Fungicidal 2-methoxybenzophenones

Abstract: Substituted benzophenone compounds are disclosed, having the formula: The compounds are useful as fungicides having high systemicities.

Description: This invention relates to certain benzophenone compounds, a process for their preparation, compositions containing such compounds, a method for combating a fungus at a locus comprising treating the locus with such compounds and their use as fungicides. Food production relies upon a variety of agricultural technologies to ensure the growing population's dietary needs remain affordable, nutritious and readily available on grocery store shelves. Fungicides are one of these agricultural technologies which are available to the world community. Fungicides are agrochemical compounds which protect crops and foods from fungus and fungal diseases. Crops and food are constantly threatened by a variety of fungal organisms, which, if left uncontrolled, can cause ruined crops and devastated harvests. In particular, ascomycetes, the causative agent for powdery mildew diseases are an ever-present threat especially to cereal and fruit crops. However, applications of fungicidal agents at disease control rates can cause phytotoxic damage to the target plants. The compounds of the present invention are disclosed in a general formula of European patent ("EP") application EP 0 727 141, published on August 21, 1996. The EP application discloses compounds having activity against phytopathogenic fungi, but relatively low systemicity. There is no disclosure in the EP application of substituted benzophenones, wherein the first phenyl group is substituted by a methoxy group in the 2-position and by a halogen atom or an alkyl group in the 6-position and the second phenyl group is substituted by three alkoxy groups and one methyl group. The present invention provides a compound of formula I wherein R 1 represents a halogen atom or an alkyl or haloalkyl group; R 2 represents a hydrogen or halogen atom, or an alkyl, haloalkyl, alkoxy or nitro group; or R 1 and R 2 together represent a group of formula -CH=CH-CH=CH-; R 3 and R 4 each independently represent an optionally substituted alkyl group; and n is an integer from 0 to 3. The compounds combine relatively excellent selective fungicidal activities in various crops with comparably high systemicities. It is an object of the present invention to provide highly systemic fungicidal compounds. It is also an object of the invention to provide methods for controlling an undesired fungus by contacting said plants with a fungicidally effective amount of the compounds. It is another object of the invention to provide selective fungicidal compositions containing the compounds as active ingredients. These and other objects and features of the invention will be more apparent from the detailed description set forth hereinbelow, and from the appended claims. It has surprisingly been found that the compounds of formula I in which R 1 through R 4 and n have the meaning given above combine relatively excellent fungicidal activity against phytopathogenic fungi, in particular those that cause powdery mildew diseases and have comparably high systemicity. In general terms, unless otherwise stated, as used herein the term halogen atom may denote a bromine, iodine, chlorine or fluorine atom, and is especially a bromine, chlorine or fluorine atom, in particular a bromine or chlorine atom. Optionally substituted moieties may be unsubstituted or have from one up to the maximal possible number of substituents. Typically, 0 to 2 substituents are present. Each optionally substituted group independently is substituted by one or more halogen atoms or nitro, cyano, cycloalkyl, preferably C 3-6 cycloalkyl, cycloalkenyl, preferably C 3-6 cycloalkenyl, haloalkyl, preferably C 1-6 haloalkyl, halocycloalkyl, preferably C 3-6 halocycloalkyl, alkoxy, preferably C 1-6 alkoxy, haloalkoxy, preferably C 1-6 haloalkoxy, phenyl, halo- or dihalo-phenyl or pyridyl groups. In general terms, unless otherwise stated herein, the terms alkyl and alkoxy as used herein with respect to a radical or moiety refer to a straight or branched chain radical or moiety. As a rule, such radicals have up to 10, in particular up to 6 carbon atoms. Suitably an alkyl or alkoxy moiety has from 1 to 6 carbon atoms, preferably from 1 to 5 carbon atoms. A preferred alkyl moiety is the methyl, ethyl, n-propyl, isopropyl or n-butyl group. In general terms, unless otherwise stated herein, the term haloalkyl as used herein with respect to a radical or moiety refers to a straight or branched chain radical or moiety being substituted by one or more halogen atoms. As a rule, such radicals have up to 10, in particular up to 6 carbon atoms. Suitably haloalkyl moieties are fluoroalkyl moieties having from 1 to 6 carbon atoms, preferably 1 or 2 carbon atoms. The fluoroalkyl groups include alkyl groups in which one or more, in particular all hydrogen atoms have been replaced by fluorine. A preferred fluoroalkyl moiety is represented by the formula -(CH 2 ) m -(CF 2 ) n -Y, in which m is 0, 1 or 2, n is 1, 2, 3, 4 or 5 and Y represents a hydrogen or fluoro atom. Particularly preferred is the difluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, pentafluoroethyl, or n-heptafluoropropyl, group. The invention especially relates to compounds of the general formula I in which any alkyl part of the groups R 1 through R 4 , which may be straight chained or branched, contains up to 10 carbon atoms, preferably up to 9 carbon atoms, more preferably up to 6 carbon atoms, and in which each optionally substituted group independently is substituted by one or more halogen atoms or nitro, cyano, cycloalkyl, preferably C 3-6 cycloalkyl, cycloalkenyl, preferably C 3-6 cycloalkenyl, haloalkyl, preferably C 1-6 haloalkyl, halocycloalkyl, preferably C 3-6 halocycloalkyl, alkoxy, preferably C 1-6 alkoxy, haloalkoxy, preferably C 1-6 haloalkoxy, phenyl, or pyridyl groups, in which the phenyl moiety is optionally substituted by one or two substituents selected from halogen atoms, cyano, C 1-6 alkyl and C 1-6 alkoxy groups. The invention especially relates to compounds of the general formula I in which R 1 represents a halogen atom, in particular chlorine, a straight-chained or branched C 1-10 alkyl, in particular a straight-chained C 1-3 alkyl group, most preferably being a methyl group being unsubstituted or substituted by at least one optionally substituted phenyl group; or a straight-chained or branched C 1-10 fluoroalkyl, in particular a straight-chained C 1-3 fluoroalkyl group, most preferably being a trifluoromethyl group. The invention especially relates to compounds of the general formula I in which R 2 represents a hydrogen or halogen atom, in particular a chlorine, bromine or iodine atom, a nitro, a C 1-10 alkyl or a C 1-10 haloalkyl group, most preferred being a hydrogen, chlorine or bromine atom or a trifluoromethyl group. If R 2 is different from hydrogen, it is most preferably attached in the ortho-position to radical R 1 . The invention especially relates to compounds of the general formula I in which R 3 and R 4 each independently represent an optionally substituted straight-chained or branched C 1-5 alkyl, in particular a straight-chained C 1-3 alkyl group, most preferably an unsubstituted or substituted methyl group. This methyl group is preferably unsubstituted or substituted by a phenyl group which is unsubstituted or substituted by one to five, preferably one or two halogen atoms or C 1-4 alkyl or C 1-4 alkoxy groups. The benzophenone compounds according to formula I are oils, gums, or crystalline solid materials and possess valuable fungicidal properties. For example, they can be used in agriculture, or related fields such as horticulture and viticulture, for the control of phytopathogenic fungi, especially ascomycetes, in particular powdery mildew diseases such as those caused by Blumeria (Erysiphe) graminis, Erysiphe cichoracearum, Podosphaera leucotricha, Uncinula necator and the like. Said benzophenone compounds possess a high fungicidal activity over a wide concentration range and may be used in agriculture without harmful phytotoxic effects. Moreover, the compounds according to the invention show enhanced curative and residual control of fungi and fungal diseases such as cereal, cucumber, apple and grape powdery mildew, and improved foliar systemicity compared with conventional fungicides. Useful results in terms of control of phytopathogenic fungi are obtained with a compound as defined in formula I wherein: R 1 represents a chloro atom or a methyl or trifluoromethyl group; R 2 represents a hydrogen, chloro or bromo atom or trifluoromethyl group; R 3 represents a C 1-5 alkyl group; R 4 represents a C 1-5 alkyl group or a benzyl group being optionally substituted by one or more halogen atoms or one or more C 1-4 alkyl or alkoxy groups; and n is 0 or 2, in particular 0. If R 2 represents Cl, Br or CF 3 , it is preferably attached to the benzene ring in the ortho-position with respect to radical R 1 . Furthermore preferred are those compounds of formula I, wherein at least one of the radicals R 1 and R 2 represents a trifluoromethyl group In particular the compounds of formula IA are preferred: in which R 1 represents a chloro atom or a methyl or trifluoromethyl group, R 2 represents a hydrogen, chloro or bromo atom or a methyl or trifluoromethyl group, and R' represents a hydrogen atom or a C 1-4 alkyl or a phenyl group being optionally substituted by one or more fluorine atoms or one or more C 1-4 alkyl groups. In particular the compounds of formula IB are preferred: in which R' represents a hydrogen atom or a C 1-4 alkyl or a phenyl group being optionally substituted by one or more fluorine atoms or one or more C 1-4 alkyl groups. Especially good results in terms ofcontrol ofphytopathogenic fungi are obtained by using, for example, the following compounds of formula I: 6,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone, 6,6'-dimethyl-3'-pentoxy-2,2',4'-trimethoxy-benzophenone, 5-bromo-6,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone, 5-chloro-6,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone, 5-iodo-6,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone, 6-chloro-6'-methyl-2,2',3',4'-tetramethoxy-benzophenone, 5-bromo-6-chloro-6'-methyl-2,2',3',4'-tetramethoxy-benzophenone, 6-chloro-5,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone, 2'-n-butoxy-6-chloro-6'-methyl-2,3',4'-trimethoxy-benzophenone, 2'-n-butoxy-6-chloro-5,6'-dimethyl-2,2',3'-trimethoxy-benzophenone 6-chloro-2'-(2-fluorobenzyloxy)-6'-methyl-2,3',4'-trimethoxy-benzophenone, 6-chloro-2'-(4-fluorobenzyloxy)-6'-methyl-2,3',4'-trimethoxy-benzophenone, 5-bromo-6,6'-dimethyl-3'-n-pentyloxy-2,2',4'-trimethoxy-benzophenone 6-chloro-6'-methyl-2'-n-pentyloxy-2,3',4'-trimethoxy-benzophenone, 6-chloro-2'-(3-methylbutyloxy)-6'-methyl-2,3',4'-trimethoxy-benzophenone, 2'-benzyloxy-6-chloro-6'-methyl-2,3',4'-trimethoxy-benzophenone, 6-chloro-2'-(3-methylbenzyloxy)-6'-methyl-2,3',4'-trimethoxy-benzophenone, 6-chloro-2'-(4-methylbenzyloxy)-6'-methyl-2,3',4'-trimethoxy-benzophenone, 6-chloro-2-difluoromethoxy-6'-methyl-2',3',4'-trimethoxy-benzophenone, 1-(6-methyl-2,3,4-trimethoxybenzoyl)-2-methoxynaphthalene, 1-(6-methyl-2,3,4-trimethoxybenzoyl)-2-difluoromethoxynaphthalene, 5-chloro-6,6'-dimethyl-3-ethoxy-2,2',4'-trimethoxy-benzophenone, 5-chloro-6,6'-dimethyl-3'-n-propyloxy-2,2',4'-trimethoxy-benzophenone, 6,6'-dimethyl-2,2',3',4'-tetramethoxy-5-trifluoromethyl-benzophenone, 6'-methyl-2,2',3',4'-tetramethoxy-6-trifluoromethyl-benzophenone, 5-bromo-6'-methyl-2,2',3',4'-tetramethoxy-6-trifluoromethyl-benzophenone. The present invention further provides a process (A) forthe preparation of a compound of formula I, wherein n is 0, which comprises treating a compound of the general formula II wherein R 1 , R 2 , R 3 and R 4 have the meaning given above and X represents a fluoro or chloro atom, with an alkali methylate, preferably sodium methylate. Another possibility for the preparation of the compounds of formula I is a process (B) which comprises the steps of (a) reacting a compound of formula III, wherein R 1 , R 2 and n have the meaning given above and Y represents a leaving group, in particular a chloro atom or a hydroxy group, with compound of formula IV, wherein R 3 has the meaning given for claim 1; in the presence of a Lewis acid (Y= leaving group) or a dehydrating agent (Y = OH), preferably phosphorous pentoxide or POCl 3 ; and (b) optionally treating the resulting benzophenone of formula I, wherein R 4 represents a methyl group, with a compound of formula V, R 4 -O-Met wherein R 4 represents an optionally substituted alkyl group, being different from methyl, and Met denotes an alkali metal atom, preferably sodium. The compounds of formula III, wherein R 2 represents a halogen atom, are preferably obtained by a process (C) which comprises the steps of (a) reacting a compound of formula VI, wherein R 1 and n have the meaning given for claim 1 and R" represents a hydrogen atom or an alkyl group, with a halogenating agent, (b) optionally hydrolyzing the resulting halogenated alkyl benzoate (R" = alkyl), and (c) optionally treating the resulting halogenated benzoic acid with thionyl chloride. Said process (C) is novel except when n is zero, R 1 is methyl and R" is methyl or ethyl (cf. J. Chem. Res.(S), 1991,29). The compounds of formula I, wherein R 2 represents a trifluoromethyl group are preferably obtained by treating a compound of formula I, wherein R 2 represents a halogen atom, with trifluoroacetate in the presence of a copper salt at elevated temperatures. The starting materials of formulae II, IV, V and VI are known products, the starting materials of formula III are partly known and partly novel products. Accordingly, the invention provides novel intermediate of formula IIIA wherein R 1 represents an alkyl group, in particular a methyl group and R 2 represents a bromo atom or a trifluoromethyl group. The starting materials of formulae II, IV, V and VI may be prepared according to established methods or routine adaptations thereof. Substituents which are not compatible with the selected reaction conditions may be introduced after formation of the benzophenone. They may be generated by known methods such as subsequent derivatization or substitution of a suitable group or by cleaving off a suitable protecting group. The reaction between the 2-halobenzophenone of formula II and the alkali metal methylate is preferably carried out in the presence of a solvent, such as ethers like tetrahydrofuran, diethylether, tert -butyl-methylether or dimethoxyethane or methanol or in mixtures of these solvents. The molar ratio between formula II and the alkali metal methylate is preferably in the range of 0.3 to 1.9 at a temperature between 25 and 120 °C. The Friedel Crafts reaction between formula III and IV is effected in the presence of a Lewis acid catalyst according to well-established procedures (Y = Cl). Suitable catalysts include FeCl 3 , AlCl 3 , SnCl 4 , ZnCl 2 , TiCl 4 , SbCl 5 and BF 3 , which may be in a molar equivalent amount (based on the benzoyl chloride of formula III). However, it is also possible to use lesser amounts of catalyst at elevated temperatures, suitably under reflux temperatures, preferred catalysts under these conditions being FeCl 3 , I 2 , ZnCl 2 , iron, copper, strong sulphonic acids such as F 3 CSO 3 H, and acidic ion exchange resins such as Amberlyst® 15 and Nafion®. The preferred catalyst is FeCl 3 in a 0.001 to 0.2 molar ratio at a temperature of about 50 to 180°C. The reaction can be carried out in a solvent inert under the reaction conditions, for example ethylene or methylene chloride, benzene, octane, decane or solvent mixtures, or in the absence of solvent, conveniently by employing one of the reactants in excess, e. g. in the range of 1:5 to 5:1. If AlCl 3 is being used, the molar ratio is preferably in the range of 0.5 to 2 and the suitable solvents are e.g. dichloromethane or ethylenechloride at a temperature usually between -10 and 70°C. In another preferred process according to the invention the benzoic acid of formula III (Y = OH) is reacted with a compound of formula IV in the presence of phosphorous pentoxide at temperatures of about 0 to 50 °C, preferably at room temperature or in the presence of POCl 3 at temperatures of about 50 to 150 °C, preferably under reflux. The halogenation of the benzoate of formula VI is preferably carried out in the presence of an inert solvent. Preferred halogenating agents are for example sulfuryl chloride, bromine and N-halo-succinimide. If R 1 represents a halogen atom highly polar solvents such as alcohols or carboxylic acids, in particular acetic acid are preferred. If R 1 represents an alkyl group, in particular a methyl group, apolar solvents such as tetrachloromethane are preferred. If the reaction is carried out with bromine at a temperature between 0 and 40 °C, preferably at room temperature, the halogenation takes place predominately in the ortho-position with respect to radical R 1 . In a preferred embodiment the compounds of formula III, in which R 2 represents a bromo atom are prepared by reacting a compound of formula VI, wherein R 1 represents an alkyl group, n is 0, and R" represents a hydrogen atom, with bromine. This bromination step is preferably carried out in the presence of a polar, protic solvent, such as an aliphatic alcohol or an aliphatic carboxylic acid, in particular acetic acid. The bromination may be carried out advantageously in the presence of a weak base or a buffer system, such as sodium acetate or sodium carbonate. One embodiment of the process of the instant invention is a process wherein bromine is employed in an amount selected from a value in the range between 1.0 to 1.5, in particular 1.05 to 1.2 molar equivalents with respect to starting compound of formula VI. The reaction between the compound of formula VI and bromine is as a rule carried out at a temperature sufficient to optimally convert the compound of formula VI to the compound of formula III. This term represents a temperature sufficiently high to maintain the conversion, but also sufficiently low to avoid decomposition of the starting material and the product. The reaction is carried out preferably at temperatures between 0 °C and 40 °C, in particular at ambient temperature. The reaction between the compound of formula VI and bromine is as a rule carried out at a length of time sufficient to optimally convert the compound of formula VI to the compound of formula III. This term represents a period of time sufficiently long to convert the maximum amount of the starting material to the compound of formula III. The reaction is carried out preferably at reaction time between 1 and 40 hours, in particular between 5 and 24 hours. The transformation of a compound of formula I, wherein R 2 represents a halogen atom, into a compound of formula I, wherein one of R 2 represents a trifluoromethyl group, is carried out analogously to J. Chem. Soc. Perkin Trans. PT1 (1988) N4, page 924. Preferably sodium trifluoroacetate is reacted with the halogen compound in the presence of a copper salt, preferably copper-(I) halides, in particular copper-(I) iodide. As a rule the reaction is carried out in a high-boiling polar aprotic solvent such as 1-methyl-2-pyrrolidone. The reaction is carried out preferably at temperatures between 120 °C and 200 °C, in particular between 150 °C and 170 °C. The reaction between the compound of formula I, R 2 represents a halogen atom, and sodium trifluoroacetate is as a rule carried out at a length of time sufficient to optimally to transform the halogen compound into a trifluoromethyl compound. This term represents a period of time sufficiently long to convert the maximum amount of the starting material to the compound of formula I, wherein R 2 represents a trifluoromethyl group. The reaction is carried out preferably at a reaction time between 40 and 140 hours, in particular between 60 and 100 hours. The processes described above and below can analogously be applied to other starting compounds, if desired. Due to excellent plant tolerance, the compounds of formula I may be used in cultivation of all plants where infection by the controlled fungi is not desired, e.g. cereals, vegetables, legumes, apples, vine. The absence of target crop phytotoxicity at fungus control rates is a feature of the present invention. Accordingly the invention further provides a fungicidal composition which comprises a carrier and, as active ingredient, at least one compound of formula I as defined above. A method of making such a composition is also provided which comprises bringing a compound of formula I as defined above into association with at least one carrier. Such a composition may contain a single compound ora mixture of several compounds of the present invention. It is also envisaged that different isomers or mixtures of isomers may have different levels or spectra of activity and thus compositions may comprise individual isomers or mixtures of isomers. A composition according to the invention preferably contains from 0.5% to 95% by weight (w/w) of active ingredient. A carrier in a composition according to the invention is any material with which the active ingredient is formulated to facilitate application to the locus to be treated, which may for example be a plant, seed or soil, or to facilitate storage, transport or handling. A carrier may be a solid or a liquid, including material which is normally a gas but which has been compressed to form a liquid. The compositions may be manufactured into e.g. emulsion concentrates, solutions, oil in water emulsions, wettable powders, soluble powders, suspension concentrates, dusts, granules, waterdispersible granules, micro-capsules, gels and other formulation types by well-established procedures. These procedures include intensive mixing and/or milling of the active ingredients with other substances, such as fillers, solvents, solid carriers, surface active compounds (surfactants), and optionally solid and/or liquid auxilaries and/or adjuvants. The form of application such as spraying, atomizing, dispersing or pouring may be chosen like the compositions according to the desired objectives and the given circumstances. Solvents may be aromatic hydrocarbons, e.g. Solvesso® 200, substituted naphthalenes, phthalic acid esters, such as dibutyl ordioctyl phthalate, aliphatic hydrocarbons, e.g. cyclohexane or paraffins, alcohols and glycols as well as their ethers and esters, e.g. ethanol, ethyleneglycol mono- and dimethyl ether, ketones such as cyclohexanone, strongly polar solvents such as N-methyl-2-pyrrolidone, or γ-butyrolactone, higher alkyl pyrrolidones, e.g. n-octylpyrrolidone or cyclohexylpyrrolidone, epoxidized plantoil esters, e.g. methylated coconut or soybean oil ester and water. Mixtures of different liquids are often suitable. Solid carriers, which may be used for dusts, wettable powders, waterdispersible granules, or granules, may be mineral fillers, such as calcite, talc, kaolin, montmorillonite or attapulgite. The physical properties may be improved by addition of highly dispersed silica gel or polymers. Carriers for granules may be porous material, e.g. pumice, kaolin, sepiolite, bentonite; non-sorptive carriers may be calcite or sand. Additionally, a multitude of pre-granulated inorganic ororganic materials may be used, such as dolomite or crushed plant residues. Pesticidal compositions are often formulated and transported in a concentrated form which is subsequently diluted by the user before application. The presence of small amounts of a carrier which is a surfactant facilitates this process of dilution. Thus, preferably at least one carrier in a composition according to the invention is a surfactant. For example, the composition may contain two or more carriers, at least one of which is a surfactant. Surfactants may be nonionic, anionic, cationic or zwitterionic substances with good dispersing, emulsifying and wetting properties depending on the nature of the compound according to general formula I to be formulated. Surfactants may also mean mixtures of individual surfactants. The compositions of the invention may for example be formulated as wettable powders, water dispersible granules, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols. Wettable powders usually contain 5 to 90% w/w of active ingredient and usually contain in addition to solid inert carrier, 3 to10% w/w of dispersing and wetting agents and, where necessary, 0 to 10% w/w of stabilizer(s) and/or other additives such as penetrants or stickers. Dusts are usually formulated as a dust concentrate having a similar composition to that of a wettable powder but without a dispersant, and may be diluted in the field with furthersolid carrier to give a composition usually containing 0.5 to 10% w/w of active ingredient Water dispersible granules and granules are usually prepared to have a size between 0.15 mm and 2.0 mm and may be manufactured by a variety of techniques. Generally, these types of granules will contain 0.5 to 90% w/w active ingredient and 0 to 20% w/w of additives such as stabilizer, surfactants, slow release modifiers and binding agents. The so-called "dry flowables" consist of relatively small granules having a relatively high concentration of active ingredient. Emulsifiable concentrates usually contain, in addition to a solvent or a mixture of solvents, 1 to 80% w/v active ingredient, 2 to 20% w/v emulsifiers and 0 to 20% w/v of other additives such as stabilizers, penetrants and corrosion inhibitors. Suspension concentrates are usually milled so as to obtain a stable, non-sedimenting flowable productand usually contain 5 to 75% w/v active ingredient, 0.5 to 15% w/v of dispersing agents, 0.1 to 10% w/v of suspending agents such as protective colloids and thixotropic agents, 0 to 10% w/v of other additives such as defoamers, corrosion inhibitors, stabilizers, penetrants and stickers, and water or an organic liquid in which the active ingredient is substantially insoluble; certain organic solids or inorganic salts may be present dissolved in the formulation to assist in preventing sedimentation and crystalization or as antifreeze agents for water. Aqueous dispersions and emulsions, for example compositions obtained by diluting the formulated product according to the invention with water, also lie within the scope of the invention. Of particular interest in enhancing the duration of the protective activity of the compounds ofthis invention is the use of a carrier which will provide slow release of the pesticidal compounds into the environment of a plant which is to be protected. The biological activity of the active ingredient can also be increased by induding an adjuvant in the spray dilution. An adjuvant is defined here as a substance which can increase the biological activity of an active ingredient but is not itself significantly biologically active. The adjuvantcan either be included in the formulation as a coformulant or carrier, or can be added to the spray tank together with the formulation containing the active ingredient. As a commodity the compositions may preferably be in a concentrated form whereas the end user generally employs diluted compositions. The compositions may be diluted to a concentration down to 0.001% of active ingredient. The doses usually are in the range from 0.01 to 10 kg a.i./ha. Examples of formulations according to the invention are: Emulsion Concentrate (EC) Active Ingredient Compound of Example 6 30 % (w/v) Emulsifier(s) Atlox ® 4856 B / Atlox ® 4858 B 5 % (w/v) (mixture containing calcium alkyl aryl sulfonate, fatty alcohol ethoxylates and light aromatics / mixture containing calcium alkyl aryl sulfonate, fatty alcohol ethoxylates and light aromatics) Solvent Shellsol ® A to 1000 ml (mixture of C 9 - C 10 aromatic hydrocarbons) Suspension Concentrate (SC) Active Ingredient Compound of Example 6 50 % (w/v) Dispersing agent Soprophor ® FL 3 % (w/v) (polyoxyethylene polyaryl phenyl ether phosphate amine salt) Antifoaming agent Rhodorsil ® 422 0.2 % (nonionic aqueous emulsion of polydimethylsiloxanes) (w/v) Structure agent Kelzan ® S 0.2 % (Xanthan gum) (w/v) Antifreezing agent Propylene glycol 5 % (w/v) Biocidal agent Proxef ® 0.1 % (aqueous dipropylene glycol solution containing 20% 1,2-benisothiazolin-3-one) (w/v) Water to 1000 ml Wettable Powder (WP) Active Ingredient Compound of Example 6 60 % (w/w) Wetting agent Atlox ® 4995 2 % (w/w) (polyoxyethylene alkyl ether) Dispersing agent Witcosperse ® D-60 3 % (w/w) (mixture of sodium salts of condensed naphthalene sulfonic acid and alkylarylpolyoxy acetates Carrier / Filler Kaolin 35 % (w/w) Water Dispersible Granules (WG) Active Ingredient Compound of Example 6 50 % (w/w) Dispersing / Witcosperse ® D-450 8 % (w/w) Binding agent (mixture of sodium salts of condensed naphthalene sulfonic acid and alkyl sulfonates) Wetting agent Morwet ® EFW 2 % (w/w) (formaldehyde condensation product) Antifoaming agent Rhodorsil ® EP 6703 ) 1 % (w/w) (encapsulated silicone) Disintegrant Agrimer ® ATF ) 2 % (w/w) (cross-linked homopolymer of N-vinyl-2-pyrrolidone) Carrier / Filler Kaolin 35 % (w/w) The compositions of this invention can also comprise other compounds having biological activity, e.g. compounds having similar or complementary pesticidal activity or compounds having plant growth regulating, fungicidal or insecticidal activity. These mixtures of pesticides can have a broader spectrum of activity than the compound of general formula I alone. Furthermore, the other pesticide can have a synergistic effect on the pesticidal activity of the compound of general formula I. The other fungicidal compound can be, for example, one which is capable of combating diseases of cereals (e.g. wheat) such as those caused by Erysipha, Puccinia, Septoria, Gibberella and Helminthosporium spp., seed and soil borne diseases and downy and powdery mildews on vines and powdery mildew and scab on apples etc. These mixtures of fungicides can have a broader spectrum of activity than the compound of general formula I alone. Examples of the other fungicidal compounds are anilazine, azoxystrobin, benalaxyl, benomyl, binapacryl, bitertanol, blasticidin S, Bordeaux mixture, bromuconazole, bupirimate, captafol, captan, carbendazim, carboxin, carpropamid, chlorbenzthiazon, chlorothalonil, chlozolinate, copper-containing compounds such as copper oxychloride, and copper sulfate, cycloheximide, cymoxanil, cypofuram, cyproconazole, cyprodinil, dichlofluanid, dichlone, dichloran, diclobutrazol, diclocymet, diclomezine, diethofencarb, difenoconazole, diflumetorim, dimethirimol, dimethomorph, diniconazole, dinocap, ditalimfos, dithianon, dodemorph, dodine, edifenphos, epoxiconazole, etaconazole, ethirimol, etridiazole, famoxadone, fenapanil, fenarimol, fenbuconazole, fenfuram, fenhexamid, fenpiclonil, fenpropidin, fenpropimorph, fentin, fentin acetate, fentin hydroxide, ferimzone, fluazinam, fludioxonil, flumetover, fluquinconazole, flusilazole, flusulfamide, flutolanil, flutriafol, folpet, fosetyl-aluminium, fuberidazole, furalaxyl, furametpyr, guazatine, hexaconazole, imazalil, iminoctadine, ipconazole, iprodione, isoprothiolane, kasugamycin, kitazin P, kresoxim-methyl, mancozeb, maneb, mepanipyrim, mepronil, metalaxyl, metconazole, methfuroxam, myclobutanil, neoasozin, nickel dimethyldithiocarbamate, nitrothalisopropyl, nuarimol, ofurace, organo mercury compounds, oxadixyl, oxycarboxin, penconazole, pencycuron, phenazineoxide, phthalide, polyoxin D, polyram, probenazole, prochloraz, procymidione, propamocarb, propiconazole, propineb, pyrazophos, pyrifenox, pyrimethanil, pyroquilon, pyroxyfur, quinomethionate, quinoxyfen, quintozene, spiroxamine, SSF-126, SSF-129, streptomycin, sulfur, tebuconazole, tecloftalame, tecnazene, tetraconazole, thiabendazole, thifluzamide, thiophanate-methyl, thiram, tolclofosmethyl, tolylfluanid, triadimefon, triadimenol, triazbutil, triazoxide, tricyclazole, tridemorph, triflumizole, triforine, triticonazole, validamycin A, vinclozolin, XRD-563, zarilamid, zineb, ziram. In addition, the co-formulations according to the invention may contain at least one benzophenone of formula I and any of the following classes of biological control agents such as viruses, bacteria, nematodes, fungi, and other microorganism which are suitable to control insects, weeds or plant diseases or to induce host resisitance in the plants. Examples of such biological control agents are: Bacillus thuringiensis , Verticillium lecanii, Autographica californica NPV, Beauvaria bassiana, Ampelomyces quisqualis, Bacilis subtilis, Pseudomonas fluorescens, Steptomyces griseoviridis and Trichoderma harzianum. Moreover, the co-formulations according to the invention may contain at least one benzophenone of formula I and a chemical agent that induces the systemic acquired resistance in plants such as for example nicotinic acid or derivatives thereof, 2,2-dichloro-3,3-dimethylcyclopropylcarboxylic acid or BION. The compounds of general formula I can be mixed with soil, peat or other rooting media for the protection of the plants against seed-borne, soil-borne or foliar fungal diseases. The invention still further provides the use as a fungicide of a compound of the general formula I as defined above or a composition as defined above, and a method for combating fungus at a locus, which comprises treating the locus, which may be for example plants subjectto or subjected to fungal attack, seeds of such plants or the medium in which such plants are growing or are to be grown, with such a compound or composition. The present invention is of wide applicability in the protection of crop and ornamental plants against fungal attack. Typical crops which may be protected include vines, grain crops such as wheat and barley, rice, sugar beet, top fruit, peanuts, potatoes, vegetables and tomatoes. The duration of the protection is normally dependent on the individual compound selected, and also a variety of external factors, such as climate, whose impact is normally mitigated by the use of a suitable formulation. The following examples further illustrate the present invention. It should be understood, however, that the invention is not limited solely to the particular examples given below. Example 1 Preparation of 6,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone 1A 2-Methoxy-6-methylbenzoic acid A mixture of ethyl 2-methoxy-6-methylbenzoate (5.0 g, 25 mmol), water (10 ml), methanol (40 ml) and sodium hydroxide (2.1 g, 50 mmol) is heated under reflux with stirring. The reaction mixture is diluted with water (150 ml) and acidified with concentrated hydrochloric acid. The solid material is collected by filtration, washed with water and dried yielding dark yellow crystals, 2.1 g, mp 136 °C. 1B 2-Methoxy-6-methylbenzoyl chloride A mixture of 1A (1.7 g, 10.2 mmol) and thionyl chloride (2 ml) is heated under reflux for 1 hour. The mixture is concentrated and the resulting benzoylchloride is used without further purification. 1C 6,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone A mixture of 3,4,5-trimethoxytoluene (1.86 g; 10.2 mmol), 1B (10.2 mmol), aluminium chloride (1.33 g, 10 mmol) and dichloromethane (20 ml) is stirred at 0° C. The reaction sets up at 0 °C with formation of hydrogen chloride. Subsequently, the reaction mixture is stirred for another 4 hours at room temperature. A mixture of dilute hydrochloric acid and ethyl acetate (1:1 v/v; 100 ml) is then slowly added at 0 °C. The organic phase is concentrated and the residue is recrystallized from methanol. The solid material is collected by vacuum filtration, three times washed with methanol/water (3:1 v/v; 100 ml each) and dried yielding white crystals, 1.0 g (30.3 %), mp 84 °C. Example 2 Preparation of 6,6'-dimethyl-2'-n-butoxy-2,3',4'-trimethoxy-benzophenone A mixture of n-butanol (5 ml) and sodium hydride (60 % in oil, 10 mmol) is stirred until the formation of H 2 gas ceases. A mixture of 1C (0.7 g, 2,2 mmol) and dimethoxyethane (15 ml) is added to the resulting reaction mixture. Subsequently, the reaction mixture is heated under reflux with stirring for 24 hours. A mixture of water and ethyl acetate (1:1 v/v; 100 ml) is then slowly added at room temperature. The organic phase is separated, concentrated and the residue is purified by column chromatography (petrol ether: ethyl acetate, 95:5 v/v) yielding the pure product as a yellow oil, 0.2 g, (24.4 %). Example 3 Preparation of 6-chloro-2'-pentyloxy-6'-methyl-2,3',4'-trimethoxy-benzophenone A mixture of sodium methylate in methanol (5.4 mol/l, 19.6 mmol), 2,6-dichloro-3',4'-dimethoxy-6'-methyl-2'-pentyloxy-benzophenone (obtained according to EP 0 727 141, 2.69 g, 6.5 mmol) and dimethoxyethane (20 ml) is heated to 80 °C with stirring for 24 hours. A mixture of water and ethyl acetate (1:1 v/v; 100 ml) is then slowly added at room temperature. The organic phase is separated and concentrated and the residue is purified by column chromatography (dichloromethane) yielding the pure product as a yellow oil, 0.52 g, (19.7 %). Example 4 Preparation of 5-bromo-6-chloro-6'-methyl-2,2',3',4'-tetramethoxy-benzophenone 4A Ethyl 5-bromo-6-chloro-2-methoxybenzoate A mixture of ethyl 6-chioro-2-methoxybenzoate (1.8 g, 8.4 mmol), bromine (1.41 g, 8.8 mmol) and acetic acid (5 ml) is stirred at room temperature for 24 hours. The reaction mixture is poured into water and extracted with ethyl acetate. The organic phase is separated and concentrated and the residue is purified by column chromatography (petrol ether : ethyl acetate, 95:5 v/v) yielding the pure product as a yellow oil, 1.7 g, (69 %). 4B 5-Bromo-6-chloro-2-methoxybenzoic acid A mixture of 4A (1.7 g, 5.8 mmol), water (10 ml), ethanol (20 ml) and sodium hydroxide (0.5 g, 12.5 mmol) is heated under reflux with stirring. The reaction mixture is diluted with water (80 ml) and acidified with concentrated hydrochloric acid. The solid material is collected by filtration, washed with water and dried yielding white crystals, 1.3 g (85 %), mp 186-188 °C. 4C 5-Bromo-6-chloro-2-methoxybenzoyl chloride A mixture of 4B (1.2 g, 4.6 mmol), dichloromethane (15 ml) and oxalyl chloride (1 ml) is stirred at room temperature for 2 hours. The mixture is concentrated and the resulting benzoylchloride is used without further purification. 4D 5-bromo-6-chloro-6'-methyl-2,2'3',4'-tetramethoxy-benzophenone A mixture of 3,4,5-trimethoxytoluene (0.83 g; 4.6 mmol), 4C (4.6 mmol), aluminium chloride (0.62 g, 4.6 mmol) and dichloromethane (20 ml) is stirred at room temperature for 3 hours. A mixture of water and ethyl acetate (1:1 v/v; 50 ml) is then added. The organic phase is concentrated and the residue is crystallized from diisopropylether and recrystallized from methanol. The solid material is collected by vacuum filtration, washed with water and dried yielding yellow crystals, 0.7 g, (35.4 %) mp 87-88 °C. Example 5 Preparation of 1-(6'-methyl-2',3',4'-trimethoxybenzoyl)-2-methoxynaphthalene 5A Methyl (2-methoxynaphth-1-yl)-carboxylate A mixture of 2-hydroxynaphth-1-ylcarboxylic acid (18.82 g, 100 mmol), sodium hydroxide (8.8 g, 220 mmol), dimethylsulfate (31.5 g, 250 mmol) and water (200 ml) is heated to 70 °C with stirring for 20 hours. Subsequently, the reaction mixture is cooled to room temperature and extracted with ethyl acetate twice. The combined organic phases are concentrated and the residue is used without further purification. 5B Methyl (2-methoxynaphth-1-yl)-carboxylic acid A mixture of crude 5A (10.5 g, 48 mmol), water (100 ml), methanol (150 ml) and sodium hydroxide (12 g, 300 mmol) is heated under reflux with stirring. The reaction mixture is extracted with diethylether twice. The aqueous reaction mixture is filtered and acidified with concentrated hydrochloric acid. The solid material is collected by filtration, washed with water and dried yielding yellow crystals, 9.45 g (97.4 %), mp 175-176 °C. 5C 1-(6'-methyl-2',3',4'-trimethoxybenzoyl)-2-methoxynaphthalene A mixture of 5B (2.02 g, 10 mmol), 3,4,5-trimethoxytoluene (1.82 g; 10 mmol), P 2 O 5 (10.0 g) and dichloromethane is stirred at room temperature for 16 hours. Subsequently, the dichloromethane is distilled off and the residue is diluted with ethyl acetate. The organic phase is washed with water and concentrated. The residue is purified by column chromatography (petrol ethers:ethyl acetate, 8:2 v/v) and recrystallized from petrol ether : diisopropylether (1:1 v/v). The solid material is collected by vacuum filtration, washed with cold petrol ether: diisopropylether (1:1 v/v) and dried, yielding white crystals, 0.9 g, (24.6 %) mp 72 °C. Example 6 Preparation of 5-bromo-6,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone 6A Ethyl 5-bromo-6-methyl-2-methoxybenzoate A mixture of ethyl 6-methyl-2-methoxybenzoate (8.4 g, 43.2 mmol), bromine (6.9 g, 43.2 mmol) and tetrachloromethane (170 ml) is stirred at room temperature for 60 hours. The reaction mixture is poured into water and extracted with ethyl acetate. The organic phase is separated and concentrated. The crude product is obtained as a yellow oil, 10.3 g (87 %) and is used without further purification. 6B 5-Bromo-6-methyl-2-methoxybenzoic acid A mixture of 6A (9.8 g, 34.1 mmol), water (40 ml), ethanol (80 ml) and sodium hydroxide (2.7 g, 68.3 mmol) is heated under reflux with stirring for 42 hours. The reaction mixture is diluted with water (80 ml), acidified with concentrated hydrochloric acid and extracted with dichloromethane. The organic phase is separated and concentrated. The solid material is collected by filtration, washed with water and dried yielding off-white crystals, 5.4 g (61 %), mp 81-83 °C. 6C 5-bromo-6,6'-dimethyl-2,2'3',4'-tetramethoxy-benzophenone A mixture of 6B (24 g, 10 mmol), 3,4,5-trimethoxytoluene (1.82 g; 10 mmol), P 2 O 5 (10.0 g) and dichloromethane (150 ml) is stirred at room temperature for 16 hours. Subsequently, the dichloromethane is distilled off and the residue is diluted with ethyl acetate. The organic phase is washed with water and concentrated. The residue is purified by column chromatography (petrol ether: ethyl acetate, 8:2 v/v) and recrystallized from diisopropylether. The solid material is collected by vacuum filtration, washed with cold petrol ethers:diisopropylether (1:1 v/v) and dried, yielding white crystals, 2.2 g (54 % ), mp 89-91 °C. Examples 7-62 Using essentially the same procedures described hereinabove for Examples 1 to 6 and employing standard derivatization techniques where appropriate, the following compounds are prepared and shown in Tables I and II: Example 63 Preparation of 5-bromo-6,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone 63A 6-methyl-2-methoxybenzoic acid A mixture of ethyl 6-methyl-2-methoxybenzoate (642.0 g, 3.3 mol), water (2.5 l), ethanol (4.0 I) and sodium hydroxide (270 g, 6.6 mol) is heated under reflux with stirring for 20 hours. Subsequently, ethanol is distilled off and the reaction mixture is diluted with water, acidified with concentrated hydrochloric acid. The solid material is collected by vacuum filtration, washed with water and dried yielding off-white crystals, 460.0 g (83.9 %). 63B 5-Bromo-6-methyl-2-methoxybenzoic acid A mixture of bromine (102 ml, 2.0 mol) and acetic acid (225 ml) is added to a mixture of 63A (304.0 g, 1.8 mol),), sodium acetate (164.0 g, 2.0 mol) and acetic acid (3.0 I) at a temperature of 10 to 15 °C. The reaction mixture is stirred at room temperature for 16 hours. The solid material is collected by vacuum filtration, washed with water and dried yielding off-white crystals 321.0 g (72.6. %), mp 81-83 °C. 63C 5-bromo-6,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone 63B (240 g, 1.0 mol) is reacted with 3,4,5-trimethoxytoluene (182 g; 1.0 mol) in the presence of P 2 O 5 (1.0 kg) and dichloromethane as described in Example 6 yielding white crystals, 220 g (54 % ), mp 89-91 °C. The sequence of the saponification (with sodium hydroxide) and bromination steps described above in Examples 63A and 63B, respectively, are reversed in Examples 6B and 6A, above. The bromination described in Examples 63B and 6A is with the free acid and ester, respectively. The reaction conditions also differ, such as Example 63B which uses a polar protic solvent (acetic acid) and a buffering salt (sodium acetate). Example 6A uses a non-polar aprotic solvent (tetrachloromethane). Example 64 Preparation of 6,6'-dimethyl-2,2',3',4'-tetramethoxy-5-trifluoromethyl-benzophenone A mixture of 63C (6.15 g, 0.015 mol), sodium trifluoroacetate (9.52 g, 0.07 mol), copper-(I) iodide (13.37 g, 0.07 mol) and 1-N-methyl-2-pyrrolidinone (100 ml) is heated to 160 °C for 118 hours. The reaction mixture is cooled to room temperature and diluted with ether and water. The organic phase is separated and concentrated and the residue is purified by column chromatography (petrol ether: ethyl acetate, 95:5 v/v) yielding the pure product as white crystals, 1.3 g, (22 %) having a melting point of 95-96 °C. Example 65 Preparation of 6'-methyl-2,2',3',4'-tetramethoxy-6-trifluoromethyl-benzophenone 65A 2-methoxy-6-trifluoromethylbenzoic acid A mixture of potassium methylate in methanol (15 ml, 15 %) and 2-fluoro-6-trifluoromethylbenzoic acid (2.08 g, 0.01 mol) is heated to reflux with stirring for 40 hours. Upon cooling to room temperature water is added. The reaction mixture is filtered and the filtrate is acidified with concentrated hydrochloric acid. The solid material is collected by filtration, washed with water and dried yielding white crystals, 1.4 g (64 %), mp 130-131 °C. 65B 6'-methyl-2,2',3',4'-tetramethoxy-6-trifluoromethyl-benzophenone 65A (1.38 g, 0.00625 mol) is reacted with 3,4,5-trimethoxytoluene (1.14 g; 0.00625 mol) in the presence of P 2 O 5 (5.0 g) and dichloromethane (100 ml) as described in Example 6 yielding white crystals, 1.68 g (69.8 % ), mp 69-70 °C. Example 66 Preparation of 5-chloro-6,6'-dimethyl-3'-ethoxy-2,2',4'-trimethoxybenzophenone 66A 5-chloro-6,6'-dimethyl-3'-propionyloxy-2,2',4'-trimethoxybenzophenone 5-Chloro-2-methoxy-6-methylbenzoic acid (6.00 g, 0.03 mol) is reacted with 3,5-dimethoxy-4-propionyloxytoluene (6.73 g; 0.03 mol) in the presence of P 2 O 5 (18.0 g) and dichloromethane (200 ml) as described in Example 6 yielding white crystals, 6.65 g (56.4 % ), mp 150-151 °C. 66B 5-chloro-6,6'-dimethyl-3'-hydroxy-2,2',4'-trimethoxybenzophenone A mixture of 66A (6.65 g), potassium carbonate (7.0 g), water (50 ml) and methanol (100 ml) is heated to reflux for 3 hours. Upon cooling to room temperature water is added. The reaction mixture is filtered and the filtrate is acidified with concentrated hydrochloric acid. The solid material is collected and used without further purification. 66C 5-chloro-6,6'-dimethyl-3'-ethoxy-2,2',4'-trimethoxybenzophenone A mixture of 66B (1.15 g), potassium carbonate (1.0 g), diethylsulfate (0.54 g) and acetonitrile (20 ml) is heated to reflux for 3 hours. Upon cooling to room temperature water is added. The solid material is collected and the residue is re-crystallized from methanol yielding white crystals, 1.07 g (85.6%), mp 131-132 °C. Example 67 Preparation of 6,6'-dimethyl-5-fluoro-2,2',3',4'-tetramethoxybenzophenone 67A 2- tert -butyl-4-fluoromethylphenol A mixture of 4-fluoro-3-methylphenol (12.60 g, 0.1 mol), tert -butylchloride (25 ml) and FeCl 3 is heated to reflux for 16 hours. The excess of tert -butylchloride is distilled off and the residue is purified by column chromatography (petrol ether: ethyl acetate, 95:5 v/v) yielding the pure product as a yellow oil, 15.3 g (84 %). 67B 6-bromo-2- tert -butyl-4-fluoro-5-methylphenol A mixture of 67A (0.91 g), tetrachloromethane (20 ml), N-bromosuccinimide (0.89 g) and AlCl 3 is stirred at ambient temperature for 3 days. The reaction mixture is filtered and concentrated. The obtained yellow oil (1.25 g) is used without further purification. 67C 2-bromo-4-fluoro-3-methylphenol A mixture of 67B (18.5 g), benzene (120 ml) and AlCl 3 (6.5 g) is heated to reflux for 5 hours. The reaction mixture is cooled to room temperature and diluted with ethyl acetate and water. The organic phase is separated and concentrated. The residue is purified by column chromatography (petrol ether: ethyl acetate, 95:5 v/v) yielding the pure product as white crystals 9.0 g, (62 %). 67D 2-bromo-6-fluoro-3-methoxytoluene A mixture of 67C (9.0 g), potassium carbonate (6 g), dimethylsulfate (6 g) and acetonitrile (150 ml) is heated to reflux for 1 hour. The reaction mixture is cooled to room temperature, diluted with water and extracted with diethyl ether twice. The organic phase is separated and concentrated and the residue (9.0 g) is used without further purification. 67E 3-fluoro-6-methoxy-2-methylbenzoic acid A solution of n-butyllithium in hexane (18.1 ml, 2.5 mol/l) is slowly added to a mixture of 67D (9.0 g) and tetrahydrofuran (90 ml) at -78°C. The resulting reaction mixture is saturated with carbon dioxide at -78°C and allowed to warm up to ambient temperature. The reaction mixture is poured into water, acidified and extracted with diethylether twice. The organic phase is extracted with an aqueous solution of sodium hydroxide (5 %). The aqueous extract is acidified and extracted with diethylether twice. The organic phase is dried and concentrated. The residue (3.9 g) is used without further purification. 67F 6,6'-dimethyl-5-fluoro-2,2'3',4'-tetramethoxybenzophenone 67E (3.9 g, 0.021 mol) is reacted with 3,4,5-trimethoxytoluene (3.85 g; 0.021 mol) in the presence of P 2 O 5 (12.0 g) and dichloromethane (150 ml) as described in Example 6 yielding white crystals, 0.34 g, mp 58°C. Biological Investigations A Foliar Systemicity Wheat Powdery Mildew (WPM): HOST: Wheat ( Triticum aestivum L.) variety Kanzler PATHOGEN: Blumeria (Erysiphe) graminis DC. f.sp. tritici E. Marchal TEST PROCEDURE: 1. Wheat seed (8/pot) is planted in 8 cm diameter plastic pots in the greenhouse. 2. When the primary leaf is fully expanded, the plants are cut back to four in each pot of which two are marked with a permanent marker 5 cm below the leaf tip on the upper leaf surface. Thus there are two band-treated and two untreated plants in each pot. 3. A pipette is used to apply 5 µl of the formulated compound in a band on the lower leaf surface opposite the mark. The application band should cover the whole leaf width. After application, the plants are not moved until the bands are dry (half an hour or so later). 4. After treated plants have dried, they are moved to the greenhouse and kept there for 2 days to allow for movement of the compounds. The plants are maintained with bottom watering. 5. Two days after application, the plants are inoculated by dusting them with powdery mildew conidia in the greenhouse. Evaluations are typically made 7 - 8 days after inoculation. Evaluation Three types of compound movement are assessed by evaluating disease in three areas of each band-treated leaf. Translaminar movement: The percent disease area is assessed for the translaminar band area (marked area of the upper leaf surface directly opposite where band was applied on the lower leaf surface; width of band approximately 5 mm). Translaminar disease control is then calculated using the following formula: % disease control = 100 - % disease in treated plants % disease in untreated plants x 100 Distal movement and proximal movement: The distal and proximal disease-free zones on the upper leaf surface are measured in mm. The distal direction is from the band toward the leaf apex and the proximal direction is from the band toward the leaf base. The percent of the disease-free zone relative to the entire distance between the band and leaf apex or base is calculated. If disease is noticeably lighter in the distal or proximal area this is also noted. FORMULATION AND CONTROLS: 1. The compounds are formulated in a solvent/surfactant system consisting of 5% acetone and 0.05% Tween 20 in deionized water. Formulated compounds are prepared using deionized water. Compounds are typically tested at 400 ppm. 2. Two kinds of controls are included: Plants band-treated with the solvent/surfactant solution and inoculated (Solvent Blank). Untreated plants which are inoculated (Inoculated Control). The results of this evaluation are shown in Table III: Foliar Systemicity Example No. Proximal Movement (mm from band) Distal Movement (mm from band) Translaminar Activity ( % ) 1 10 50 100 10 6 46 100 Standard 1 4 5 100 Standard 2 8 28 100 The following compounds, which are known from EP 0 727 141 have been used as standards: Standard 1 2,6-dichloro-6'-methyl-2',3',4'-trimethoxybenzophenone Standard 2 2',3',4'-trimethoxy-2,6,6'-trimethylbenzophenone B-1 Comparison of the fungicidal activity of the 2-methoxy-benzophenones to a 2,6-dichloro- and 2,6-dimethyl-benzophenone Test diseases: (a) Wheat Powdery Mildew (WPM): HOST: Wheat ( Triticum aestivum L.) variety Kanzler PATHOGEN: Blumeria (Erysiphe) graminis DC. f.sp. tritici E. Marchal (b) Barley Powdery Mildew (BPM): HOST: Barley ( Hordeum vulgare L.) variety Golden Promise PATHOGEN: Blumeria (Erysiphe) graminis DC. f.sp. hordei E. Marchal TEST PROCEDURE: This test is a zero day protectant test for control of wheat and barley powdery mildews. 1. Wheat or barley seed (approximately 8-10/pot) is planted in 6 cm diameter plastic pots and maintained in the greenhouse. 2. When the primary leaf is fully expanded, formulated test compounds are sprayed with a single nozzle overhead track sprayer at a rate of 200 l/ha. Plants are then allowed to air-dry. 3. Inoculation follows about three hours after compound application. Plants are set up on greenhouse benches with bottom watering mats and inoculated by dusting them with conidia from powdery mildew infected plants (stock cultures at an age of 10-14 days). 4. Disease on the primary leaf as percent leaf area with disease symptoms/signs is evaluated about 7 days after inoculation. The tips and bases of the leaves are excluded from the evaluation. Percent disease control is then calculated by the following formula: % disease control = 100 - % infection in treated plants % infection in untreated plants x 100 FORMULATION, REFERENCE COMPOUNDS AND CONTROLS: 1. Technical compounds are formulated in a solvent/surfactant system consisting of 5% acetone and 0.05% Tween 20 in deionized water. Compounds are dissolved in acetone prior to addition of the water; the Tween 20 can be added through either the acetone or the water. Dilutions are made using the solvent/surfactant system. Test compounds are typically tested over a range of concentrations covering several orders of magnitude and then ED values are calculated for comparison of compounds. Formulated compounds are prepared using deionized water. 2. Two kinds of controls are included: Plants treated with the solvent/surfactant solution and inoculated (Solvent Blank). Untreated plants which are inoculated (Inoculated Control). The results of this evaluation are shown in Table IV: Fungicidal activity of 2-methoxybenzophenones (ED90 values) Comparison of the fungicidal activity of the 2-methoxy-benzophenones to a 2,6-dichloro- and 2,6-dimethyl benzophenone Results are from 0 day protectant tests in which all analogs were tested side-by-side. ED90 (ppm) Disease 2-methoxybenzophenone Example Reference Standard 1 Standard 2 1 4 6 7 10 48 Quinoxyfen WPM 28 20 4 5 0.1 7 7 0.1 12 BPM 24 8 6 7 0.9 6 8 <0.1 26 Compounds applied as technical material formulated in 0.5% acetone 0.05% Tween 20 water B-2 Comparison of the curative and residual fungicidal activity of the 2-methoxy-benzophenones to a 2,6-dichloro- and 2,6-dimethylbenzophenone Test diseases: (a) Wheat Powdery Mildew (WPM): HOST: Wheat (Triticum aestivum L.) variety Kanzler PATHOGEN: Blumeria (Erysiphe) graminis DC. f.sp. tritici E. Marchal (b) Cucumber Powdery Mildew (QPM): HOST: Cucumber ( Cucumis sativus L.) variety Bush pickle PATHOGEN: Erysiphe cichoracearum DC TEST PROCEDURE: This test procedure is for curative and residual control of powdery mildew diseases. 1. Wheat seed (approximately 8-10/pot) or cucumber seed (1 seed / pot) is planted in 6 cm diameter plastic pots and maintained in the greenhouse. 2. When the primary leaf (wheat) or the cotyledons (cucumber) is/are fully expanded, formulated test compounds are sprayed with a single nozzle overhead track sprayer at a rate of 200 l/ha. Plants are then allowed to air-dry. 3. Inoculation precedes treatment by 2 or 3 days in the case of curative evaluations and follows treatment by 3 or 4 days in case of residual evaluations. For inoculation, plants are set up on greenhouse benches with bottom watering mats and inoculated by dusting them with conidia from powdery mildew infected plants (stock cultures at an age of 10-14 days). Between inoculation and treatment for curative evaluations and between treatment and inoculation for residual evaluations, plants are maintained in the greenhouse with bottom watering. 4. Disease on the primary leaf (wheat) or on the cotyledons (cucumber) as percent leaf area with disease symptoms/signs is evaluated about 7 days after inoculation. In the case of wheat, the tips and bases of the leaves are excluded from the evaluation. Percent disease control is then calculated by the following formula: % disease control = 100 - % infection in treated plants % infection in untreated plants x 100 FORMULATION, REFERENCE COMPOUNDS AND CONTROLS: 1. Technical compounds are formulated in a solvent/surfactant system consisting of 5% acetone and 0.05% Tween 20 in deionized water. Compounds are dissolved in acetone prior to addition of the water; the Tween 20 can be added through either the acetone or the water. Dilutions are made using the solvent/surfactant system. Formulated compounds are prepared using deionized water. 2. Two kinds of controls are included: Plants treated with the solvent/surfactant solution and inoculated (Solvent Blank). Untreated plants which are inoculated (Inoculated Control). The results of this evaluation are shown in Tables V and VI: Curative and Residual Fungicidal activity of 2-methoxy-benzophenones compared with standard compounds Disease control (% efficacy) Disease Test Rate (ppm) 2-methoxy benzophenone Example Standard 1 Standard 2 1 6 4 7 Test A B A / B A / B B C WPM 1250 79 92 88 / 85 98 / 87 61 97 2 da C 125 60 74 79 / 65 95 / 89 71 93 12,5 31 55 69 / 52 90 / 61 55 73 WPM 1250 100 100 100 / 100 100 / 100 100 100 3 da R 125 83 81 100 / 100 100 / 100 100 100 12,5 75 70 90 / 100 100 / 100 99 99 QPM 1250 100 89 100 / 100 100 / 100 100 100 3 da R 125 0 6 5 / 61 92 / 92 97 89 12,5 0 14 2 / 3 2 / 35 8 2 2 da C = 2 day curative Inoculation 2 days BEFORE application 3 da R = 3 day residual Inoculation 3 days AFTER application Curative and Residual Fungicidal activity of 2-methoxy-benzophenones against wheat powdery mildew Test Rate (ppm) Disease control (% efficacy) 2-methoxy-benzophenone Example 6 58 59 64 65 WPM 3 da C 125 64 66 69 72 58 25 60 58 63 60 48 5 43 48 48 48 23 1 27 29 28 37 23 0.2 17 17 13 10 10 WPM 4 da R 125 100 100 100 100 100 25 100 100 100 100 99 5 100 100 100 99 93 1 90 95 95 89 50 0.2 58 68 85 51 25 3 da C = 3 day curative Inoculation 3 days BEFORE application 4 da R = 4 day residual Inoculation 4 days AFTER application

Claims: A compound of formula I: wherein R 1 represents a halogen atom or an alkyl group or haloalkyl group; R 2 represents a hydrogen or halogen atom, or an alkyl, haloalkyl, alkoxy or nitro group; or R 1 and R 2 together represent a group of formula -CH=CH-CH=CH-; R 3 and R 4 each independently represent an optionally substituted alkyl; and n is an integer from 0 to 3. A compound as claimed in claim 1, wherein R 1 represents a chloro atom or a methyl or trifluoromethyl group; R 2 represents a hydrogen, chloro or bromo atom or a trifluoromethyl group; R 3 represents a C 1-5 alkyl group; R 4 represents a C 1-5 alkyl group or benzyl group, being optionally substituted by at least one halogen atom, or C 1-4 alkyl or alkoxy group; and n is 0. A compound as claimed in claim 1, wherein at least one of the radicals R 1 and R 2 represents a trifluoromethyl group. A compound as claimed in claim 1 being selected from the group consisting of 6,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone, 6,6'-dimethyl-3'-pentoxy-2,2',4'-trimethoxy-benzophenone, 5-bromo-6,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone, 5-chloro-6,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone, 5-iodo-6,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone, 6-chloro-6'-methyl-2,2',3',4'-tetramethoxy-benzophenone, 5-bromo-6-chloro-6'-methyl-2,2',3',4'-tetramethoxy-benzophenone, 6-chloro-5,6'-dimethyl-2,2',3',4'-tetramethoxy-benzophenone, 2'-butoxy-6-chloro-6'-methyl-2,3',4-trimethoxy-benzophenone, 2'-butoxy-6-chloro-5,6'-dimethyl-2,2',3'-trimethoxy-benzophenone 6-chloro-2'-(2-fluorobenzyloxy)-6'-methyl-2,3',4'-trimethoxy-benzophenone, 6-chloro-2'-(4-fluorobenzyloxy)-6'-methyl-2,3',4'-trimethoxy-benzophenone, 5-bromo-6,6'-dimethyl-3'-pentyloxy-2,2'4'-trimethoxy-benzophenone 6-chloro-6'-methyl-2'-pentyloxy-2,3',4'-trimethoxy-benzophenone, 6-chloro-2'-(3-methylbutyloxy)-6'-methyl-2,3',4'-trimethoxy-benzophenone, 2'-benzyloxy-6-chloro-6'-methyl-2,3',4'-trimethoxy-benzophenone, 6-chloro-2'-(3-methylbenzyloxy)-6'-methyl-2,3',4'-trimethoxy-benzophenone, 6-chloro-2'-(4-methylbenzyloxy)-6'-methyl-2,3',4'-trimethoxy-benzophenone, 6-chloro-2-difluoromethoxy-6'-methyl-2',3',4'-trimethoxy-benzophenone, 1-(6'-methyl-2',3',4'-trimethoxybenzoyl)-2-methoxynaphthalene, 1-(6'-methyl-,2',3',4'-trimethoxybenzoyl)-2-difluoromethoxynaphthalene, 5-chloro-6,6'-dimethyl-3'-ethoxy-2,2',4'-trimethoxy-benzophenone, 5-chloro-6,6'-dimethyl-3'-n-propyloxy-2,2',4'-trimethoxy-benzophenone, 6,6'-dimethyl-2,2',3,4'-tetramethoxy-5-trifluoromethyl-benzophenone, 6'-methyl-2,2',3',4-tetramethoxy-6-trifluoromethyl-benzophenone, 5-bromo-6'-methyl-2,2',3',4'-tetramethoxy-6-trifluoromethyl-benzophenone. A process for the preparation of the compound of claim 1, wherein n is 0, which comprises reacting a compound of formula II: wherein R 1 , R 2 , R 3 and R 4 are as described in claim 1, and X represents a fluoro or chloro atom, with an alkali methanolate. A process for the preparation of the compound of claim 1, which comprises (a) reacting a compound of formula III: wherein R 1 , R 2 and n are as described in claim 1, and Y represents a leaving group or a hydroxy group, with a compound of formula IV: wherein R 3 is as described in claim 1, in the presence of a Lewis acid or a dehydrating agent; and (b) optionally treating the product obtained with a compound of formula V: R 4 -O-Met wherein R 4 represents an optionally subsituted alkyl or aryl group with the proviso that the alkyl group is not methyl, and Met denotes an alkali metal atom. A process for the preparation of a compound of formula I according to claim 1, wherein one of the radicals R 1 and R 2 represents a trifluoromethyl group, which comprises treating a compound of formula I, wherein one of the radicals R 1 and R 2 represents a halogen atom with trifluoroacetic acid in the presence of a copper salt at elevated temperatures. A process for the preparation of a formula III compound of claim 6, wherein R 2 represents a halogen atom, which comprises reacting a compound of formula VI: wherein R 1 and n are as described in claim 1, and R" represents a hydrogen atom or an alkyl group, provided that n is not zero if R 1 is methyl and R" is methyl or ethyl, with a halogenating agent. A process according to claim 8, which comprises (a) reacting a compound of formula VI, wherein R" represents an alkyl group, with a halogenating agent; (b) optionally hydrolyzing the resulting halogenated alkyl benzoate; and (c) optionally treating the resulting halogenated alkyl benzoic acid with thionyl chloride. A compound having the formula IIIA wherein R 1 represents an alkyl group and R 2 represents a bromo atom or a trifluoromethyl group. A process for the preparation of a compound of formula IIIA according to claim 10 which comprises reacting a compound of formula VI according to claim 8, wherein R 1 is an alkyl group, with bromine and optionally treating the resulting bromo compound with trifluoroacetate in the presence of a copper salt at elevated temperatures. A process for the preparation of a compound of formula IIIA according to claim 10, wherein the reaction between the compound of formula VI and bromine is carried out in the presence of a polar protic solvent. A composition which comprises a fungicidally effective amount of at least one compound of claim 1, and a carrier. A method of combating fungus or a fungal plant disease at a locus, which comprises treating the locus with a compound of claim 1. A method of combating fungus or a fungal plant disease at a locus, which comprises treating the locus with a composition of claim 13. The method of claim 14 wherein the fungal plant disease is ascomycetes. The method according to claim 14 wherein the fungus is a member of the subgroup Erysiphales. The method of claim 15 wherein the fungus is selected from Blumeria (Erysiphe) graminis, Erysiphe cichoracearum, Podospharea leucotricha or Uncinula necator. The method according to claim 15 wherein the fungus is a member of the subgroup Erysiphales. The method of claim 19 wherein the fungus is selected from Blumeria (Erysiphe) graminis, Erysiphe cichoracearum, Podospharea leucotricha or Uncinula necator.

Inventors: ALBERT GUIDO, COTTER HENRY VAN TUYL, CURTZE JUERGEN, MORSCHHAEUSER GERD, REHNIG ANNEROSE EDITH ELISE, REICHERT GUNTHER, SIMON WERNER, STUMM KARL-OTTO, WALDECK ANDREAS, ALBERT, GUIDO, COTTER, HENRY VAN TUYL, CURTZE, JUERGEN, MORSCHHAEUSER, GERD, REHNIG, ANNEROSE EDITH ELISE, REICHERT, GUNTHER, SIMON, WERNER, STUMM, KARL-OTTO, WALDECK, ANDREAS
Applicants: BASF AG, BASF AKTIENGESELLSCHAFT
Application year: 1998
Main classification: C07C49
IPC codes: C07C45, C07C205, A01N35, C07C65, C07C49