ANTIFUNGAL COMPOUNDS

Abstract: Compounds having the formula (I): (R1R2N)CH2-CH=CH-CH2(NR3R4) wherein R1, R2, R3 and R4, which may be the same or different represent hydrogen atoms, an alkyl group having from 1 to 6 carbon atoms, a cycloalkyl group of 3 to 6 carbon atoms, a heterocyclic group, an aryl group, a heteroaryl group having from 3 to 6 atoms, an amidino group or R1, R2 and/or R3 and R4 together represent a carbocyclic or heterocyclic group comprising from 3 to 6 atoms with the proviso that R1, R2, R3 and R4 cannot simultaneously represent hydrogen and salts thereof are fungicides especially mildewicides. Preferred compounds are those wherein the groups R represent methyl or ethyl groups.

Description: ANTI UNGAL COMPOUNDS Field of the invention This invention is in the field of the control of fungal infection in plants. Description of the prior art Polyamines are essential for the growth and development of all organisms, including plants and fungi. However, whereas plants possess two pathways for polya ine biosynthesis, i.e. via the enzymes ornithine decarboxylase [ODC] and arginine decarboxylase [ADC], fungal polyamine biosynthesis appears to be a result of ODC activity only. Plants are attacked by a wide range of fungi which are the cause of considerable losses of yield and quality. Since fungi possess only the ODC pathway of polyamine biosynthesis, the inhibition of this enzyme should control their growth. Such inhibitors have been extensively researched but the major breakthrough was directly attributable to the synthesis of enzyme-activated irreversible inhibitors of ODC and ADC notably difluoromethylornithine CDFMO], which has been tested as an anti-cancer agent and also as . an anti-parasitic agent, and difluoro ethylarginine [DFMAL Recent work has shown that DFMO can reduce fungal growth and has led to the investigation of the use of DFMO as a fungicide, see for example W088/02986 (Weinstein and Galston) and US 4,760,091 (Carson e ϋl.). The effect of compounds (including DFMO) which interfere with polyamine metabolism on the growth of the fungus Botrvtis cinerea has been investigated (Smith et aj.. , 3. Gen. Microbiol. 1990, , 985). This work demonstrated that the DFMO inhibition of fungal growth could be reversed with the addition of putrescine, cadaverine, spermidine and spermine. "Butenediamine", caused some inhibition of fungal ' growth but significantly reversed the inhibitory effect of DFMO. Summary of the invention It has surprisingly been found that certain derivatives of 2-butene-l ,4-d amine exhibit considerable anti-fungal activity. Accordingly, the invention provides the use as a fungicide of compounds having the general formula (I) below: wherein R-- , R 2 , R3 and R4, which may be the same or different represent a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, a cycloalkyl group having from 3 to 6 carbon atoms, a heterocyclic group, an aryl group, a heteroaryl group, having from 3 to 6 atoms or an amidino group or R- j and R 2 and/or R 3 and R4 together represent a carbocyclic or heterocyclic group comprising from 3 to 6 atoms, with the proviso that R- j , R 2 , R3 and R4 cannot simultaneously represent hydrogen atoms. Description of the preferred embodiments The antifungal activity of the compounds of formula (I) is thought to be due mainly to their properties of polyamine metabol sm interference. However, other mechanisms may play a role in the activity of these compounds as antifungal agents. The groups R- | , R 2 , R3 and R in formula (I) may be the same or different. Preferaby the groups R- j and R 2 identical and the groups R3 and R4 are identical and even more preferably, the groups Ri-, R , R3 and R 4 are all identical. Preferred compounds are those wherein at least one of R- j , R 2 , R3 and R 4 are alkyl groups, preferably having 1 to 3 carbon atoms. More preferably at least one of R- j and R 2 and at least one of R 3 and R4 represents an alkyl group having from 1 to 3 carbon atoms. A particularly preferred compound is E-(N'N'-dimethyl)-l ,4- d amino but-2-ene. Another preferred group of compounds are those wherein R- | , R 2 , R3 and R4 all represent alkyl groups having from 1 to 4 carbon atoms. A particularly preferred compound is'E-(N,N,N' ,N- tetraethyl)-l,4-d aminobut-2-ene (TED). Where the groups R- | , R 2 , R 3 and R4 represent groups other than hydrogen atoms, those groups may themselves be substituted for example with one or more halogen atoms, hydroxyl groups, alkyl groups or alkoxy groups especially those comprising from 1 to 4 carbon atoms. The compounds of formula (I) may be synthesised using the conventional techniques of synthetic organic chemistry. The substituted diamines may be synthesised by displacement of bromine from (JE)-l ,4-dibromo-2-butene by a primary or secondary a ine. The compounds of formula (I) also exhibit antifungal activity when prepared in the form of their acid salts and such salts may be utilised as fungicides according to this invention. The compounds can form salts with mineral acids such as HC1, HBr, HI, H 2 S0 , HNO3, H3PO4 or with organic acids such as formic, acetic, trifluoroacetic, propionic, benzoic, maleic, fumaric, succinic, tartaric, citric, oxalic, glyoxylic, alkyl- or aryl-sulphonic, salicylic, malonic and ascorbic. These salts may be prepared by standard techniques and procedures well known in the art. The present invention also provides a method for the fungicidal treatment of plant material in either a preventative or curative mode. The treatment may be applied to growing or harvested plant materials. If the plant material is growing, then the plants may be treated before they are infected by the fungi. This can be carried out by either treating the whole plant (e.g. by spraying it with a solution/emulsion or suspension of the antifungal compounds) or by applying the compounds to specific parts of the plant, e.g. the leaves, stems, fruits or even seeds prior to planting. Treatment of the soil is another alternative since the antifungal compounds of the invention are systemic in their mode of action. Plants which have come into contact with fungi and thus already infected may be treated locally at site of infection or the whole plant may be treated. The present invention also includes treatment of harvested plant parts for the control of fungal diseases. For this, various ways of carrying out the treatment can be employed. These will be well known to those skilled in the art, for example, treatment can be to the harvested plant itself by for example dipping the plant part into a solution of the antifungal agent, or by impregnating fungicide into the wrapper, carton, crate, etc. in which the plant will be transported. Alternatively, the harvested plant material may be fumigated with the fungicide in a special room, car or tank. This invention also provides fungicidal compositions comprising at least one compound having the formula (I) together with a suitable diluent or carrier. Such diluents or carriers must not be phytotoxic to the plant materials. Suitable diluents and carriers include water and organic solvents. Preferably the concentration of the compounds is between 0.001-0.1 molar. Seeds may be treated prior to planting and again this may be carried out among other methods by fumigation. Thus, the compounds can be dispersed on a finely-divided solid to form a dust. Also, the compounds can be dispersed in water, typically with the aid of a wetting agent, and the resulting aqueous dispersion employed as a spray. In other procedures the compounds can be employed as a constituent of organic liquid compositions, oil-in-water and water-in-oil emulsions or dispersions, with or without the addition of wetting, dispersing or emulsifying agents. Suitable adjuvants of the foregoing type are well known to those skilled in the art. The methods of applying the solid or liquid fungicidal formulations are similarly well known. The concentration of the active compounds in solid or liquid compositions generally is from about 1 to about 20 percent by weight or more. Concentrations from about 5 to about 10 percent by weight are often employed. In compositions to be employed as concentrates, the active compound can be present in a concentration from about 15 to about 50 weight percent, preferably 20 weight percent. The compositions containing the active compounds can also contain other compatible additives, for example, phytotoxicants, plant growth regulants, pesticides, other fungicides and the like which are suitable for application to agricultural, horticultural, forestry and amenity crops. The present compositions can be applied by the use of power dusters, boom and hand sprayers, spray dusters and by other conventional means. The compositions can also be applied from airplanes as a dust spray since the ingredients are effective at very low application rates. The exact rate to be applied is dependent not only on the specific diamine being applied, but also on the particular treatment desired (e.g. seed, soil, or foliage) the particular crop being treated, climatic conditions, severity of any infection and the like. Thus, it is also to be understood that all of the active compounds of the present invention and compositions containing the same may not be equally effective at similar concentrations or against the same fungal species. In foliar treatments, the active compounds of the present invention are usually applied at an approximate rate of from about 50 to 500 g/ha, a rate of from about 80 to 400 g/ha being preferred and a rate of from about 100 to about 350 g/ha being particularly preferred. In seed treatments, the active compounds of the present invention are usually applied at an approximate rate of from about 60 to about 250g per 100 kg seed, a rate of from about 100 to about 200g per 100kg seed being preferred and a rate of from about 140 to about 180g per 100kg seed being particularly preferred. In soil treatments, the active compounds of the present invention are usually applied at an approximate rate of from about 50 to about 350 g/ha, a rate of from about 100 to about 300 g/ha being preferred and a rate of from about 200 to about 280 g/ha being particularly preferred. A typical solid composition is formulated by dry milling the active compound with BARDEN clay. This solid formulation or dust can contain the active compounds in amounts of from about 1 to about 25 percent by weight or more if desired. The dust is suitable for application to cereal seeds prior to planting. A typical liquid composition is formulated by dissolving the active compound in a mixture of water and isopropanol (80:20 water/isopropanol ratio) containing a surfactant. This liquid formulation can contain the active compound in amounts of from about 15 to about 40 percent by weight or more if desired. The aqueous formulation is suitable for application to cereal foliage or application as a seed drench, after suitable dilution with water. The invention will now be illustrated by the following Examples. Example 1 Synthesis of (E)-N.N.N'N'-Tetraethyl-l .4-diaminobut-2-ene (TED) Dihydrobenzoate The synthesis of the free base was carried out by the general procedure of J. 3. Roberts and W. C. 3. Ross (3. Chem. Soc, 1952, 4288). Diethyla ine. (3.285 g, 0.045 mol) was added during 15 min to a cooled solution (0°C) of (E)-l ,4-dibromobut- 2-ene (1.07 g, 0.005 mol) (1) in benzene (5 ml). The product was diluted with chloroform (25 ml) and the organic layer was washed with water (4 x 25 ml). The chloroform layer was dried, filtered, and concentrated in vacuo to give (E)-N,N,N'N'-tetra- ethyl-l,4-diaminobut-2-ene as an oil (0.82 g, 82%). δ H (90 MHz, CDC1 3 ) 1.10 (12H, t), 2.60 (8H, q), 3.20 (4H, m) and 5.75 (2H, m). (E)-N . N.N'N'-Tetraethyl-l,4-diaminobut-2-ene (0.72 g, 3.6 mmol) was stirred with benzoic acid (0.87 g, 7.13 mmol ) in benzene (5 ml) for 1 h. The precipitate was filtered and washed with ether to afford (E)-N,N,N'N'-tetraethyl-l ,4-diam nobut- 2-ene (TED) dihydrobenzoate as a white solid (1.11 g, 69%). δ H (200 MHz, D 2 0) 1.00 (12H, t), 2.90 (8H, q), 3.58 (4H, m), 5.89 (2H, m) and 7.34 (10H, m). Other compounds were prepared by this method: TED phosphate (0.56 g, 72%). δ H (200 MHz, D 2 0) 1.07 (12H, t), 3.00 (8H, q), 3.66 (4H, m) and 5.93 (2H, m) . TED fumarate (1.21 g, 68%). δ H (200 MHz, D 2 0) 1.09 (12H, t), 3.00 (8H, q), 3.66 (4H, m) , 5.95 (2H, m) and 6.51 (2H, s). TED propionate (0.72 g, 58%). δ H (90 MHz, D 2 0) 0.8 (6H, t), 1.0 (12H, t), 1.9 (4H, q), 2.9 (8H, q) , 3.6 (4H, m> and 5.9 (2H, m). (E)-N,N'-Diethyl-1 ,4-diaminobut-2-ene Dihydrobenzoate (free base 0.2 g, 28%) (salt 1.8 g, 33%). δ H (90 MHz, D 2 0) 1.2 ( 6H, t), 3.0 ( 4H, q), 3.6 (4H, m) , 5.9 (2H, m) and 7.8 (10H, m) . ( E ) -N,N'-Dipropyl-l ,4-diaminobut-2-ene Dihydrobenzoate (free base 0.73 g, 85%) ( salt 1.25 g, 68%). δ H (90 MHz, D 2 0) 1.0 (6H, t), 1.6 (4H, m), 3.0 (4H, t) , 3.6 (4H, m) , 5.9 (2H, m) and 7.8 (10H, m). (E)-N,N'-Dibutyl-1 ,4-diaminobut-2-ene Dihydrobenzoate (free base 0.45 g, 45%) (salt 2.03 g, 91%). δ H (90 MHz, D 2 0) 0.7 (6H, t), 1.3 (8H, m), 2.8 (4H, t), 3.5 (4H, m), 5.9 (2H, m) and 7.8 (10H, m). Example 2 Synthesis of (E)-N.N'-Dimethyl-l ,4-diaminobut-2-ene Dihvdro- chloride The synthesis of the free base was carried out by modifying the general procedure of 3. 3. Roberts and W. C. J. Ross (J. Chem. Soc, 1952, 4288). (E)-l ,4-Dibromobut-2-ene (2.14 g, 10 mmol) in benzene (50 ml) was added dropwise to a stirred solution of methylamine (30% w/v in methylated spirits, 21 ml, 200 mmol) in benzene (50 ml) at room temperature. The resulting solution was stirred for 24 h at room temperature, then chloroform (100 ml) was added and the solution was washed with water (3 x 100 ml). The organic layer was concentrated in vacuo to an oily residue which -was partioned between chloroform (50 ml) and HC1 (2 M, 50 ml). The aqueous layer was decanted, washed with chloroform (2 x 25 ml) and concentrated to dryness i n vacuo to afford (E)-N , N ' -dimethyl-l ,4- d ami nobut-2-ene di hydrochlori de (2.26 g, 82%) . δ H (90 MHz, D 2 0) 3.09 (6H , s) , 4.02 (4H , m) and 5.80 (2H , m) . Exampl e 3 (E)-N.N.N'N'-Tetraethyl-l ,4-diaminobυt-2-ene (TED) Dihvdrobromide Diethylamine (1.5 g, 20 mmol) in toluene (50 ml) was added to a stirred solution of (E)-l ,4-dibromobut-2-ene (2.14 g, 10 mmol) in toluene (50 ml) at room temperature, and the solution was stirred for 4 h. The white precipitate formed was filtered off, washed with ether (2 x 20 ml), and dissolved in hot aqueous ethanol . The solution was allowed to cool and acetone was added. The white precipitate formed was filtered off and washed with acetone to yield (E)-N,N,N'N'-tetraethyl-l ,4-diaminobut- 2-ene (TED) d hydrobrom de (2.16 g, 60%). δ H (90 MHz, D 2 0) 1.10 (12H, t), 3.15 (8H, q), 3.98 (4H, m) and 5.90 (2H, m). Example 4 (E)-N.N.-Dιethyl-l ,4-diaminobut-2-ene Dihydrochloride This procedure was based on the work of D. 3. Robins (J. Chem. Res. (S), 1983, 326). Potassium phthalimide (18.5 g, 0.1 mol) was added in portions over 5 h to a stirred solution of (E)-l ,4-dibromobut- 2-ene (21.4 g, 0.1 mol) in acetone (200 ml) at 85°C. The suspension was stirred for 24 h at 85°C, then cooled and filtered. The filtrate was concentrated in vacuo to afford a white solid, which was recrystallised three times from acetone to yield (E)-l-phthalim do-4-bromobut-2-ene (15.76 g, 56.2%). δ H (90 MHz, CDC1 3 ) 3.88 (2H, d), 4.28 (2H, d), 5.92 (2H, m) and 7.80 (4H, m). The second stage of this synthesis was adapted from the procedure of K. Samejima, Y. Takeda, M. Kawase, M. Okada and Y. Kyogoku (Chem. Pharm. Bull., 1984, 21, 3428). (E)-T-Phthalimido-4-bromobut-2-ene (4.2 g, 15 mmol), diethylamine (1.1 g, 15 mmol) and KF supported on Celite (7.5 g) were stirred together in acetonitrile (75 ml) at 40°C for 18 h. The solution was filtered, and the filtrate was concentrated jjn vacuo to afford an oil, which was dissolved in glacial acetic acid (30 ml) and cone. HC1 (30 ml). The mixture was heated at reflux for 30 h. The solution was cooled, filtered and the solvents were removed in vacuo to afford (E)-N-N-diethyl-1 ,4- diaminobut-2-ene dihydrochloride as an oil (1.32 g, 41%). δ H (90 MHz, D 2 0) 1.19 (6H, m) 3.24 (4H, q), 4.05 (4H, m) and 5.96 (2H, m>. Example 5 Effect of E-(N.N.N l N'tetraethyl)-1.4-diaminobut-2-ene dihydrobromide (TED) and E-(N'N'-dimethyl)-l ,4-diaminobut-2-ene dihydrobromide (DMD) on powdery mildew infection of barley seedlings Method Seeds of barley (Hordeu vulqare L Golden Promise) were sown in Fison's Levington compost in 36 cm seed trays. Plants were grown in a glasshouse under natural daylight supplemented for 16 h daily by 400 W mercury vapour lamps. The maximum temperature was 24°C during the day and fell to a minimum of 9 β C at night. Plants at growth stage 12 (second leaf unfolded, Zadok's scale) were used for experiments. Seedlings were sprayed to run-off with solutions of the compounds containing 0.01% Tween 20. In all cases solutions were adjusted to pH 7.0 prior to spraying (using either sodium hydroxide of HC1). Sprays were applied using a Shandon spray unit either before or after inoculation with powdery mildew. Plants were inoculated with mildew conidia by shaking infected stock plants over them. Intensity of infection was assessed, 6, 8 and 10 days after inoculation by estimating the percentage leaf area infected using a standard area diagram. Barley powdery mildew normally sporulates 6-7 days after inoculation. Both compounds gave substantial control of mildew infection of barley seedlngs. The results are shown in Table 1 below. Table 1 Example 6 The following compounds were tested for their effect on mildew infection in barley:- a) trans (N,N,N' ,N'-tetramethyl)-l ,4-diamino but-2-ene b) bis (amid no) trans l,4-diaminobut-2-ene The post-inoculation treatment of seedlings was carried out as described in Example 5. The results are shown in Table 2 below. Table 2 % mildew infection Control 62.0 ± 4.4 a 29.3 ± 2.6 b 25.6 ± 1.7 The results show that the compounds have antifungal activity. Examp e 7 Effect of salts of TED on mildew infection of barley seedlings Salts of TED prepared as described in Example 1 were tested for their effect on mildew infection of barley seedlings by the procedure described in Example 5. All compounds were applied as post inoculation sprays at ImM. Mildew infection was assessed - 11 - at 8 days after inoculation. The results are shown in Table 3 below. Table 3 % mildew infection % control on barley Control 32.0 ± 2.5 E-TED benzoate 16.1 ± 1.1 50 E-TED phosphate 12.6 ± 0.5 61 E-TED fumarate 12.8 ± 0.6 60 E-TED propionate 16.7 ± 1.2 48 E-TED 80 Example 8 The following compounds were tested for their effect on mildew infection in barley. a ) ( E ) - ( N,N'-diethyl ) -l,4-diaminobut-2-ene b ) ( E ) - ( N,N'-dipropyl)-l,4-diaminobut-2-ene c) ( E ) - ( N,N'-dibutyl)-l,4-diaminobut-2-ene d) (E)-N'-ethyl-1 ,4-diaminobut-2-ene The post-inoculation treatment of seedlings was carried out as described in Example 5. The results are shown in Table 4 below. Table 4 Compound % mildew infection of barley

Claims: CLAIMS 1. The use of compounds having the formula (I): or a salt thereof wherein R 1 , R 2 , R 3 and R 4 , which may be the same or different represent hydrogen atoms, an alkyl group having from 1 to 6 carbon atoms, a cycloalkyl group having from 3 to 6 carbon atoms, a heterocyclic group, an aryl group, a heteroaryl group having from 3 to 6 atoms or an amidino group or R- j and R 2 and/or R3 and R 4 together represent a carbocyclic or heterocyclic group comprising from 3 to 6 atoms with the proviso that R 1 , R 2 , R 3 and R 4 cannot simulteously represent hydrogen atoms as a fungicide. 2. Use of a compound according to claim 1 characterised in that R- j and R 2 are identical and R and R4 are identical. 3. Use of a compound according to either of claims 1 or 2 characterised in that the groups R- j , R 2 , R3 and R 4 are identical. 4. Use of a compound according to any of claims 1 to 3 character sed in that R- j , R 2 , R3 and R 4 represent alkyl groups having from 1 to 3 carbon atoms. 5. The use of E-(N,N,N' ,N'-tetraethyl ) -l ,4-diaminobut-2-ene as a fungicide. 6. The use of a compound according to claim 5 characterised in that one of the groups R-- and R 2 and one of the groups R3 and. R4 represents an alkyl group having from 1 to 3 carbon atoms. 7. A use according to claim 6 characterised in that the other one of the groups R-* and R 2 and R3 and R 4 represents a hydrogen atom. 8. The use of E-(N'N'-diemthyl)-l ,4-diaminobut-2-ene as a fungic de. 9. A use according to any of claims 1 to 8 to treat plant material to prevent fungal infection thereof. 10. A use according to any of claims 1 to 8 to treat plant material in order to reduce a fungicidal infection therein. 11. A use according to either of claims 9 or 10 characterised in that said plant materials are seeds. 12. A use according to either of claims 9 or 10 characterised in that said plant materials are leaves. 13. A use according to either of claims 9 or 10 characterised in that said plant materials are stems. 14. A use according to either of claims 9 or 10 characterised in that said plant materials are fruits. 15. A use according to either of claims 9 or 10 characterised in that said plant materials are growing plants. 16. A use according to either of claims 9 or 10 characterised in that said plant materials are harvested plant materials. 17. A use according to either of claims 9 or 10 characterised in that it comprises the treatment of packaging for harvested plant materials. 18. A use according to any of claims 1 to 8 characterised in that it comprises the treatment of soil in which plant materials are growing or will be grown to prevent or cure fungal growth. 19. A fungicidal composition useful in the uses of any of claims 1 to 18 which comprises a compound of formula 1 or a salt thereof in admixture with a carrier or diluent. 20. A composition according to claim 19 characterised in that the diluent is water. 21. A composition according to claim 19 characterised in that the diluent is an organic solvent. 22. A composition according to any of claims 19 to 21 which comprises from 0.001 to 0.1 molar proportions of a compound having the formula I. 23. A composition according to claim 19 characterised in that the carrier is a finely divided inert solid. 24. A concentrated composition according to claim 19 which comprises from 15 to 50 percent by weight of a compound of formula I.

Inventors: ROBINS DAVID JOHN, WALTERS DALE RONALD, ROBINS, DAVID, JOHN, WALTERS, DALE, RONALD
Applicants: BRITISH TECH GROUP, BRITISH TECHNOLOGY GROUP LTD.
Application year: 1992
Main classification: A01N33
IPC codes: A01N33, A01N47, C07C211