FR2660158A1 - Use, as herbicides, of 5,6-dihydro-2-methyl 4-phenyl-2H-1,2,4-oxadiazin-3(4H)-one derivatives, new derivatives thereof, process for preparing them and the intermediates in this process - Google Patents

Abstract

The subject of the invention is the use, as herbicides, of the products of formula (I): in which R represents an alkyl radical containing 1 to 4 carbon atoms and Z an oxygen or sulphur atom, the products corresponding to the formula (II): in which R has the meaning indicated above, the process for preparing them and the intermediates in this process.

Description

 The present invention relates to the use as herbicides of 5,6-dihydro-2-methyl-4-phenyl-2H-1,2,4-oxadiazin-3 (4H) -one derivatives.

dans laquelle R représente un radical alkyle renfermant de un à quatre atomes de carbone et Z un atome d'oxygène ou de soufre.The subject of the invention is the use as herbicides of the products of formula (I)

in which R represents an alkyl radical containing from one to four carbon atoms and Z represents an oxygen or sulfur atom.

 By alkyl radical containing from one to four carbon atoms is meant linear or branched alkyl radical in all its stereoisomeric forms such as methyl, ethyl, propyl, butyl, isopropyl, isobutyl, sec-butyl (R) or (S) or tert-butyl.

 The subject of the invention is in particular the use as herbicides of the products of formula (I) as defined above, the names of which follow - 5,6-dihydro-2-methyl-4- (4- (methylthio) -3- (trifluoromethyl) ) phenyl] 2H-1,2,4-oxadiazin-3 (4H) -one - 5,6-dihydro-4- (4- (isopropylthio) -3- (trifluoromethyl) phenyl] 2-methyl-2H-1,2, 4-oxadiazin-3 (4H) -one - 5,6-dihydro 4- [4- (propylthio) -3- (trifluoromethyl) phenyl] -2-methyl-2H-1,2,4-oxadiazin-3 (4H) - one - 4- [4- (butylthio) -3- (trifluoromethyl) phenyl] 5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one - 5,6-dihydro 4 - [4-Methoxy-3- (trifluoromethyl) phenyl] -2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one - 5,6-dihydro-4- (4-isopropoxy-3- (trifluoromethyl) phenyl] 2 2-methyl-1,2,4-oxadiazin-3 (4H) -one - 4- (4-tert-butoxy-3- (trifluoromethyl) phenyl] -5,6-dihydro-2-methyl-1,2,4-methyl -oxadiazin-3 (4H) -one - 4- [4-E (S) -sec-butoxy] -3- (trifluoromethyl) phenyl] -5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 ( 4H) -one.

 The products of formula (I) as defined above and in which Z represents a sulfur atom are generally known and their preparation is described in French Patent 2327788.

 The products of formula (I) as defined above and in which Z represents an oxygen atom are new.

dans laquelle R a la signification indiquée ci-dessus, principalement ceux dont les noms suivent - le 5,6-dihydro 4-[4-méthoxy 3-(trifluorométhyl) phényl] 2méthyl 2H-1,2,4-oxadiazin-3(4H)-one - le 5,6-dihydro 4-(4-isopropoxy 3-(trifluorométhyl) phényl] 2-méthyl 2H-1,2,4-oxadiazin-3(4H)-one - le 4-(4-tert-butoxy 3-(trifluorométhyl) phényl] 5,6-dihydro 2-méthyl 2H-1,2,4-oxadiazin-3(4H)-one - le 4-[4-t(S)-sec-butoxy] 3-(trifluorométhyl) phényl] 5,6dihydro 2-méthyl 2H-1,2,4-oxadiazin-3(4H)-one et leur procédé de préparation caractérisé en ce que les isocyanates de formule (III)

dans laquelle R a la signification décrite précédemment, sont soumis à l'action d'un sel de N-(méthyl) hydroxylamine de formule (IV) :
CH3-NH-OH (IV) pour donner les produits de formule (V)

qui, traités par un 1,2-dihalo éthane en milieu basique et de préférence dans un solvant polaire conduisent aux produits de formule (II). The subject of the invention is therefore also the products of formula (I) as defined above corresponding to formula (II)

in which R has the meaning indicated above, principally those whose names follow - 5,6-dihydro 4- [4-methoxy-3- (trifluoromethyl) phenyl] -2-methyl-1,2,4-oxadiazin-3 ( 4H) -one - 5,6-dihydro 4- (4-isopropoxy-3- (trifluoromethyl) phenyl] -2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one - 4- (4- tert-butoxy-3- (trifluoromethyl) phenyl] -5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one - 4- [4- (S) -sec-butoxy] 3- (trifluoromethyl) phenyl] 5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one and process for their preparation, characterized in that the isocyanates of formula (III)

in which R has the meaning previously described, are subjected to the action of an N- (methyl) hydroxylamine salt of formula (IV):
CH 3 -NH-OH (IV) to give the products of formula (V)

which, treated with a 1,2-dihalo ethane in a basic medium and preferably in a polar solvent lead to the products of formula (II).

 The formation reaction of the products of formula (V) is preferably carried out in a solvent such as dimethylformamide in the presence of a nitrogenous base such as triethylamine or dimethylaminopyridine.

 The 1,2-dihaloethane used in the cyclization reaction leading to the products of formula (II) may be 1,2-dichloroethane or 1,2-dibromoethane. The polar solvent preferentially chosen is dimethylsulfoxide.

The isocyanates of formula (III) are known and their preparation is described in
Kogyo Kagaku Zasshi 70 (4), 491-4 (1967) and
Kogyo Kagaku Zasshi 69 (11), 2229 (1969).

est soumis à un réactif de O-alkylation des phénols pour conduire aux produits de formule (II) et à titre de produits industriels nouveaux les produits de formules (V) et (VI) telles que définies ci-dessus.The subject of the invention is also a variant of the process for the preparation of the products of formula (II) as described above, characterized in that the product of formula (VI)

is subjected to an O-alkylation reagent of phenols to give the products of formula (II) and as new industrial products the products of formulas (V) and (VI) as defined above.

dont la préparation est décrite dans Justus Liebieg Annalen 597 (1955) p. 235. Le produit de formule (VI) est préparé comme indiqué aux stades A à D de l'exemple 2.By O-alkylation reagent of phenols is meant reagents which allow the conversion of phenols to the corresponding (alkyloxy) benzenes such as alkyl halides, alkyl aryl or alkylsulfonates or else 2- (tert-butyl) 1 3-diisopropyl isourea of formula

whose preparation is described in Justus Liebieg Annalen 597 (1955) p. 235. The product of formula (VI) is prepared as indicated in Steps A to D of Example 2.

 The products of formula (I) in which Z represents a sulfur atom have been described and claimed in French Patent 2,327,788 as local anti-androgens.

 The applicant surprisingly discovered that they possessed herbicidal properties and that this was also the case for their oxygenated counterparts.

 This new characteristic of the products of formula (I) has been demonstrated according to a methodology described below. The results clearly show the interest for their use either as a total weed killer or as a selective weed killer in the pre- or post-emergence period. These products can be used as selective herbicides in cereal crops such as wheat, barley, oats, rye or maize, or in rice, soybean, cotton or sunflower crops.

 The present invention finally relates to herbicidal compositions characterized in that they contain as active ingredient, at least one of the products of formula (I) as defined above.

 The compositions according to the invention can be prepared by mixing the active ingredient with an inert filler, and thus be easily applicable by means of usual apparatus.

 It is thus possible to prepare solid compositions in powder form by grinding the active material with finely divided inert fillers such as talcs and clays, bentonite, pumice stone, fulling earth, pyrophillite, silicates, kieselguhr and other solid inert materials customarily used or by impregnating a solid support with a solution of the active ingredient followed by evaporation of the solvent.

 These solid compositions may thus be in the form of dusting powder, wettable powder or granules. The compositions according to the invention may also be in the form of a suspension, an emulsion or a solution, by mixing the active ingredient with a liquid carrier and / or anionic, cationic or nonionic surfactant, further ensuring uniform dispersion. substances of compositions.

 The liquid vehicle may be water, alcohol, hydrocarbons or other organic solvents such as aromatic or ketonic solvents. The proportion of solvent varies from 1 to 90% depending on the solubility of the active ingredient.

 The examples and the biological study described below illustrate the invention without however limiting it.

EXAMPLE 1: 5,6-Dihydro-4-t-4-methoxy-3- (trifluoromethyl) phenyl) -2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one
STAGE A: N-hydroxy N '- (4-methoxy-3- (trifluoromethyl) phenyl]
N-methyl urea
5.85 g of N-methylhydroxylamine hydrochloride are mixed with 70 cm 3 of dimethylformamide; after the slow addition of 9.75 cc of triethylamine, the triethylamine hydrochloride is stirred for 15 minutes at room temperature and 10.85 g of 4-methoxy-3- (trifluoromethyl) phenyl isocyanate are added (obtained according to Kogyo Kagaku Zasshi). 70 (4), 491-4 (1967) and 69 (11), 2229 (1969)), 30 cm3 of dimethylformamide and left for 4 hours at room temperature.

The reaction mixture is then poured into water after wringing and drying to give 10 g of the desired product. Rf = 0.12 (thin layer chromatography, silica support, eluent: hexane-ethyl acetate (1-1)).
STAGE B: 5,6-Dihydro 4- (4-Methoxy-3- (trifluoromethyl) phenyl] -2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one
5 g of the product obtained in Stage A are dissolved in 50 cm3 of dimethylsulfoxide with 25 grams of potassium carbonate; the mixture is stirred under nitrogen and 4 cm3 of 1,2-dichloroethane are added in 5 minutes at room temperature and stirring is continued for 16 hours at this temperature.

The solution is then poured on 100 cm3 of water. After extraction with ethyl acetate, drying over sodium sulfate, filtration and evaporation of the solvent, 6 g of an oil are collected which, after chromatography on silica eluting with hexane-ethyl acetate (1- 1), gives 3.2 g of the desired product in the form of crystals. PF = 98 ° C;
Rf = 0.16 (eluent: hexane-ethyl acetate (1-1)).

Microanalysis: C12H13F3N2O3 = 290.44
CHFN% calculated 49.66 4.51 19.64 9.65% found 49.7 4.6 19.6 9.5 EXTENT 2: 5,6-Dihydro 4- (4-isopropyl 3- (trifluoromethyl) phenyl) ) 2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one
STAGE A: 4- (benzyloxy) 3- (trifluoromethyl) phenyl isocyanate
45 cm3 of trichloromethyl chloroformate are added to a solution of 148 g of 4- (benzyloxy) 3 (trifluoromethyl) aniline hydrochloride (prepared according to CA 078-042982) in 450 cm3 of dioxane 1-4 with stirring and under a nitrogen atmosphere. nitrogen.

After heating for 17 hours at 50 ° -55 ° C., the mixture is brought to dryness and the desired isocyanate, used as for the following stage, is thus obtained.

STAGE B: N '- [4- (benzyloxy) 3- (trifluoromethyl) phenyl] N-hydroxy N-methyl urea
58 g of N-methylhydroxylamine hydrochloride are mixed with 580 cm.sup.3 of dimethylformamide, the solution is stirred under nitrogen and cooled to 0.degree. C. for the introduction over approximately 15 minutes of 70.8 g of triethylamine.

 After stirring for 1 hour at 20 ° C., the precipitate obtained is filtered off and the filtrate collected is cooled to 0 ° C., stirred under nitrogen and a solution of 143 g of isocyanate obtained in stage A in 600 cm 3 of dimethylformamide is added thereto. .

Stirring is continued for 17 hours at 20 ° C. and the solution is then poured into water and extracted with isopropyl ether.

After drying over magnesium sulphate and evaporation of the solvent, 169 g of the desired urea are obtained. Rf = 0.28 (eluent: methylene chloride-tetrahydrofuran (9-1)).

Infra red spectrum (CHCl 3 in cm 1) 1536: secondary amide 1669, 1690: C = O 1624, 1604, 1508: aromatic nuclei 3424: = C-NH3534: -OH
STAGE C: 4- [4- (benzyloxy) -3- (trifluoromethyl) phenyl] 5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one.

 3.40 g of the product prepared in Stage B are dissolved in 10 cm3 of dimethylsulfoxide. After adding 6.9 g of potassium carbonate and then 3 g of 1,2-dichloroethane, the mixture is stirred under nitrogen overnight, poured into water, extracted with isopropyl ether, dried and concentrated. An oil is obtained which is chromatographed on silica eluting with toluene-ethyl acetate (9-1) to yield 2.3 g of the desired product.

Microanalysis: C18H17F3N2O3 = 366.34
CHFN% calculated 59.01 4.67 15.55 7.64% found 58.9 4.7 15.7 7.4
STAGE D: 4- (4-hydroxy-3- (trifluoromethyl) phenyl] 5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one
64.6 g of the product prepared in Stage C are mixed with 800 cm 3 of methanol and subjected to hydrogenation in the presence of 6 g of 50% palladium-on-charcoal hydroxide.

 After absorption of 3.9 liters of hydrogen, the catalyst is filtered and the filtrate brought to dryness. After recrystallization of the dry extract in 100 cm3 of hot methanol, 40.2 g of the desired product are obtained. Rf = 0.2 (eluent: methylene chloride-tetrahydrofuran (95-5)).

Microanalysis: C11H11F3N2O3 = 276.217
CHFN% calculated 47.83 4.01 20.63 10.14% found 47.7 4.1 20.5 10.00
STAGE E: 5,6-Dihydro 4- (4-Isopropoxy-3- (trifluoromethyl) phenyl] -2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one
3 g of the product prepared in Stage D are mixed under nitrogen and at ambient temperature, with 50 cm 3 of acetone, 3 g of potassium carbonate and 2.5 cm 3 of isopropyl iodide.

 After refluxing for 17 hours, the solution is cooled to 20 ° C., poured into water and extracted with methylene chloride.

 The organic phase is washed, dried over magnesium sulfate and filtered; the filtrate is brought to dryness and purified by chromatography eluting with methylene chloride-ethyl acetate (95-5). Thus collected 3.40 g of the desired product.

Rf = 0.4 (eluent: methylene chloride-ethyl acetate (955)).

Microanalysis: C14H17F3N2 3 = 318.297
CHFN% calculated 52.83 5.38 17.91 8.8% found 52.5 5.3 18.1 8.8
EXAMPLE 3: I-14-I (R) -sec-butolyl) 1- (trifluoromethyl) phenyl] -5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one
372 mg of 50% sodium hydride in the oil are added in a 0 C solution of 2.05 g of the product obtained in Step D of Example 2 in 20 cm3 of dimethylformamide.

 After 0.5 hour of stirring, a solution of 1.7 g of (S) -2- (tosyloxy) butane in 10 cm3 of dimethylformamide is poured. The mixture is stirred for 18 hours at room temperature, poured into 100 cm3 of water and then acidified with 6 cm3 of 2N hydrochloric acid and extracted with isopropyl ether.

 The organic phase is washed, dried, filtered and evaporated and the residue obtained is chromatographed on a column eluting with methylene chloride-hexane (9-1). 1.3 g of the desired product are thus collected.

Rf = 0.13 (eluent: methylene chloride-hexane (90-10)).

talpha] D = -23 + 2 (C = 0.5 in CHCl3)
Microanalysis: C15H19F3N2O3 = 332.33
CHFN% calculated 54.21 5.76 17.15 8.43% found 54.2 5.9 17.2 8.4
EXAMPLES 4: 4- [4 - [(S) -sec-butoxy] -3- (trifluoromethyl) phenyl] -5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one.

 Operating in the same manner as in Example 14 from 360 mg of sodium hydride, 1.98 g of the product obtained in Step D of Example 2 and 1.63 g of (R) -2 - (tosyloxy) butane, 1.63 g of the desired product is obtained.

Rf = 0.1 (eluent: methylene chloride).

(alpha) = +22 + 2 (C = 0.5 in CHCl3)
Microanalysis: C15H19F3N2O3 = 332.33
CHFN% calculated 54.2 5.76 17.15 8.4% found 54.2 5.8 17.1 8.2
EXAMPLE 5 4- (4-tert-butoxy-3- (trifluoromethyl) phenyl) -5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one
1.6 g of the product prepared in Stage D of Example 2 are mixed with 60 cm 3 of ethyl acetate; 11 g of 2- (tert-butyl) -1,3-diisopropyl is then added and stirred for 17 hours at room temperature, the precipitate filtered and washed with ethyl acetate. The filtrate is brought to dryness and chromatographed on silica eluting with a mixture of methylene chloride and isopropyl ether (95-5). 1.68 g of the desired product are thus collected.

Rf = 0.5 (eluent: methylene chloride - ethyl acetate (95-5)).

Microanalysis: C15H19F3N2 3 = 332.324
CHFN% calculated 54.21 5.76 17.15 8.43% found 54.1 5.8 16.85 8.4
Using the method described in French Patent No. 2,327,788, the following products were prepared in this way:
Preparation 1 - 4- [4- (sec-butylthio) -3- (trifluoromethyl) phenyl] -2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one. Rf = 0.35 (eluent: methylene chloride-isopropanol (95-5))
Preparation 2 - 5,6-Dihydro 4- [4- (isopropylthio) -3- (trifluoromethyl) phenyl] -2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one, mp = 78 ° C.

Preparation 3 - 4- (4- (butylthio) 3- (trifluoromethyl) phenyl] 5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one, mp = 68 ° C.

Preparation 4 4- (4- (tert-Butylthio) 3-trifluoromethyl) phenyl] 2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one. Rf = 0.2 (eluent: hexane-tetrahydrofuran (8-2)).

Preparation 5 - 5,6-Dihydro 4- [4- (propylthio) -3- (trifluoromethyl) phenyl] -2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one. Rf = 0.18 (eluent hexane-ethyl acetate (7-3)).

Preparation 6 - 5,6-Dihydro-2-methyl-4- [4- (methylthio) -3- (trifluoromethyl) phenyl) -2H-1,2,4-oxadiazin-3 (4H) -one. PF = 50C.

Study of herbicidal activity 1) Method.

 Horticultural test plant crops containing 5 seedlings per pot in an earthy mixture of clay loam-sandy loam (75%), river sand (12.5%) and potting soil (12.5%) are treated either immediately after sowing (pre-emergence test (H)), or at the two-leaf stage of the seedling (post-emergence test (K)), by spraying a suspension of the active ingredient in a water mixture -acetone at the rate of 2.5 kilograms per hectare.

 The controls in the pre-emergence tests are carried out 28 days after treatment and in the post-emergence tests 21 days after treatment.

 This defines an overall efficiency (EF) taking into account, on the one hand, the actual mortality (MR) and, on the other hand, the weight reduction (RP) of the still alive samples, (MR) and (RP) being expressed as a percentage compared to untreated controls.

MR + ((100 - MR) x RP]
EF =
100
The following table summarizes for each product the overall efficacy calculated from the results of the 2.5 kg / ha trials on the following species - Triticum sativum (Winter Soft Wheat Variety Festival) (BTH) - Beta vulgaris (Ceres monogamous beet variety Cerès) (BE) - Brassica sp (winter rape variety Jet New) (CH) - Galium apasine (Cleavers) (G) - Chenopodium album (Goosefoot) (C) - Alopecurus myosuroïdes (Vulpin ) (V).

2) Results.

<Tb>

<SEP> I <SEP> I <SEP> I <SEP> I <SEP> I <SEP> I <SEP> I <SEP> I
<tb> Product <SEP> of <SEP> TEST <SEP> BTH <SEP> V <SEP> BE <SEP> CH <SEP> C <SEP> G
<tb> the <SEP> prepa- <SEP> H <SEP> 20 <SEP> 44 <SEP> 65 <SEP> 100 <SEP> 100 <SEP> 75
<tb><SEP> ration <SEP> 6 <SEP> K <SEP> 0 <SEP> 100 <SEP> 100 <SEP> 100 <SEP> 80 <SEP> 100
<tb> the <SEP> prepa- <SEP> H <SEP> 25 <SEP> 94 <SEP> 100 <SEP> 100 <SEP> 100 <SEP> 99
<tb><SEP> ration <SEP> 1 <SEP> K <SEP> 44 <SEP> 99 <SEP> 100 <SEP> 100 <SEP> 100 <SEP> 100
<tb> the <SEP> prepa- <SEP> H <SEP> 0 <SEP> 94 <SEP> 100 <SEP> 100 <SEP> 98 <SEP> 81
<tb><SEP> ration <SEP> 5 <SEP> K <SEP> 40 <SEP> 75 <SEP> 100 <SEP> 100 <SEP> 75 <SEP> 100
<tb><SEP> I <SEP>#<SEP> I <SEP> I <SEP> I <SEP> I <SEP> I
<tb> the <SEP> prepa- <SEP> H <SEP> 0 <SEP> 25 <SEP> 100 <SEP> 99 <SEP> 62 <SEP> 50
<tb><SEP> ration <SEP> 3 <SEP> K <SEP> 25 <SEP> 65 <SEP> 100 <SEP> 100 <SEP> 100 <SEP> 100
<tb> the example <SEP> H <SEP> 85 <SEP> 100 <SEP> 100 <SEP> 100 <SEP> 100 <SEP> 97
<tb><SEP> 1 <SEP> K <SEP> 20 <SEP> 85 <SEP> 97 <SEP> 100 <SEP> 100 <SEP> 97
<tb> the example <SEP> H <SEP> 50 <SEP> 100 <SEP> 100 <SEP> 99 <SEP> 100 <SEP> 99
<tb><SEP> 2 <SEP> 1 <SEP> I <SEP> I
<tb><SEP> K <SEP> 81 <SEP> 100 <SEP> 100 <SEP> 100 <SEP> 94 <SEP> 100
<tb> the example <SEP> H <SEP> 50 <SEP> 99 <SEP> 100 <SEP> 100 <SEP> 100 <SEP> 100
<tb><SEP> 5 <SEP> K <SEP> 62 <SEP> 100 <SEP> 94 <SEP> 99 <SEP> 75 <SEP> 94
<tb> the example <SEP> H <SEP> 0 <SEP> 100 <SEP> 92 <SEP> 99 <SEP> 100 <SEP> 25
<tb><SEP> 4 <SEP> K <SEP> 25 <SEP> 100 <SEP> 100 <SEP> 100 <SEP> 100 <SEP> 100
<Tb>
These results clearly show the interest of the products of Examples 1, 2 and 5 for their use as a total herbicide in pre or post-emergence, or the product of Example 1 for use as a selective herbicide post-emergence in plants. wheat cultures or products of preparations 5 and 3 and of example 4, for their use as a selective herbicide in pre-emergence in wheat crops.

 The dose of 2.5 kilograms per hectare of use of the products of formula (I) is not limiting and according to the crop, the state of the soil, the climatic conditions and the method of spreading, can vary from 0, 1 to 10 kilograms per hectare.

EXAMPLE 6 Emulsifiable concentrate according to the invention
A composition containing 15% by weight of product of Example 1, 6.4% of atlox 4851 (oxyethylene triglyceride combined with a sulfonate, acid number 1.5) was prepared. 3.2% of atlox 4855 (oxyethylene triglyceride combined with a sulfonate, acid number 3) and 75.4% xylene.

EXAMPLE 7 Wettable Powder According to the Invention
A wettable powder containing 25% of compound of Example 1, 15% of ekapersol (condensation product of sodium naphthalene sulphonate, 0.5% of brecolane) was prepared.
NVA (sodium alkyl naphthalene sulfonate) 34.5% zeozil 39 (synthetic hydrated silica precipitated) and 25% vercoryl "S" (colloidal kaolin).

Claims (8)

1) Use as herbicides of the products of formula (I)

 in which R represents an alkyl radical containing from one to four carbon atoms and Z represents an oxygen or sulfur atom. 2) Use as herbicides, products of formula (I) as defined in claim 1 whose names follow - 5,6-dihydro-2-methyl 4- [4- (methylthio) 3- (trifluoromethyl) phenyl) ] 2H-1,2,4-oxadiazin-3 (4H) -one - 5,6-dihydro 4- [4- (isopropylthio) -3- (trifluoromethyl) phenyl] -2-methyl-2H-1,2,4 oxadiazin-3 (4H) -one - 5,6-dihydro-4- [4-propylthio) -3- (trifluoromethyl) phenyl] -2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one 4- [4-butylthio) -3- (trifluoromethyl) phenyl] 5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one - 5,6-dihydro 4- (4- Methoxy 3- (trifluoromethyl) phenyl] 2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one - 5,6-dihydro-4- (4-isopropoxy-3- (trifluoromethyl) phenyl] -2-methyl-2H- 1,2,4-oxadiazin-3 (4H) -one - 4- (4-tert-butoxy-3- (trifluoromethyl) phenyl] 5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one - 4- (4- ((S) -sec-butoxy] -3- (trifluoromethyl) phenyl] -5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one . 3) herbicidal compositions characterized in that they contain as active principle, at least one of the products of formula (I) as defined in any one of claims 1 to 2. 4) The products of formula (I) as defined in claim 1 corresponding to formula (II):

 in which R has the meaning indicated in claim 1. 5) The products of formula (II) as defined in claim 4 whose names follow - 5,6-dihydro 4- [4-methoxy-3- (trifluoromethyl) phenyl] -2-methyl-1,2,4-oxadiazine -3 (4H) -one - 5,6-dihydro 4- (4-isopropoxy-3- (trifluoromethyl) phenyl] -2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one - 4- [4-tert-butoxy-3- (trifluoromethyl) phenyl) -5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one - 4- (4 - ((S) -sec butoxy] 3- (trifluoromethyl) phenyl] 5,6-dihydro-2-methyl-2H-1,2,4-oxadiazin-3 (4H) -one. 6) Process for the preparation of the products of formula (II) as defined in claim 4 or 5, characterized in that the isocyanates of formula (III):

 in which R has the meaning previously described, are subjected to the action of an N- (methyl) hydroxylamine salt of formula (IV):  CH 3 -NH-OH (IV) to give the products of formula (V)

 which, treated with a 1,2-dihalo ethane in a basic medium and preferably in a polar solvent lead to the products of formula (II). 7) variant of the process according to claim 6 for the preparation of the products of formula (II) characterized in that the product of formula (VI)

 is subjected to an O-alkylation reagent of phenols to yield the products of formula (II). 8) As new industrial products the products of formulas (V) and (VI) as defined in claims 6 and 7.