FR2474025A1 - NEW UNSATURATED ALCOHOLS AND THEIR USE IN THE PREPARATION OF OXOLANES - Google Patents

Abstract

Unsaturated alcohols of the general formula in which R<1> and R<2> independently of one another in each case denote a hydrogen atom or an optionally substituted alkyl, cycloalkyl or aryl group or R<1> and R<2> together denote an alkylene group, R<3>, R<4> and R<5> and R<6> independently of one another denote a hydrogen atom or an optionally substituted alkyl, alkoxy or aryl group, R<7> denotes an optionally substituted alkyl group and R<8> denotes a hydrogen atom or an optionally substituted alkyl group, can be cyclised to form an oxolane of the general formula which is suitable for the preparation of herbicidally active compounds.

Description

The present invention relates to novel unsaturated alcohols and their use in the preparation of oxolanes. German publication OS No. 2749974 and European patent application No. 0000002 disclose that certain oxolane derivatives are useful as herbicides.

dans laquelle les groupes R1 à R9 oDt diverses significations et Àr est un groupe phényle éventuellement substitué. La demande de brevet britannique NO 7900613 décrit des oxolanes similaires dans lesquels Ar est un noyau complètement saturé éventuellement substitué ayant 5 ou 6 atomes dans le cycle dont un est un atome d'azote et les autres sont des atomes de carbone. Généralement, les composés les plus intéressants pour utilisation comme herbicides sont les composés de la formule cidessus dans lesquels R7 est un groupe alcoyle éventuellement substitué. On peut préparer de tels composés en faisant réagir un alcool d'oxolane de la formule généraie

avec un composé de formule

sans laquelle Hal est un atome d'halogène.These oxolanes have the general form

wherein the groups R1 to R9 have various meanings and λr is an optionally substituted phenyl group. British Patent Application NO. 7900613 describes similar oxolanes in which Ar is an optionally substituted fully saturated ring having 5 or 6 ring atoms of which one is nitrogen and the others are carbon atoms. Generally, the most valuable compounds for use as herbicides are those compounds of the above formula wherein R7 is an optionally substituted alkyl group. Such compounds can be prepared by reacting an oxolane alcohol of the general formula

with a compound of formula

without which Hal is a halogen atom.

Oxolane alcohols are however quite difficult to obtain by synthesis. We have now found a new class of olefin alcohols which can be processed to give the desired oxolane alcohols.

dans laquelle R1 et R2 représentent chacun indépendamment un atome d'hydrogène ou un groupe alcoyle, cycloalcoyle ou aryle éventuellement substitué, ou R et R représentent ensemble un groupe alcoylène ; R3, R4, R5 et R6 représentent chacun indépendamment un atome d'hydrogène ou un groupe alcoyle, alcoxy ou aryle éventuellement substitué ; R7 représente un groupe alcoyle éventuellement substitué ; et R8 représente un atome d'hydrogène ou un groupe alcoyle éventuellement substitué.The present invention therefore relates to a compound of the general formula

wherein R1 and R2 each independently represent a hydrogen atom or an optionally substituted alkyl, cycloalkyl or aryl group, or R and R together represent an alkylene group; R3, R4, R5 and R6 each independently represent a hydrogen atom or an optionally substituted alkyl, alkoxy or aryl group; R7 represents an optionally substituted alkyl group; and R8 represents a hydrogen atom or an optionally substituted alkyl group.

The optional substituents in an optionally substituted group referred to in the present description may be, for example, one or more substituents independently selected from halogen atoms, especially chlorine and fluorine atoms, and alkyl, alkoxy, alkoxyalkoxy groups. , aryl and aryloxy. The alkyl, cycloalkyl, aryl, alkylene, alkoxy, alkoxyalkoxy and aryloxy groups each preferably contain up to 8 carbon atoms. preferred aryl and aryloxy groups are phenyl and phenoxy.

Preferably, R1 and R2 each independently represent a hydrogen atom, an alkyl group having up to 6 carbon atoms or an optionally substituted phenyl group, or R1 and R2 together represent an alkylene group having up to 6 carbon atoms. carbon atoms. Particularly preferably, R1 and R2 each independently represent a hydrogen atom, a methyl group or an ethyl group or R and R together represent a pentamethylene group.

Preferably, R3, R4, R5 and R6 each independently represent a hydrogen atom or an alkyl or alkoxy group having up to 6 carbon atoms optionally substituted by an alkoxy or alkoxyalkoxy group having up to 6 carbon atoms.

Particularly preferably, three of the substituents R3, R4, R5 and R6 represent hydrogen atoms and the fourth represents a hydrogen atom or a methoxy group optionally substituted by a methoxy-ethoxy group.

Preferably, R7 represents an alkyl group having up to 6 carbon atoms which may or may not be substituted. Particularly preferably, R7 represents a methyl, ethyl, halomethyl or metho + methyl group.

Preferably R8 represents a hydrogen atom.

As specified above, compounds of general formula I can be cyclized to form oxolane alcohols.

dans laquelle R1, R2, R3, R4, R5, R6, R7 et R ont les significations indiquées pour la formule générale I, selon lequel on fait réagir un composé de la formule générale I avec un agent époxydant électrophile.the invention therefore also relates to a process for the preparation of a compound of the general formula

wherein R1, R2, R3, R4, R5, R6, R7 and R have the meanings given for general formula I, according to which a compound of general formula I is reacted with an electrophilic epoxidizing agent.

Suitable electrophilic epoxidizing agents are, for example, hydrogen peroxide, alkali metal peroxides or hypohalites, metal perborates, peroxyacetyl nitrate and silver oxide. Especially useful electrophilic epoxidizing agents are peroxyacids, for example aliphatic peroxyacids such as peroxracetic acid or peroxyformic acid or, preferably, aromatic peroxyacids such as a substituted or unsubstituted peroxybenzoic acid. Particularly useful agents are halogenated peroxybenzoic acids, for example acids in which the phenyl ring is substituted by one or two chlorine and / or bromine atoms.

Meta-chloroperoxy-benzoSque acid is preferred.

The reaction is suitably carried out in the presence of an inert solvent, for example of a liquid hydrocarbon, of a chlorinated hydrocarbon, of an ether or of an ester, for example of benzene, toluene, chloride of methylene, carbon tetrachloride, ethyl ether or ethyl acetate. Mixtures of solvents can be used.

The reaction is preferably carried out at a temperature between -10 and 800C, especially between 0 and 200C. It may be convenient in some cases to carry out the reaction at the reflux temperature of the solvent used.

The molar ratio of the compound of the general formula I to the electrophilic epoxidizing agent is not of critical importance. Preferably, the compound of general formula I and the electrophilic epoxidizing agent are mixed in approximately equimolar amounts, or a slight excess of the epoxidizing agent is used. Preferably, the molar ratio of the compound of the general formula I to the electrophilic epoxidizing agent is between 1: 1 and 1: 2, especially between 1: 1 and 1: 1.5. Useful yields, however, can be obtained by using a molar ratio of up to 1:10 or higher.

dans laquelle Ral représente un atome d'haolègne,
R9 représente un atome dthydrogène ou un groupe alcoyle éventuellement substitué ou un groupe hétérocyclique complètement insaturé éventuellement substitué ayant 5 ou 6 atomes dans le cycle dont l'un est un atome d'azote et les autres sont des omets de carbone ; pour donner un composé de la formule générale

dans laquelle R1 à 29 et Ar ont les significations indiquées ci-dessus.If desired, the resulting compound of general formula II can be extracted from the reaction mixture by any suitable processing technique. However, it may be advantageous to carry out a subsequent chemical reaction using the compound of general formula II either after its isolation or directly in situ in the reaction mixture. In a preferred embodiment of the cyclization process according to the invention , at least a part of the resulting compound of the general formula II is converted into an alkali metal or alkaline earth metal salt thereof and the salt is reacted with a compound of the general formula

in which Ral represents a halogen atom,
R9 represents a hydrogen atom or an optionally substituted alkyl group or an optionally substituted completely unsaturated heterocyclic group having 5 or 6 atoms in the ring of which one is a nitrogen atom and the others are carbon omits; to give a compound of the general formula

in which R1 to 29 and Ar have the meanings given above.

Preferably, R9 represents a hydrogen atom.

Preferably, Ar is not substituted or is substituted by one or more identical or different substituents selected from halogen atoms, especially chlorine or fluorine atoms, and alkyl groups having up to 6 carbon atoms. , especially methyl or ethyl groups. For example, Ar may represent an optionally substituted phenyl group, especially an unsubstituted phenyl group or a 2-methyl-, 2-fluoro-, 2-chloro or 2,6-dichloro-phenyl group.

When the term "optionally substituted completely unsaturated heterocyclic groups" is used, it should be understood that these are optionally substituted pyridyl, pyrrolyl and azacyclopentadienyl groups. Thus, the group Ar can for example represent one of the groups:

If Ar represents a heterocyclic group, this group is preferably linked to the rest of the molecule through a carbon atom and the nitrogen atom in the ring is preferably adjacent to this carbon atom. For example, Ar can represent a g-pyridyl group which is unsubstituted or is substituted in the 3- or 6-position by a chlorine or fluorine atom or by a methyl or ethyl group.

Reaction of the salt of the compound of the general formula II with the compound of the general formula
III is carried out very conveniently either without isolation of the compound of the general formula II from the reaction mixture resulting from the cyclization reaction, or by reaction of the crude product resulting from the evaporation of the solvent from this reaction mixture.

The oxolane alcohol of formula II can be converted into a salt of this compound by reaction with a base. Alkali metal hydroxides, alcoholates or hydrides are suitable bases. The alcohol can be converted to its salt before mixing with the compound of formula III, or the salt can be formed in situ by mixing the compounds of formulas II and
III in the presence of a base. Any suitable solvent can be used for the reaction, for example an aromatic hydrocarbon such as benzene or toluene. The reaction can be carried out for example at a temperature between 50 and 1500C. Conveniently, the reaction is carried out at the reflux temperature of the solvent used.

compounds of general formula I can be prepared by methods analogous to known methods. The precise method chosen will of course depend on the meanings desired for the substituents R1 to R8. Three suitable methods are as follows.

avec un réactif de Grignard de la formule générale

dans laquelle Hal est un atome de chlore, de brome ou d'iode, dans les conditions usuelles nécessaires quand on utilise des réactifs de Grignard.1. - A process which is carried out in a very satisfactory manner when at least one of the substitutes R3 and R4 is hydrogen and R1 and R2 are other than hydrogen, or when R1, R2, R3 and R4 are all hydrogen, and which is generally not usable when one of the substituents R3 and R4 is an alkoxy group, involves the reaction of an epoxide of the general formula

with a Grignard reagent of the general formula

in which Hal is a chlorine, bromine or iodine atom, under the usual conditions necessary when Grignard reagents are used.

dans laquelle X a la même signification que le symbole
R2 dans la formule générale I, ou X est un groupe alcoxy, avec un réactif de Grignard de la formule générale RlassHal (VIII) dans laquelle Hal représente un atome de chlore, de brome ou d'iode et R a la sigtiication indiquée pour la formule générale I, à l'exception d'un atome d'hydrogène. Si X représente un groupe alcoxy, on obtient un composé de formule générale I dans lequel R2 a la même signification que RI, puisque le groupe X est perdu par la molécule tandis que deux groupes R1 sont ajoutés.2. - A process for preparing compounds in which at least one of the substituents R1 and R2 is other than a hydrogen atom involves the reaction of a compound of the general formula

where X has the same meaning as the symbol
R2 in the general formula I, where X is an alkoxy group, with a Grignard reagent of the general formula RlassHal (VIII) in which Hal represents a chlorine, bromine or iodine atom and R has the sigtiication indicated for general formula I, with the exception of a hydrogen atom. If X represents an alkoxy group, a compound of general formula I is obtained in which R2 has the same meaning as R1, since the X group is lost from the molecule while two R1 groups are added.

3. - To prepare compounds of the general formula I in which R1 and R2 each represent hydrogen atoms, an ester of the formula VII in which X is an alkoxy group may be reacted with a selective reducing agent, for example lithium aluminum hydride.

In some cases, it can be very convenient to prepare a compound of the general formula I by first preparing a corresponding compound in which one of the groups R1 to R8 has a meaning different from that desired and then converting this group to the desired one. .

The following examples illustrate the invention.

the results of RkS indicated are obtained relative to tetramethylsilane in CDCl3.

PL: E 1 -
Preparation of 2-ethyl-4-methoxyethoxymethoxy-5-hydro- xy-5-metbyl-hex-1 -ene

(a) 5.9 g of sodium are dissolved in 300 cm3 of absolute ethanol and methyl acetoacetate (31.72 g) is added. The mixture was stirred for 15 minutes, 2-bromomethyl-but-1-ene (40 g) was added over 30 minutes and then the mixture was heated under reflux for 2 hours. The mixture is then poured onto brine, extracted several times with ethyl ether, washed with brine and concentrated. Distillation of the residue under vacuum gives 29 g, corresponding to a yield of 60%, of 2-ethyl-4-methylcarbonyl-4-ethoxy-carbonylbut-1-ene, boiling point 120-127 C at a pressure of 10 mm of Hg.

(b) The product of (a) (25 g) is added to 6.2 g of a 50 / o solution of sodium hydride in oil, the mixture is dissolved in benzene (250 cm3) and stirred for two hours. Dibenzoyl peroxide (C6H5CO2) 2 (20.4 g) in benzene (200 cm3) is added over 30 minutes. The mixture was stirred for a further 2 hours, then poured onto water and extracted several times with ethyl ether, dried and distilled in vacuo to obtain 24 g, corresponding to a yield in step (b) of 89.5%, of 2-ethyl-4-methyl-carbonyl-4-ethoxycarbonyl-4-benzoyloxybut-1-ene, boiling point 1600C at a pressure of 1 mm of Rg.

(c) Sodium (250 mg) is dissolved in anhydrous ethanol (250 cm3) and the product of (b) above (22.65 g) is added. The mixture is stirred overnight and then heated under reflux for 2 hours. Ammonium chloride (0.5 g) and water (0.25 cc) were added and stirring continued for 1/2 hour. The mixture is then filtered and the solvent evaporated. The residue is dissolved in ethyl ether, the mixture is filtered and the ether is evaporated off to leave 2-ethyl-4-hydroxy-4-ethoxyearbonyl. - but-1-ene which is identified by R} B. This residue was dissolved in methylene chloride (200 cm3) containing methosWrethoxymethyl chloride (12.5 cm3) and ethyl diisopropylamine (22.5 cm3) and the mixture was stirred overnight. A further 5 cm3 of methoxyethoxymethyl chloride and 10 cm3 of ethyl diisopropylamine are added. The mixture is heated under reflux for 3 hours and then poured onto water, washed with 10% hydrochloric acid and then with brine, dried over potassium carbonate and concentrated. The residue is eluted by lowering it through a column of silica gel using methylene chloride. The solvent is then evaporated off and the product is distilled off.

14.5 g of 2-ethyl-4-methoxyethoymethoxy-4-ethoxycarbonyl-but-1-ene, boiling point 158-162 C at a pressure of 12 mm Rg, are obtained.

(d) Magnesium (3.3 g) is dissolved in a solution of methyl iodide (19.1 g) in ethyl ether and an ethereal solution of 14 g of the ester prepared in (c) above is added over 20 minutes to the solution heated to reflux. The mixture is then stirred for a further 2 hours. Then a saturated solution of ammonium chloride is added, the mixture is extracted with ethyl oxide, washed with brine, dried over magnesium sulfate and concentrated by evaporation. the residue to obtain 9.5 g of the title compound, boiling at 115-1200C at a pressure of 2 mm Rg. Its NMR spectrum is as follows: 0.9 (3H, triplet); 1.2 (6H, singlet); 1.8-2.3 (4E, complex); 3.2 (1H, broad); 3.3 (3H, singlet); 3.5 (5H, complex); 4.7 (4E, complex).

- EXAMPLE 2 -
Preparation of L-dimé hy- 2,2-dimethyl-3-methoxyethoxynethoxy-5-hydroxy-methyl-5-ethyloxolane
The olefinic alcohol prepared in Example 1 (9.5 g) is dissolved in methylene chloride and added to m-chloroperoxybenzoque acid (8.65 g of 85% pure material) in methylene chloride to OOC in 30 minutes. The mixture was stirred for 20 hours and then washed successively with aqueous solutions of sodium sulfite, sodium bicarbonate and sodium chloride and dried.

The solvent is evaporated to leave a crude product which is identified as a mixture of isomers of the desired product using NMR, as follows 0.9 (3H, triplet); 1.2 (6H, doublet); 1.4-2.5 (5H, complex); 3.3 (3H, singlet); 3.4-4.1 (7H, complex); 4.7 (2H, singlet).

Be-product is reacted without further purification as described in Example 3.

- EXAMPLE 3
Preparation of 2,2-dimethyl-3-methoxyetboxymethoxy-5-benzylomethyl-5-ethyloxolane
All of the crude product obtained in Example 2 is dissolved in toluene (80 cm3) and the solution is added, with stirring, to a solution of sodium hydride (2.15 g of a 50% suspension in oil) in anhydrous toluene (150 cm3) over 15 minutes.

The mixture is heated under reflux for 40 minutes and then a solution of benzyl bromide (8.25 G) in toluene (50 cm3) is added dropwise. Heating under reflux and stirring are continued for 18 hours. The mixture was then poured onto brine, treated by etraction with ethyl ether and dried over magnesium sulfate. The solvent was removed to obtain 17.5 g of crude material, which was purified on a silica gel column using an acetone / gasoline mixture as eluent, to obtain 8.2 g of the desired pure product. NMR shows that a mixture of geometric isomers is present.

0s9 (3H, triplet); 1.2 (6H, doublet); 1.4-2.4 (4H, complex); 3.3 (3R, singlet); 3.5 (6H, complex); 4.1 (1H broad triplet); 4.5 (2H, singlet); 4.7 (2H, singlet) 7.2 (5H, singlet).

Elemental analysis CH
Calculated for C20H32O5 68.15 9.5
Found 67.5 9.7 - EX, 2LELE 4 2-methyl -4-methoxyethoxymethoxy- 5-hydroxy-5 -methylhex- 1-ene ~~~~ ~~~~~~~~~~~
The title compound is prepared by a method analogous to that described in Example 1, using 2-bromomethyl-propene as the starting material.

1.1 NMR (5H, singlet); 1.7 (3E, broad singlet); 2.2 (2H, complex); 3.3 (3H, singlet); 3.5 (6E, complex 4.7 (4H, broad doublet).

- EXAMPLE 5 2, 2-dimethyl-3-methoxymethoxymethoxy-5-benzyloxymethyl-5-methyl-oxolane
The title compound is prepared by a method analogous to that described in Example 2 using the compound of Example 4 as the starting material.

RU, EW shows that the product is a mixture of geometric isomers.

1.2 NMR (9H, singlet); 1.5-2.5 (2H, complex); 2.3 (3H, singlet); 3.4 (6H, complex); 3.9 (1H, broad triplet) 4.4 (2H, singlet), 4.6 (2H, broad singlet); 7.2 (5H, singlet).

Elemental analysis CH
Calculated for C19H3005 67.4 8.94
Found 67.4 9.3 - EXAMPLE 6
Preparation of 2-ethyl-5-hydroxy-5-spirocyclohexyl-pent-1-ene

3.21 g of magnesium are added to 75 cm3 of ethyl ether and the mixture is cooled to 000.

Under a nitrogen atmosphere, 2-bromoathylbut-1-ene (13.3 g) in ethyl ether (50 cm3) is added over 3 hours. The cooling bath is then removed and stirring is continued for an additional hour. Methylenecyclohexane oxide (0.5 g) in ethyl ether (25 cm3) is added over 20 minutes and stirring is continued for a further 30 minutes. The mixture is then poured onto aqueous ammonium chloride and the organic phase is separated, washed with brine, dried over sodium sulfate and concentrated by evaporation. The residue is distilled off under reduced pressure to give 11.18 g of a crude product which is purified by chromatography using 25% of acetone in gasoline as eluent. 7.85 g of the desired product are obtained, corresponding to a yield of 81%. Its Ri spectrum is as follows: 1.0 (3H, triplet); 1.5 (12H, broad singlet); 2.0 (5H, complex); 4.6 (2H, broad singlet).

- EXEL2LE 7
Preparation of 2-spirocyclohexyl-5-hydroxymethyl-5-eth * a-loxolane
The olefinic alcohol prepared in Example 6 (5.5 g) is dissolved in methyl chloride (20 cm3) and added dropwise to mchloroperoxybenzoic acid (6.5 g) in methylene chloride (120 cm3) at 0 C). the mixture is left overnight at room temperature and then filtered, washed successively with brine containing sodium sulfite, aqueous sodium carbonate, and brine, dried over magnesium sulfate and concentrated by evaporation. The residue is distilled to obtain 5.6 g of the desired product, boiling point 85-86 C at a pressure of 0.9 mm Hg.

- EXAMPLE 8
Preparation of 2-ethyl-5-hydroxy-5-ethyl-hept-1-ene

le composé désiré est obtenu avec un rendement de 88,6% et a le spectre de iEN suivant : 1,O(1011,multiplet) ; 1,6(611,multiplet) 2X0(4H,multiplet) ; 4,7(2H,singulet large).The process described in Example 6 is repeated, replacing the epoxide with

the desired compound is obtained in a yield of 88.6% and has the following iEN spectrum: 1, O (1011, multiplet); 1.6 (611, multiplet) 2X0 (4H, multiplet); 4.7 (2H, broad singlet).

Elemental analysis CH
Calculated for C11H220 77.6 13.02
Found 76.4 13.2 - EXAMPLE 9 2,2-Diethyl-5-hydroxymethyl-5-ethyloxolane repair
The process described in Example 7 is repeated using the product of Example 8 as the starting material. The product is obtained with a yield of 80.5%.

- EXEL; iPLE 10 Preparation of 2-ethyl-3-methoxyethoxymethoxy-5-hydro- xy-5-methylhex-1-ene
Magnesium (2.36 g) is dissolved in 120 cm3 of ethyl ether containing methyl iodide (6.2 cm3). 2-ethyl-3-methoxyethoxymethoxy-4-ethoxy carbonylbut-1-ene (9.84 g) dissolved in 20 cm3 of ethyl ether is added dropwise over 2C minutes, the rate of addition being such that 'moderate reflux is maintained. A heavy oily precipitate separates. An excess of saturated ammonium chloride solution is added, the mixture is treated by extraction with ethyl ether, washed with brine, dried over magnesium sulfate and concentrated by evaporation. The crude product is purified on a silica gel column using 5% acetone in gasoline as eluent. 7.5 g of the desired product are obtained.

1.1 NMR (3H, triplet); 1.3 (6H, doublet); 1.6-2.2 (4H, complex); 3.3 (3H, singlet); 3.4 (5H, complex); 4.5 (1H, multiplet); 4.6 (2H, broad singlet); 4.9 (1H, broad singlet); 5.0 (1H, broad singlet).

Claims (15)

1) A compound of the general formula

wherein R1 and R2 each independently represent a hydrogen atom or an optionally substituted alkyl, cycloalkyl or aryl group, or R1 and R2 together represent an alkylene group; R3, R4 R5 and R6 each independently represent a hydrogen atom or an optionally substituted alkyl, alkoxy or aryl group; R7 represents an optionally substituted alkyl group; and R8 represents a hydrogen atom or an optionally substituted alkyl group. 2) A compound according to claim 1, characterized in that R1 and R2 each independently represent a hydrogen atom, an alkyl group having up to 6 carbon atoms or an optionally substituted phenyl group, or R and R2 together represent a an alkylene group having up to 6 carbon atoms. 3) A compound according to claim 2, characterized in that R1 and R2 each independently represent a hydrogen atom, a methyl group or 1 ethyl group, or R and 2 an ethyl group, or R and R together represent a pentamethylene group. 4) A compound according to one of claims 1 to 3, characterized in that R3, R4, R5 and R6 each independently represent a hydrogen atom or an alkyl or alkoxy group having up to 6 carbon atoms optionally substituted by an alkoxy or alkoxyalkyl group having up to 6 carbon atoms. 5) A compound according to one of claims 1 to 4, characterized in that R7 represents a methyl, ethyl, halogenomethyl or methoxymethyl group. 6) A compound according to one of claims 1 to 4, characterized in that R8 represents a hydrogen atom. 7) A compound according to claim 1, characterized in that it is named in one of Examples 1, 4, 6, 8 and 10. 8) A process for the preparation of alum compound of the general formula

in which R1 R2 R3, R4, R5, R6 R7 and R8 have the meanings given for the general formula I, characterized in that a compound of general formula I is reacted with an electrophilic epoxidizing agent. 9) A method according to claim 8, characterized in that the epoxidizing agent is an aliphatic or aromatic peroxyacid. 10) A method according to claim 9, characterized in that the epoxidizing agent is meta-chloroperoxybenzoSque acid. 11) A method according to one of claims 8 to 10, characterized in that it is carried out at a temperature between -10 and 800C. 12) A method according to one of claims 8 to 11, characterized in that the molaire ratio of the compound of general formula I to the epoxidizing agent is between 1: 1 and 1: 2. 13) A method according to one of claims 8 to 12 characterized in that it also comprises an additional step in which at least part of the compound resulting from the general formula It is converted into an alkali metal or alkaline metal salt earth of this compound and which is reacted with a compound of the general formula

in which Hal represents a halogen atom, R9 represents a hydrogen atom or an optionally substituted alkyl group and Ar represents an optionally substituted phenyl group or an optionally substituted completely unsaturated ring having 5 or 6 atoms in the ring of which one is a nitrogen atom and the others are carbon atoms; to give a compound of the general formula

in which R1 to R9 and AR have the meanings indicated above. 14) A compound of formula II characterized in that it is prepared by a process according to one of claims 8 to 12. 15) A compound of formula IV characterized in that it is prepared by a process according to claim 13.