Benzoylpyrazole compounds and herbicide

Details Benzoylpyrazole compounds and herbicide Benzoylpyrazole compounds and herbicide

2000-10-18

2001-06-12

Lambkin, Deborah C. (Department: 1626)

Plant protecting and regulating compositions

Plant growth regulating compositions

Organic active compound containing

C548S240000, C548S247000

Reexamination Certificate

active

06245716

ABSTRACT:

FIELD OF INVENTION
The present invention is related to novel pyrazole compounds substituted with a specific benzoyl groups at the
4
th position of the pyrazole ring and a herbicide.
BACKGROUND ART
For cultivation of agricultural and horticultural crops, many herbicides have been used for weed control, which requires enormous labors in the past. However, herbicides cause phytotoxicity to crops, residue in environment and spoil to the environment, and therefore, new herbicides capable of firmly controlling weeds with lower doses and using safely have been desired.
In WO96/26206, a herbicide represented by a general formula (A);
wherein a benzoyl group is substituted at the 4
th
position of the pyrazole ring and a heterocyclic ring is substituted on the benzene ring, is disclosed.
Whereas, in WO97/46530, a herbicidal compound represented by a general formula (B) is disclosed.
However, among such disclosed herbicidal compounds, only compounds of which heterocyclic ring represented by A is 1-methyl-1H -pyrazole-3-yl are disclosed with their physical data, and no biological activity data is described for those compounds.
Whereas, in WO97/41118, herbicidal compounds represented by a general formula (C) are disclosed.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a herbicide, which can be synthesized advantageously in an industrial scale, giving firm herbicidal activity with lower doses, being used safely, having good selectivity in the activity for crops and weeds, and being composed of a novel pyrazole compound as the active ingredient.
The present invention is directed to a herbicide composed of a compound represented by a general formula (1);
wherein R
1
, R
2
and R
3
are each independently halogeno, C
1-6
alkyl, C
1-6
alkoxy, C
1-6
haloalkyl, C
1-6
haloalkoxy, C
1-6
alkylthio, C
1-6
alkylsulfinyl or C
1-6
alkylsulfonyl, R
4
and R
5
are each independently hydrogen, C
1-6
alkyl, C
1-6
alkenyl or C
1-6
alkynyl, Het is a substituent represented by the following formulas;
wherein R
6
represents hydrogen or C
1-4
alkyl, or the salt or 1 or more than 2 of the said compounds.
In the general formula (1) described above, Het represents isoxazole-3-yl, isoxazole-4-yl, isoxazole-5-yl, 4,5-dihydroisoxazole-3-yl, 4,5-dihydroisoxazole-4-yl, or 4,5-dihydroisoxazole-5-yl, all of which may be optionally-substituted.
For the example of Het, isoxazole-3-yl, isoxazole-4-yl, isoxazole-5-yl, 3-methylisoxazole-4-yl, 3-methylisoxazole-5-yl, 4-methylisoxazole-3-yl, 4-methylisoxazole-5-yl, 4,5-dihydroisoxazole-3-yl, 4,5-dihydroisoxazole-4-yl, 4,5-dihydroisoxazole-5-yl, 3-methyl-4,5-dihydroisoxazole-4-yl, 3-methyl-4,5-dihydroisoxazole-5-yl, 4-methyl-4,5-dihydroisoxazole-3-yl, 4-methyl-4,5-dihydroisoxazole-5-yl and the like can be preferably given.
In the general formula (1), R
1
, R
2
and R
3
each independently represent halogeno, such as fluorine, chlorine, bromine and iodine, C
1-6
alkyl, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, s-butyl and t-butyl, C
1-6
alkoxy, such as methoxy, ethoxy, propoxy, isopropoxy, butoxy and t-butoxy, C
1-6
haloalkyl, such as trifluoromethyl, trichloromethyl, fluoromethyl, chloromethyl, difluoromethyl, dichloromethyl, 2,2,2-trifluoroethyl and pentafluoroethyl, C
1-6
haloalkoxy, such as trifluoromethoxy, trichloromethoxy, difluoromethoxy and trifluoroethoxy, C
1-6
alkylthio, such as methylthio, ethylthio, propyltwio and isopropylthio, C
1-6
alkylsulfinyl, such as methylsulfinyl, ethylsulfinyl, propylsulfinyl and isopropylsulfinyl, and C
1-6
alkylsulfonyl, such as methylsulfonyl, ethylsulfonyl, propylsulfonyl and isopropylsulfonyl.
R
4
and R
5
each independently represent hydrogen, C
1-6
alkyl, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, s-butyl and t-butyl, C
2-6
alkenyl, such as vinyl, 1-propenyl, allyl and 2-butenyl, and C
2-6
alkynyl, such as ethynyl, 1-propynyl and 2-propynyl.
R
6
represents C
1-4
alkyl, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, s-butyl and t-butyl.
MODE FOR CARRYING OUT THE INVENTION
The compounds of the present invention are prepared according to a process shown in the following reaction diagram.
wherein R
1
through R
5
and Het are as defined above, and X represents a halogen atom.
In the process above, intermediates (5a) and (5b) are obtained by subjecting either a compound (2) or a compound (4) to a reaction with hydroxypyrazole (3), and then an objective compound (1) is obtained from the intermediates (5a) and (5b).
The compound (4) is prepared from the compound (2) according to generally-known synthetic chemical reaction using an inorganic halogenation agent, such as thionyl chloride and phosphorus pentachloride.
The intermediates (5a) and (5b) are obtainable by subjecting the compound (4) and the compound (3), each in an amount of 1 mole, or using either one in an excess amount, to a reaction in the presence of a base either in an amount of 1 mole or in an excess amount.
As the base used in the reaction, an alkali metal hydroxide, such as KOH and NaOH, an alkali metal carbonate, such as sodium carbonate and potassium carbonate, an alkaline earth metal hydroxide, such as calcium hydroxide and magnesium hydroxide, an alkaline earth metal carbonate such as calcium carbonate, a tertiary amine, such as triethyl amine and diisopropyl ethyl amine, an organic base such as pyridine, sodium phosphate and the like can be given.
As the solvent used in the reaction, water, dichloromethane, chloroform, toluene, ethyl acetate, N,N-dimethyl formamide (DMF), tetrahydrofuran (THF), dimethoxy ethane (DME), acetonitrile and the like can be used.
The mixture for the reaction is stirred until the completion of the reaction at a temperature of from 0° C. to the boiling point of the solvent used. Alternatively, the reaction can be performed in two solvents system by using a phase-transfer catalyst, such as quaternary ammonium salt.
Further, the compound (5a) and the compound (5b) are obtainable by subjecting the compounds (2) and (3) to a reaction in the presence of a dehydrating and condensing agent like dicyclohexylcarbodimide (DCC).
As examples for the solvent used in the reaction, dichloromethane, chloroform, toluene, ethyl acetate, DMF, THF, DME, acetonitrile, t-pentyl alcohol and the like can be given.
The mixture for the reaction is continuously stirred until the completion of the reaction at a temperature of from −10° C. to the boiling point of the solvent used and then processed according to common procedure.
The compound (5a) and the compound (5b) may be directly used as a mixture for the following rearrangement.
The rearrangement is carried out in the presence of a cyanide and a less reactive base. Namely, the compound (1) is obtainable by subjecting the compounds (5a) and (5b) each in an amount of 1 mole to a reaction with the base in an amount of from 1 to 4 moles, and preferably from 1 to 2 moles, and the cyanide in an amount of from 0.01 to 1.0 mole, and preferably from 0.05 to 0.2 mole.
As the base used in the reaction described above, alkali metal hydroxides, such as KOH and NaOH, alkali metal carbonates, such as sodium carbonate and potassium carbonate, alkaline earth metal hydroxides, such as calcium hydroxide and magnesium hydroxide, alkaline earth metal carbonate such as calcium carbonate, tertiary amines, such as triethyl amine and diisopropyl ethyl amine, organic bases such as pyridine, sodium phosphate and the like can be used.
As the cyanide used in the reaction described above, a polymer carrying any of potassium cyanide, sodium cyanide, acetone cyanohydrine, hydrogen cyanide and potassium cyanide and the like can be used. It is preferable to add a small amount of a phase-transfer catalyst, such as crown ether, into the reaction system as the phase-transfer catalyst can contribute to complete the reaction in a shorter time.
The solvent used in the reaction are dichloroethane, benzene, toluene, acetonitrile, chloroform, ethyl acetate, DMF, methyl isobutyl ketone, THF, DME and the like. The reaction may smoothly pr

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