MXPA97004260A - Process for the preparation of 2,3-piridinodicarboximi - Google Patents

Abstract

The present invention relates to: A process for the preparation of 2,3-pyridinodicarboximides having the structural formula I is presented. The 2,3-pyridinodicarboximides are useful as intermediates in the preparation of 5- (alkoxymethyl) -2- (2 -imidazolin-2-yl) -nicotinic, esters and herbicide salts

Description

PROCESS FOR THE PREPARATION OF 2.3- PIRIDINODICARBOXIMIDAS BACKGROUND OF THE INVENTION The 2,3-pyridinodicarboximides are useful as intermediates in the preparation of ester compounds and herbicidal salts of 2- (2-imidazolin-2-yl) nicotinic acids. Methods for the preparation of 2,3-pyridinodicarboximides are known in the art (see, for example, U.S. Patent No. 4,748,244; U.S. Patent No. 4,754,033 and EP 308,084-A1) . However, the methods described in those patents and patent application are not completely satisfactory for the commercial manufacture of the 2,3-pyridinodicarboximides. Therefore, an object of the present invention is to present an effective and efficient process for the preparation of 2,3-pyridinodicarboximides. It is also an object of the present invention to present a compound that is useful in the process of the present invention. These and other objects and features of the present invention will become apparent from the detailed description thereof which is set forth below. SUMMARY OF THE INVENTION The present invention presents an effective and efficient process for the preparation of 2,3-pyridinodicarboximide having the structural formula I (I) wherein REF: 24611 R is hydrogen, C6-C6alkoxymethyl-C6alkyl; R is hydrogen, C? -C6 alkyl, C (O) R2, phenyl optionally substituted with any combination of one to four halogen groups, C1-C4 alkyl, C1-C4 alkoxy, nitro or cyano, benzyl optionally substituted on the ring of phenyl with any combination of one to four halogen groups, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, nitro or cyano, or - C-R.; 1 R.

R2 is C? -C? Alkyl, benzyl or phenyl optionally substituted with any combination of one to four halogen groups, C1-C4 alkyl, C1-C4 alkoxy. nitro or cyano, each of R3 and R4 is, independently, C1-C4 alkyl; and R5 is cyano or CONH2; process comprising reacting an oxime or hydrazone of structural formula II (II) wherein R is as described above; R6 is C? -C6 alkyl? R8 is hydrogen, C? -C6 alkyl, C (O) Rn, phenyl optionally substituted with any combination of one to four halogen groups, C1-C4 alkyl, C1-C4 alkoxy. nitro or cyano, benzyl optionally substituted on the phenyl ring with any combination of one to four halogen groups, C 1 -C 4 alkyl, C 1 -C 4 alkoxy. nitro or cyano; Rn is C? -C6 alkyl, OR? 2l NR12Ri3, benzyl or phenyl optionally substituted with any combination of one to four halogen groups, C1-C4 alkoxy alkyl, nitro or cyano; Each of R 2 and R 13 is independently hydrogen, C 1 -C 7 alkyl, benzyl or phenyl optionally substituted with any combination of one to four halogen groups, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, nitro or cyano; and R9 and R10 are each independently hydrogen, C6-C6 alkyl, benzyl or phenyl optionally substituted with any combination of one to four halogen groups, C1-C4 alkyl, C1-C4 alkoxy, nitro or cyano with a maleimide having structural formula III ep which R1 is as described above. This invention also relates to the oximes of formula II described above. DETAILED DESCRIPTION OF THE INVENTION In a preferred embodiment of the present invention, an oxime or hydrazone represented by formula II is reacted with a maleimide represented by formula III, preferably in a temperature range from about 20 ° C to 160 ° C, in the presence of a solvent. Favorably, it has now been discovered that 2,3-pipdmodicarboximides can be obtained in high yield and / or high purity by means of the efficient and efficient process of the present invention. 2,3-p-dino-dicarboximides can be isolated by diluting the reaction mixture with water and filtering the product of formula I from the aqueous mixture. The compounds of the product of the formula I can also be isolated by concentrating the reaction mixture in vacuo and filtering the product of the formula I from the concentrated mixture. On the other hand, the reaction mixture can be integrated into the process used to prepare the final herbicidal agent without isolating the compound of formula I. Examples of halogen mentioned above are fluorine, chlorine, bromine and iodine. In another embodiment of the present invention, a Lewis acid is present. Preferably, the Lewis acid is present in an amount of up to about one molar equivalent to the compound of the formula II when R8 is hydrogen. The Lewis acids suitable for use in the present invention include any conventional Lewis acid. Preferred Lewis acids include aluminum chloride and titanium (IV) chloride. Suitable solvents for use in the process of the present invention preferably have a boiling point of at least about 60 ° C and include aromatic hydrocarbons such as toluene, xylenes, mesitylene and mixtures thereof.; halogenated aromatic hydrocarbons such as mono- and dihalobenzenes and mixtures thereof; polynuclear aromatic hydrocarbons such as naphthalene, alkylnaphthalenes and mixtures thereof; ethers such as tetrahydrofuran and mixtures thereof, glycols such as 1,2-diethoxyethane and mixtures thereof; an alkanoic acid such as acetic acid, propionic acid and mixtures thereof; a mixture of alkanoic acid / water such as a mixture of acetic acid / water; acetonitrile a mixture of acetonitrile / water; and mixtures thereof. Preferred solvents include toluene, xylenes, mesitylene, acetonitrile, a mixture of acetonitrile and water, acetic acid and mixtures thereof, with toluene and acetonitrile being most preferred. In another preferred embodiment of the present invention, the oximes of the formula II are reacted in which R is ORβ with maleimides of the formula III preferably - in a temperature range of 60 ° C to 160 ° C, more preferably of about 75 ° C to 135 ° C. The hydrazones of the formula II in which R is NR9R10 are also reacted with maleimides of the formula III preferably in a temperature range from 20 ° C to 160 ° C, more preferably from about 20 ° C to 135 ° C. In another preferred embodiment of the present invention, there is a base present when R is alkoxymethyl C? -Cβ- The base is used to reduce the amount of 5-methyl-2,3-pyridinodicarboximides that are generated as harmful byproducts when R is alkoxymethion C? -C6. Suitable bases for use in the process of the present invention include, but are not limited to, C2-C4 tri (alkyl) amines such as triethylamine, N, N-diethylisopropylamine, N, N-diisopropylethylamine and the like, metal acetates. alkaline such as sodium acetate, potassium acetate, and the like, and mixtures thereof. Preferred bases include triethylamine, sodium acetate and potassium acetate. The base is preferably present in an amount of at least about one molar equivalent to the compound of formula II.

In another embodiment of the present invention, there is a phase transfer catalyst when the base is present. Preferably, the phase transfer catalyst is present when there is an alkali metal acetate. Suitable phase transfer catalysts for use in the present invention include any conventional phase transfer catalyst. Preferred phase transfer catalysts include crown ethers such as 18-crown-6 and 15-crown-5. In a preferred process according to the present invention, R is hydrogen, C 1 -C 4 alkyl or C 1 -C 4 alkoxymethyl; R1 hydrogen, C1-C4 alkyl, phenyl optionally substituted with any combination of one to four halogen groups, C1-C4 alkyl, C1-C4 alkoxy, nitro or cyano, or -C-Rs; R4 each of R3 and R4 is independently C1-C4 alkyl; R5 is cyano or CONH2; R6 is C1-C4 alkyl; R7 is OR8; and R8 is hydrogen or C? -C6 alkyl. In a more preferred process of the present invention, R is hydrogen, methyl, ethyl or methoxymethyl; C- "R 'RT is methyl, phenyl or; 5' CH (CH.) 2 R5 is cyano or CONH2, R6 is methyl or ethyl, R7 is ORa ^ and Rβ is hydrogen or methyl. formula II in which R7 is OR8; and Re is hydrogen, C?-Cß alkyl) phenyl optionally substituted with any combination of one to four halogen groups, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, nitro or cyano, or benzyl optionally substituted on the phenyl ring with any combination of one to four halogen groups, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, nitro or cyano, can be prepared by reacting a 3-alkoxy-2 -propene of the formula IV with a substituted hydroxylamine of the formula V optionally in the presence of a base The reaction is set forth below in Process Diagram I.

PROCESS DIAGRAM I OR.

(IV) OR.

OR.

On the other hand, the oximes of the formula II in which Re is C? -C6 alkyl can be prepared by reacting a compound of the formula II in which R "is hydrogen with a dialkyl sulfate of the formula VI in the presence of a base such as sodium hydroxide or an alkali metal alkoxide. The reaction scheme is illustrated in Process Diagram II. PROCESS DIAGRAM II i ß Base i ß 0- (C1-C6 alkyl) The oximes of the formula II in which R "is C (0) Rn can be prepared by reacting a compound of the formula II in which R" is hydrogen with an acid chloride of the formula VII or an anhydride of the formula VIII according to what is illustrated in Process Diagram III.

PROCESS DIAGRAM N OC (0) Rl x The hydrazones of the formula II can be prepared by reacting a 3-alkoxy-2-propenal of the formula IV with a hydrazine of the formula IX optionally in the presence of an acid catalyst such as acetic acid. The reaction scheme appears in the Process Diagram IV.

IV PROCESS NAG IV (IV) H ' i ß The 3-alkoxy-2-propene compounds of the formula IV can be prepared according to the procedures described by E. Breitmaier and others in Synthesis, pages 1-9 (1987). The maleimide compounds of formula III are known in the art and can be prepared according to the methods described by M. Cava et al. In Organic Synthesis, 41 page 93 (1961). On the other hand, compounds of the formula IV in which R is methoxymethyl can be prepared by reacting a 3- (dialkylamino-2-propeneal of the formula X with formaldehyde and methanol in the presence of a mineral acid such as sulfuric acid to form a 3- (dialkylamino) -2- (methoxymethyl) -2-propenal of the formula XI, and reacting the compound of the formula XI with a base such as an alkali metal hydroxide and a dialkyl sulfate of the formula VI. of reactions is illustrated in Process Diagram V.

V PROCESS DIAGRAM - (CrC4 alkyl) (X) H ' ? "(CrC alkyl) CH3OCH2 O (XI) ilo -0) 2S0, the) The present invention also relates to a process for the preparation of an ester herbicidal compound and 5- (alkoxylmethyl) -2- (2-midazole? N-2-yl) -nicotinic acid salt, which has the formula wherein R is as defined above, R14 is d-C4 alkyl; R 15 is C 1 -C 4 alkyl, C 3 -C 7 cycloalkyl or R 14 and R 15, taken together with the atom to which they are attached, represents a C 3 -C 6 cycloalkyl group optionally substituted with methyl and R is hydrogen, lower dialkylimino, dC 2 alkyl optionally substituted with one of the following groups: C 1 -C 3 alkoxy, halogen, hydroxy, C 3 -C 6 cycloalkyl benzyloxy, furyl, phenyl, halophenyl, lower alkylphenyl, lower alkoxyphenyl, nitrophenyl, carboxyl, lower alkoxycarbonyl, cyano or lower alkylammonium; C3-C12 alkenyl optionally substituted with one of the following groups: d-C3 alkoxy, phenyl, halogen or lower alkoxycarbonyl or with two C1-C3 alkoxy groups, or two halogen groups; C3-C6 cycloalkyl optionally substituted with one or two alkyl groups or a cation preferably selected from the group consisting of alkali metals, alkaline earth metals, manganese, copper, iron, zinc, cobalt, lead, silver, nickel, ammonium and organic ammonium; process comprising: (a) preparing a compound that has the formula I (I) in which R and R are as previously defined, by a process specified above; and (b) converting said compound of formula I to the compound having formula XII. The term "lower" used above in relation to the alkyl and alkoxy groups means that the alkyl or alkoxy group contains from 1 to 6, preferably from 1 to 4, carbon atoms. The conversion of the compound of the formula I to the compound having the formula XII can be effected in various ways. Paths can be planned by combining known reactions for the conversion of one carboxylic acid derivative to another. The methods that can be used to create imidazolinone herbicides are illustrated in the book "The Imidazolinone Herbicides" edited by D. L Shaner and SL O'Connor, published in 1991 by CRC Press, Boca Raton, Florida, with specific reference to Chapter 2 entitled "Synthesis of Imidazolinone Herbicides", pages 8-14 and references cited therein. The following patent references also illustrate the methods that can be used to convert the carboxylic acid derivatives to imidazolinone end products: U.S. Patent Nos. 5,371,229, Argentine Patent Application 326,416; 5,334,576, Argentine patent application 308,271; 5,250,694; 5,276,157; 5,110,930; 5,122,608; 5,206,368, Argentine patent application 316,418; 4,925,944; 4,921,961; 4,959,476, Argentine patent application 313,080; 5,103,009, patent application 313,080; 4,816,588, Argentine patent 245,697; 4,748,244; 4,754,033; 4,757,146; 4,798,619; 4,766,218; 5,001,254; 5,021,078; 4,723,011, Argentine patent 241,244; 4,709,036, corresponding to Argentine patent application 304,259; 4,658,030; 4608: 079; 4,719,303, corresponding to patent application 298,596; 4,562,257, corresponding to patent application 298,466; 4,518,780; 4,474,962; 4,623,726, corresponding to Argentine patent 240,910; 4,750,978, Argentine patent 240,910; 4,638,068; 4,439,607; 4,459,408; 4,459,409; 4,460,776; 4,125,727 and 4,758,667, and European Patent Applications Nos. EP-A-0-041,623 corresponding to Argentine patent 240,928 and EP-A-0-308,084. To facilitate a better understanding of the invention, the following examples are presented, primarily for the purpose of illustrating the more specific details thereof. The invention is not to be considered limited by the examples, since the full scope thereof is defined in the claims. Example 1 Preparation of the Oxime of 3-ethoxy-2-methyl-2-propen-1-one. fE) - y (ZV- + (NH. * OH) 2 • H2SO4 + NaOAc 3-Ethoxy-2-methyl-2-propenal, (E) - and (Z) - (30.0 g, 0.25 mol) are added dropwise to a mixture of hydroxylamine sulfate (33.0 g). , 0.2 mol) and sodium acetate (33.4 g, 0.4 mol) in water (200 g). The resulting reaction mixture is stirred overnight and filtered to obtain a solid. The solid is washed with water and dried to give the title product as a white solid (23.2 g, mp 78 ° C, 71% yield). Using essentially the same procedure, although replacing hydroxylamine sulfate with methoxylamine hydrochloride, O-methyloxime is obtained from 3-ethoxy-2-methyl-2-propen-1-one, (E) - and (Z) - in yellow oil shape. Example 2 Preparation of the O-methyloxime of 3-ethoxy-2-methyl-2-pr? Den-1-one? F? - and? OCH, CH, I 2 3 + (CH30) 2S02 + (CH37, COK OCH.CH i A mixture of the oxime of 3-ethoxy-2-methyl-2-propen-1-one, (E) - and (Z) - (0.5 g, 3.87 mmol) and potassium tert-butoxide (0) , 48 g, 4.2 mmol) and tetrahydrofuran is stirred for ten minutes at 10 ° C, treated by dripping with dimethyl sulfate (0.59 g, 4.6 mmol), stirred for two hours and filtered. The resulting filtrate is concentrated in vacuo to give the title product as a yellow oil (0.74 g, 100% yield). Example 3 Preparation of 5-methyl-N-phenyl-2,3-? Iridinodicarboximide Toluenr A solution of N-phenylmaleimide (1.69 g, 9.8 mmol) in toluene (16 g) is heated under reflux for 24 hours. During the reflux period, the O-methyloxime of 3-ethoxy-2-methyl-2-propen-1-one, (E) - and (Z) - (1.58 g, 11 mmol) is added portionwise. the reaction mixture. Then, the final reaction mixture is concentrated in vacuo to give the title product as an orange solid (1.2 g, 52% yield). Examples 4-7 Using essentially the same procedure described in Example 3, but substituting the O-methyloxime for 3-ethoxy-2-methyl-2-propen-1-one, (E) - and (Z) - for the oxime of 3-ethoxy-2-methyl-2-propen-1-one, (E) - and (Z) -, 5-methyl-N-phenyl-2,3-pyridinodicarboximide is produced in the yields shown in the Table I (O or III> TABLE I Preparation of 5-methyl-N-phenyl-2,3-pyridinodicarboximide Example Eq of N-Eq Solvent acid reflux hours% yield feryralleride Lewis 4 0.3 AICI3 / 0.2 toluene 27 20 5 0.3 TiCl4 / 0.3 toluene 10 10 6 0.2 - fihßHß 12 15 00 (1: 1) 2.0 - CHaCCy-l 9 15 Example 8 Preparation of 3-dimethylamino) -2- (methoxymethyl) -2-DroDenal. (R- and (7).

N (CH Concentrated sulfuric acid (1 ml) is slowly added to a solution of 3- (dimethylamino) -2-propenal (200 g, 2.01 mol) and paraformaldehyde (90 g, 3 mol) in methanol (1 l). The resulting solution is brought to reflux overnight, concentrated in vacuo to a volume of 200 ml, diluted with toluene and distilled until the vapor temperature is 105 ° C. Then, the solution is concentrated in vacuo to give the title product as an orange oil (251.4 g, 87% yield).

Example 9 Preparation of 3-methoxy-2- (methoxymethin-2-propenal. (R- and (7).

, A solution of 3- (dimethylamino) -2- (methoxymethyl) -2-propenal, (E) - and (Z) - (53.06 g, 0.37 mol) and a solution of the same are maintained at reflux for 20 minutes. Sodium hydroxide (29.7 g, 50%, 0.37 mol) in methanol (60 ml) and concentrated in vacuo to obtain a white solid. A solution of the solid in water (250 ml) is treated dropwise with dimethyl sulfate (46.75 g, 0.37 mol), stirred at room temperature for one hour and extracted with methylene chloride. The organic extract is dried over anhydrous sodium sulfate, concentrated in vacuo and distilled to give the title product as a colorless liquid (19.66 g, bp 80 ° C / 0.5 mm Hg, 41% yield). ). Ejempjo Preparation of 5- (methoxymethin-N-phenyl-2,3-pyridinodicarboximide OCH, CH. OCH. c CH. OCH. - J A solution of methoxyamine hydrochloride (1.7 g, 20 mmol) and sodium acetate (2, 1 g, 25.6 mmol) in water (30 ml) is treated by dripping with 3-methoxy-2- (methoxymethyl) -2-propenal, (E) - and (Z) - (2.2 g, , 9 mmol), stirred at room temperature for 30 minutes and extracted with methylene chloride. The organic extract is dried over anhydrous sodium sulfate and concentrated in vacuo to obtain the O-methyloxime of 3-methoxy-2- (methoxymethyl) -2-propen-1-one. A mixture of the O-methyloxime of 3-methoxy-2- (methoxymethyl) -2-propen-1-one, N-phenylmaleimide (2.9 g, 16.8 mmol) and diisopropylethylamine (2.2 g, 17, 0 mmol) in toluene (50 ml) is maintained at reflux for 23 hours. During the reflux period, more N-phenylmaleimide (2.9 g, 16.8 mmol, is added to the reaction mixture.) The final reaction mixture is concentrated in vacuo to give the title compound as a solid (0, 36 g, 8% yield) with a ratio of 5- (methoxymethyl) -N-phenyl-2,3-pyridinedicarboximide to 5-methyl-N-phenyl-2,3-pyridinedicarboximide of 50: 1. 3-ethoxy-2-methylacrolein dimethylhydrazone ÍR- v (7).

OCH2CH3 OCH CH, I 3 A mixture of 3-ethoxy-2-methyl-2-propenal, (E) - and (Z) - (4.0 g, 35 mmoi), 1,1-dimethylhydrazine (2.73 g, 46 mmol) and acid Acetic acid (0.04 g, 0.7 mmol) in diethyl ether is refluxed for 1 hour, cooled, washed sequentially with water and brine, dried over anhydrous magnesium sulfate and concentrated in vacuo to give the title product in the form of yellow oil.

EXAMPLE 12 Preparation of 5-methyl-N-phenyl-2,3-Diridinodicarboximide from N. phenylmaleimide v dimethyl id ratio of 3-ethoxy-2-methylacrolein (E) - v (Z) - CH3CN A solution of N-phenylmaleimide (1.1 g, 6.4 mmol) in acetonitrile is refluxed for 19 hours. During the reflux period, 3-ethoxy-2-methylacrolein (E) - and (Z) - dimethylhydrazone is added to the reaction mixture in portions. Next, the final reaction mixture is concentrated in vacuo to give the title product as a dark oil.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from this -5 description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (10)

1. A process for the preparation of a 2,3-pyridinodicarboximide having the structural formula I (I) wherein R is hydrogen, C 1 -C 6 Alkoxymethyl C 2 Ce alkyl; R is hydrogen, C Cg alkyl, C (0) R2, phenyl optionally substituted with any combination of one to four halogen groups, alkyl 4 ^, C44 alkoxy nitro or cyano, benzyl optionally substituted on the phenyl ring with any combination of one to four halogen groups, CrC4 alkyl, C44 alkoxy nitro or cyano, or R 3 -C-R 5; R2 is CrC6 alkyl, benzyl or phenyl optionally substituted with any combination of one to four halogen groups, alkyl 0, -04, C, -C4 alkoxy, nitro or cyano, each of R3 and R4 is, independently, C-alkyl, ^; and R5 is cyano or CONH2; the μrocñao horn because it is necessary to react a year or hydrazpna of the structural fa ila II R is alkyl OR12, NR12R13, benzyl or phenyl optionally substituted with any combination of one to four halogen groups, CrC4 alkyl, CrC4 alkoxy nitro or cyano; each of R 12 and R 13 is independently hydrogen, C 1 -C 6 alkyl, benzyl or phenyl optionally substituted with any combination of one to four halogen groups, C 4 alkyl, C 1 -C 4 alkoxy, nitro or cyano; and R9 and R10 are each independently hydrogen, C6-6alkyl, benzyl or phenyl optionally substituted with any combination of one to four halogen groups, CT-C ^ alkyl C44alkyl, nitro or cyano with a maleimide having the formula structural III wherein R ^ is as described above.

2. The process of agreement with the re-diffusion, characterized in that R is hydrogen, C 4 alkyl or C 4 alkoxymethyl; RT hydrogen, C, -C-alkyl optionally substituted with any combination of one to four halogen groups, C 1 -C 4 alkyl, C 4 -C 4 alkoxy nitro or cyano, or ? - C-Rc; i s R 4. R6 is C4 alkyl; R7 is OR8; and Re is hydrogen or C | -C6 alkyl.

3. The process according to claim 1, characterized in that the oxime or hydrazone of the formula II is reacted with the maleimide of the formula III ep in the presence of a solvent selected from the group consisting of an aromatic hydrocarbon, a hydrocarbon halogenated aromatic, a polynuclear aromatic hydrocarbon, a glycol, an alkanoic acid, a mixture of alkanoic acid / water, acetonitrile, a mixture of acetonitrile and water, and mixtures thereof, and the boiling point of the solvent is at least approximately 60 ° C.

4. The process according to claim 1, tasting telzacb for which the jerky or hydrazone of formula II is reacted with the maleimide of formula III at a temperature of about 20 ° C to 160 ° C.

5. The process according to claim 1, further characterized by a Lewis acid selected from the group consisting of aluminum chloride and titanium (IV) chloride.

6. The process of agreement with the. reivjjs? cacri? i 1, characterized in that in addition to a base selected from the group consisting of tri (alkyl) amine C -C4, an alkali metal acetate and mixtures thereof, when R is alkoxymethyl C C6-

7. A compound that has the structural formula ORe 1 i «catri: | n i zpdp perqué R is hydrogen, alkyl or C, -C6 alkoxymethyl; R6 is CrC6 alkyl R8 is hydrogen, CrC6 alkyl, C (O) Rn, phenyl optionally substituted with any combination of one to four halogen groups, C, -C4 alkyl, CrC4 alkoxy, nitro or cyano, optionally substituted benzyl in the ring phenyl with any combination of one to four halogen groups, C 1 -, C 4 alkyl, CrC 4 alkoxy, nitro or cyano; R is Cg alkyl, OR12, NR12R13, benzyl or phenyl optionally substituted with any combination of one to four halogen groups, C, -C4 alkyl, CrC4 alkoxy, nitro or cyano; Each of R 12 and R 13 is independently hydrogen, C 1 Cg alkyl, benzyl or phenyl optionally substituted with any combination of one to four halogen groups, C 1 -C alkyl, C 1 -C 4 atoxy nitro or cyano; and and the cis and trans isomers thereof.

8. The ratio according to claim 7, characterized in that R is hydrogen, C 1 Cg alkyl or CrC 6 alkoxymethyl; R6 is C, -C6 alkyl and R8 is hydrogen or C6 alkylC

9. The compound according to claim 8 selected from the group consisting of the O-methyloxime of 3-ethoxy-2-methyl-2-propen-1-one; the O-methyloxime of 3-methoxy-2- (methoxymethyl) -2-propen-1-one; the oxime of 3-ethoxy-2-methyl-2-propen-1-one; and the oxime of 3-methoxy-2- (methoxymethyl) -2-propen-1-one

10. A process for the preparation of an imidazolinone herbicidal compound having the formula XII wherein R is as defined in claim 1; R14 is CrC4 alkyl; R 15 is C 3 -C 4 alkyl, C 3 -C 6 cycloalkyl or R 14 and R 15, taken together with the atom to which they are attached, represents a C 3 -C 6 cycloalkyl group optionally substituted with methyl and R 16 is hydrogen, lower dialkylimino, CrC 12 alkyl optionally substituted with one of the following groups: C1-C3 alkoxy, halogen, hydroxy, C3-C6 cycloalkyl, benzyloxy, furyl, phenyl, halophenyl, lower alkylphenyl, lower alkoxyphenyl, nitrophenyl, carboxyl, lower alkoxycarbonyl, cyano or lower trialkylammonium; C3-C12 alkenyl optionally substituted with one of the following groups: C3-C3 alkoxy, phenyl, halogen or lower alkoxycarbonyl or with two C3-C3 alkoxy groups, or two halogen groups; C3-C6 cycloalkyl optionally substituted with one or two C3 alkyl groups; or a cation; the A) in n 1, by a process claimed in claim 1; and (b) converting said compound of the formula I to the compound having the formula XII.