IE42229B1 - Benzothiazole derivatives and their use as fungicides - Google Patents

Abstract

Novel benzothiazoles of the formula I in which R is a hydrogen atom, a hydroxyl group or a methyl group, and R<1> is a methyl group, an ethyl group, a chlorine atom, a fluorine atom or a methyl group in the 5-position, are obtained by cyclising a compound of the formula III or the isomer thereof of the formula IV in which R<2> in the formulae III and IV is a methyl group, a methoxy group or a hydrogen atom, where the compounds of the formulae III and IV can optionally be prepared in situ during the cyclisation by acylation of compounds of the formula II with introduction of an acyl group of the formula -CO-R<2>. The novel substances are fungicides.

Description

This invention relates to the field of agricultural chemistry, and provides to the art new compounds which control phytopathogens.

Agricultural chemistry has long attempted to 5 improve on existing fungicides. Many classes of organic compounds have been used, and new compounds are constantly being made and evaluated. Some of the prior art which may be relevant to the present invention is discussed below.

Dreikorn, U.S. Patents 3,764,681 and 3,839,569, 10 disclosed the fungicidal efficacy of tetrazolo[1,5-a]quinolines and s-triazolo[4,3-a]quinolines. Belgian Patent 803,098 and West German Offenlegungsschrift 2,249,350 disclosed that certain imidazoquinoxalines are also useful as agricultural fungicides.

Tamura et al., Novel Syntheses of Thiazolo[3,2b]-s-Triazoles, J. Hetero. Chem. X, 947-51 (1973), published February 16, 1974, disclosed a similar compound having no substituent on the phenyl ring.

Potts et al., Synthesis of the Thiazolo[2,3-c]20 s-Triazole and the Thiazolo[3,2-b]-s-Triazole Systems, J. Org. Chem. 36, 10-13 (1971), and Japanese Patent 71 26,500, C_.A. 75, 140863(g) (1971), disclosed thiazolo[3,2-b]-^triazoles, which were said to be useful as bactericides and agricultural chemicals.

Mosby et al., U. S. Patent 3,389,137, disclosed a tetrazolo[5,l-b]benzothiazole, which was described only as an intermediate to phosphene imide compounds. -242228 The compounds of this invention are of the general formula ,LU wherein R is hydrogen, hydroxy or methyl; and is methyl, ethyl, chloro, fluoro, or methoxy; and provided that the methoxy R* group occupies only the 5position.

The compounds of formula (I) wherein R. ie hydrogen or methyl may be prepared by reacting a compound of the general formula '~T~ J_I =NH -NH (II) wherein is defined as before, with a cyclizing agent.

The compounds of formula (I) are preferably prepared by reacting a compound of the general formula II =N-C-R2 -NH (III) wherein R1 is defined as before; and R is methyl, methoxy, or hydrogen, with a cyclizing agent, to produce a compound of formula (I) 2 , 2 where R is methyl when R is methyl, R is hydroxy when R is methoxy and R is hydrogen when R is hydrogen. - 3 42229 Also, tin* isomer of formula (ill) can br reacted in a similar· manlier to provide the compounds of formula (I). This isomer lias the general, formula 2 wherein R and R are defined as before. The reaction of a compound of formula (IV) to provide a compound of formula (I) gives a compound of formula (i) where R is methyl, when R 2 is methyl, R is hydroxy when R is methoxy and R is hydrogen 2 when R is hydrogen.

A preferred group of compounds comprises the compounds of formula (l) wherein R is hydrogen.

The preferred R^ substituents are methyl, chloro and fluoro, and the preferred location for the R^ substituents is the 5-position.

The compounds below are typical of the compounds of formula (X) 6- chloro-s-triazolo [5,1-b] benzpthiazole 7- fluoro-2-hydroxy-sytriazolo [5,1-bJ benzothiazole fi-ethyl-s-triazolo [5,1—b| benzothiazole 7-ethyl-2-hydroxy-s-triazolo 1-b] benzothiazole ; 5-methoxy-2-hydroxy-s-triazolo [5,l-T] benzothiazole 7- chloro-s-triazolo [5,1-b] benzothiazole 8- fluoro-s-triazolo [5, 1-b] benzothiazole 7-ethyl-2-methyl-s-triazolo j5,1-b] benzothiazole The preferred compounds of formula (I) are 5methyl-sytriazolo [5,1-b] benzo -thiazole,5-fluoro-s-triazolo [5,1-b] benzothiazole, 5-chloro-s^-triazolo [5, 1-b] benzothiazole, 5-methoxy-s-triazolo [5,1-b] benzothiazole, and 2,5-dimethyl-Sytriazolo IT, 1-3 benzothiazole. - 4 42229 The compounds of formula (X) may be made from 2aminobenzothiazoles, which are readily obtained. The R^ substituents of the compounds may be provided by corresponding substituents on the starting 2-aminobenzothiazoles.

Various processes for the synthesis of the new compounds can be used. Tamura, cited above, taught a process which began with the preparation of 3-amino-2iminobenzothiazoline, which he described as a 2,3-diamino compound, by the reaction of the 2-aminobenzothiazole compound with O-mesitylenesulfonylhydroxylamine at ice bath temperature in methylene dichloride. The amino-imino compound, produced as the mesitylene sulfonate salt, was refluxed with acetic anhydride to produce 2-methyl-striazolo[5,1-bJbenzothiazole in 80 percent yield.

The Tamura process can be used, but it produces the 2-acetylamino-3-acetylimino compound as a side product.

The best route for the preparation of the compounds of formula (I) wherein R is methyl proceeds by the cyclization with polyphosphoric acid of an intermediate 2-alkanoylimino-3-aminobenzothiazoline of formula (III).

The compounds named below are typical of the compounds of formula (III). 2- acetylimino-3-amino-6-chlorobenzothiazoline 3- amino-7-ethyl-2-methoxyoarbonyliminobenzothiazoline -542339 2-acetylimino-3-amino-4-methoxybenzothiazoline 2-acetylimino-3-amino-6-fluorobenzothia>oline 2- acetylimino-3-amino-5-chlorobenzothidZolino 3- amino-4-ethyl-2-methoxycarbonyliminobenzothiaζ zoline 2-acetylimino-3-amino-4-fluorobenzothiazoline 2- acetylimino-3-amino-6-ethylbenzothiazoline 3- amino-4-methoxy-2-methoxycarbonyliminobenzothiazoline The intermediate is conveniently prepared by the reaction with O-mesitylenesulfonylhydroxylaniinc of a 2-aminobenzothiazole, in an aromatic solvent or a halogenated solvent such as methylene dichloride at a temperature from the freezing point of the reaction mixture to room temperature, pre15 ferably ice bath temperature, to produce a 3-amino-2-imino compound as the mesitylene sulfonate salt. The salt is converted to the free base by treatment with a strong base, and the free base reacted with acetyl halide to produce the acylated intermediate. The acylation may be done at the same , temperature as the amination step in an aromatic, alkane or halogenated solvent, or in an ether such as tetrahydrofuran, in the presence of an acid scavenger such as triethylamine, or other tertiary amines, or a strong inorganic base such as ah alkali metal carbonate. 2$ The amination step described above, using 0mesitylenesulfonylhydroxylamine can also be done using one of the following amining agents, chloramine, p-bromophenylsulfonylhydrOxylamine, g-toluenesulfonylhydroxylamine, methanesulfonylhydroxylamine, and phenylsulfonyl30 hydroxylamine. -642229 The cyclization of the intermediate is conveniently carried out in neat polyphosphoric acid. The reaction goes most efficiently at relatively high temperatures such as from 100 to 120uC., at which temperatures the reaction goes in good yields in about 1 to 2 hours.

The compounds of formula (I) wherein R is hydrogen are conveniently made by cyclizing an intermediate 3-amino-2-iminobenzothiazoline of formula (II) with triethylorthoformate in an inert reaction solvent. Xylene is the preferred solvent, but other aromatic solvents are also useful. The mixture is heated slowly, and the ethanol released by the reaction should be removed by the use of a Dean-Stark trap or a similar device on the reaction flask.

Compounds having a 2-methyl group can be made in the same way by using triethylorthoacetate or a mixed anhydride in place of triethylorthoformate.

Compounds wherein R is hydrogen are also made by cyclizing the amino-imino salt intermediate with neat formic acid at reflux temperature for 12-24 hours. i The compounds wherein R is hydroxy may be made by the 1 cyclization of a 2-methoxycarbonylimino-3-aminobenzothiazoline of formula (III). The intermediate is conveniently produced by acylating a 3-amino-2-imino compound with chloroformic acid methyl ester, in the usual fashion. The intermediate may be cyclized either thermally, at the melting point neat, or by treatment with an alkali metal hydride in an inert solvent such as an ether, an alkane, or an aromatic solvent, preferably tetrahydrofuran, at reflux temperature. -742329 Another useful method of synthesis for the compounds of formula (I) begins with a l-acyl-2-phenylhydrazine, which is reacted with an alkali metal thiocyanate in an aromatic solvent at an elevated temperature from 40°C. to reflux temperature. The intermediate product is a 4-acyl3-phenylthiosemicarbazide, which may be cyclized with bromine in a halogenated solvent at a temperature from about 30°C. to the reflux temperature of the reaction mixture to produce a 3-acylamino-2-iminobenzothiazoline as the HBr salt. The salt may be reduced to the free base of formula (IV) by contact with a strong base as described above, and may be cyclized by heating at the reflux temperature in acetic acid to produce the desired product. Other reagents which could be used in place of the acetic acid are sulfuric acid, heat, and acetic anhydride.

The following preparative examples illustrate the synthetic methods used in preparing the starting compounds of formulae II, III and IV.

Example A A 7.2 'g. portion of 2-amino-4-methoxybenzothiazole was slurried in methylene dichloride. The mixture was cooled in an ice bath, and an 11 g. portion of mesitylenesulfonylhydroxylamine was added, as a methylene dichloride solution at ice.bath temperature. The reaction mixture was allowed to warm gradually to room temperature over a threehour period. The reaction mixture was then diluted with ethyl ether and filtered.

The solids were slurried in 100 ml. of chloroform.

A solution of 6 g. of KOH in 75 ml,, of water was added over -842229 a 30-minute period. The solid crude product was separated by filtration, and the chloroform layer was evaporated to dryness under vacuum to produce more product. The products were combined and recrystallized from ethyl acetate to produce 4.8 g. of 3-amino-2-imino-4-methoxybenzothiazoline, m.p. 131-32°c., which was identified by nuclear magnetic resonance analysis.

Example B A 1.7 g. portion of 3-amino-2-imino-4-methyl10 benzothiazoline was dissolved in about 50 ml. of tetrahydrofuran, and 1.1 g. of triethylamine was added. The reaction mixture was cooled in an ice bath, and 1 g. of acetyl chloride, dissolved in 2 ml. of tetrahydrofuran, was added dropwise while the mixture was stirred. After the addition was complete, the reaction mixture was stirred at ice bath temperature for about 8 hours, and was then diluted with an equal volume of water. The tetrahydrofuran was removed under vacuum, and the remaining aqueous mixture was filtered to recover the product. After recrystallization from ethanol, the yield of purified product was 2.0 g. of 3-amino-4-methyl-2-acetyliminobenzothiazoline, m.p. 1545°C. The product was identified by nuclear magnetic resonance and ultraviolet analysis and by elemental microanalysis.

Theoretical Found 54.28% 54.59% .01 .42 18.99 18.11 42239 Example C A 1.8 g. portion of 3-amino-2-imino-4-mcthylbenzothiazoline was slurried in about 50 ml. of tetrahydrofuran, and 1.3 g. of triethylamine was added. The reaction mixture was then cooled in an ice bath, and 1.04 g. of chloroformic acid methyl ester was added dropwise. The reaction mixture was stirred at ice bath temperature for about 4 hours after completion of the addition, and the reaction mixture was then worked up as described in Example B. The product was identified as 3-amino-2methoxycarbonylimino-4-methylbenzothiazoline by nuclear magnetic resonance and ultraviolet analysis, and by elemental microanalysis as follows: , Theoretical Found C 50.26% 50.86% 4.67 4.91 N 17.71 17.66 Example D The reaction scheme of Example C was followed, using 2.0 g. of 3-amino-4-chloro-2-iminobenzothiazoline in 30 ml, of tetrahydrofuran in the presence of 1.1 g. of triethylamine. The starting compound was acylated with 1.5 g. of chloroformic acid methyl ester, and the reaction time was only about 2 hours. The product was identified as 3-amino-4-chloro-2-methoxycarbonyliminobenzothiazoline, m.p. 222-23°C., by nuclear magentic resonance and ultraviolet analysis, mass spectroscopy and elemental microanalysis. -1042228 Theoretical Found c 41.95% 41.92% li 3.13 3.16 N 16.37 16.10 ίο The following examples illustrate the preparation of the compounds of formula (I).

Example 1 A 9.2 g. portion of 3-amino-2-methoxycarbonylimino-4-methylbenzothiazoline, produced by the process of Example C, was heated in a flask in a Woods metal bath at approximately 220°C. for approximately 1-1/2 hours. The flask was then allowed to cool, and the product was reerysfdlIized from dimethylformamide to produce 9.9 g. of 2-hydroxy-b-methy1-s-triazolo15,1-b|benzothiazole, m.p. higher than 300°C., the elemental microanalysis of which was as follows.

Theoretical Found C 52.67% 52.62% H 3.44 3.59 N 20.47 20.33 Example 2 A 4 g. portion of 3-amino-4-chloro-2-iminobenzothiazoline was slurried in 50 ml. of xylene. To the mixture was added 3.7 g. of triethylorthoformate dissolved in about ml. of xylene. The mixture was then heated very slowly to the reflux temperature. The ethanol which distilled from the mixture was collected in a Dean-Stark trap. After about 1 hour, the mixture was allowed to cool. The cooled reaction mixture was filtered, and the solids were washed with -1142229 benzene. The yield was 2.8 g. of 5-chloro-s-triazolo[5,1-b]benzothiazole, m.p. 203-05°C., which was identified by nuclear magnetic resonance analysis and elemental micro- analysis. Theoretical Found C 45.83% 45.99% H 1.92 1.99 Example 3 N 20.04 19.94 A 15 g. portion of 1-acetyl- 2-(2-methylphenyl)- hydrazine was mixed with 75 ml. of benzene, and 16.4 g. of sodium thiocyanate was added. The reaction mixture was heated to 45°C., and 16 g. of trifluoroacetic acid was added. The mixture was then heated to reflux temperature, and stirred at that temperature for 3-1/2 hours. Excess benzene was then decanted, and the thick residue was poured into water. An equal volume of ethyl acetate was added, and the solids were separated from the mixture by filtration and washed with ethyl acetate to yield 4-acetyl-3-(2-methylphenyl)thiosemicarbazide.

The above intermediate product was slurried in 70 ml. of ethylene dichloride, and 5.3 g. of bromine dissolved in 30 ml. of ethylene dichloride was added dropwise with stirring. The mixture was heated to reflux temperature and stirred.at that temperature for 1-1/2 hours. The mixture was then allowed to cool to room temperature and stirred overnight. Then the reaction mixture was diluted with an equal volume of ethyl ether, and the white solids were separated by filtration and washed with additional ethyl -1242229 ether. The product was identified as 3-acetylamino-2imino-4-methylbenzothiazoline, HBr salt, by infrared and nuclear magnetic resonance analysis.

The above product was slurried in 100 ml. of water. The mixture was made neutral with NH^OH, and the product was recovered by filtration. The product was 3acetylamino-2-imino-4-methylbenzothiazoline.

One g. of the above product was dissolved in 50 ml. of acetic acid, and the solution was stirred at reflux temperature for 28 hours. Dioxane was then added, and most of the acetic acid was removed as an azeotrope by distillation. The remaining reaction mixture was poured into a large amount of water, and the aqueous mixture was neutralized with potassium bicarbonate. The mixture was then repeatedly extracted with ethyl acetate, and the ethyl acetate layers were combined and evaporated under vacuum to leave an oil, which partially solidified on standing. The residue was triturated in a 4:1 mixture of ethyl ether: chloroform, and the mixture was filtered. The filtrate was chromatographed on a silica gel column, eluting with a 2:1 mixture of benzene:ethyl acetate. The product-containing fractions were combined and evaporated under vacuum, to produce 2,5-dimethyl-s-triazolo[5,1-b]benzothiazole, m.p. 121-23°C.

Example 4_ A 2.2 g. portion of the intermediate product made in Example B was slurried in 15 ml. of polyphosphoric acid. The mixture was heated to about 110°C. for about -1343229 1-1/2 hours. The mixture was then allowed to cool to room temperature, and was diluted with a large amount of water. The aqueous mixture was neutralized with Nli^OH and filtered to separate the crude product. After re5 crystallizing there was obtained 2,5-dimethyl-s-triazolo[5,l-b]benzothiazole, m.p. 121-23°C.

The synthetic methods of examples 1-4 are used, with appropriate variations which can be supplied by an ordinarily skilled organic chemist, to produce all of the compounds of formula (I), such as the following examples. Example _5 , -methyl-s-triazolo[5,l-b]benzothiazole, m.p. 134-35°C. Example (5 2,5-dimethyl-s^-triazolo [5,l-b]benzothiazole, m.p. 121-23°C j Example 7 -fluoro-s-triazolo[5,l-b]benzothiazole, m.p. 165-67°C. Example 8 -fluoro-2-methyl-s-triazolo[5,l-b]benzothiazole, m.p. 162-64°C.

Example -methoxy-s-triazolo[5,l-b]benzothiazole, m.p. 142-43°C. Example 10 7-methyl-s-triazolo[5,l-b]benzothiazole, m.p. 156-58°C. Example 11 2,7-dimethyl-s-triazolo[5,l-b]benzothiazole, m.p. 118-19°C Example 12. -chloro-2-methy1-s-triazolo[5,l-b]benzothiazole, m.p. 263-64°C. -1442229 Example 13 -chloro-2-hydroxy-s-triazolo[5,1-b]benzothiazole, m.p. 340-41°C. dec.

Example 14_ -methoxy-2-methyl-s-triazolo[5,1-b]benzothiazole, m.p. 146-47°C.

Example 15 -ethyl-s-triazolo[5,1-b]benzothiazole, m.p. 93-96°C.

Example 1_6 -ethyl-2-methyl-sytriazolo[5,1-b]benzothiazole, m.p. ’ 5 ‘ The compounds of formula (I) in accordance with various of the preceding Examples have been shown in a number of in vivo tests to reduce tho adverse el foots of foliar fungi. The first group of tests befow illustrate the tests in which the compounds have been evaluated against fungi.

The compounds of formula (I) were formulated for testing by dissolving or suspending about 3.5 weight percent of each compound in 50:50 acetone:ethanol containing about 10 g./ΙΟΟ ml. of a nonionic surfactaht. The solution was then dispersed in deionized water in a quantity such that the water dispersion contained the various compound concentrations indicated in the tables below. Concentrations Were measured in parts per million by weight. The compound dispersions were applied to the test plants by spraying them with an air atomizer, using sufficient dispersion to wet the plants thoroughly. Compounds were formulated and applied differently in the bean rust tests, as shown below. -1542233 Untreated, infected controls and untreated, normal controls were included in each test. The results ire reported on a 1-5 rating scale where 1 indicates severe disease and 5 indicates complete control of the disease. An empty space in the tables shows that the indicated compound was not tested at the indicated rate. In some cases, more than one test was performed against a given phytopathogen, and the results in such cases are reported as averages. Compounds are identified by the example numbers used above.

The following specific test methods were used.

Test 1 helminthosporium leaf spot of wheat Healthy wheat seed was planted in sterile greenhouse soil. When the seedlings were 4-5 inches tall, they were sprayed with test compound dispersions. The day after treatment, the plants were inoculated with a spore suspension of Helminthosporium sativum which had been grown on potato dextrose agar. The plants were placed in a moist growth chamber for two days to start disease growth, and were then transferred to the greenhouse. About a week after treatment, the plants were observed and the results were recorded.

Test 2 late blight of tomato Four-week-old tomato seedlings were sprayed with aqueous dispersions containing test compounds. The following day, the foliage was inoculated with an aqueous suspension of propagules of Phytophthora infestans. The inoculum had been reared on infected wheat seed. The plants were held and observed as described above. -1642229 Test 3 powdery mildew of bean The host plants were 10-day-old bean seedlings. After aqueous dispersions containing test compounds had been sprayed on the foliage of the beans and allowed to dry, the plants were placed in the greenhouse and inoculated by storing them under other bean plants which were heavily infected with powdery mildew (Erysiphe polygon!). After about 10 days, the plants were observed and the results recorded as usual.

Test 4 anthracnose of cucumber Aqueous dispersions containing test compounds were applied to healthy cucumber seedlings grown in sterilized greenhouse soil. The following day, the plants were inoculated with Colletotrichum lagenarium conidia as an aqueous suspension. The fungus had been grown on potato dextrose agar in petri dishes. The plants were held in a moist chamber for two days and transferred to the greenhouse, and the disease was observed and rated approximately 12 days after application of the test compounds.

Test 5 rice blast of rice The test compound dispersions were applied to healthy rice seedlings growing thickly in plastic pots. The plants were inoculated on the next day with Piricularia oryzae (grown on rice polish agar) and the plants were held in a moist chamber for two days. The plants were then held in the greenhouse for 5-7 days and observed. -174 2239 Test £ bean rust of bean Pinto bean seedlings were raised in plastic pots in the greenhouse. One week after the seeds were planted, ml. of a 400 ppm. aqueous dispersion of the compound to be tested was added to the soil in which each treated plant was growing, providing a rate of 12.3 kg./ha. The following day, the plants were inoculated with spores of bean rust tUromyces phaseoli var. typica) which were grown on pinto bean plants and applied to the test plants as an aqueous dispersion. The plants were held for two days in a moist chamber, transferred to the greenhouse, and observed about 10 days after inoculation with the phytopathogen.

Test 7 cercospora leaf spot of sugar beet Sugar beet seedlings were transplanted into square plastic pots and allowed to grow for three weeks. Aqueous dispersions containing the compounds to be tested were sprayed on the leaf surfaces. After the dispersions dried, but within 24 hours, the plants were inoculated with a conidial suspension of Cercospora beticola which had been grown on sugar beet leaf decoction agar. After the plants were held in a moist chamber for two days, they were transferred to the greenhouse and observed 2-3 weeks later.

Test 8 botrytis of grape Sound grape berries were sterilized by immersion in diluted sodium hypochlorite and thoroughly rinsed. The berries were placed on wire screen shelves in compartmented -1842229 Pyres plates (Pyrex is a registered Trade Mark). The berries were then flamed and sprayed with test chemical dispersions. The following day, the berries were inoculated by spraying 5 ml. of a conidial suspension of Botrytis cinerea over each plate containing 12 berries. The inoculum had been grown on frozen lima bean agar. A small amount of water was added to each plate and a cover was sealed over each plate. After 48 hours at 25°C., the berries were observed and disease ratings recorded.

Test 9 apple scab of apple Apple seedlings at the 4-6 leaf stage were sprayed with aqueous dispersions of the test compounds. The following day, the plants were sprayed with a suspension of fresh conidia of Venturia inaequalis obtained from infected apple seedlings kept as a source of inoculum. The plants were held for two days in a 20°C. moist chamber to start disease growth and were then transferred to the greenhouse. About two weeks after application of the compounds, the plants were observed and the results were recorded.

Test 10 downy mildew of grape Young expanding grape leaves were detached from healthy vines on the day of the test. Leaves were placed individually in plastic petri dishes, bottom side up, on top of an expanded plastic mat. Water was added to each petri dish, and the petiole of each leaf was wrapped with a water-soaked wad of cotton. Each leaf was sprayed with an aqueous dispersion of the compound to be tested. -1942329 After the test compound dispersions had dried, the leaves were inoculated by atomizing a conidial suspension of Plasmopara viticola (grown on infected leaf tissue) evenly over the leaf surface. The plates were then covered and were stored in a growth room at about 18°C. and 100% relative humidity where they were exposed to 8 hours a day of artificial light. After about a week of storage, all the leaves were observed and the signs of disease were evaluated.

The following table reports results of testing typical compounds of formula (I) by the above methods. -2042229 Ejodsonjoal m 1-1 MSpItW AuMOfl ΓΛ CO Π* OJ qvos sjddv uinTJOds -oqquiuixsH qqfiTTS qsntf ueag Table STqZjqog qsBia ΘΟΤΗ in co H rd Gsouoejqquv Λθρχτρί AjapMOj Γ- rd e rd Φ · ftp S Qi rt a < a 04 in C'3 in CN TJ β 3 Ο Οι · a»w g o g 0 nJ2 0 « υ w euodsoouaa ΜΟΡΠΗ Aumoq quos ai[ddy umjuods -oqguTuixaH tqbTia θ+εί r~ rn m *3 Table 1 Continued qsna ueag STqXjqog ^st?T9 BOTH esouo^jxi^uv Msp.tTW XzapMOa c Η Φ · ft-ρ e ft β ft < 05 ft} Ό C β ft * fty-i g o g Ο β 2 0 X a w m m <*i Η 400 -2242229 euodsooiteo «OPTTW Aumoq qeos eiddv umxjods -oqguTUixeH qq&ns sgeg Table 1 Continued '4 sn>j UUOfl StgAjgog I qseia eoja ©souoBzq^uv MGpTTW AuepMoj β η ο · ft+j ε ft m ft < « Q4 T3 c Γ—( 0, Q.IU g 0 e ο β z 0 X U M CN CM in <—I H CN in in κ cn m *12.3 kg./ha. 2342229 Compounds of foi'mula (X) in accordance with various of the Examples have also been tested in a system which evaluated the compounds* ability to control rice blast systemically. The compounds were applied either to the soil in which rice plants were grown, or to rice seed, and the extent to which the compound controlled artificially inoculated rice blast was observed.

Test 11 seed soak test Test compound dispersions were prepared as described above, except that ethanol was used in place of ace tone: ethanol, and the final aqueous dispersions always contained 0.5 percent of ethanol regardless of tho concentration of the active compound. Compound concentrations of 250, 500 and 1000 ppm. were used.

Rice seed was treated by shaking 20 ml. of Nato rice and 20 ml. of a compound dispersion for 48 hours in a stoppered flask. After the shaking period, the rice seed was drained and thoroughly rinsed with tap water. The seed was planted, and the seedlings were inoculated with P. oryzae by spraying the foliage with a P. oryzae culture.

The inoculated plants were held for 2 days in a moist chamber and observed.

Test 12 soil surface-applied test The compounds were formulated as described at the beginning of the test method discussion, and were applied to the soil surface of pots in which 10-cm. rice seedlings were growing. The volume of test compound dispersions was always 75 ml., and rates from 28 kg./ha. to 1.4 kg./ha. were used. -2442229 Two days after application of the compounds, the plants were inoculated and held for observation as described in the test method immediately above.

Test 13 soil-incorporated test Sterile greenhouse soil was treated with the? proper amounts of test compounds, dissolved in ethanol, to provide treatment rates from 1.4 to 28 kg./ha. The compounds were thoroughly mixed with the soil in a rotating drum mixer. Rice seed was planted in the treated soil, and the emerged rice seedlings were inoculated and observed as described above.

Seed Soak Treatment Compound . ol . Example No. Λρρ]n. Ra te ppm. 1) i.sease Rating 2 1000 4.3 500 4.3 250 3 5 1000 3.3 500 3 250 2.7 6 1000 1.3 500 1.3 250 1.3 7 1000 4 500 4 250 3 9 1000 3.3 500 1.3 250 1 -2542229 Seed Soak Treatment Compound of Example Appln. Rate Disease 5 No. ppm. Rating 12 1000 2 500 1.3 250 1.7 15 1000 2.3 10 500 2 250 2.3 Soil Surface Treatment 15 Compound of Example No. Appln. Rate ppm. Disease Rating 4 2 5.6 2.8 1.7 1.4 3 20 5 28 4.3 14 4 7 4.3 5.6 4.3 2.8 3.7 1.4 2 -2642229 Soil Surface Treatment Compound of Example No. Appln. Ra te PEm· Disease Rating 6 28 1 14 1.3 7 1.3 5.6 5 2.8 4. i 1.4 2.7 7 · 28 5 14 5 7 4.3 9 28 1.3 14 1.7 7 1 . 3 15 28 2.7 14 2 7 2 43329 Soil Incorporation Treatment 5 Compound of Example No. Appln. Rate kg./ha. Disease Rating 2 5.6 4 2.8 4 1.4 1 5 5.6 3 10 2.8 1.7 1.4 1.3 7 5.6 4.3 2.8 3.7 1.4 2 15 9 28 1.3 7 1.3 15 28 3 14 1 7 1.3 -2842229 The method of reducing the adverse effects ol' plant foliage-attacking fungi is carried out according to the methods and principles which are well known in agricultural chemistry. Detailed discussion of the method will be provided'to assure that agricultural chemists can gain the best advantage from the use of the compounds of formula (I) described herein.

The present method of reducing the adverse effects of plant foliage-attacking fungi comprises contacting the fungi with an effective fungus-inhibiting amount of one of the new compounds of formula (1). The preferred use of the method is in reducing the adverse effects of P. oryzae on rice. The compounds with which the method is preferably carried out., arc 5-chloro-s-triazolo [5,1-b]benzothiazole, -methyl-£-triazolo[5,1-nJ benzothiazole, 5-fluoro-s-triazolo[5,1-b]benzothiazole, and 2,5-dimethyl-s-triazolo[ 5,1-b]benzothiazole.

Practice of the method need not necessarily kill all of the contacted fungi in order to confer its benefit on the treated plants. Proper use of the method kills part of the fungi, and inhibits another part of the fungi by injuring, or slowing growth of, the organisms. As the data above show, application of a sufficient amount of a compound to inhibit the fungi reduces the adverse effects of the disease, whether all of the fungus population is killed by the compound or not.

As is usual in the plant protection art, best results are obtained by applying the compound several times -2942339 during the growing season at intervals of from 3 to a few weeks, depending on the weather.and the severity of the disease. The methods of formulating the compounds and preparing dispersions of the formulations, and the methods of applying dispersions of the compounds to the plants to be protected, are entirely conventional in the plant protection art. Some explanation of the methods of application will be given merely to assure that those skilled in the art can carry out the invention without undue experimentation.

The compounds of formula (I) can be used for the control of foliage-attacking fungi by either applying the compound to the foliage oL' the plants, where they directly contact the fungi, or by applying the compounds to the soil, where they are absorbed by the roots of the plants and carried through the plant's tissues to the foliage where they contact the fungi and reduce their adverse effects.

Both methods of application are regularly in use in the plant protection art.

It is usual in describing foliar applications of plant protectants to measure the application rate by the concentration of the dispersion in which it is applied. The application rate is measured in this way because it is customary to apply a sufficient amount of the dispersion to cover the foliage with a thin film. The amount of dis25 persion applied is thus dependent on the foliar area of the plant, and the quantity of plant protecting compound is dependent upon its concentration in the dispersion.

Compound concentration in the range of from about 25 to about 1500 parts of compound per million parts by -304222 ; weight of the dispersion are used in the practice of the antifungal method of this invention, when the fungi are contacted by applying the compound to the foliage. Of course, from time to time, higher or lower concentrations will be useful, depending on the severity of the infection and the characteristics of the specific compound in use.

The named range, however, encloses the usual optimum concentrations of the compounds.

When the method is carried out by applying the compound to the soil in which the plants grow, it is most meaningful to describe the application rate in terms of the amount of compound applied per unit area of soil. Compound application rates in the range of from about 1 to about 50 kg./ha. are used in the practice of this invention to reduce the adverse effects of foliage-attacking fungi. As previously described, application rates higher and lower than the named range will at times be useful.

The dispersions in which the compounds are applied to foliage are most often aqueous suspensions or emulsions prepared from concentrated formulations of the compounds. Such water-suspendible or emulsifiable formulations arc either solids usually known as wettable powders or liquids usually known as emulsifiable concentrates. Wettable powders comprise an intimate mixture of the active compound, an inert carried and surfactants. The concentration of the active compound is usually from about 10 percent to about 90 percent by weight. The inert carrier is usually chosen from among the attapulgite clays, the montmorillonite clays, the -3142229 diatomaceous earths, or the purified silicates. Effective surfactants, comprising from about 0.5 percent to pbout 10 percent of the wettable powder, are found among the sulfonated lignins, the condensed naphthalenesulfonates, the naphthalenesulfonates, the alkylbenzenesulfonates, the alkyl sulfates, and nonionic surfactants such as ethylene oxide adducts of alkyl phenol.

Typical emulsifiable concentrates of the compounds comprise a convenient concentration of the compound, such as from about 100 to about 500 g. per liter of liquid, dissolved in an. inert carrier which is a mixture of waterimmiscible organic solvent and emulsifiers. Useful organic solvents include the aromatics, especially the xylenes, and the petroleum fractions, especially the high-boiling naphthalenic and olefinic portions of petroleum such as heavy aromatic naphtha. Other organic solvents may also be used, such as the terpenic solvents including rosin derivatives, and complex alcohols such as 2-ethoxyethanol. Suitable emulsifiers for emulsifiable concentrates are chosen from the same types of surfactants used for wettable powders.

Adjuvants are frequently used to improve the ability of the aqueous dispersion to coat and adhere to foliage. Such adjuvants as gums, emulsified polybutenes, cationic surfactants and lignin derivatives can often increase the potency of the method in a specific use.

Less frequently, the compounds are applied in the form of dusts. Agricultural chemical dusts typically comprise the compound in a finely powdered form, dispersed in a -3242329 powdered inert carrier. Most often, the carrier is a powdered clay, such as pyrophyllite, bentonite, a volcanic deposit, or montmorillonite. Dusts are usually prepared to contain concentrations of the compound at the highest part of the concentration range, such as 1500 ppm., and may contain even more active ingredient.

Dispersions of the compounds are applied to foliage in the usual manners. Low-pressure sprayers, high-pressure sprayers and low-volume air blast equipment are all effective for the application of water-dispersed compounds of formula (I). Dust dispersions are readily applied by means of the usual equipment which blows the dust into intimate contact with the foliage.

I The same types of dispersions used for application to plant foliage can also be applied to the soil. In addition, the compounds can economically and conveniently be applied to the soil in the form of granular formulations. Such formulations, well known to the agricultural chemical art, are prepared by dispersing the compound on an inert carrier of controlled granular character. Most often, the carrier is a coarsely ground clay, such as attapulgite or kaolin clay, having a particle size in the range of from 0.5 to 3 mm. Such granular formulations are easily applied to the soil with applicators which are specially designed to apply accurately controlled amounts of the granular products to the soil.

Claims (25)

1. CLAIMS:1. A compound of the general formula wherein U is hydrogen, hydroxy or methyl; and R 1 is methyl, ethyl, chloro, fluoro, or methoxy; and provided that the methoxy R^ group occupies only the 5position.

2. A compound according to Claim 1 wherein R is hydrogen and R^ is methyl, chloro or fluoro.

3. 2-hydroxy-5-methyl-s-triazolO(5,1-b]benzothiazole

4. 5-chloro-sytriazolo[5,1-b]benzothiazole

5. 5-fluoro-2-methyl-s-triazolo(5,1-b]benzothiazole

6. 5-methyl-sytriazolo[5,1-b]benzothiazole

7. . 2,5-dimethyl-s-triazolo[5,1-b]benzothiazole

8. 5-fluoro-s-triazolo[5,1-b]benzothiazole

9. . 5-methoxy-s-triazolo[5,1-b]benzothiazole

10. . 7-methyl-s-triazolo[5,1-b]benzothiazole

11. 2,7-dimethyl-S5triazolo[5,1-b]benzothiazole

12. . 5-chloro-2-methyl-s-triazolo[5,1-b]benzothiazole

13. · 5-chloro-2-hydroxy-s-triazolo[5,1-b]benzothiazole

14. . 5-methoxy-2-methyl-s-triazolo[5,1-b]benzothiazole

15. 5-ethyl-s-triazolo[5,1-b]benzothiazole

16. 5-ethyl-2-methyl-s-triazolo[5,1-b]benzothiazole -3442229

17. Λ process for the preparation of a compound as defined in any one of claims 1, 2, 4 to 12 and 14 to 16, wherein R is hydrogen or methyl, the process comprising reacting a compound of the general formula wherein is defined as in Claim 1 with a cyclizing agent.

18. Λ process for the preparation of a compound as defined in any one of claims 1 to 16, the process comprising reacting a compound of the general formula or hydrogen, with a cyclizing agent, to produce a compound 2 of formula (X) where R is methyl when R is methyl, where 2 R is hydroxy and R is methoxy and where R is hydrogen when 2 15 R is hydrogen.

19. Λ process for the preparation of a compound as del'ined in any one of claims 1 to 16, the process comprising reacting a compound of the general formula NH -NH-C-R 2 (IV) 35 43229 whci’ein R.1 is as defined as in claim ί; and 2 R Is methyl, methoxy, or hydrogen, with a cyclizing agent, to produce a compound of formula (I) where R is methyl when 2 2 5 R is methyl, R is hydroxy when R is methoxy and R is hydrogen when R is hydrogen.

20. Λ fungicidal composition comprising as active ingredient 10 to 90 weight percent of a compound according to any one of claims 1 to 16. 10

21. A fungicidal composition according to claim 20 wherein the active ingredient is one or more of the compounds of claims 3 to 16.

22. A method of reducing the adverse effects of foliageattacking fungi which comprises contacting the fungi with an 15 effective fungus-inhibiting amount of a compound according to any of claims 1 to 16.

23. A process for the preparation of a compound as defined in claim 1 substantially as hereinbefore described with particular reference to any of the Examples. 20

24. A composition as defined in claim 20, substantially as hereinbefore described.

25. A method as defined in claim 22 substantially as hereinbefore described.