IE903240A1 - Novel Oxazolidinones and -thiones as Plant-Growth-Regulators - Google Patents

Abstract

3-Phenyl-oxazolidin-2-one- and -2-thione-5-carboxylic acid derivatives of the formula I below in all stereoisomeric forms are suitable as plant growth regulators. In this formula, X represents oxygen or sulphur; A represents -COOR1, -COSR1, -COO<(-)>M<(+)>, -CONR2R3 or -COCl; R represents hydrogen, halogen or mono-, di- or trihalomethyl; n represents 1, 2 or 3; R1 represents hydrogen, C1-C4-alkyl, C2-C6-alkenyl or C2-C6-alkynyl; R2 and R3 independently of one another represent hydrogen, C1-C4-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, C3-C7-cycloalkyl, aryl or heterocyclyl; or R2 and R3 together with the nitrogen atom to which they are bonded represent a saturated C3-C7-heterocycle which is optionally up to trisubstituted by C1-C4-alkyl or C1-C4-alkoxy; and M<(+)> is the equivalent of an alkali metal cation or alkaline earth metal cation or HN<(+))

Description

Novel Qxazolidinones and -thiones as Plant - Growth - Regulators The present invention relates to novel 3-phenyl-oxazolidine-2-one-or-2-thione-5-carboxylic acid derivatives in all their stereoisometric forms, to processes for their preparation, to compositions containing these active substances, and to the use of these active substances and compositions containing them for regulating plant growth.

US Patent Specification No. 4,013,445 discloses l-(bis-trifluoromethylphenyl)-2-oxopyrrolidine-4-carboxylic acid derivatives as herbicides and for regulating plant growth.

The use of l-phenyl-2-oxopyrrolidine-4-carboxylic acids and of derivatives thereof which are unsubstituted on the phenyl ring or which are substituted by halogen atoms and/or a trifluoromethyl group, is known from French Patent Specification 1,363,615 and US Patent Specification 3,136,620 as active substances for influencing plant growth.

It has now been found that the 3-phenyl-oxazolidine-2-one- and-2-thione-5-carboxylic acid derivatives of this invention in all their stereoisometric forms, have good plant-growth-regulating properties.

The 3-phenyl-oxazolidine-2-one- and-2-thione-5-carboxylic acid derivatives which are proposed according to the invention are those of the formula I wherein (I) X is oxygen or sulfur, A is -CCXORp -COSRp -COO®M®, -CONR2R3 or -COCI; R is hydrogen, halogen, mono-, di-or trihalomethyl, n is 1, 2 or 3 Rj is hydrogen, C1-C4alkyl, C2-C6alkenyl or C2-C6alkynyl; R2 and R3 independently of -2one another are hydrogen, C1-C4alkyl, C2-C6alkenyl, C2-C6alkynyl or C3-C7cycloalkyl; or R2 and R3 together with the nitrogen atom to which they are bonded are a saturated 3- to 7-membered heterocycle, which can contain an additional hetero atom, selected from the group comprising Ο, N and S and which is unsubstituted or up to trisubstituted by C1-C4alkyl, and M® is the equivalent of an alkali metal cation or an alkaline earth metal cation or HN®(R2)3.

In the above definitions halogen stands for fluorine, chlorine, bromine and iodine. Alkyl is understood as meaning straight-chain or branched alkyl, for example methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl or tert-butyl.

Alkenyl is understood as meaning straight-chain or branched alkenyl; for example: vinyl, allyl, 2-propenyl, methallyl, 3-butenyl, 2-butenyl, 3-pentenyl, 2-methyl-4-pentenyl and 3-hexenyl.

Alkynyl in the definitions is understood as meaning straight-chain or branched alkynyl; for example: propargyl, ethinyl, 2-propinyl, 3-butinyl, 2-methyl-3-pentinyl and 1,2-dimethyl3-butinyl.

Cycloalkyl is, for example, cyclopropyl, dimethylcyclopropyl, cyclobutyl, cyclopentyl, methylcyclopentyl, cyclohexyl or cycloheptyl, but preferably cyclopropyl, cyclopentyl or cyclohexyl.

Particularly suitable cations M® are those of alkali metals, for example lithium, sodium or potassium, and those of alkaline earth metals, for example magnesium or calcium. In particular, M® is HN®(R2)3, where the substituents R2 can be identical or different, or M® is a cation of sodium or potassium.

When A is the amide radical -CONR2R3, the radicals mentioned below are particularly preferred: -CONH2, -CON(CH3)2, -CON(C2H5)2, ,ch3 CH — CHo / I 3 c2h5 -CON CH3 Xch3 -CONI , -CONH (R4)m -CON 9032*0 -3-CONH TT -CONH-^-^ * -CONH—ft (R4)m N (R4)m -CONH N—(R4)m -CONH—¢/ N N -CONH (R4)m whereby R4 is halogen, CrC3alkyl, CrC3alkoxy C1-C3haloalkoxy and m is 0, 1, 2 or 3 Examples of the heterocycles formed by the substituents R2 and R3 together with the nitrogen atom carrying them, are pyrrolidine, pyrrole, imidazole, pyrazole, piperazine, piperidine, morpholine, pyridine, pyrimidine, thiazole, thiomorpholine, triazine and triazole.

Examples for aryl are phenyl and naphthyl, which radicals are unsubstituted or mono- to tetrasubstituted by halogen, alkyl, alkoxy, alkylthio, haloalkyl, haloalkoxy, nitro, cyano, carboxyl, carbamoyl alkoxycabonyl, alkylcarbonyl, alkylsulfonyl, sulfamoyl and alkylsul famoyl.

Preferred compounds of the formula I are those in which A is -COOR! or -COO®M®. Individual compounds from this group which are to be mentioned are: 3-(3,5-bis-trifluoromethyl)-oxazolidine-2-one-5-carboxylic acid, 3-(3,5-bis-trifluoromethyl)-oxazolidine-2-one-5-carboxylic acid-methyl ester and 3-(3,5-bis-trifluoromethyl)-oxazolidine-2-one-5-carboxylic acid-tributylammonium salt.

Particularly well acting groups of compounds of the formula I are formed by the optically active compounds of the formulae (R)-I and (S)-I where A is as defined in formula I. Compounds from this group which are particularly noticeable by their good biological action are those in which A is -COOR! or -COO®M® The following are to be mentioned as preferred individual compounds of the formulae (R)-I and (S)-I: -(R)-3-(3,5-bis-trifluoromethylphenyl)-oxazolidine-2-one-5-carboxylic acid -(R)-3-(3,5-bis-trifluoromethylphenyl)-oxazolidine-2-thioine-5-carboxylic acid-methyl ester.

-(S)-3-(3,5-bis-trifluoromethylphenyl)-oxazolidine-2-one-5 -carboxylic acid and -(S)-3-(3,5-bis-trifluoromethylphenyl)-oxazolidine-2-thione-5 -carboxylic acid-methyl ester.

The compound of the formula I according to the invention can be prepared in a manner known per se by reacting, in the case of the racemic compounds of the formula I, an aniline of the formula II NH2 (Π) wherein n and R have the meaning given under formula I, is reacted with racemic glycidol ((±)-2,3-epoxy-1 -propanol) of the formula ΙΠ O ch2'ch-ch2-oh to the 1,2-propanediolanilide of the formula IV -5OH wherein n and R have the meaning given under formula I, and then cyclysing this diol in an appropriate solvent, in the presence of a base, with diethylcarbonate to form a 3-phenyl-5-hydroxymethyloxazolidine of the formula V, wherein n and R have the meaning given under formula I, and oxydizing this compound by means of an oxydizing agent to form a 3-phenyl-oxazolidone-2-one-5-carboxylic acid of the formula la wherein n and R have the meaning given under formula I, and if desired transforming this acid in a manner known per se to a salt or by reacting it with a compound formula VI H-B (VI) -6wherein B is the radical of an alcohol, a mercaptane or of an amine, to form an ester, wherein A n and R have the meaning given under formula I.

An ester of the formula Ic wherein A', n and R have the meaning given under formula Ic can optionally be transformed to a 3-phenyloxazolidine-2-thione-5-carboxylic acid derivative of the formula Id, wherein n and R have the meaning given under formula I and A' is COORj and Ri -7C!-C4alkyl, by means 2,4-bis-(4-methoxyphenyl)-l,3-dithia-2,4-diphosphethane-2,4-disulfide (Lawesson’s reagent) or with another reagent capable of introducing the thioxy group.

Reagents which are suitable for introducing the thioxo group are, for example, phosphorus pentasulfide and the arylthionophosphine sulfides derived therefrom. Such reagents are described e.g. in Tetrahedron 41 5061-5087 (1985).

Reactions for producing the compounds of the formula V are known and disclosed e.g. in Tetrahedron 45, 1323-1326 (1989), Chimie Therapeutique 1973, 324-327 or the French patent No 2,458, 547.

The oxydation of the 3-phenyl-5-hydroxymethyl-oxazolidine-2-one of the formula V to the 3-phenyl-5-oxazolidine-2-one-5-carboxylic acid of the formula la is carried out according to Jones (Fieser and Fieser, Reagents for Organic Synthesis, John Wiley and Sons, N.Y. Vol I 1967 p. 142) in an aprotic organic solvent, at a low temperature of between-10°C to room temperature, by means of a chromic-anhydride/sulfuric acid mixture. Appropriate solvents for this oxydation are ketones, such as acetone, methylethylketone, acetophenone, cyclohexanone, dioxane or higher molecular ethers such as tetrahydrofuane or diisopropylether.

The optically active isomers of the formula I, which are represented by the sub-formulae (R)-I and (S)-I are likewise a subject of the present invention. They can be prepared in a manner known per se, by starting in the reactions sequence given above, with optically active glycidol of the formula ((-+)-ΠΙ) or ((-)-111), which is commercially available, or from a racemic 3-phenyl-oxazolidine-2-one-5-carboxylic acid of the formula la COOH N (la) Rn wherein n and R have the meaning given under formula I, which is converted by fractional - 8crystallization, in a method known per se, in the presence of a chiral auxiliary, for example an optically active base, in particular an optically active 1-phenylethylamine, into the optically active 5-(R)(-)-3-phenyl-oxazolidine-2-one-5-carboxylic acid of the formula (R)-Ia COOH N' (R)-(Ia) Rn wherein n and R have the meaning given under formula I, and the optically active -(S)(+)-3-phenyl-oxazolidine-2-one-5-carboxylic acid of the formula (S)-Ia .COOH (S)-(Ia), wherein n and R have the meaning given under formula I and, if desired, these isomers are converted in a manner known per se, into the derivatives according to the definition of the formula (R)-Ic and (S)-Ic, Rn Rn -9where A' is -COORj and Rj is Cj-C4alkyl and n and R have the meaning given under formula I.

By subsequent reaction with a reagent capable of introducing the thioxo group, the corresponding compounds of the formulae (R)-Id and (S)-Id are obtained wherein A' is -COOR! and R! is Ci-C4alkyl, and n and R are as defined under formula I, and these compounds can if desired then be converted, in a manner known per se, into the other derivatives according to the definition, of the formulae (R)-Ie and (S)-Ie where in A n and R are as defined in formula I.

Reagents which are suitable for introducing the thioxo group are, for example, phosphorus pentasulfide and the arylthionophosphine sulfides derived therefrom. Such reagents are described e.g. in Tetrahedron 41 5061-5087 (1985). 2,4-Bis-(4-methoxyphenyl)-l,3dithia-2,4-diphosphetane 2,4-disulfide (Lawesson’s reagent) has proved to be a particularly highly suitable reagent for introducing the thioxo group. -10The compounds of the formula (R)-Ia and (S)-Ia are converted into the other derivatives of the formulae (R)-Ib and (S)-Ib, respectively, according to the definition, in a manner known per se, for example: by reacting the free carboxylic acids or the corresponding acid chlorides with alcohols RiOH, or by esterifying the free carboxylic acid by generally known methods.

The racemic 3,phenyloxazolidine-2-thione-5-carboxylic esters of the formule Ie and their optically active isomers of the formulae (R)-Ie and (S)-Ie are converted into the other derivatives of the formula Ie according to the definition in a manner known per se, for example: - to give the free carboxylic acids (A = -COOH), by acid hydrolysis of the esters of the formulae II, (R)-IIb or (S)-IIb. - to give the acid chlorides (A = -COCI), by reacting the free carboxylic acids with suitable chlorinating agents, for example thionyl chloride, oxalyl chloride, phosgene or PC15.

Ro Z - to give amides (A = -CO-N ), by reacting the acid esters, acid chlorides or free R3 carboxylic acids with amines Ro Ro - to give thioesters (A = -COSRj), by reacting the acid chloride with mercaptans HSRp - to give alkali metal salts or alkaline earth metal salts, by reacting the free carboxylic acids with hydroxides, alcoholates or carbonates of alkali metals or alkaline earth metals, such as Na, K, Li, Ca and Mg hydroxide, sodium methylate, potassium methylate, sodium ethylate and potassium ethylate; • 11 - to give amine salts, by reacting the free carboxylic acid with amines N(R2)3.

The invention also relates to plant-growth regulating compositions containing a novel active substance of the formula I, and to methods for inhibiting plant growth.

Plant growth regulators are substances which cause agronomically desired biochemical and/or physiological and/or morphological alterations in/on the plant.

The active substances contained in the compositions according to the invention have various effects on the plant growth, depending on the point in time of application, the dosage, the type of application and the environmental conditions. For example, plant growth regulators of the formula I can inhibit the vegetative growth of plants. This type of action is interesting on lawns, in the production of ornamental plants, in orchards, on verges, on sports grounds and industrial terrain, but also in the targeted inhibition of secondary shoots, such as in tobacco. In arable farming, inhibition of the vegetative growth in cereals by means of thickened stems results in reduced lodging, and similar agronomical effects are achieved in oil seed rape, sunflowers, maize and other crop plants. Moreover, inhibition of the vegetative growth makes it possible to increase the number of plants per unit area. Another field of application of growth inhibitors is the selective control of ground-cover plants in plantations or crops with substantial distances between the rows by powerful inhibition of growth without killing these ground-cover plants, which results in the elimination of competition with the main crop but agronomically positive effects, such as prevention of erosion, nitrogen fixation and loosening of the soil, are retained.

A method for inhibiting plant growth is taken to mean that man interferes with the natural development of the plant without altering, in the sense of a mutation, the life cycle of the plant which is determined by the genetic make-up. The method of growth regulation is applied at a point in time of development of the plant to be determined in the individual case. The active substances of the formula I can be applied before or after emergence of the plants, for example as early as in the seed stage, or to the seedlings, to roots, tubers, stalks, leaves, flowers or other parts of the plant. This can be effected for example by applying the active substance itself or in the form of an agent to the plants and/or by treating the culture substrate of the plant (soil). - 12It is preferred to employ the compounds of the formula I according to the invention for inhibiting the growth in dicotyledon crops by post-emergence application.

The compounds of the formula I are employed as they are, or preferably as agents in conjuntion with the auxiliaries conventionally used in formulations, and as such are processed by known methods to give, for example, emulsion concentrates, directly sprayable or dilutable solutions, dilute emulsions, wettable powders, soluble powders, dusts, granules and capsules, for example in polymeric subtstances. The method of application, such as spraying, atomization, dusting, scattering or watering, is chosen, as is the type of agent, according to the intended purpose and the prevailing conditions.

The formulations, i.e., the agents, preparations or compositions containing the active substance of the formula I and, if desired, a solid or liquid additive, are prepared in a known manner, for example by intimately mixing and/or grinding the active substances with extenders, for example with solvents, solid carriers, and, if desired, surface-active compounds (surfactants).

The following are suitable as solvents: aromatic hydrocarbons, preferably the fractions Cg to Cj2, for example xylene mixtures or substituted naphthalenes, phthalic esters, such as dibutyl phthalate or dioctyl phthalate, aliphatic hydrocarbons, such as cyclohexane or paraffins, alcohols and glycols as well as their ethers and esters, such as ethanol, ethylene glycol, ethylene glycol monomethyl ether or ethylene glycol monoethyl ether, ketones, such as cyclohexanone, strongly polar solvents, such as N-methyl-2-pyrrolidone, dimethyl sulfoxide or dimethylformamide, and epoxidized or unepoxidized vegetable oils, such as epoxidized coconut oil or soya oil; or water.

Examples of solid carriers which are generally used, for example for dusts and dispersible powders, are natural ground minerals, such as calcite, talc, kaolin, montmorillonite or attapulgite. To improve the physical properties, it is also possible to add highly-disperse silica or highly-disperse, absorptive polymers. Particulate, absorptive granule carriers are porous types, for example pumice, brick grit, sepiolite or bentonite, and examples of non-sorptive carrier materials are calcite or sand. Moreover, a large number of pregranulated materials of inorganic or organic nature, such as, in particular, dolomite or comminuted plant residues, can be used.

Suitable surface-active compounds are non-ionic, cationic and/or anionic surfactants - 13having good emulsifying, dispersing and wetting properties, depending on the nature of the active substance of the formula I to be formulated. Surfactants are also understood as meaning mixtures of surfactants.

Anionic surfactants which are suitable can be either so-called water-soluble soaps or water-soluble synthetic surface-active compounds.

Soaps which may be mentioned are the alkali metal salts, alkaline earth metal salts or substituted or unsubstituted ammonium salts of higher fatty acids (C10-C22), for example the Na or K salts of oleic or stearic acid, or of natural mixtures of fatty acids which can be obtained from, for example, coconut or tallow oil. Mention must also be made of the fatty acid methyl-taurinates.

However, so-called synthetic surfactants are used more frequently, in particular fatty sulfonates, fatty sulfates, sulfonated benzimidazole derivatives or alkylarylsulfonates.

The fatty sulfates or fatty sulfonates are usually in the form of alkali metal salts, alkaline earth metal salts or substituted or unsubstituted ammonium salts and have an alkyl radical having 8 to 22 C atoms, alkyl also including the alkyl moiety of acyl radicals, for example the Na or Ca salt of ligninsulfonic acid, of the dodecylsulfuric ester or of a fatty alcohol sulfate mixture prepared from natural fatty acids. This group also includes the salts of the sulfuric esters and sulfonic acids of fatty alcohol/ethylene oxide adducts. The sulfonated benzimidazole derivatives preferably contain 2 sulfonyl groups and a fatty acid radical having 8 to 22 C atoms. Examples of alkylarylsulfonates are the Na, Ca or triethanolamine salts of dodecylbenzenesulfonic acid, of dibutylnaphthalenesulfonic acid or of a naphthalenesulfonic acid/formaldehyde condensation product.

Other suitable compounds are appropriate phosphates, for example salts of the phosphoric ester of a p-nonylphenol/(4-14)-ethylene oxide adduct, or phospholipids.

Suitable non-ionic surfactants are mainly polyglycol ether derivatives of aliphatic or cycloaliphatic alcohols, saturated or unsaturated fatty acids and alkylphenols which can contain 3 to 10 glycol ether groups and 8 to 20 carbon atoms in the (aliphatic) hydrocarbon radical and 6 to 18 carbon atoms in the alkyl radical of the alkylphenols.

Other suitable non-ionic surfactants are the water-soluble polyethylene oxide adducts with - 14polypropylene glycol, ethylenediaminopolypropylene glycol and alkylpolypropylene glycol which have 1 to 10 carbon atoms in the alkyl chain and contain 20 to 250 ethylene glycol ether groups and 10 to 100 propylene glycol ether groups, the abovementioned compounds generally containing 1 to 5 ethylene glycol units per propylene glycol unit.

Examples of non-ionic surfactants which may be mentioned are nonylphenolpolyethoxyethanols, castor oil polyethylene glycol ether, polypropylene/polyethylene oxide adducts, tributylphenoxypolyethoxyethanol, polyethylene glycol and octylphenoxypolyethoxyethanol.

Other suitable substances are fatty acid esters of polyoxyethylene sorbitan, such as polyoxyethylene sorbitan trioleate.

The cationic surfactants are mainly quaternary ammonium salts which contain at least one alkyl radical having 8 to 22 C atoms as N-substituents and lower, halogenated or unhalogenated alkyl, benzyl or lower hydroxyalkyl radicals as further substituents. The salts are preferably in the form of halides, methylsulfates or ethylsulfates, for example stearyltrimethylammonium chloride or benzyldi(2-chloroethyl)-ethylammonium bromide.

The surfactants conventionally used in the art of formulation are described, inter alia, in the following publications: Me Cutcheon’s Detergents and Emulsifiers Annual MC Publishing Corp., Ridgewood, New Jersey, 1981; H. Stache, Tensid-Taschenbuch [Surfactants Guide], 2nd edition, C. Hanser Verlag, Munich, Vienna, 1981; M. and J. Ash. Encyclopedia of Surfactants, Vol. I-ΙΠ, Chemical Publishing Co., New York, 1980-1981.

As a rule, the agrochemical preparations contain 0.1 to 95 %, in particular 0.1 to 80 %, of active substance of the formula 1,1 to 99.9 % of a solid or liquid additive and 0 to 25 %, in particular 0.1 to 25 %, of a surfactant.

Preferred formulations have particularly the following compositions; (% = per cent by weight). - 15Emulsifiable concentrate: Active ingredient: Surface-active agent: Liquid carrier: Dusts: Active ingredient: Solid carrier: Suspension concentrates: Active ingredient: Water: Surface-active agent: Wettable powder: Active ingredient: Surface-active agent: Solid carrier: Granules: Active ingredient: Solid carrier: to 20 %, preferred: 5 to 10 % to 30 %, preferably 10 to 20 % 50 to 94 %, preferably 70 to 85 % 0.1 to 10 %, preferably 0.1 to 1 % 99.9 to 90 %, preferably 99.9 to 99 % to 75 %, preferably 10 to 50 % 94 to 24 %, preferably 88 to 30 % 1 to 40 %, preferably 2 to 30 % 0.5 to 90 %, preferably 1 to 80 % 0.5 to 20 %, preferably 1 to 15 % 5 to 99 %, preferably 15 to 90 % 0.5 to 30 %, preferably 3 to 15 % 99.5 to 70 %, preferably 97 to 85% While relatively concentrated agents are preferred as merchandise, the end user, as a rule, uses dilute agents. The use forms can be diluted down to 0.001 % of active substance. As a rule, the application rates are 0.01 to 10 kg of active compound/ha, preferably 0.025 to 5 kg of active compound/ha.

The agents can also contain other additives, such as stabilizers, defoamers, viscosity regulators, binders, tackifiers as well as fertilizers or other active substances for achieving specific effects.

Preparation Examples The following examples illustrate the preparation of some compounds according to this invention. - 16IE 903240 Example 1: Preparation of racemic 3-(3,5-bis-trifluoromethyl-phenyl)-5-carboxyl-oxazolidone-2-one.

To a solution of 24.7 g (0.075 mole) of 3-(3,5-bis-trifluoromethyl-phenyl)-5-hydroxymethyl-oxazolidine-2-one in 500 ml of acetone which is cooled down to 0°C, is added dropwise, while stirring, 62 ml of chromic anhydride/sulfonic acid mixture (3.25 mole C2O3 in 5.29 mol H2SO4). (The starting material was prepared according to the method described in Chimie therapeutique 1973 324-327 from 3,5-bis-trifluoromethylaniline and racemic glycidal). After the addition is completed, the reaction mixture is stirred for 14 hours at room temperature. To the green suspension thus obtained is then added, first 100 ml of isopropanol, then 11 of ethyl-ether and finally 11 of saturated salt solution. After all the chrome salts have dissolved, the organic layer is separated and the aqueous layer extracted with ether. The organic phase is dried over magnesium-sulfate and concentrated in a rotatory evaporator. The residue crystallized to give 25.86 g of a tan-coloured substance which, after recrystallisation from ether/petrolether leaves 19.42 g of title-product in the form of white crystals which have a melting point at 165-169°C.

Example 2: Preparation of racemic 3-(3,5-bis-trifluoromethyl)-5-methoxycarbonyl-oxazolidine-2-one - 17IE 903240 A mixture consisting of 52.2 g (0.152 mole) of 3-(3,5-bis-trifluoromethylphenyl)-5-carboxyl-oxazolidine-2-one (example 1) and 77.8 g of ®Amberlyst-resin (20 to 50 mesh, strongly acid) and 60 ml of absolute methanol is heated under reflux for two hours and then left standing overnight. The resin is then filtered off and the filtrate concentrated in a rotatory evaporator. The brown oily residue is taken up in ethyl-ether, washed neutral with sodium-bicarbonate solution and then with water, died over magnesium-sulfate and evaporated to dryness.

In this manner, one isolates 50.9 g of crude 3-(3,5-difluoromethyl-phenyl)-5-methoxy-carbonyl-oxazolidine-2-one as an orange-coloured oil. This is dissolved in methylene-chloride and mixed with silicium-oxide. After filtering off the silicic acid, the solution is evaporated to dryness and the residue is taken up in petrol ether and well triturated. The crystals which have formed are filtered off and dried under vacuo at 40°C. In thus manner 45.9 g (84,5 % of the theorie) of methyl ester is obtained in the form of white crystals, which melt at 71-74°C.

In an analogous manner, the compounds of Table 1 are prepared.

A Rn - 18IE 903240 Table 1: Compound No. A Rn 1.01 (R)-COOCH3 3,5 (CF3)2 1.02 ± -cooch3 3,5 (CF3)2 1.03 (S)-COOCH3 3,5 (CF3)2 1.04 (R)-COOH 3,5 (CF3)2 1.05 (S)-COOH 3,5 (CF3)2 1.06 ± -COOH 3,5 (CF3)2 1.07 (R)-COOCH2CH3 3,5 Cl2 1.08 (S)-COOCH2CH3 3,5 Cl2 1.09 ± -COOCH2CH3 3,5 Cl2 1.10 (R)-COO-CH-CH3 ch3 3,5 F2 1.11 (S)-COO-CH-CH3 ch3 3,5 F2 1.12 ± -coo-ch-ch3 ch3 3,5 F2 1.13 (R)-COO-CH2CH2CH2CH3 3,5 Br2 1.14 (S)-COO-CH2CH2CH2CH3 3,5 Br2 1.15 ± -COO-CH2CH2CH2CH3 3,5 Br2 1.16 (R)-COO-tert.-C4H9 3,5 (CF3)2 1.17 (S)-COO-tert.-C4H9 3,5 (CF3)2 1.18 ± -COO-tert.-C4H9 3,5 (CF3)2 1.19 (R)-COOCH2-CH=CH2 3-C1 1.20 (S)-COOCH2-CH=CH2 3-C1 1.21 ± -COOCH2-CH=CH2 3-C1 1.22 (R)-COOCH2-ChCH 3,5 (CF3)2 phys. data mp. 86° mp. 71-74° mp. 165 - 169 mp. 137 - 139 - 19IE 903240 Table 1: Continuation Compound No. A Rn 1.23 (S)-COOCH2-C^CH 3,5 (CF3)2 1.24 ± -COOCH2-C=CH2 3,5 (CF3)2 1.25 (R)-COOCH2-CH=CH ch3 3,5 I2 1.26 (S)-COOCH2-CH=CH ch3 3,5 I2 1.27 ± -cooch2-ch=ch z 1 ch3 3,5 I2 1.28 (R)-COOCH2-C=C-CH3 3-F 1.29 (S)-COOCH2-C=C-CH3 3-F 1.30 ±-cooch2-c=c-ch3 3-F 1.31 (R)-COCl 3,5 (CF3)2 1.32 (S)-COCl 3,5 (CF3)2 1.33 ± -COCI 3,5 (CF3)2 1.34 (R)-COSCH3 3,5 (CF3)2 1.35 (S)-COSCH3 3,5 (CF3)2 1.36 ± -cosch3 3,5 (CF3)2 1.37 (R)-COS-n-C4H9 2, 3, 5 F3 1.38 (S)-COS-n-C4H9 2, 3, 5 F3 1.39 ± -COS-n-C4H9zCH3 2, 3, 5 F3 1.40 (R)-CON CH3 /Ch3 3,5 Cl2 1.41 (S)-CON xch3 /CH3 3,5 Cl2 1.42 ± -CON XCH3 3, 5 Cl2 1.43 (R)-COO®Na® 3, 5 (CF3)2 1.44 (S)-COO®Na® 3, 5 (CF3)2 1.45 ± -COO®Na® 3, 5 (CF3)2 1.46 [(R)-COO®]2®Ca2® 3,5F2 1.47 [(S)-COO®]2®Ca2® 3,5F2 phys. data oil mp. 54 - 56° mp. 105° dec. -20Table 1: Continuation Compound No. A Rn 1.48 ± -COO®] 2® Ca2® 3, 5 F2 1.49 (R) -COO®®NH(C4H9)3 3, 5 Cl2 1.50 (S) -COO®®NH(C4H9)3 3, 5 Cl2 1.51 ± -COO®®NH(C4H9)3 3,5 Cl2 1.52 (R) -COO®®NH4 3, 5 (CC13)2 1.53 (S) -coo®®nh4 3,5(CC13)2 1.54 ± -coo®®nh4 3, 5 (CC13)2 1.55(R)-CO-N^ 2 ch3 3-Br 1.56 (S) -CO-- ch3 + / \ 3-Br 1.57 ± -CO —N ) P ch3 3-Br 1.58 (R)-CO-NH 4-CF3 1.59 (S)-CO-NH 4-CF3 1.60± -CO-NH 4-CF3 1.61 ± -COS-n-C4H9 3,5(CF3)2 1.62 ± -COOCH2CH=CH2 3,5(CF3)2 1.63 ± -COO®H®N(n-C4H9)3 3, 5 (CF3)2 1.64 + -CO-NH 3-Br oil oil mp. 65 - 72° mp. 132-134 phys. data Formulation Examples: Example Fl: Formulation examples of active substances of the formula I (% = per cent by weight) a) Wettable powders a) b) c) Active substance from Table 1 20% 50% 0.5 % Na ligninsulfonate 5% 5% 5% Na lauryl sulfate 3% 5% 5% Na diisobutylnaphthalenesulfonate - 6% 6% Octylphenol polyethylene glycol ether (7-8 mol of EO) - 2% 2% Highly disperse silica 5% 27 % 27 % Kaolin 67 % 10% - Sodium chloride . . 59.5 % The active substance is thoroughly mixed with the additives, and the mixture is ground thoroughly in a suitable mill. This gives wettable powders which can be diluted with water -22to give suspensions of any desired concentration. b) Emulsion concentrate a) b) Active substance from Table 1 10 % 1 % Octylphenol polyethylene glycol ether (4-5 mol of EO) 3 % 3 % Ca dodecylbenzenesulfonate 3 % 3 % Castor oil polyglycol ether (36 mol of EO) 4% 4% Cyclohexanone 30 % 10 % Xylene mixture 50 % 79 % Emulsions of any desired concentration can be prepared from this concentrate by dilution with water. c) Dusts a) b) Active substance from Table 1 0.1 % 1 % Talc 99.9 % Kaolin - 99 % Ready-to-use dusts are obtained by mixing the active substance with the carrier and grinding the mixture on a suitable mill. d) Extruder granules a) b) Active substance from Table 1 10 % 1 % Na ligninsulfonate 2 % 2 % Carboxymethylcellulose 1 % 1 % Kaolin 87 % 96 % The active substance is mixed with the additives, and the mixture is ground and moistened with water. This mixture is extruded and then dried in a stream of air. e) Coated granules Active substance from Table 1 Polyethylene glycol (MW 200) Kaolin 3% 3 % 94% -23The kaolin is moistened with polyethylene glycol and uniformly coated in a mixer with the finely ground active substance. In this manner, dust-free coated granules are obtained. f) Suspension concentrate a) b) Active substance from Table 1 40% 5% Ethylene glycol 10% 10% Nonylphenol polyethylene glycol ether (15 mol of EO) 6% 1 % Na ligninsulfonate 10% 5 % Carboxymethylcellulose 1 % 1 % 37 % aqueous formaldehyde solution 0.2% 0.2% Silicone oil in the form of a 75 % aqueous emulsion 0.8 % 0.8 % Water 32 % 77 % The finely-ground active substance is mixed intimately with the additives. In this manner, a suspension concentrate is obtained from which suspensions of any desired concentration can be prepared by dilution with water. g) Salt solution Active substance from Table 1 5 % Isopropylamine 1 % Octylphenol polyethylene glycol ether (78 mol of EO) 3 % Water 91 % Biological examples The following examples illustrate the activity of some compounds according to this invention in plant-regulatory tests.

Example Β1: Inhibition of growth in tropical leguminous cover crops The plants (for example Centrosema pubescens or Psophocarpus palustris) are propagated by cuttings in 4 cm peat pots with field soil (45 %), peat (45 %) and zonolite (10 %). They are grown in the greenhouse at a day temperature of 27°C and a night temperature of 23°C. The plants are illuminated for at least 14 hours/day at an intensity of at least 7000 -24lux.

About 50 days after planting the cuttings, they are repotted in 13 cm pots, 4-5 plants/pot. After a further 60 days, the plants are cut back to a height of about 15 cm, and subjected to the application treatment. In this treatment, they are sprayed with 0.3 to 3 kg of active substance/ha (formulated, as a rule, as a 25 % concentration) in an aqueous spray liquor. The amount of water applied is about 2001/ha.

The experiment is evaluated 4 weeks after the application. In this evaluation, the additional growth is scored and weighed in comparison with the control, and the phytotoxicity is rated. In this experiment, the plants treated with the active substances from Table 1 show a marked reduction of additional growth without inflicting damage on the experimental plants.

Example B2: Growth regulation in soya beans The plants (for example cultivar Williams) are sown in 11 cm clay pots with field soil (45 %), peat (45 %) and zonolite (10 %), and grown in a growth cabinet at a day temperature of 24°C and a night temperature of 19°C. The plants are illuminated for a period of 16 hours per day at an intensity of about 2900 lux.

About 24 days after sowing, repotting into 18 cm pots is effected, 2 plants per pot. After a further 12 days and in the stage where 5-6 trifoliate leaves have appeared, up to 100 g of active substance/ha is applied to the plants, the formulation being, as a rule, 25 % concentration and in aqueous spray liquor. The amount of water applied is about 200 1/ha.

The experiment is evaluated about 4 weeks after the application. In comparison with the untreated control plants, the active substances from Table 1 that were tested, result in a markedly reduced growth without phytotoxicity.

Example B3: Selective growth inhibition of oil seed rape and clover in maize The compounds of Table 1 are highly suitable for selectively and strongly inhibiting cover crops in a maize crop and therefore preventing the undersown crop from competing for water and nutrients, while simultaneously maintaining the agronomically desired effects of the undersown crop, such as protection from erosion, nitrogen fixation and reduction of soil compaction. This is tested for the crop combinations maize/white clover and maize/oil seed rape, as follows: -25 Blizzard maize is sown in 15 cm pots with field soil and grown for 15 days in the greenhouse at day/night temperatures of 22/19°C and an illumination period of at least 13.5 hours/day in the case of post-emergence application, pre-emergence application being carried out one day after sowing.

Bienvenue oil seed rape is sown in 15 cm pots with field soil, and grown for 7 days at day/night temperatures of 22/19°C, then for 17 days at 10/5°C and then for 7 days at 15/10°C until the application was effected.

Ladino white clover is grown in 15 cm pots with a mixture of field soil (60 %), peat substrate (30 %) and zonolite (10 %) for 40 days at day/night temperatures of 21/18°C and a minimum illumination period of 13.5 hours.

All crops are fed and watered as required, the compound No. 1.01 (formulated in a 25 % concentration) is applied in 2001 of water/ha and at application rates of 30 to 500 g/ha. 28 days after application, the height of the additional growth is measured, and the action is represented in per cent growth inhibition in comparison with the untreated control. 100 % action denotes no additional growth at all, 0 % action denotes growth as in the untreated control.

The compounds of Table 1 that were tested showed in this test good growth-inhibitory activity in clover and rape, while the growth of the maize plants was not inhibited.

Example B4: Selctive growth inhibition of weeds in culture plants The compounds of Table 1 are also highly suitable for inhibiting selectively and strongly weeds in cultures of crop plants and therefore preventing the competitive growth of weeds, without destroying them completely. This is tested as shown below with the crop plants barley, wheat and maize and the weeds Ipomoea purpurea, Solanum nigrum, Xanthium strumarium, Chenopodium album, Galium aparine, Veronica persica and Chrysanthemum leucanthemum.

The above crop plants and weeds are grown in the greenhouse and when they had reached the 4- to 6-leaf stage, they were treated with an aqueous suspension of an active compound of Table 1. The treated plants are then cultivated further in the greenhouse. The test is evaluated 15 days after the treatment and the growth inhibition is given in percent (see -26Table 2) O= no growth inhibition, 100 % = complete stop of the growth after the treatment. As an example, the results obtained with compound 1.02 (of Table 1) are given in the Table 2 below Table 2: plants Growth-inhibition at active substance/ha 1000 60 125 250 500 barley 0 0 0 0 10 wheat 0 0 0 0 0 maize 0 0 0 0 0 Jpomoea 10 60 70 90 90 Solanum 0 40 70 80 80 Xanthium 10 40 80 80 90 Chenopodium 0 20 30 70 70 Galium 10 20 70 90 100 Chrysanthemum 40 60 80 90 90 Veronica 30 50 60 80 90

Claims (18)

Claims

1. A 3-phenyl-oxazolidine-2-one and -2-thione-5-carboxylic acid derivative in all its stereoisometric forms of the formula I wherein X is oxygen or sulfur A is -COORj, -COSR 2 , -COO®M®, CONR 3 R 4 or COCI, R is hydrogen, halogen, mono-, di- or trihalomethyl n is 0,1,2 or 3 Rj is hydrogen,Cp^ alkyl, C 2 -Cg alkenyl or C 2 -C 6 alkynyl R 2 and R 3 independently of one another are hydrogen, CpC 4 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl or C 3 -C 3 cylcloalkyl aryl or heterocyclyl R 2 and R 3 together with the nitrogen atom, to which they are bonded, are a saturated 3- to 2. ,4-bis-(4-methoxyphenyl)-l,3-dithio-2,4-diphosphethane-2,4-disulfide (Lawesson’s reagent) or with another reagent capable of introducing the thioxo groups.

2. An optically active compound according to claim 1 of the formula (R)-I and (S)-l wherein A, n, R and X have the meaning given in claim 1.

3. A compound of the formula I according to claim 1 wherein A is -COORj or -28-COO®M®, R is halogen or trifluoromethyl, n is 1 or 2 and Ri and M® have the meaning given in claim 1.

4. A 3-phenyI-oxazolidine-2-one-5- cabonic acid-derivative according to claim 1 in all its stereoisometric forms, of the formula lb Rn wherein A, n and R have the meaning given in claim 1.

5. A 3-phenyl-oxazolidine-2-thione-5-carboxylic acid derivative according to claim 1 in all its stereoisometric forms of the formula Ie (Ie) Rn wherein A, n and R have the meaning given in claim 1.

6. A 3-phenyl-oxazolidine-2-one according to claim 1 selected from the group consisting of 3-(3,5-bis-trifluoromethylphenyl)-oxazolidine-2-one-5- carboxylic acid, 3-(3,5-bis-trifluoromethylphenyl)-oxazolidine-2-one-5-carboxylic acid-methyl ester, 5-(R)-3-(3,5-bistrifluoromethylphenyl)-oxazolidine-2-one-carboxylic acid, 5-(R)-3-(3,5-bis-trifluoromethylphenyl)-oxazolidine-5-carboxylic acid-methyl ester, 5-(S)-3-(3,5-bis-trifluoromethylphenyl)-oxazolidine-5-carboxylic acid, 5-(S)-3-bis-trifluoromethylphenyl)-oxazolidine-5-carboxylic acid-methyl ester and 5-(3,5-bis-trifluoromethylphenyl)-oxazolidiΙΕ 903240 -29ne-5-carboxylic acid-tributylammonium salt. Ί. A process for preparing a 3-phenyl-oxazolidine-2-one or 3-phenyl-oxazolidine-2-thione of formula I, according to claim 1, which comprises reacting an aniline of formula II, NH 2 (Π) wherein n and R have the meaning given in claim 1, with a racemic glycidol ((±)2,3-epoxy- 1-propanol) of formula III, ch 2 Xh-ch 2 -oh ( ΠΙ ) to the 1,2-propanediolanilide of the formula IV, OH (IV) wherein n and R have meaning given in claim 1, and then cyclysing this diol in an appropriate solvent, in the presence of a base, with diethylcarbonate to form a 3-phenyl-5-hydroxymethyloxazolidine of the formula V, (V) wherein n and R have the meaning given in claim 1, and oxydizing this compound by means of an oxydizing agent to form a 3-phenyl-oxazolidone-2-one-5-carboxylic acid of the formula la wherein n and R have the meaning given in claim 1, and if desired transforming this acid in a manner known per se to a salt or by reacting it with a compound of the formula VI H-B (VI) wherein B is radical of an alcohol, a mercaptan or of an amine, to form an ester, thioester or amide of the formula lb -31 wherein A, n and R have the meaning given in claim 1.

7. - membered heterocycle, which can contain an additional hetero atom, selected from the group comprising Ο, N and S and which is unsubstituted or up to trisubstituted by Cp^ alkyl, and M® is the equivalent of an alkaline earth metal cation or HN®(R 2 ) 3 .

8. A process for the preparation of a 3-phenyl-oxazolidine-2-thione-5-caboxylic acid according to claim 1 of the formula Id, wherein n and R have the meaning given in claim 1 A' is -COOR! and R! is Ομο C 4 alkyl, which is characterised in treating a 3-phenyl-oxazolidine-2-one of the formula Ic wherein A', n and R have the meaning given above with

9. A process for the preparation of a 3-phenyl-oxazolidine-2-thione-5-carboxylic acid derivative according to claim 1 of the formula Ie, Rn (Ie) wherein A, n and R have the meaning given in claim 1, which comprises saponifying a racemic or optically active 3-phenyl-oxazolidine-2-thione of the formula Id, Rn wherein n and R have the meaning given in claim 1, A' is COOR! and Ri is C!-C 4 alkyl in a manner known per se, into free acid and transforming the free acid in a manner known per se into with a compound of the formula VI H-B (VI) wherein B is the radical of an alcohol, a mercaptan or an amine, to form an ester thioester or an amide of the formula Ie.

10. A composition for regulating plant growth, containing besides inert carriers and adjuvants, as active component, a plant-growth regulatory effective amount of a 3-phenyl-oxazolidine-2-one or -2-thione of the formula I, according to claim 1.

11. A composition according to claim 10, which contains between 0.1 % and 95% of an active compound of the formul I according to claim 1.

12. A process for inhibiting plant-growth, which comprises applying to the plants or their -33enviroment, a plant-growth-inhibitingly effective amount of a compound of· the formula I according to claim 1 or of a composition containing such a compound.

13. A process according to claim 12, which comprises applying an amount of active substance according to claim 1 of between 0.01 and 10 kg per hectare.

14. A 3-phenyl-oxazolidine -2-one or -2-thione-5-carboxylic acid derivative in all its stereoisometric forms of the formula (1) given and defined in Claim 1, substantially as hereinbefore described and exemplified.

15. A process for preparing a 3-phenyl-oxazolidine -2-one or -2-thione-5-carboxylic acid derivative in all its stereoisometric forms of the formula (1) given and defined in Claim 1, substantially as hereinbefore described and exemplified

16. A 3-phenyl-oxazolidine -2-one or -2-thione-5-carboxylic acid derivative in all its stereoisometric forms of the formula (1) given and defined in Claim 1, whenever prepared by a process claimed in any one of claims 7-9 or 15.

17. A composition according to claim 11, substantially as hereinbefore described and exemplified.

18. A process according to claim 12 for inhibiting plantgrowth, substantially as hereinbefore described.