Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
1999-11-15
2001-04-03
Killos, Paul J. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C560S011000
Reexamination Certificate
active
06211403
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a process for the preparation of herbicidal 1-alkyl-4-(2-chloro-3-alkoxy-4-alkylsulfonylbenzoyl)-5-hydroxypyrazole compounds and of certain 1-halo-2-chloro-3-alkoxy-4-alkylsulfonylbenzene compounds that are useful intermediates in the manufacture of these herbicidal compounds. More particularly, the present invention concerns the preparation of 2-chloro-3-alkoxy-4-alkylsulfonylbenzoic acids and esters by carbonylation of the corresponding 1-chloro compounds.
A number of 1-alkyl-4-(2-chloro-3-alkoxy-4-alkylsulfonylbenzoyl)-5-hydroxypyrazole compounds were disclosed in U.S. Pat. RE-34,779 and were reported to possess excellent herbicidal properties. These compounds were prepared by the reaction of a 1-alkyl-5-hydroxypyrazole compound with a 2-chloro-3-alkoxy-4-alkylsulfonylbenzoic acid compound. The preparation of the 2-chloro-3-alkoxy-4-alkylsulfonylbenzoic acid compounds used as starting materials was carried out by alkylation of 2-chloro-3-hydroxy-4-alkylsulfonylbenzoic acid compounds. The 2-chloro-3-hydroxy-4-alkylsulfonylbenzoic acid compounds required for this procedure can be obtained by hydrolysis of a 2,3-dichloro-4-alkylsulfonylbenzoic acid compound. This reaction and the alkylation process were disclosed in U.S. Pat. No. 4,898,973. The preparation of 1-alkyl-4-(2-chloro-3-alkoxy-4-alkylsulfonylbenzoyl)-5-hydroxypyrazole compounds by this route requires many reaction steps and produces large quantities of unusable by-products and waste. More direct and economical methods of production are highly desirable.
SUMMARY OF THE INVENTION
It has now been found that 1-alkyl-4-(2-chloro-3-alkoxy-4-alkylsulfonylbenzoyl)-5-hydroxypyrazole compounds can be prepared by the reaction of 1-alkyl-4-(2,3-dichloro-4-alkylsulfonylbenzoyl)-5-hydroxypyrazole compounds with alkali metal alkoxide compounds. The reaction takes place in a surprisingly selective manner and in a surprisingly high yield. It has also been found that certain 1-halo-2-chloro-3-alkoxy-4-alkylsulfonylbenzene compounds, which can be used as intermediates in the production of the same herbicidal compounds, can be prepared in the same way from 1-halo-2,3-dichloro-4-alkylsulfonylbenzene compounds in the same surprisingly selective manner and surprisingly high yield.
The primary process of the invention includes the preparation of 3-alkoxybenzene compounds of Formula I:
wherein
X represents Cl, Br, CO
2
H, or a 1-alkyl-5-hydroxypyrazole-4-carbonyl moiety of Formula II:
R represents a C
1
-C
4
alkyl group optionally substituted with a C
1
-C
4
alkoxy or C
1
-C
4
alkylthio group or with a 3-6 membered alicyclic moiety composed of one oxygen or sulfur atom and 2-5 carbon atoms or represents a 3-6 membered alicyclic moiety composed of one oxygen or sulfur atom and 2-5 carbon atoms;
R″ represents H or C
1
-C
4
alkyl; and
R′ and R′″ each independently represents C
1
-C
4
alkyl;
which process comprises combining a 3-chlorobenzene compound of Formula III:
wherein X and R′″ are as defined hereinabove with an alkali metal alkoxide compound of Formula IV:
wherein
R is as defined hereinabove and
M+ represents lithium, sodium, or potassium cation in a liquid medium, optionally in the presence of a phase transfer catalyst, at a temperature of about 20° C. to about 110° C.
A compound of Formula I wherein X represents a 1-alkyl-5-hydroxypyrazole-4-carbonyl moiety of Formula II is often preferably employed as the 3-chlorobenzene compound starting material. Sodium and potassium salts of 2-methoxyethanol are often preferred alkali metal alkoxide compounds of Formula IV. The process is most often used to prepare the compound 4-(2-chloro-3-(2-methoxyethoxy)-4-methylsulfonylbenzoyl)-1-ethyl-5-hydroxypyrazole or intermediates conveniently convertible to it.
Compounds of Formulas I and III wherein X represents chloro or bromo, which are valuable intermediates in the production of herbicides, are other embodiments of the invention.
The invention further includes processes for converting compounds of Formulas I and III wherein X represents chloro into compounds of Formulas I and III wherein X represents hydroxycarbonyl, alkoxycarbonyl, or a 1-alkyl-5-hydroxypyrazole-4-carbonyl moiety of Formula II, which processes involve their reactions with carbon monoxide in the presence of a palladium II salt:trihydrocarbylphosphine complex catalyst, such as the complex between palladium acetate and 1,4-bis(diphenylphosphino)-butane.
DETAILED DESCRIPTION OF THE INVENTION
The primary process of the present invention can be characterized as a method of converting the chloro substituent in the 3-position of a 2,3-dichloro-4-alkylsulfonylbenzene compound of Formula III:
wherein X represents a chloro, bromo, CO
2
H, or a 1-alkyl-5-hydroxypyrazole-4-carbonyl moiety of Formula II:
into an alkoxy substituent by selective nucleophilic substitution with an alkoxide ion reagent. The 3-position chloro substituent (chloro substituent ortho to the alkylsulfonyl substituent) reacts preferentially to the 2-position chloro substituent (chloro substituent meta to the alkylsulfonyl substituent) and, when present, the 1-position chloro or bromo substituent (chloro or bromo substitutent para to the alkylsulfonyl substituent). The products obtained are herbicidal 1-alkyl-4-(2-chloro-3-alkoxy-4-alkylsulfonylbenzoyl)-5-hydroxypyrazole compounds of Formula IA:
or compounds of Formula IB:
wherein X represents chloro, bromo, or C
02
H, and R, R′, R″, and R′″ are as defined for compounds of Formula I in the Summary of the Invention. The compounds of Formula IB are useful as intermediates in the preparation of inter alia the herbicidal compounds of Formula IA.
The process of the invention is generally carried out by combining a 3-chlorobenzene compound of Formula III:
wherein R′″ and X are as defined in the Summary of the Invention with an alkali metal alkoxide compound of Formula IV:
RO
−
M
wherein R and M
+
are as defined in the Summary of the Invention under suitable reaction conditions.
The term ‘alkyl’ as employed herein includes normal, branched chain, and cyclic alkyl moieties. The alicyclic moiety substituents (R) of the invention are bonded through a carbon atom and are viewed as substituted cyclic alkyl groups.
R in Formulas I, IA, IB, and IV represents an alkyl group such a C
1
-C
4
alkyl group optionally substituted with a C
1
-C
4
alkoxy or C
1
-C
4
alkylthio group or with a 3-6 membered alicyclic moiety composed of one oxygen or sulfur atom and 2-5 carbon atoms or represents a 3-6 membered alicyclic moiety composed of one oxygen or sulfur atom and 2-5 carbon atoms. Groups that are suitable R groups include methyl, ethyl, 1-methylethyl, butyl, cyclo-propyl, 2-methoxyethyl, 3-ethoxypropyl, 2-methylthio-1,1-dimethylethyl, 3-(oxacyclopentyl)methyl, 4-oxacyclohexyl, and the like. C
1
-C
4
alkyl groups and 2-(C
1
-C
4
alkoxy)ethyl groups are often preferred. 2-Methoxyethoxy is usually an especially preferred group.
R′ in Formulas I, IA, II, and III represents an alkyl group, including a C
1
-C
4
alkyl group. Such groups include methyl, ethyl, 1-methylethyl, 1,1-dimethylethyl, and cyclo-propyl. Methyl and ethyl are generally preferred.
R″ in Formulas I, IA, II, and III represents hydrogen or an alkyl group, including a C
1
-C
4
alkyl group. Such alkyl groups include methyl, ethyl, 1-methylethyl, 1,1-dimethylethyl, and cyclo-propyl. Hydrogen is generally preferred.
R′″ in Formulas I, IA, IB, and III represents an alkyl group including a C
1
-C
4
alkyl group. Such alkyl groups include methyl, ethyl, propyl, 1-methylethyl, 1,1-dimethylethyl, and cyclo-propyl. Methyl is generally preferred.
X in Formulas I and III represents a halogen, including chloro or bromo, hydroxycarbonyl, or a pyrazole moiety, including a moiety of Formula II wherein R′ and R″ are as defined in the Summary of the Invention. A moiety of Formula II is generally preferred. The moiety of Formula II wherein R&prime
Emonds Mark V. M.
Krumel Karl L.
Schomaker Jennifer M.
Siddall Thomas L.
Zettler Mark W.
Dow AgroSciences LLC
Killos Paul J.
Mixan Craig E.
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