yl and 6-oxo-5-phenoxy-1-phenyl-1H-pyridazin-4-yl phosphorus esters was prepared from the corresponding alkali pyridazin-4-olates and their insecticidal and acaricidal activities studied. Many of the compounds, especially the diethyl and dimethyl phosphates and OO-diethyl and OO-dimethyl phosphorothioates, showed high insecticidal and acaricidal activity.     

Studies on residues and the metabolic pathway of methidathion in tomato fruit

The residues and metabolism of methidathion [S-(2, 3-dihydro-5-methoxy-2-oxo-1, 3, 4-thiadiazol-3-ylmethyl) O, O-dimethyl phosphorodithioate] and its secondary metabolites: demethyl-methidathion [S-(2, 3-dihydro-5-methoxy-2-oxo-1, 3, 4-thiadiazol-3-ylmethyl) O-methyl O-hydrogen phosphorodithioate] ( IV ), the sulphide (2,3-dihydro-5-methoxy-3-methylthiomethyl-1,3,4-thiadiazol-2-one) ( I ), tsulphoxide(2,3-dihydro-5-methoxy-3- methylsulphinylmethyl-1,3,4-thiadiazol-2-one) ( II ) and the sulphone (2,3-dihydro-5-methoxy-3-methylsulphonylmethyl-1,3,4-thiadiazol-2-one ( III ) were studied in laboratory-treated tomato fruit. The metabolites and residues of methidathion were determined for the applied doses of 1, 7 and 14 mg of methidathion kg^?1 of fruit. Methidathion was metabolised extensively over a 14-day period. The amount of metabolites formed was a function of both the applied dose as well as the time after application. Major water-soluble metabolites were found to be IV and the cysteine conjugate S-(2,3-dihydro-5-methoxy-2-oxo-1,3,4-thiadiazol-3-ylmethyl)-L-cysteine ( VI ). The chloroform-soluble metabolites were identified as the oxygen analogue of methidathion [S-(2,3-dihydro-5-methoxy-2-oxo-1,3,4-thiadiazol-3-ylmethyl) O, O-dimethyl phosphorothioate] ( V ), the sulphoxide II , and the hydroxy compound 2,3-dihydro-3-hydroxymethyl-5-methoxy-1,3,4-thiadiazol-2-one. The oxygen analogue of methidathion ( V ) was found in small amounts, corresponding to <5% of the added methidathion. Demethyl-methidathion ( IV ) appeared to be a precursor in the formation of the cysteine conjugate VI . The sulphide I seemed to be more reactive in forming the cysteine conjugate than the sulphoxide II or the sulphone III .     

Light-induced transformations of tribenuron-methyl in aqueous solution

Tribenuron-methyl a sulfonylurea herbicide, readily photodegraded in aqueous solution under sunlight and UV light. The photoproducts identified were N-methyl-4-methoxy-6-methyl-1,3,5-triazine-2-amine, methyl 2-(aminosulfonyl) benzoate, o-benzoic sulfimide, N-(4-methoxy-6-methyl1,3,5-triazin-2-yl)-N-methyl urea and N-(2-carbomethoxyphenyl)-N-(4-methoxy-6-methyl-1,3,5triazin-2-yl)-N′-methyl urea. The rate of photodegradation of tribenuron-methyl in different types of water followed first-order kinetics with significant correlation coefficient, increased with increase in pH and was also dependent upon the dissolved impurities. © 1999 Society of Chemical Industry     

1-甲基-3-二氟甲基吡唑酰胺类化合物的合成及抑菌活性

以1-甲基-3-二氟甲基吡唑-4-甲酸为原料,经过1-甲基-3-二氟甲基吡唑-4-甲酰氯与相应的氨基苯并杂环类、芳胺类化合物反应,得到了14个未见文献报道的吡唑-4-甲酰胺类化合物(6a~6g、7a~7g),其结构均通过1H NMR、MS和IR表征。抑菌活性测试结果表明,在100 mg/L下,目标化合物对供试植物病原菌均有不同程度的抑制作用,其中7a~7g的抑菌活性较高,部分对苹果炭疽病菌的抑制率在90%以上。     

新型含吡唑杂环邻氨基苯甲酰胺类化合物的合成与杀螨活性

以氯虫苯甲酰胺和氟虫腈的结构为基础,通过活性亚结构拼接的方法,设计合成了24个新型含吡唑杂环邻氨基苯甲酰胺类化合物,其结构经1H NM R、IR及APCI-M S表征。初步生物活性测试结果表明:化合物5-溴-N-[4-氯-2-甲基-6-(甲氨基甲酰基)苯基]-1-1-[2,6-二氯-4-(三氟甲基)苯基]-4-三氟甲基亚磺酰基-1H-吡唑-3-甲酰胺(5k)和5-溴-N-[4-溴-2-甲基-6-(甲氨基甲酰基)苯基]-1-[2,6-二氯-4-(三氟甲基)苯基]-4-三氟甲基亚磺酰基-1H-吡唑-3-甲酰胺(5l)在500 mg/L下对朱砂叶螨Tetranychus cinnabarinus的致死率为100%,但在100 mg/L下其致死率则分别降至30%和50%。所得结果可为邻氨基苯甲酰胺类化合物构效关系研究提供参考。     

新化合物吡唑并嘧啶衍生物(BDO-1)和哒嗪酮衍生物(PDZ-1)的诱导抗病性研究

吡唑并嘧啶衍生物 ((E)-N-(2-氟-4-三氟甲基苯乙烯基)-1-甲基-1H-吡唑并[3,4-d]嘧啶-4-胺,简称BDO-1) 和哒嗪酮衍生物 (4-羟基-1-(4-甲氧基苯基)-6-氧代-1,6-二氢吡嗪-3-甲酸甲酯,简称PDZ-1) 是由华东理工大学创制并合成的新化合物,本研究分别测定了其离体抑菌活性及其诱导抗病活性,并对田间应用技术进行了研究。结果表明:离体抑菌试验结果显示,BDO-1和PDZ-1对供试黄瓜的尖孢镰孢菌和多主棒孢菌并无杀菌活性;温室盆栽试验发现,2个化合物对7种蔬菜病害具有明显的诱导抗病活性,其中:BDO-1在10 mg/L下对黄瓜细菌性角斑病、黄瓜棒孢叶斑病、黄瓜枯萎病、黄瓜霜霉病、番茄早疫病、番茄灰叶斑和辣椒疫病的防治效果分别为58.81%、61.79%、69.88%、64.14%,54.42%、54.85%和63.59%;PDZ-1在10 mg/L下对黄瓜细菌性角斑病和黄瓜棒孢叶斑病的防治效果分别为62.33%和59.15%。田间防治效果验证结果表明,BDO-1和PDZ-1对黄瓜枯萎病的防治效果分别为62.95 %和48.45%。研究发现,BDO-1和PDZ-1在质量浓度为10 mg/L、诱导5次、每次间隔5d的条件下施用,对黄瓜枯萎病和棒孢叶斑病可发挥最佳防治效果。     

Kinetics and products of the hydrolysis of 3,4-dihydroprecocene I 3,4-epoxide in aqueous organic solvents

The hydrolysis of 3, 4-dihydroprecocene I 3, 4-epoxide (3, 4-dihydro-7-methoxy-2, 2-dimethyl-3, 4-epoxy-2H-benzo[b]pyran), the putative ultimate cytotoxin of the insect growth regulator precocene I (7-methoxy-2, 2-dimethyl-2H-benzo[b]pyran), has been studied and found to exhibit first-order kinetics [k = 0.17 s^?1 in 10 mm-phosphate buffer pH 7.0, containing 1, 4-dioxane (1 + 1 by volume), ionic strength 0.1]. Plots of log k versus pH, and k versus buffer concentration, suggest that the reaction is subject to both specific and general acid catalysis. High-performance liquid chromatography showed the reaction products to be predominantly the corresponding stereoisomeric diols (3, 4-dihydro-7-methoxy-2, 2-dimethyl-2H-benzo[b]pyran-3, 4-diol), the trans : cis ratio of which varied from 1.8: 1 to 2.2: 1 but was constant over the pH range 6-8, at a given buffer concentration. The results indicate that acid-catalysed hydration of 3, 4-dihydroprecocene I 3, 4-epoxide is an S_N1 reaction, involving a trigonally hybridised carbocation at C4, even at physiological pH. Similar studies on 3, 4-dihydroiso-precocene I 3, 4-epoxide (3, 4-dihydro-6-methoxy-2, 2-dimethyl-3, 4-epoxy-2H-benzo-[b]pyran), a biologically inactive isomer of 3, 4-dihydroprecocene I 3, 4-epoxide suggest that an S_NI mechanism also contributes to its hydrolysis, but the rate constant is 4000 times lower than that for 3, 4-dihydroprecocene I 3, 4-epoxide. Knowledge of the reactivity and mechanism of reaction of such compounds forms an important part of the basis for rational prediction of biological activity in precocene analogues, and hence their possible use as pest control agents.     

Synthesis and Anthelmintic Activity of 7-Hydroxy- 5-oxo-5H-thieno[3,2-b]pyran-6-carboxanilides and -6-thiocarboxanilides

7-Hydroxy-5-oxo-5H-thieno[3,2-b]pyran-6-carboxanilides and -6-thio-carboxanilides represent a novel series of anthelmintic compounds, with broad-spectrum activity against important parasitic nematodes in sheep and dogs. In particular, an improved efficacy against Trichostrongylus colubriformis in sheep over the related 3-carbamoyl-4-hydroxycoumarins has been noted. New synthetic routes to the key intermediate, 7-hydroxythieno[3,2-b]pyran-5-one, have been developed.     

Quantification of GST and esterase activities in pyrethrin-resistant mosquitoes using pyrethroid-like fluorescent substrates

Botanical pyrethrins and synthetic pyrethroids are highly potent and environmentally safe insecticides that are used to control a wide range of disease vector and pest arthropods. Unfortunately, resistance to these insecticides has been demonstrated in numerous medically important mosquito species. In this study, adult Culex pipiens sensu lato were captured in agricultural and urban locations in Fresno County, California, and subsequently exposed to a commercial formulation of pyrethrin insecticide by ultra-low-volume spraying. Following insecticide exposure, two pyrethroid-like, fluorescent substrates (4-methyl-2-oxo-2H-chromen-6-yl, cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate (cis-DCVC) and 4-methyl-2-oxo-2H-chromen-6-yl, cis-3-((Z)-2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate (cis-TFMCVC)) and 1-chloro-2,4-dinitrobenzene (CDNB) were used to measure esterase and glutathione S-transferase (GST) activities in surviving mosquitoes. Elevated esterase activity (2.5-fold) was found in surviving urban mosquitoes at 12-h post-pyrethrin exposure (in comparison to non-insecticide-exposed control mosquitoes) when cis-TFMCVC was used as a substrate. Additionally, when CDNB was used as a substrate, 2.8-fold higher GST activity was found. A simple assay was established using our pyrethroid-like, fluorescent substrates that was able to detect low-level esterase activities in homogenates made from individual mosquitoes. The cis-TFMCVC-based assay suggested that esterase activity plays a role in pyrethrin resistance in urban mosquitoes in California.     

A root bioassay procedure for the determination of chlorsulfuron, diclofop acid and sethoxydim residues in soils

Measurement of the root lengths of pre-ger-minated oat seedlings (Avena sativa L. var. Sioux) grown in the dark in treated soils was used to assay residues of diclofop acid (2-[4-(2,4-dichloro-phenoxy)phenoxy]propionate) and sethoxydim (2-[1-(ethoxyimino)-butyl]-5-[2-(ethylthio)-propy]-3-hydroxy-2-cyclohexene-1-one). Similar measurements involving maize seedlings (Zea Mays L. var. Sunny Vee) were also used to determine residues of the herbicide chlorsulfuron (2-chloro-N-[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)aminocarbony]benzenesulfonamide) in soils. The procedure appeared to be reproducible with residues of chlorsulfuron, diclofop acid and sethoxydim being detectable at amounts of 0.001, 0.2 and 0.05 μg g^?1 respectively.     

Pyrazole phenyl ether herbicides inhibit protoporphyrinogen oxidase

Two isomeric pairs of pyrazole phenyl ether herbicides [AH 2.429, 4-chloro-1-methyl-5-(4-nitrophenoxy)-3-(trifluoromethyl)-1H-pyrazole; AH 2.430, 4-chloro-1-methyl-3-(4-nitrophenoxy)-5-(trifluoromethyl)-1H-pyrazole; AH 2.431, 5-((4-chloro-1-methyl-5-(trifluoromethyl)-1H-pyrazol-3-yl)oxy)-2-nitrobenzoic acid; and AH 2.432, 5-((4-chloro-1-methyl-3-(trifluoromethyl)-1H-pyrazol-5-yl)oxy)-2-nitrobenzoic acid were evaluated for herbicidal activity in both intact plants and in tissue sections. Their capacity to induce accumulation of porphyrins in tissue sections and to inhibit protoporphyrinogen oxidase (Protox) in vitro were determined. In whole plant tests, the order of herbicidal activity was AH 2.430 AH 2.431 > AH 2.429 > AH 2.432. AH 2.430 consistently caused light-dependent membrane leakage in both green and far-red light grown cucumber cotyledon and barley primary leaf tissue sections after incubation for 20 hr in darkness in 0.1 mM solutions. The same treatment caused marked increases in protoporphyrin IX (PPIX) content during the 20-hr dark incubation. AH 2.429 and 2.431 were less effective and not effective in all tissues in causing herbicidal damage and PPIX accumulation. AH 2.432 was ineffective in tissue section assays. Mg-PPIX levels were not significantly affected by any of the compounds. Protochlorophyllide levels were decreased by AH 2.430 and 2.431 in barley and increased by AH 2.429, 2.431, and 2.432 in cucumber. A positive relationship was found between herbicidal activity and the amount of PPIX that was caused to accumulate by each compound. All of the compounds inhibited Protox activity. Positive correlations were found between herbicidal activity in planta over a 300-fold range and in vitro Protox inhibition and the amount of PPIX caused to accumulate in vivo. These data support the view that the pyrazole phenyl ethers exert their herbicidal activity entirely through inhibition of Protox.     

Synthesis and fungicidal activity against Pyricularia oryzae of 6-(1,2,4-triazol-4-yl) chromone and -1-thiochromone derivatives

A series of novel 6-(1,2,4-triazol-4-yl) chromone and -1-thiochromone (benzo[b]thiazin-4-one) derivatives was obtained by cyclisation via thiosemicarbazides which were prepared by reaction of hydrazines and the corresponding isothiocyanates. Their fungicidal activity was evaluated against the rice blast fungus Pyricularia oryzae. Of this series, 2,5,8-trimethyl-6-(1-propyl-5-thioxo-3-trifluoromethyl-1,2,4-triazol-4-yl) chromone, 6-(1-butyl-5-thioxo-3-trifluoromethyl-1,2,4-triazol-4-yl)-2,5,8-trimethylchromone, 6-(1-hexyl-3-methyl-5-thioxo-1,2,4-triazol-4-yl)-2,5,8-trimethylchromone and 6-(1-allyl-5-thioxo-3-trifluoromethyl-1,2,4-triazol-4-yl)-2,5,8-trimethylchromone were highly active (pEC₅₀>6·0). Structure–activity relationship studies using the capacity factor k′ as a hydrophobicity index suggested that the log k′ optimum for 2,5,8-trimethyl-chromone and -1-thiochromone derivatives was around 1·0, equivalent to a log P_ow value of c. 4·4. © 1998 SCI     

Differential Metal Binding Interactions of the Imidazolinones Revealed by NMR and UV Spectroscopy

NMR and UV spectroscopy and molecular modeling methods were applied to probe the interaction of the two imidazolinones, imazethapyr (5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid) and its structural isomer CL 303,135 (5-ethyl-3-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)picolinic acid), with metal ions. Both the imidazolinones inhibit the enzyme acetohydroxyacid synthase (AHAS) in vitro. However, while imazethapyr is a herbicide that is used widely in agriculture, CL303,135 does not exhibit herbicidal activity. Imazethapyr and CL303,135 exhibited considerable differences in their interactions with metals. In the metal complex of imazethapyr, the carboxyl moiety binds strongly and the pyridine nitrogen binds weakly with metals. In the case of CL303,135, both the pyridine nitrogen and the carboxyl group that are positioned ortho to each other participated strongly in the binding and were found to act together as a strong bidentate ligand to a metal ion. Both of the imidazolinones form predominantly 2:1 complexes with multivalent metal ions. However, imazethapyr binds two orders-of-magnitude more weakly (1·0×10⁹ M ^-2) with metal ions compared to CL303,135 (1·7×10¹¹ M ^-2). The interactions of the model compounds, nicotinic acid and picolinic acid, with metals were examined similarly. It was concluded that the strong affinity of CL303,135 for metals compared to imazethapyr may affect its absorption from soil into plants, or its translocation in plants, thereby explaining the differences in herbicidal activity of imazethapyr and CL303,135. © 1997 SCI.     

Heterocyclic Insecticides Acting at the GABA-Gated Chloride Channel: 5-Alkyl-2-arylpyrimidines and -1,3-thiazines

5-tert-Butyl-2-(4-ethynylphenyl)pyrimidine and the corresponding 2,5-disubstituted-4H-1,3-thiazine block the GABA-gated chloride channel at c.20and c.200 nm , respectively, measured as 50% inhibition of the binding of 1-(4-ethynylphenyl)-4-[³H]propyl-2,6,7-trioxabicyclo[2.2.2]octane (4′-ethynyl-4-n-[³H]propylbicycloorthobenzoate; [³H]EBOB) in house fly and mouse brain membranes, and they are also toxic to topically-treated flies with LD₅₀ values of 6–27 μg g⁻¹ alone and 2–6 μg g⁻¹ with piperonyl butoxide (PB) as synergist. In the pyrimidine series, the general pattern of effectiveness of substituents in the 5-position is tert-butyl>isopropyl≈cyclohexyl≈cyclopropyl>methyl, phenyl and 3- and 4-fluorophenyl, and in the 2-position is 4-ethynylphenyl≪4-bromophenyl. These planar pyrimidines and nearly-planar 4H-1,3-thiazines with 2-ethynylphenyl or 2-bromophenyl and 5-tert-butyl or 5-isopropyl substituents are more effective than the corresponding 6H-1,3-thiazine, 6-oxo-1,3-thiazines and 4,6-dioxo-1,3-thiazine examined, but they are less active than the analogous conformationally flexible trans-1,3-dioxanes and -1,3-dithianes. The heterocyclic moiety confers a region of high electron density and positions the 2- and 5-substituents in a linear or parallel relationship for optimal affinity at the receptor. Two observations indicate that the new pyrimidines and thiazines probably act as chloride channel blockers. First, the poisoning signs are identical to those of EBOB in both mice and house flies. Second, each of the pyrimidines, thiazines and dioxanes falls on the same correlation line for inhibition of [³H]EBOB binding and toxicity to house flies (with PB) as that obtained earlier for EBOB analogs, dithianes and polychlorocycloalkanes, suggesting that they all act at the same or closely coupled binding sites in the GABA-gated chloride channel.     

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。     

Quantitative bioassays for determining residues and availability to plants of sulphonylurea herbicides

A bioassay procedure for quantitative determination of sulphonylurea herbicides is described. Turnips (Brassica rapa) were found very suitable as test plants and gave results within 10 days. Six sulphonylurea compounds were investigated for their activity in three widely differing soils. The potential availability to plants was calculated from the dose-response curves of vermiculite (non-sorptive substrate) and the corresponding ED₅₀-values of the soils. The dose-response relationship (logistic curve) was described by a computer model by a position parameter, the slope of the curve and the minimum and maximum fresh weights of plants. The limit of quantitative detection in the range of ED₃₀ in vermiculite was 0·06 μg 1^?1 for sulfometuron and 1·03 μg 1^?1 for DPX-L5300, methy12-([4-methoxy-6-methyl-1,3,5-triazin-2-yl (methyl)carbamoyl]-sulphamoyl) benzoate. Results with turnips showed that sulfometuron was the most active compound in all substrates (ED₅₀ in vermiculite 0·12 μg 1^?1) followed by chlorsulfuron, metsulfuron-methyl, triasulfuron, DPX-M6316, methyl 3-([(4-methoxy-6-methyl-1,3,5-triazin-2-yl)aminocarbamoyl]-aminosulphaphamoyl)-2-thiophenecarboxylate, and DPX-L5300 which had ED₅₀ or 1·98 μg 1^?1, The Horotiu sandy loam soil showed the highest ED₅₀-values and the lowest plant availability for all compounds compared to the other soils. Probit and logistic evaluation methods for deriving dose-response relationships are compared and their applicability is discussed.     

Fungitoxicity of 6H-pyrazolo[3,4-c][l,2,5]thiadiazine-2,2-dioxides

A base-promoted cyclisation of 4-nitroso-5-benzylsulphonamidopyrazoles (VII) afforded 6 H -pyrazolo[3,4-c][1,2,5]thiadiazine-2,2-dioxides (VIII). They were tested in vitro for antifungal activity against a series of phytopathogenic fungi of different taxonomic classes. Five of the compounds had noteworthy activity; in particular 6H-3-phenyl-5-methyl-7–(3,4-dichlorophenyl) pyrazolo[3,4-c][1,2,5]thiadiazine-2,2-dioxide (VIIIc) at the concentration of 200 mg litre^?1 completely inhibited the growth of Pythium ultimum, Corticium solani and Sclerotinia minor.