GB2124615A - Heterocyclic compounds having fungicidal, herbicidal and plant- growth regulating properties - Google Patents

Abstract

Novel compounds of the general formula <IMAGE> in which one of R<1> and R<2> represents an optionally-substituted 6-membered heteroaromatic ring containing 1 or 2 nitrogen atoms, and the other of R<1> and R<2> also represents such a ring or represents an optionally-substituted phenyl group; R<3> represents an acyl group derived from a carboxylic acid; and R<4> represents a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms; or an acid addition salt, N-oxide or metal salt complex thereof; provided that if R<1> represents an optionally substituted pyridyl group, R<2> must represent an optionally substituted heterooaromatic ring; if R<1> represents an optionally substituted phenyl group, R<3> must represent an acyl group derived from an acid other than an optionally substituted benzoic acid; if R<1> represents an unsubstituted phenyl group, R<2> represents an unsubstituted 2-or 3-pyridyl group and R<3> represents a group of formula CH3CO-, phenyl.CH=CH.CO-, C2H5CO-, or (phenyl)2CH.CO-. then R<4> must represent an alkyl group; if R<2> represents a phenyl group substituted by an SO2NH2 group, R<4> must represent an alkyl group; and if both of R<1> and R<2> represent optionally substituted pyridyl groups, neither of these groups is substituted by an amino, acylamino, alkylamino or dialkylamino group; exhibit fungicidal, herbicidal and plant-growth regulating properties.

Description

SPECIFICATION Heterocyclic compounds having fungicidal, herbicidal and plant-growth regulating properties The present invention relates to heterocyclic compounds, to a process for their preparation, to biologically-active compositions containing them and to their use as fungicides, herbicides and plantgrowth regulants.

An article by Carelli et al in Farmaco (Pavia) Ed. Sci. vol. 16 pages 375-81(1961) discloses that certain N-acyl derivatives of N-pyridylmethylaniline have pharmaceutical properties, U.S. Patent 4,082,851 relates to compounds again having pharmacecutical properties, in this case to certain benzylaminoheterocylic compounds substituted by an SO2NH2 group.

It has now been found that certain N-acyl derivatives of heterocyclic compounds have useful fungicidal, herbicidal and plant-growth regulating properties.

The present invention provides a method of combating fungus at a locus, and/or combating or regulating plant growth at a locus which comprises applying to the locus a compound of the general formula

in which one of R' and R2 represents an optionally-substituted 6-membered heteroaromatic ring containing 1 or 2 nitrogen atoms, and the other of R' and R2 also represents such a ring or represents an optionally-substituted phenyl group; R3 represents an acyl group derived from a carboxylic acid; and R4 represents a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms; or an acid addition salt, N-oxide or metal salt complex thereof.

Unless otherwise stated, any aliphatic moiety present in R', R2 or R3 preferably has up to 6, more preferably up to 4, carbon atoms.

The acyl group represented by R3 may for example be a formyl group, an alkoxycarbonylcarbonyl group or an optionally substituted alkanoyl, alkenoyl, cycloalkanoyl or aroyl group. Most preferably R3 is derived from an aliphatic or cycloaliphatic acid.

Suitable substituents which may be present in an alkanoyl or alkenoyl group which is substituted include halogen atoms and alkoxy, phenyl, phenoxy, carboxy and alkoxycarbonyl groups. Preferably the group is unsubstituted or substituted by up to 3 halogen atoms or by a phenyl, phenoxy, C( 1-4) alkoxy, especially methoxy, methoxycarbonyl or ethoxycarbonyl group. Especially preferred a Ikanoyl and alkenoyl groups are unsubstituted groups having up to 6 carbon atoms in the alkyl or alkenyl moiety. Alkanoyl groups are preferred, and a tertiary butylcarbonyl group is especially preferred.

Suitable optionally substituted cycloalkanoyl groups include those having 3 to 6 carbon atoms in the ring, especially cyclopropylcarbonyl and cyclohexylcarbonyl groups. Suitable substituents include halogen atoms and alkyl groups, especially methyl groups. Thus an optionally substituted cycloalkanoyl group may for example be a cyclopropylcarbonyl, 1 -methylcyclopropylcarbonyl, 2,2-dichloro-3,3dimethylcyclopropylcarbonyl or cyclohexylcarbonyl group.

An optionally substituted aroyl group is preferably an optionally substituted benzoyl group.

Preferred substituents which may be present in the phenyl ring are the same preferred substituents described below for a phenyl ring R1 or R2.

An alkoxycarbonylcarbonyl group suitably has from 1 to 6 carbon atoms in the alkoxy moiety, for example,aC2H5 .0. O . CO . COgroup or a CH3 . O . CO . COgroup.

Thus typical groups R3 will include formyl, alkanoyl, for example t-butylcarbonyl or 2,2dimethylpropylcarbonyl, alkoxyalkanoyl, for example methoxymethylcarbonyl, cycloalkanoyl, for example cyclopropylcarbonyl, alkylcycloalkanoyl, for example 1 -methylcyclopropylcarbonyl, and optionally substituted aroyl, for example benzoyl optionally substituted by an alkyl group having 1 to 4 carbon atoms or by a halogen atom.

Preferably R4 represents a methyl group or, especially, a hydrogen atom.

A heteroaromatic ring represented by R' or R2 may be an optionally substituted pyrimidinyl, pyridazinyl or, preferably pyridyl or pyrazinyl ring, and a heteroaromatic or phenyl ring represented by R' or R2 may be unsubstituted or substituted. A heteroaromatic ring is preferably unsubstituted and a phenyl ring is preferably mono- or di- substituted. A ring may for example be substituted by one or more of the same or different substituents selected from halogen atoms and nitro, alkyl, haloalkyl, hydroxyalkyl, alkoxy, haloalkoxy, hydroxyalkoxy and hydroxy groups, as well as cyano, alkylsulphonyi,.

alkylcarbonyl, alkoxycarbonyl, carboxy and alkylthio groups. Preferably it is unsubstituted or substituted by one or two of the same or different substituents selected from halogen atoms and alkyl, alkoxy and nitro groups. Most preferably, it is unsubstituted or substituted by a halogen atom, especially a fluorine or chlorine atom, or an alkyl group, for example a methyl group, or disubstituted by halogen, especially fluorine or chlorine, atoms, and/or alkyl, especially methyl, groups.

If one or both of R' and R2 represent a pyridyl ring, this ring is preferably bound to the NR3 . CHR4 moiety of the molecule in a 3-position relative to the ring nitrogen atom. One preferred group of compounds for use in the process of the invention is that in which R' represents an optionally substituted phenyl group and R2 represents an optionally substituted pyridyl group, especially a 3pyridyl group. Such compounds have especially useful fungicidal activity.

A second preferred group of compounds is that in which R1 represents an optionally substituted pyrazinyl group and R2 represents an optionally substituted phenyl group. Such compounds have especially useful plant growth regulating effects. In such a compound, the pyrazinyl group is preferably unsubstituted and the phenyl group is preferably unsubstituted or substituted by one or more, preferably one or two, of the preferred substituents listed above. Especially preferred is the compound of the general formula I in which R' represents a pyrazinyl group, R2 represents a 4-chlorophenyl group, R3 represents a t-butylcarbonyl group and R4 represents a hydrogen atom; or an acid addition salt, Noxide or metal salt complex thereof.

Compounds of the general formula i form N-oxides; acid addition salts with acids, for example mineral acids such as sulphuric or hydrochloric acid or organic acids such as citric or tartaric acid; and complexes with metal salts, for example complexes of the compound of the general formula I with a salt, for example a halide, of calcium, copper or iron, in the ratio of 2:1, 1:1 or 1:2. The use of such derivatives forms part of the present invention, and the derivatives may be prepared from compounds of the general formula I by methods analogous to known methods.

The method of the invention may be used to combat fungus, especially barley powdery mildew.

Further, it may be used to combat and/or regulate the growth of plants as a result of the range of herbicidal and plant growth regulating properties exhibited by compounds of the formula I. Amongst the plant-growth regulating properties which have been exhibited by various compounds of the general formula i, are reduction in growth of plants, the production of very dark green leaves, enlarged cotyledons, and the production of shorter, broader leaves.These properties may for example be harnessed in the following applications, using certain compounds under certain conditions: reduction of growth of plants to alleviate stress in plant tissue, or to prevent lodging in tali plants such as cereals; increase in photosynthesis per unit area as a result of the production of very dark green leaves, giving better growth under poor light conditions; production of silage crops having a lower than normal water content; shape control in horticultural crops such as chrysanthemums and poinsettias; prevention of growth of unproductive flowers or runners in crops such as cotton, tobacco, lucerne, sugar beet or strawberries; and sugar cane ripening by prevention of growth at the end of the season. Certain of the compounds may also act to increase the yield of crops such as soyabeans.

Certain of the compounds of the general formula I may be useful as "herbistats": application of the compound to the p!ants, seed, or the soil in which the plants are growing or are to be grown, results in much reduced growth of the plants. This is useful, for example, in controlling the ground cover vegetation in plantations and orchards, in controlling aquatic vegetation, for example in cereals, and in reducing the cutting frequency of grassy areas ("chemical lawn mowing").

Under certain circumstances, the plant growth regulating effects of compounds of the general formula I, which are often very long lasting, can be amended or reversed by application of plant hormones such as auxins, cytokinins, phytosterols and, especially, gibberellic acid. Possible uses of this effect may, for example, include seed treatments; seeds of crops may be coated with gibberellic acid and sown normaliy. When the crop area is then treated with a compound of the general formula I having "herbistat" or herbicidal properties the growth of weeds is inhibited, but because of their local environment of gibberellic acid, the growth of the crop seed is not affected. This may be useful in crops such as sugar beet, where the annual sugar beet which occurs as a weed is virtually impossible to combat by conventional herbicide treatment.

Certain commercial plant growth regulating compounds have a tendency to produce plants which are very susceptible to fungal attack. Thus the use as a plant growth regulator of a compound having both plant growth and fungicidal activity would have obvious advantages.

In the method according to the invention, the compound of the general formula I or acid addition salt, N-oxide or metal salt complex thereof, is suitably applied to the locus to be treated at a dosage in the range of from 0.1 to 3 kg/ha. Most conveniently it is applied in the form of a composition containing the compound together with one or more suitable carriers.

Certain compounds of the general formula I are novel, and the invention therefore also provides these compounds per se. The novel compounds are those of the general formula I and acid addition salts, N-oxides and metal salt complexes thereof, in which R1, R2, R3, and R4 have the meanings given above; provided that if R1 represents an optionally substituted pyridyl group, R2 must reprsent an optionally substituted heteroaromatic ring; if R1 represents an optionally substituted phenyl group, R3 must represent an acyl group derived from an acid other than an optionally substituted benzoic acid; if P1 represents an unsubstituted phenyl group, R2 represents an unsubstituted 2- or 3-pyridyl group and R3 represents a group of formula CH3CO-, C2H5CO-, (phenyl)2CH .00-or phenyl . CH=CH . CO-, then R4 must represent an alkyl group; if R2 represents a phenyl group substituted by an SO2NH2 group, R4 must represent an alkyl group; and if both of R1 and R2 represent optionally-substituted pyridyl groups, neither of these groups is substituted by an amino, acylamino, alkylamino, or dialkylamino group.

Preferred meanings for R1, R2, R3 and R4 in novel compounds according to the invention, are as given above for the method according to the invention, with, of course, the necessary exclusions.

The invention also provides a process for the preparation of a novel compound according to the invention, which comprises acylating a compound of the general formula

in which R1, R2 and R4 have the meanings given for the novel compounds of the general formula I, using a suitable acylating agent.

Any suitable acylating agent, for example a carboxylic acid or an acid anhydride or, preferably, acid halide, derived from a carboxylic acid, may be used, Acid chlorides are especially suitable, and the reaction is then preferably carried out in the presence of an acid binding agent, which may be an organic or inorganic base. Organic amines, for example triethylamine, are especially suitable acidbinding agents. The reaction is preferably carried out in the presence of an inert solvent, for example a hydrocarbon such as benzene, at a temperature in the range of from 50 to 1 500 C, preferably 60 to 1000C. The reaction is conveniently carried out under reflux.

The compound of the general formula II may for example be prepared by reduction of a compound of the general formula

in which R1, R2 and R4 have the meanings given for the novel compounds of the general formula I. The reduction may for example be carried out using gaseous hydrogen and a catalyst, or using formic acid.

When formic acid is used the reaction conditions may be chosen such that at least some of the compound of the general formula Il produced is formylated in situ, thus directly producing a compoundof the general formula I in which R3 represents a formyl group starting from a compound of the general formula Ill.

The compound of the general formula Ill may be prepared by methods analogous to methods known in the art, for example by coupling a compound of the general formula R1NH2 with a compound of the general formula R2COR4.

As stated above the method of combating or regulating plant growth according to the invention is suitably carried out using a composition which comprises the active compound together with a suitable carrier. The invention therefore also provides a biologically active composition which comprises a novel compound according to the invention together with a suitable carrier. Preferably the amount of active ingredient in the composition is in the range of from 0.05 to 95% by weight of the composition.

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 a material which is normally gaseous but which has been compressed to form a liquid, and any of the carriers normally used in formulating agricultural compositions may be used.

Suitable solid carriers include natural and synthetic clays and silicates, for example natural silicas such as diatomaceous earths; magnesium silicates, for example tabs; magnesium aluminium silicates, for example attapulgites and vermiculites; aluminium silicates, for example kaolinites, montmorillonites and micas; calcium carbonate; calcium sulphate; synthetic hydrated silicon oxides and synthetic calcium or aluminium silicates; elements, for example carbon and sulphur; natural and synthetic resins, for example coumarone resins, polyvinyl chloride, and styrene polymers and copolymers; solid polychlorophenols; bitumen; waxes, for example beeswax, paraffin wax, and chlorinated mineral waxes; and solid fertilisers, for example superphosphates.

Suitable liquid carriers include water; alcohols, for example isopropanol and glycols; ketones, for example acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers; aromatic or araliphatic hydrocarbons, for example benzene, toluene and xylene; petroleum fractions, for example kerosine and light mineral oils; chlorinated hydrocarbons, for example carbon tetrachloride, perchloroethylene and trichloroethane. Mixtures of different liquids are often suitable.

Agricultural 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 surface-active agent facilitates this process of dilution.

A surface-active agent may be an emulsifying agent, a dispersing agent or a wetting agent; it may be nonionic or ionic. Examples of suitable surface-active agents include the sodium or calcium salts of polyacrylic acids and lignin sulphonic acids; the condensation products of fatty acids or aliphatic amines or amides containing at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; fatty acid esters of glycerol, sorbitan, sucrose or pentaerythritol; condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohol or alkyl phenols, for examplep-octylphenol orp-octylcresol, with ethylene oxide and/or propylene oxide; sulphates or sulphonates of these condensation products; alkali or alkaline earth metal salts, preferably sodium salts, of sulphuric or sulphonic acid esters containing at least 10 carbon atoms in the molecule, for example sodium lauryl sulphate, sodium secondary alkyl sulphates, sodium salts of sulphonated castor oil, and sodium alkylaryl sulphonates such as sodium dodecylbenzene sulphonate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.

The compositions of the invention may for example be formulated as wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols.

Wettable powders usually contain 25, 50 and 75% w of active ingredient and usually contain, in addition to solid inert carrier, 3-10% w of a dispersing agent and, where necessary, 0-10% w of stabiliser(s) and/or other additives such as penetrants or stickers. Dusts are usually formulated as a dust concentrate having a similar compositions to that of a wettable powder but without a dispersant, and are diluted in the field with further solid carrier to give a composition usually containing ±1 0% w of active ingredient. Granules are usually prepared to have a size between 10 and 100 BS mesh (1.676-0.152 mm), and may be manufactured by agglomeration or impregnation techniques.

Generally, granules will contain -1-25% w active ingredient and 0-10% w of additives such as stabilisers, slow release modifiers and binding agents. Emulsifiable concentrates usually contain, in addition to a solvent and, when necessary, co-solvent, 10-50% w/v active ingredient, 2-20% w/v emulsifiers and 0-20% w/v of other additives such as stabilisers, penetrants and corrosion inhibitors.

Suspension concentrates are usually compounded so as to obtain a stable, non-sedimenting flowable product and usually contain 10-75% w active ingredient, O.515% w of dispersing agents, 0.1 - 10% w of suspending agents such as protective colloids and thixotropic agents. 0-10% w of other additives such as defoamers, corrosion inhibitors, stabilisers, 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 or as anti-freeze agents for water.

Aqueous dispersions and emulsions, for exmaple compositions obtained by diluting a wettable powder or a concentrate according to the invention with water, also lie within the scope of the present invention. The said emulsions may be of the water-in-oil or of the oil-in-water type, and may have a thick 'mayonnaise'-like consistency.

The compositions of the invention may also contain other ingredients, for example, other compounds possessing insecticidal, herbicidal, plant growth regulating or fungicidal properties.

The following Examples illustrate the invention. ~ - - Example 1 N-t-butylcarbonyl-3-(3'-pyridylmethyl)aminopyridine (a) To a solution of 3-(3'-pyridyliminomethyl)pyridine (18.3 g, 0.1 mole) in dry toluene (50 ml) was added formic acid (98%, 10.8 g), and the mixture was stirred and heated under leflux for 16 hours.

Toluene and formic acid were removed in vacuo, and to the residue was added 10% HCI (100 ml) and toluene (100 ml). After shaking, the aqueous layer was separated and made alkaline by the addition of a concentrated aqueous solution of KOH. The product was extracted into methylene chloride, and the extracts dried (MgSO4). After removal of solvent the product was purified by column chromatography (neutral alumina/5% methanol in diethyl ether) and distillation. Tne pure 3-(3'pyridylmethyl)aminopyridine was obtained in 27% yield as a colouriess material, boiling point 176 178 C at pressure 1 mm Hg, melting point 66-69 C.

Analysis C H N Calculated for N3C"Htt 71.35 5.95 22.7% Found 71.7 -6.3 23.0% (b) To a stirred solution of 3-(3'-pyridylmethyl)aminopyridine (3.7 g, 0.02 mole) in dry benzene (50 ml) was added a solution of trimethylacetylchloride (2.8 g, 0.024 mole) in dry benzene (1 5 ml) followed by a solution of dry triethylamine (2.6 g, 0.024 mole) in dry benzene (10 ml). The mixture was stirred and heated under reflux for 7 hours. After cooling, the reaction mixture was washed 3 times with water and dried (MgSO4). Solvent was removed in vacuo and the residue was chromatographed on neutral alumina, eluting with 5% methanol in dethyl ether. N-t-butylcarbonyl-3-(3'-pyridylmethyl)aminopyridine was thus obtained in 65% yield as a colourless solid, melting point 69-70 C.

Analysis C H N Calculated for N30Cr6Hrg 71.38 7.06 15.61% Found 71.1 7.5 15.6% Example 2 N-benzoyl-4-fluoro-N-(3'-pyridylmethyl)aniline (a) To a solution of 3-(4'-fluorophenyliminomethyl)pyridine (67.0 g, 0.335 mole) in dry toluene (200 ml) was added formic acid (98%, 36.18 g), and the mixture was stirred and heated under reflux for 20 hours. Toluene and formic acid were removed in vacuo, and to the residue was added 10% HCI (120 ml). After extracting with toluene, the aqueous layer was separated and made alkaline by the addition of a concentrated aqueous solution of potassium hydroxide. The product was extracted into diethyl ether, and the extracts dried (MgSO4). After removal of solvent, the residue was subjected to column chromatography (neutral alu mina/diethyl ether).The pure 4-fluoro-N-(3'-pyridylmethyl)aniline was obtained in 10% yield as a colourless solid, melting point 8587CC.

Analysis C H N Calculated for N2FC12H,1 71.29 5.45 13.86% Found 71.2 5.8 14.0% (b) To a stirred solution of 4-fluoro-N-(3'-pyridylmethyl)aniline (3.03 g, 0.01 5 mole) in dry benzene (50 ml) was added a solution of benzoyl chloride (2.4 g, 0.017 mole) in dry benzene (15 ml) followed by a solution of dry triethylamine (1.8 g, 0.018 mole) in dry benzene (10 ml). The mixture was stirred and heated under reflux for 1 6 hours. After cooling, the reaction mixture was washed with water (X3) and dried (MgSO4). Solvent was removed in vacuo, and the residue triturated with a little ether.

The solid product was filtered off, washed with a little ether and dried. The yield of pure N-benzoyl-4fluoro-N-(3'-pyridylmethyl)aniline thus obtained was 89%. Melting point 162--1630C.

Analysis C H N Calculated for N20FClgH,s 74.51 4.90 9.15% Found 74.4 4.8 9.1% Example 3 N-t-butylcarbonyl-N-(4'-chlorophenylmethyl)aminopyrazine (a) To a suspension of 4-chloro-(pyrazineiminomethyl)benzene (21.75 g, 0.1 mole) in dry toluene (50 ml) was added formic acid (98%, 10.8 g), and the mixture was stirred and heated under reflux for 16 hours. Toluene and formic acid were removed in vacuo, and to the residue was added 10% HCI (100 ml). After extracting with 100 ml toluene, the aqueous layer was separated and made alkaline by the addition of a concentrated aqueous solution of KOH. The product was extracted into diethyl ether, and the extracts dried (MgSO4). After removal of solvent, the product was purified by column chromatography (neutral alumina/diethyl ether).The pure N-(4'-chlorophenylmethyl)aminopyrazine was obtained in 27% yield as a colourless material, melting point 8687CC.

Analysis C H N Cl Calculated for N3CICllH1o 60.14 4.56 19.13 16.17% Found 60.4 4.8 19.2 16.0% (b) To a stirred solution of N-(4'-chlorophenylmethyl)aminopyrazine (2.2 g, 0.01 mole) in dry benzene (30 ml) was added a solution of trimethylacetylchloride (1.4 g, 0.012 mole) in dry benzene (10 ml) followed by a solution of dry triethylamine (1.3 g, 0.013 mole) in dry benzene (10 ml). The mixture was stirred and heated under reflux for 22 hours. After cooling, the reaction mixture was washed three times with water and dried (MgSO4). Solvent was removed in vacuo and the residue was subjected to column chromatography on neutral alumina, eluting with diethyl ether/hexane (3:1). N-tbutylcarbonyl-N-(4'-chlorophenylmethyl)aminopyrazine was thus obtained in 58% yield as a colourless solid, melting point 65--80C.

Analysis C H N Calculated for N30CIC16H18 63.26 5.93 13.84% Found 63.3 5.9 13.9% Example 4 N-formyl-N-(4'-chlorophenyl methyl)-3-aminopyridine To a solution of 4-chioro-(3'-pyridyiiminomethyl)benzene (21.65 g, 0.1 mole) in dry toluene (50 ml) was added formic acid (98%, 10.8 g), and the mixture was stirred and heated under reflux for 1 6 hours. Toluene and formic acid were removed in vacuo, and to the residue was added 10% HCI (100 ml). After extracting with toluene (100 ml), the aqueous layer was separated and made alkaline by the addition of a concentrated aqueous solution of KOH. The products were extracted into diethyl ether, and the extracts dried (MgSO4). After removal of solvent, the residue was subjected to column chromatography (neutral alumina/diethyl ether).The faster eluting material was N-(4'-chlorophenylmethyl)-3-aminopyridine while the desired product N-formyl-N-(4'-chlorophenylmethyl)-3aminopyridine was obtained, as the slower eluting material, in 13.5% yield, as an oil.

Analysis C H N Calculated for N20CIC13H11 63.29 4.46 11.36% Found 63.3 4.8 11.4% 'HNMR (CDCl3) 4.93(2H,m); 7.0-7.67(6H,m); 8.47(m) and 8.53(s) (total 3H), ppm Example 5 N-t-butylcarbonyl-N-(4'-chlorophenyl methyl)-3-aminopyridine To a stirred solution of N-(4'-phenylmethyl)-3-aminopyridine (4.5 g, 0.0206 mole) in dry benzene (50 ml) was added a solution of trimethylacetylchloride (2.9 g, 0.024 mole) in dry benzene (15 ml) followed by a solution of dry triethylamine (2.6 g, 0.026 mole) in dry benzene (10 ml). The mixture was stirred and heated under reflux for 6w hours.After cooling, the reaction mixture was washed three times with water and dried (MgSO4). Solvent was removed in vacuo, and the residue triturated with a little diethyl ether. The solid material was filtered off, washed with a little diethyl ether and dried.

Recrystallisation from hexane gave the pure N-t-butylcarbonyl-N-(4'-chlorophenylmethyl)-3- aminopyridine in 41% yield as a colourless solid, melting point 100-102 C.

Analysis C H N Calculated for N2OClC1,H1s 67.44 6.28 9.26% Found 67.6 6.4 9.2% Examples 6 to 24 Using methods analogous to those described in Examples 1 to 5, the following compounds were prepared.

Table 1 In the generatformulal Elemental analysis Melting Example No. R R R R4 C H N point C 6 2-pyridyl 4-chloro- -CO. phenyl H Calculated 70.7 4.7 8.68 106-109 phenyl Found 70.4 4.7 8.6 7 2-pyridyl 4-chloro- -CO. t-butyl H Calculated 67.4 6.3 9.26 55-57 phenyl Found 67.3 6.5 9.3 8 3-pyridyl 4-chloro- -CO. phenyl H Calculated 70.7 4.7 8.68 98-99 phenyl Found 71.3 4.8 8.8 9 4-chloro- 3-pyridyl -CO. phenyl H Calculated 70.7 4.7 8.68 128-1129 phenyl Found 70.3 4.6 8.7 10 3-pyridyl 3-pyridyl -CO. phenyl H Calculated 74.7 4.7 8.68 122-124 Found 75.0 5.3 8.7 11 4-chloro- 3-pyridyl -CO. t-butyl H Calculated 67.4 6.3 9.26 82-83 phenyl Found 67.5 6.4 9.4 12 pyrazinyl 4-chloro- -CO. phenyl H Calculated 66.7 4.3 13.0 91-92 phenyl Found 66.5 4.4 13.0 13 3-pyridyl 4-fluoro- -CO. t-butyl H Calculated 71.3 6.6 9.7 61-62 phenyl Found 70.7 6.8 9.8 14 4-fluoro- 3-pyridyl -CO. t-butyl H Calculated 71.3 6.6 9.7 103-105 phenyl Found 71.1 6.9 9.8 15 3-pyridyl 4-fluoro- -CO. phenyl H Calculated 74.5 4.9 9.1 85-86 phenyl Found 74.5 5.1 9.2 16 3-pyridyl 3-pyridyl -CO-(4-chloro- H Calculated 66.7 4.3 12.9 93-94 phenyl) Found 66.7 4.4 13.0 17 3-pyridyl 4-fluoro- -CO.CH2-OCH3 H Calculated 65.6 5.4 10.2 57-59 phenyl Found 63.8 5.4 10.2 18 4-chloro- 3-pyridyl -CO.CH2OCH3 H Calculated 61.9 5.1 9.6 Oil phenyl Found 62.0 5.5 9.6 Table 1 (cont.)

In the generatformulal Elemental analysis Melting Example No. R R R R4 C H N point C 19 4-chloro- 3-pyridyl -CO-(4- H Caculated 63.8 3.9 7.8 66-69 phenyl chlorophenyl) Found 64.1 4.0 7.9 20 4-chloro- 3-pyridyl -CO.CH2.t- H Caculated 68.2 6.6 8.8 75-76 phenyl butyl Found 68.5 6.7 8.9 21 4-chloro- 3-pyridyl -CO(2-methyl H Caculated 71.3 5.0 8.3 75-78 phenyl phenyl) Found 71.4 5.1 8.4 22 4-chloro- 3-pyridyl -CO-(2- H Caculated 66.9 4.1 8.2 90-96 phenyl fluorophenyl) Found 67.1 4.3 8.0 23 pyrazinyl 4-fluoro- -CO. t-butyl H Caculated 66.9 6.2 14.6 41-42 phenyl Found 67.9 6.7 14.3 24 pyrazinyl 4-fluoro- -CO. phenyl H Caculated 70.3 4.5 13.6 78-80 phenyl Found 71.3 4.8 13.7 25 4-chloro- 3-pyridyl -CO-(2-fluoro- H Caculated 46.15 2.75 7.69 57-58.5 phenyl phenyl) Found 47.0 2.8 7.9 26 4-chloro- 3-pyridyl -CO-CH2-O- H Caculated 68.09 4.82 7.94 68-70 phenyl phenyl Found 68.5 5.0 8.0 27 2-pyrazinyl 4-chloro- -CO-(4-chloro- H Caculated 60.34 3.63 11.73 89-91 phenyl phenyl) Found 62.4 3.8 11.8 28 2-pyrazinyl 4-chloro- -CO-CH2-t. H Caculated 64.25 6.3 13.23 53-55 phenyl butyl Found 64.8 6.6 13.1 29 4-chloro- 2-pyrazinyl -CO-t. butyl H Caculated 63.26 6.93 13.84 90-92 phenyl Found 63.1 6.1 13.8 30 2-pyrazinyl 4-chloro- # H Caculated 63.7 5.3 13.9 Oil phenyl Found 63.4 5.6 13.9 31 2-pyrazinyl 4-chloro- -CO-(2-methyl- H Caculated 67.56 4.74 12.44 Oil phenyl phenyl) Found 68.3 5.0 12.2 Table 1 (cont.)

In the generatformulal Elemental analysis Melting Example No. R R R R4 C H N point C 32 2-pyrazinyl 4-chloro- -CO-CH2-OCH3 H Calculated 57.63 4.80 14.41 Oil phenyl Found 58.0 5.3 13.5 33 2-pyrazinyl 4-chloro- -CO.CCl3 H Calculated 42.74 2.47 11.51 74-76 phenyl Found 41.5 2.8 10.7 34 2-pyrazinyl 4-chloro- -CO.CH3 H Calculated 59.66 4.59 16.06 Oil phenyl Found 60.9 5.0 16.0 35 4-fluoro- 3-pyridyl -CO.CH2-O- H Calculated 71.43 5.06 8.33 61-63 phenyl phenyl Found 68.9 5.1 8.4 36 3-pyridyl 4-chloro- -CO-CH2-O- H Calculated 68.09 4.82 7.94 109-111 phenyl phenyl Found 67.3 4.8 8.1 37 3-pyridyl 4-chloro- -CO-(2-methyl- H Calculated 71.32 5.05 8.32 108-110 phenyl phenyl) Found 71.9 5.4 8.3 38 3-pyridyl 4-chloro- -CO.CCl3 H Calculated 46.15 2.75 7.69 83-85 phenyl Found 46.3 2.8 7.8 39 4-chloro- 3-pyridyl # H Calculated 56.32 4.43 7.30 70-72 phenyl Found 56.5 4.4 7.5 40 3-pyridyl 4-chloro- -CO-(2-fluoro- H Calculated 66.96 4.11 8.22 109-111 phenyl phenyl) Found 68.9 4.1 8.6 41 3-pyridyl 4-fluoro- -CO-CH2-O- H Calculated 71.43 5.06 8.33 91-92.5 phenyl phenyl Found 73.4 5.3 8.4 42 2-pyrazinyl 4-chloro- -CO-CH2-O- H Calculated 64.50 4.53 11.88 62-63 phenyl phenyl Found 65.0 4.7 11.7 43 2-pyrazinyl 3,4-dichloro- -CO-t. butyl H Calculated 56.80 5.03 12.43 71-73 phenyl Found 56.7 6.4 12.4 44 2-pyrazinyl 4-methyl- -CO-t. butyl H Calculated 72.08 7.42 14.84 79-80 phenyl Found 72.1 7.8 14.8 Table 1 (cont.) 45 2-pyrazinyl 2,4-dichloro- -CO-t.butyl H Calculated 56.80 5.03 12.43 Oil phenyl Found 57.1 5.4 12.3 46 2-pyrazinyl phenyl -CO-t.butyl H Calculated 71.38 7.06 15.61 53-55 Found 71.9 7.5 15.7 47 2-pyrazinyl 4-chloro- -CO-cyclo- H Calculated 65.55 6.07 12.76 Oil phenyl hexyl Found 65.0 6.5 12.5 48 2-pyrazinyl 4-chloro- -CO-CH2.CH3 H Calculated 60.98 5.08 15.25 Oil phenyl Found 61.3 5.3 15.1 49 2-pyrazinyl 4-chloro- -CO-CH.(CH3)2 H Calculated 62.18 5.53 14.51 91-92 phenyl Found 62.6 5.6 14.7 50 2-pyrazinyl 4-chloro- -CO-(CH2)2CH3 H Calculated 62.18 5.53 14.51 58-60 phenyl Found 62.1 6.2 14.6 51 2-pyrazinyl 4-chloro- -CO-CH2- H Calculated 67.56 4.74 12.44 86-88 phenyl phenyl Found 67.8 4.7 12.4 52 2-pyrimidinyl4-chloro- -CO-t.butyl H Calculated 63.3 5.9 13.8 61-62 phenyl Found 63.9 6.3 14.0 53 2-pyrazinyl 4-chloro- -CO-CH2.CH. H Calculated 63.26 5.93 13.84 84-86 phenyl (CH3)2 Found 64.0 6.4 14.0 54 2-pyrazinyl 4-chloro- -CO-(CH2)4.CH3 H Calculated 64.25 6.3 13.23 29-30 phenyl Found 64.4 6.6 13.0 55 2-pyrazinyl 4-chloro- -CO(CH2)3.CH3 H Calculated 63.26 5.93 13.84 60-62 phenyl Found 63.0 6.1 13.8 56 2-pyrazinyl 4-chloro- -CO.CO2C2H5 H Calculated 56.3 4.4 13.1 Oil phenyl Found 56.8 4.9 12.9 57 2-pyrazinyl 4-chloro- -CO-CH2.CH.- H Calculated 57.6 4.8 12.6 111-112 phenyl C2H5 Found 55.7 4.8 12.6 Table 1 (cont.) In the generatformulal Elemental analysis Melting Example No.R R R R4 C H N point C 58 2-pyrazinyl 4-chloro- -CO-(4-t.- H Calculated 69.57 5.80 11.07 124-127 phenyl butylphenyl) Found 69.8 6.1 11.0 59 2-pyrazinyl phenyl -CO-t. butyl CH3 Calculated 72.08 7.42 14.84 41-42 Found 72.2 7.9 15.0 60 2-pyrazinyl 4-chloro- -CO-CH=C(CH2)2 H Calculated 63.68 5.31 13.93 54-58 phenyl Found 63.9 5.4 13.6 61 3-pyrazinyl 4-chloro- -CO-t. butyl H Calculated 63.26 5.93 13.84 134-136 phenyl Found 62.8 5.8 13.8 62 2,4-dichloro- 3-pyridyl -CO-t. butyl H Calculated 60.53 5.34 8.31 45-47 phenyl Found 62.6 5.3 8.5 63 3,4-dichloro- 3-pyridyl -CO-t. butyl H Calculated 60.53 5.34 8.31 63-65 phenyl Found 60.7 5.5 8.2 64 2,4-difluoro- 3-pyridyl -CO-t. butyl H Calculated 67.11 5.92 9.21 73.5-75.5 phenyl Found 67.1 5.1 9.0 65 3-chloro-4- 3-pyridyl -CO-t. butyl H Calculated 63.65 5.62 8.74 61-62 fluorophenyl Found 64.0 5.8 8.7 66 4-pyridazinyl 4-chloro- -CO-(4-chloro- H Calculated 60.3 5.6 11.7 118-120 phenyl phenyl) Found 60.7 5.3 11.6 67 4-pyridazinyl 4-chloro- -CO-t. butyl H Calculated 63.26 3.93 13.84 104-105 phenyl Found 62.5 3.2 13.7 68 phenyl 3-pyridyl -CO-t. butyl H Calculated 76.12 6.46 10.45 38-40 Found 76.0 5.9 10.6 69 4-bromo- 3-pyridyl -CO-t. butyl H Calculated 58.79 7.48 8.07 90-92 phenyl Found 58.8 7.7 8.1 70 2-pyrazinyl 4-chloro- -CO.C(CH3)2Br H Calculated 48.8 5.1 11.4 74-75 phenyl Found 48.9 5.2 11.3 71 4-chloro- 3-pyridyl -CO-t. butyl CH3 Calculated 68.25 4.64 8.85 Oil phenyl Found 69.2 4.2 8.9 Examples 72-77 By methods analogues to known methods, the following derivatives were prepared from compounds of the general formula I.

Elemental analysis Melting point Example No. Compound C H N "C 72 N-oxide of the compound Calculated 54.24 4.80 11.86 106-109 of Example 43 Found 54.1 5.0 11.7 73 N-oxide of the compound Calculated 60.09 5.63 13.15 121-123 of Example 3 Found 60.4 5.8 13.2 74 Complex of two moles of Calculated 57.10 5.65 12.49 186-188 the compound of Example Found 57.1 5.6 12.2 46 per mole of copper II chloride 75 Complexoftwo moles of Calculated 59.44 4.21 6.93 117-119 the compound of Example Found 58.3 4.4 6.8 21 per mole of copper II chloride 76 Complex of two moles of Calculated 51.79 4.86 11.33 145-147 the compound of Example Found 51.7 4.8 11.4 3 per mole of copper II chloride 77 Tartaric acid addition Calculated 55.51 5.29 6.17 114-11 6 salt of the compound Found 54.3 5.2 6.0 of Example 65.

Example 78 The fungicidal activity of compounds of the general formula I was investigated by means of the following tests: (a) Activity against vine downy mildew (Plasmopera viticola Pv.a) The test is a direct anti-sporulant one using a foliar spray. The lower surfaces of leaves of whole vine plants, are inoculated by spraying with an aqueous suspension containing 105 zoosporangia/ml 4 days prior to treatment with the test compound. The inoculated plants are kept for 24 hours in a high humidity compartment, 48 hours at glasshouse ambient temperature and humidity and then returned for a further 24 hours to high humidity. The plants are then dried and infected leaves detached and sprayed on the lower surfaces at a dosage of 1 kilogram of active material per hectare using a track sprayer.After drying the petioles of the sprayed leaves are dipped in water and the leaves returned to high humidity for a further 72 hours incubation, followed by assessment. Assessment is based on the percentage of the leaf area covered by sporulation compared with that on control leaves.

(b) Activity against vine downy mildew (Plasmopera viticola Pv.t) The test is a translaminar protectant one using a foliar spray. The upper surfaces of leaves of whole vine plants are sprayed at a dosage of 1 kilogram of active material per hectare using a track sprayer. The lower surfaces of the leaves are then inoculated, up to 6 hours after treatment with the test compound, by spraying with an aqueous suspension containing 105 zoosporangia/ml. The inoculated plants are kept for 24 hours in a high humidity compartment, 4 days at glasshouse ambient temperature and humidity and then returned for a further 24 hours to high humidity. Assessment is based on the percentage of the leaf area covered by sporulation with that on control leaves.

(c) Activity against vine grey mould (Botrytis cinerea B.c) The test is a direct eradicant one using a foliar spray. The under-surfaces of detached vine leaves are inoculated by pipetting ten large drops of an aqueous suspension containing 5 x 105 conidia/ml on to them. The inoculated leaves are kept uncovered overnight during which time the fungus has penetrated the leaf and a visible necrotic lesion may be apparent where the drop was made. The infected regions are sprayed directly with a dosage of 1 kg of active material per hectare using a track sprayer. When the spray has dried the leaves are covered with petri dish lids and the disease allowed to develop under the moist conditions. The extent of the necrotic lesion beyond the original drop together with the degree of sporulation is compared with that on control leaves.

(d) Activity.against potato late.blight (Phytophthora infestans P.i.e.) The test is a direct eradicant one using a foliar spray. The upper surfaces of the leaves of potato plants (12-1 8 cms high, in monopots) are inoculated by spraying with an aqueous suspension containing 5 x103 zoosporangia/ml 1 6-19 hours prior to treatment with the test compound. The inoculated plants are kept overnight at high humidity and then allowed to dry before spraying at a dosage of 1 kg of active material per hectare using a track sprayer. After spraying the plants are returned to high humidity for a further period of 48 hours. Assessment is based on a comparison between the levels of disease on the treated and control plants.

(e) Activity against potato late blight (Phytophthora infestans (P.i.p.) The test measures the direct protectant activity of compounds applied as a foliar spray. Tomato plants, Cultivar Ailsa Craig, 1-15 cms high, in monopots are used. The whole plant is sprayed at a dosage of 1 kilogram of active material per hectare using a track sprayer. The plant is then inoculated up to 6 hours after treatment with the test compound, by spraying with an aqueous suspension containing 5x 103 zoosporangia/ml. The inoculated plants are kept in high humidity for 3 days.

Assessment is based on a comparison between the levels of disease on the treated and control plants.

(f) Activity against barley-powdery mildew (Erysiphe graminis Eg.) The test measures the direct anti-sporulant activity of compounds applied as a foliar spray. For each compound about 40 barley seedlings were grown to the one-leaf stage in a plastic pot of sterile potting compost. Inoculation was effected by dusting the leaves with conidia of Erysiphe graminis, spp.

hordei. 24 hours after inoculation the seedlings were sprayed with a solution of the compound in a mixture of acetone (50%), surfactant (0.04%) and water using a track sprayer. The rate of application was equivalent to 1 kg of active material per hectare. First assessment of disease was made 5 days after treatment, when the overall level of sporulation on the treated pots was compared with that on control pots.

(g) Activity against wheat brown rust (puccinia recondita P.r.) The test is a direct antisporulant one using a foliar spray. Pots containing about 25 wheat seedlings per pot, at first leaf stage were inoculated by spraying the leaves with an aqueous suspension, containing 105 spores/ml plus a little Triton X-155 (Trade Mark), 20--24 hours before treatment with the compound undef test. The inocuiated~plants were kept overnight in a high humidity compartment, dried at glass-house ambient temperature and then sprayed at a dosage of 1 kilogram of active material per hectare using a track-sprayer. After treatment the plants were kept at glass-house ambient temperature and assessment made about 11 days after treatment.Assessment is based on the relative density of sporulating pustules per plant with that on control plants.

(h) Activity against broad bean rust (Uromyces fabae U.f.) The test is a translaminar antisporulant one using foliar spray. Pots containing 1 plant per pot were inoculated by spraying an aqueous suspension, containing 5x 104 spores/ml plus a little Triton X1 55, onto the undersurface of each leaf 20-24 hours before treatment with test compound. The inoculated plants were kept overnight in a high humidity compartment, dried at glass-house ambient temperature and then sprayed, on the leaf upper surface, at a dosage of 1 kg/ha of active material using a track sprayer. After treatment the plants were kept at glass-house tennperature and assessment made 11-14 days after treatment.Symptoms are assessed on the relative density of sporulating pustules per plant compared with that on control plants.

(i) Activity against rice leaf blast (Pyricularia oryzae P.o.) The test is a direct eradicant one using a foliar spray. The leaves of rice seedlings (about 30 seedlings per pot) are sprayed with an aqueous suspension containing 105 spores/ml 20-24 hours prior to treatment with the test compound. The inoculated plants are kept overnight in high humidity and then allowed to dry before spraying at a dosage of 1 kg of active material per hectare using a track sprayer. After treatment the plants are kept in a rice compartment at 25--300C and high humidity.

Assessment are made 4-5 days after treatment and are based on the density of necrotic lesions and the degree of withering when compared with control plants.

(j) Activity against rice sheath blight (Pellicularia sasakii P.s.) The test is a direct eradicant one using a foliar spray. 20-24 hours prior to treatment with the test compound rice seedlings (about 30 seedlings per pot) are sprayed with 5 ml of an aqueous suspension containing 0.2 g of crushed solerotia/mycelium per ml. The inoculated plants are kept overnight in a humid cabinet maintained at 25--300C, followed by spraying at a dosage of 1 kg of active material per hectare. The treated plants are then returned to high humidity for a further period of 3-4 days. With this disease brown lesions are seen that start at the base of the sheath and extend upwards. Assessments are made on the number and extent of the lesions when compared with the control.

The extent of disease control is expressed as a control rating according to the criteria: O=less than 50% disease control 1 =5080% disease control 2=greater than 80% disease control /51 and /S2 indicate systemic activity, using the same scale of rating.

The obtained control ratings are set out in Table II.

Table II Fungicidal activity Compound of Example No. Pv.a Pv.t Bc P.i.e. P.i.p. Eg P.r U.f P.o. P.s 1 2 1 2 -1 2 3 1 2 2/2S 5 2 6 0 2 7 2 9 2 10 2 11 2 12 0 1 13 2/2S 14 2 15 1 17 1S 18 2 2/1S 19 2 20 2 21 2 1 2 22 2 23 2 2/2S 24 2 2 Example 79 Further compounds of the formula I were tested for fungicidal activity against the same species as described in Example 78, except that tests on the two following species replaced tests on Pelliculada sasakii.

(k) Activity against apple powdery mildew (Podosphaera leuco tricha, P.l.) The test measures the direct anti-sporulant activity of compounds applied as a foliar spray. For each compound. apple seedlings were grown to the three to five leaf stage in a plastic pot of sterile potting compost. Inoculation was effected by spraying the leaves with a suspension in water of conidia of the test species. 48 hours after inoculation the seedlings were sprayed with a solution of the test compound in a mixture of acetone (50%), surfactant (0.04%) and water using a track sprayer. The rate of application was equivalent to 1 kg of active material per hectare. First assessment of disease was made 10 days after treatment, when the overall level of sporulation on the treated pots were compared with those on control pots.

(I) Activity against peanut leaf spot (Cercospora arachidicola C.a) The proceedure of (k) above was repeated using peanut seedlings grown to height of about 1 5 cm. Assessment of disease was made 14 days after treatment.

The results of the test of Example 79 are given in Table Ill below.

Table III Fungicidal activity Compound of Example No. Pv.a Pv.t Be P. i. e. P.ip. Eg. P.r. U.f. P.o. P.l. C.a.

25 2 1 1 26 2 2 2 27 2 1 28 1 2 1 29 1 2/2S 2 30 1 32 1S 2 33 2 2 1 34 1 1 2/1S 35 1 36 1 2 2 37 1 38 2 2 39 1 2 2 40 2 1 41 1 2/1S 1 42 2 43 1 2 2 1 44 2 1 1 2 2 45 2 2 2 46 IS 47 2 2 48 1 2 2 2 2 49 2 1 1 50 2 2 51 2 1 52 53 2 2 54 1 2 2 1 55 2 1 1 2 56 1 2 1 57 2 1 58 2 59 1/25 1S 1 60 1 1 61 2 62 2 2 2 2 63 2 2 2 64 2/2S 1 2 65 2 1 67 1 68 2 1 69 2/1S 1 70 2/1S 2 71 2 72 2 73 1 1 2/2S 74 2 1 2S 75 2 2 76 2 2 2 77 1 2/1S 1 2 Example 80 Herbicidal activity To evaluate their herbicidal activity, compounds according to the invention were tested using as a representative range of plants: maize,Zea mays (Mz); rice, Oryza sativa (R); barnyard grass, Echinochlca crusgalli (BG); oat,Avena sativa (0) linseed, Linum usitatissimum (L); mustard, Sinapis alba (M); sugar beet, Beta vulgaris (SB) and soya bean, Glycine max (S). The tests conducted were foliar spray tests, in which seedling plants were sprayed with a formulation containing the test compound.

The soil used in the tests was a prepared horticultural loam.

The formulations used in the tests were prepared by diluting with water, solutions of the test compounds in acetone containing 0.4% by weight of an alkylphenol/ethylene oxide condensate available under the trade name TRITON X-155. The acetone solutions were diluted with an equal volume of water and the resulting formulations applied at a dosage level corresponding to 5 kg of active material per hectare in a volume equivalent to 650 litres per hectare. Untreated seedlings plants were used as controls.

The herbicidal effects of the test compounds were assessed visually eleven days after spraying the foilage and were recorded on a 0--9 scale. A rating 0 indicates growth as untreated control, a rating 9 indicates death. An increase of 1 unit on the linear scale approximates to a 10% increase in the level of effect.

The results of the tests are set out in Table IV below.

Table IV Herbicidal activity Phytotoxicity rating foliar spray Compound of example No. Mz R BG O L M SB S 1 0 0 3 3 4 5 5 7 3 7 4 7 5 8 7 8 8 5 0 0 3 4 6 7 6 7 7 4 3 8 4 6 6 4 5 8 4 0 3 2 4 5 3 5 9 0 0 5 4 4 4 4 5 10 0 0 4 1 4 5 5 6 11 6 0 7 4 6 6 6 7 12 0 0 0 0 3 4 4 5 13 2 0 7 2 6 7 5 7 14 3 0 3 1 4 5 2 5 15 0 0 0 2 3 4 2 5 16 0 0 0 0 4 5 0 4 17 0 2 2 2 2 2 1 6 18 1 2 3 2 4 4 1 6 19 2 0 3 0 3 5 2 5 20 4 0 3 0 4 4 2 3 21 2 0 2 0 1 4 2 3 22 2 0 2 1 3 6 0 7 23 2 2 5 4 7 7 4 7 24 3 0 4 4 4 7 5 4 25 0 0 0 0 2 4 2 5 26 0 0 0 0 4 4 5 5 27 0 0 0 0 3 4 4 3 28 4 5 6 6 7 6 6 5 30 3 3 6 5 7 6 5 7 31 0 0 0 0 4 5 5 4 32 4 5 5 6 6 5 6 5 33 0 0 2 0 5 5 4 4 34 5 4 6 6 7 6 6 6 35 0 0 2 0 4 5 5 4 36 0 0 0 0 4 3 3 4 37 0 0 0 0 3 4 2 4 38 2 0 4 0 6 6 6 6 39 2 0 3 0 3 4 2 3 40 0 0 1 0 4 4 3 4 41 0 0 0 4 5 4 4 5 42 0 0 6 0 3 7 0 4 43 4 0 7 3 7 7 7 7 44 2 0 6 3 6 6 5 7 45 0 0 0 0 6 6 5 7 46 2 2 7 2 7 7 6 7 47 3 0 4 4 4 4 5 5 48 4 4 7 5 6 6 6 7 49 0 0 5 5 5 5 6 7 Table IV (cont) Herbicidal activity Ph yto toxicity rating foliar spray Compound of Example No. Mz R BG O L M SB S 50 5 5 6 6 8 6 7 6 52 2 0 6 4 3 5 4 4 53 4 0 7 5 5 7 5 6 54 3 0 8 0 4 5 4 6 55 4 0 7 4 5 5 5 5 57 0 0 3 3 0 3 0 2 59 4 4 7 3 6 6 9 6 60 0 0 5 3 4 5 5 4 62 5 4 7 5 5 7 6 6 63 1 0 5 3 3 5 3 5 64 5 4 6 4 5 7 6 8 65 4 0 5 4 6 7 7 5 66 2 0 0 0 2 3 0 3 67 0 0 0 0 3 2 2 5 68 2 0 4 4 6 8 8 7 69 0 0 1 0 5 5 3 4 70 0 0 5 3 7 8 5 4 71 1 2 6 3 6 7 6 6 72 4 0 5 3 5 5 4 5 73 4 2 7 3 7 5 5 6 74 2 0 4 5 5 6 5 6 75 3 1 6 0 3 4 4 4 76 5 4 6 5 7 6 6 7 77 0 0 2 2 5 6 4 5 In addition to the foliar spray tests, pre-emergence tests were carried-out in which-soil planted with seeds of the various plant species was treated with a compound according to the invention. The compounds of Examples 3, 5, 8, 13, 23,26, 28-30, 32-34, 38, 43-50, 53-59, 62 and 70-76 showed pre-emergence herbicidal activity.

Example 81 Plant growth regulating activity Observations were made throughout the tests described in Example 80 of the precise effects on the test plants of the compounds of the invention. The following effects were observed.

1. All the compounds showing activity in the herbicide tests produced a depression in growth i.e. a reduction in stem height-for some or all of the plant species.

2. Many of the compounds resulted in hyperchromism in the test plants-i.e. the production of very dark green leaves.

Various other symptoms were observed in various tests, including the production of enlarged cotyledons, the production of shortened internodes, and the production of shorter, broader leaves.

Example 82 Plant growth regulating activity The compound of Example No. 3 was examined in detail for plant growth regulating properties as follows.

Seeds of various plant species were planted and treated with various dosages of a 1:1 acetone/water solution of the test compound. The resulting growth was evaluated at weekly intervals up to at least five weeks from spraying. With the grass species, the growth was harvested at intervals and the fresh weight was recorded. All tests were conducted using untreated plants as control.

The plant species tested were as follows: Maize; Grain Sorghum; Wheat; Barley; Oat Cultivated; Oat Wild; Ryegrass; Tall fescue; Blackgrass; Barnyard grass; Browntop bent; Couchgrass; Bermuda grass; Nutsedge; Convolvulus; Soya bean; Sugar beet; Cotton; Lucerne; Kale; Velvet leaf; Mustard; Redshank; Cleavers; Pale persicaria; Plantain; Corn Marigold; Spurrey; Shepherds Purse; Mayweed; Purslane; Pigweed.

The test compound had significant growth-regulating activity against every species with the exception of nutsedge. The main symptoms produced were depression (reduced plant height), hyperchromism (dark green leaves), reduced internode length (leaves closer together on the stem), and some of the grasses had expanded leaves (leaves on treated plants were short and broad compared with those on untreated plants which were longer and thinner).

The overall effect was compacting of the growth.

The fresh weights of the harvested growths showed that the growth, compared with untreated controls, was much reduced, and that the effect was long-lasting. Further tests showed that the effect could be removed and normal growth re-established by treatment with the plant hormone gibberellic acid.

Example 83 Chemical lawn mower The effect of the compound of Example 3 on the growth of various grasses, was compared with the effect of maleic hydrazide, a commercial growth retardant.

The grasses Barren Brome (Bromus sterilis, BB), Yorkshire Fog (Holcus lanatus, YO), Tall fescue (Festuca arundinacea, TF), Common Bent (Agrostis tenuis, BT) and Perennial Ryegrass (Lolium perenne, LP) were propagated in plastic trays to produce turf which was cut back and allowed to grow five times before treatment.

The compound of Example 3 was formulated as a solution in acetone/water (25:75) containing 0.2% Triton X 1 55 (Trade Mark) as surface active agent, and applied to the test species as a root drench at dosages corresponding to 5.0, 2.5 and 1.0 kg/ha. For comparison, maleic hydrazide formulated as an aqueous solution containing 0.2% Triton X 1 55 (Trade Mark), was applied at the same dosages, but as a foliar spray, the form of application recommended commercially.

Two types of assessment were made.

a) effect on visual appearance of the turf.

Visual assessments were made 25 days after treatment. Rating was on a linear 0--9 scale, 0 indicating excellent appearance and 9 indicating a completely unacceptable appearance. The results were converted into a percentage of control, results greater than 100 indicating that the treated species had a more pleasing appearance than the untreated control plants.

b) effects on cutting frequency The commercial recommendations for maleic hydrazide state that one mowing is usually required after treatment, before chemical effects on growth rate become apparent. Grasses in the untreated trays of all the species had reached a suitable cutting height eleven days after treatment. After measuring the heights all the grasses were cut back to the tops of the trays, these being generally 1 5 mm above soil level. After this first cut the grasses were allowed to grow unchecked until they had reached the original cutting height of the untreated control turves. The cutting height of the species differed according to their growth rates and were as follows.

Barren Brome 100 mm; Yorkshire Fog 70 mm; Tall Fescue 60 mm; Common Bent 40 mm; Perennial Ryegrass 60 mm.

These heights were considered fairly realistic, lawns containing common bent usually being kept shorter than roadsides covered in coarse grasses.

The number of days required to reach the cutting height was recorded.

It was found that the compound of Example 3 produced a most attractive dark green sward.

Maleic hydrazide, on the other hand, produced symptoms of chlorosis and necrosis, severely weakening the plants. In one test, all the test plants died. The complete results are given in Table V.

Table V

Visual appearance % of control, grester than Number of days before Dosage 100 indicateds improved appearance cutting reauired Compound tested kg/ha BB YO TF BT LP BB YO TF BT LP Compound of 5.0 118 108 117 123 118 42 30 31 22 34 Example 3 2.5 114 122 117 119 114 34 29 29 20 31 1.0 100 101 100 109 100 29 24 19 14 17 Maleic 5.0 41 21 67 17 31 34 + 35 22 31 Hydrazide 2.5 92 38 77 71 83 17 24 27 20 27 1.0 97 93 96 97 97 14 17 19 14 14 Control - 100 100 100 100 100 14 14 14 14 14 +=complete death of all treated plants.

These results show the compound of Example 3 to be much more useful as a "chemicai lawn mower" than maleic hyrdazide.

Claims (21)

Claims

1. A compound of the general formula

in which one of R' and R2 represents an optionally-substituted 6-membered heteroaromatic ring containing 1 or 2 nitrogen atoms, and the other of R and R also represents such a ring or represents an optionally-substituted phenyl group;R3 represents an acyl group derived from a carboxylic acid; and R4 represents a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms; or an acid addition salt, N-oxide or metal salt complex thereof; provided that if R' represents an optionally substituted pyridyl group, R2 must represent an optionally substituted heteroaromatic ring; if R1 represents an optionally substituted phenyl group, R3 must represent an acyl group derived from an acid other than an optionally substituted benzoic acid; if R1 represents an unsubstituted phenyl group, R2 represents an unsubstituted 2- or 3-pyridyl group and R3 represents a group of formula CH3CO-, phenyl .CH=CH .00-, C2H5CO, or (phenyl)2CH . CO-, then R4 must represent an alkyl group; if R2 represents a phenol group substituted by an SO2NH2 group, R4 must represent an alkyl group; and if both of R' and R2 represent optionally substituted pyridyl groups, neither of these groups is substituted by an amino, acylamino, alkylamino or dialkylamino group.

2. A compound as claimed in claim 1, characterised in that R3 represents a formyl group, an alkoxycarbonyl group or an optionally substituted alkanoyl, alkenoyl, cycloalkanoyl, or aroyl group.

3. A compound as claimed in claim 2, characterised in that R3 represents a formyl group, an alkoxycarbonylcarbonyl group; an alkanoyl or alkenoyl group optionally substituted by one or more of the same or different substituents selected from halogen atoms and alkoxy, phenyl, phenoxy, carboxy and alkoxycarbonyl groups; a cycloalkanoyl group having from 3 to 6 carbon atoms in the ring optionally substituted by one or more of the same or different substituents selected from halogen atoms and methyl groups; or a benzoyl group optionally substituted by one or more of the same or different substituents selected from halogen atoms and nitro, alkyl, haloalkyl, hydroxyalkyl, alkoxy, haloalkoxy, hydroxyalkoxy, hydroxy, cyano, alkylsulphonyl, alkylcarbonyl, alkoxycarbonyl, carboxy and alkylthio groups.

4. A compound as claimed in claim 3, characterised in that R3 represents a formyl group; an ethoxy- or methoxycarbonylcarbonyl group; an alkanoyl or alkenoyl group optionally substituted by up to 3 halogen atoms or by a phenyl, phenoxy, C91-4)alkoxy, methoxycarbonyl or hetoxycarbonyl group; a cyclopropylcarbonyl, cyclohexylcarbonyl, 1-methylcyclopropylcarbonyl or a 2,2-dichloro-3,3dimethylcyclopropylcarbonyl group; or a benzoyl group optionally substituted by one or two halogen atoms and/or alkyl groups.

5. A compound as claimed in claim 4, characterised in that R3 represents an unsubstituted alkanoyl group having up to 6 carbon atoms in the alkyl moiety.

6. A compound as claimed in any one of claims 1 to 5, characterised in that R4 represents a hydrogen atom or a methyl group.

7. A compound as claimed in any one of claims 1 to 6, characterised in that each of the rings represented by R1 and R2 is unsubstituted or substituted by one or more of the same or different substituents selected from halogen atoms and nitro, alkyl, haloalkyl, hydroxyalkyl, alkoxy, haloalkoxy.

hydroxyalkoxy, hydroxy, cyano, alkylsulphonyl, alkylcarbonyl, alkoxycarbonyl, carboxy and alkylthio groups.

8. A compound as claimed in claim 7, characterised in that each of the rings represented by R' and R2 is unsubstituted or substituted by one or two halogen atoms and/or alkyl groups.

9. A compound as claimed in any one of claim 1 to 8, characterised in that any phenyl group represented by R1 or R2 is mono- or disubstituted, arld any heteroaromatic ring represented by R' or R2 is unsubstituted.

10. A compound as claimed in any one of claims 1 to 9, characterised in that any pyridyl group represented by R' or R2 is a 3-pyridyl group.

11. A compound as claimed in any one of claims 1 to 10, characterised in that R' represents an optionally substituted phenyl group and R2 represents an optionally substituted pyridyl group.

12. A compound as claimed in any one of claims 1 to 11, characterised in that R1 represents an optionally substituted pyrazinyl group and R2 represents an optionally substituted phenyl group.

13. A compound as claimed in claim 12, characterised in that R2 represents a 4-chlorophenyl group; R' represents an unsubstituted pyrazinyl group; R3 represents a t. butylcarbonyl group; and R4 represents a hydrogen atom.

14. A compound as claimed in claim 1 and named in any one of Examples 1, 3. 10 to 12, 14, 16, 18, 20, 23-35, and 42 to 74, 76 and 77 herein.

1 5. A process for the preparation of a compound as claimed in any one of claims 1 to 14, which comprises acylating a compound of the general formula

in which R1. R2 and R4 have the meanings given in claim 1, using a suitable acylating agent.

16. A process as claimed in claim 15, in which the acylating agent is an acid chloride derived from the appropriate carboxylic acid, and the reaction is carried out in the presence of an acid-binding agent.

17. A process claimed in either claim 15 or claim 16, in which the compound of the general formula II has been prepared by reduction of a compound of the general formula

in which Rr, R2 and R4 have the meanings given in claim 1.

18. A process as claimed in claim 1 5, carried out substantially as described in either of Examples 1 and 3 herein.

19. A compound as claimed in claim 1, whenever prepared by a process as claimed in either of claims 15 and 16.

20. A biologically active composition which comprises a compound as claimed in any one of claims 1 to 14 and 19, together with one or more carriers.

21. A composition as claimed in claim 20, which comprises at least two carriers, at least one of which is a surface-active agent.