GB2051778A - Process for the preparation of certain pyridine derivatives having herbicidal properties - Google Patents
Process for the preparation of certain pyridine derivatives having herbicidal properties Download PDFInfo
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- GB2051778A GB2051778A GB8009568A GB8009568A GB2051778A GB 2051778 A GB2051778 A GB 2051778A GB 8009568 A GB8009568 A GB 8009568A GB 8009568 A GB8009568 A GB 8009568A GB 2051778 A GB2051778 A GB 2051778A
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
- C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
- C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D213/60—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D213/62—Oxygen or sulfur atoms
- C07D213/63—One oxygen atom
- C07D213/64—One oxygen atom attached in position 2 or 6
- C07D213/643—2-Phenoxypyridines; Derivatives thereof
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Abstract
A process for the manufacture of a pyridine compound of the formula (I): <IMAGE> wherein Z and Y each represent a fluorine, chlorine, bromine, iodine or hydrogen atom, or a trifluoromethyl, difluoromethyl or chlorodifluoromethyl radical, provided that at least one of Z and Y is a halogenomethyl radical; R<1> represents hydrogen or a C1-4 alkyl radical, R<2> is a cyano group, a carbonyl group or a specified derivative thereof and n is 0 or 2, which comprises reacting together a pyridine compound of the formula (II): <IMAGE> and an organic sulphite of the formula (III) or (IV):
Description
SPECIFICATION
Process for the preparation of certain pyridine derivatives having herbicidal properties.
The invention relates to a chemical process and more particularly to a process for the preparation of certain pyridine derivatives having herbicidal properties.
According to the present invention there is provided a process for the manufacture of a pyridine compound of the formula:
wherein Z and Y each represent a fluorine, chlorine, bromine, iodine or hydrogen atom, or a trifluoromethyl, difluoromethyl, or chlorodifluoromethyl radical, provided that at least one of Z and Y is a halogeno-methyl radical;R' represents hydrogen or an alkyl radical of 1 to 4 carbon atoms; and R2 is a cyano group; a carboxyl group; a carbonamido group
wherein R3 is hydrogen or an alkyl radical and R4 is hydrogen, an optionally hydroxy or phenyl-substituted alkyl radical of 1 to 4 carbon atoms, a phenyl or chlorophenyl radical, an alkoxy radical of 1 to 4 carbon atoms, or a group -NR5R6 wherein R5 is hydrogen or alkyl of 1 to 4 carbon atoms, and R6 is hydrogen, alkyl of 1 to 4 carbon atoms, phenyl or chlorophenyl, or the group NR3R4 constitutes a pyrrolidino, piperidino, or morpholino radical; a group
wherein R7 is alkyl or phenyl; an alkoxycarbonyl group wherein the alkoxy group may be straight or branched, and which optionally bears one or more hydroxy, alkoxy, or halogen substituents, or bears a substituent of Formula (I) wherein R2 represents a
radical; a group
wherein R8 is an alkyl radical of 1 to 4 carbon atoms and m is an integer from 1 to 5 inclusive; a cyclohexyloxycarbonyl radical optionally substituted by one or more halogen atoms or methyl radicals; an alkenyl-oxycarbonyl radical in which the alkenyl group contains from 3 to 6 carbon atoms; a phenoxycarbonyl radical optionally bearing one or more halogen or methyl substituents; or a benzyl-oxycarbonyl radical, the phenyl group of which optionally bears one or more halogen or methyl substituents; n isO or 2, which comprises reacting together a pyridine compound of the formula:
and an organic sulphite of the formula:
wherein R', R2, Y, Z and n have the previously defined meanings and Rs represents an optionally substituted hydrocarbon radical.
From what follows, it will be appreciated by those skilled in the art that several of the groups R2 as hereinbefore defined may enter into complicating or modifying side-reactions underthe conditions ofthe process, for example, when R2 is a group such as hydroxyalkyl, carboxyl or carbonamido. In these instances the desired (I) may still be obtained by the simple expedient of an appropriate protection-deprotection sequence being inserted in the process, or by a single additional reaction where it is necessary to restore a modified functional group to its original state.
Reaction is carried out by heating together the two reactants, optionally in the presence of an inert solvent
Reaction proceeds with evolution of sulphur dioxide and with formation of an alcolhol as by-product. In the case in which a sulphide of formula (Ill) is used, the alcohol by-product has the formula:
R'
R2 - (CH2)n - CH - OH (V) in which R', R2 and n have the previously defined meanings. When a sulphite of formula (IV) is used the alcohol by-product has the formula: R3.OH (VI) in which R3 has the previously defined meaning.
These alcohols of formulae (V) and (VI) may be recovered and used to prepare the sulphites of formulae (III) and (IV) respectively. Alternatively, if the alcohol of formula (Vl) is a cheap alcohol such as methanol, recovery will not generally be necessary.
The pyridine compound of formula (I) is readily recovered from the reaction mixture by conventional means.
The starting material of formula (II) may be obtained, for example, by reacting a 2-halopyridine of formula:
wherein Y and Z have the previously defined meanings and W represents a chlorine or bromine atom, with a hydroquinone derivative of formula:
in which Q is H or an easily-removable protective group, for example, methyl or benzyl. Reaction is carried out at an elevated temperature, for example, 10 to 1 30 C, in a suitable organic solvent, for example, dimethylformamide or dimethylsulphoxide, in the presence of an acid-binding agent, for example, sodium hydroxide, which may be used in the form of an aqueous solution.The reaction product, having the formula:
is then, when Q is not hydrogen, further reacted to remove the protective group Q, which when Q is methyl or benzyl may be achieved by heating the compound of formula (IXt with a suitable dealkylation agent such as concentrated aqueous hydrobromic acid or pyridine hydrochloride.
The pyridine compounds of formula (I) may also be obtained by several variants of the previously described process.
Thus according to a further feature of the invention a pyridine compound of formula (I) is obtained by heating a compound of the formula:
wherein R1, R2, Y, Z and n have the previously defined meanings.
According to a yetfurtherfeature of the invention a pyridine compound of formula (I) is obtained by reacting together a compound of formula:
our a compound of the formula:
and an alcohol of formula:
wherein R1, R2, Y, Z and n have the previously defined meanings and Ar represents an optionally substituted aryl radical.
The alcohol or formula (V) is preferaly used'is: large molar excess over the compound of formula (Xl) or formula (XII).
As in the case of the first-defined process, reaction is carried out by heating together the two reactants, optionally in the presence of an inert solvent. Again reaction proceeds with evolution of sulphur dioxide and with formation of the compound of formula:
as by-product when the starting material is a compound of formula lXl), or with compound of formula:
Ar.OH (will) as by-product when the starting material is a compound of formula (Xll). These by-product phenols may be recovered and used to prepare the compounds of formulae (Xl) and (XII) respectively. Alternatively, if the compound of formula (XIII) is a relatively cheap phenol itself, recovery will not generally be necessary.
Pyridine compounds of formula (I) may also be obtained by the known method of reacting a 2-halopyridine of formula (VII) with a compound of formula:
in which R1, R2 and n have the previously defined meanings, in a polar solvent such as dimethylsulphoxide and in the presence of a small amount of an acid-binding agent such as aqueous or powdered sodium hydroxide.
The compound of formula (XIV) may be obtained by reaction of a compound of formula:
with the alcohol of formula:
in which R1 R2 and n have the previously defined meanings, and this process constitutes a further feature of the invention.
The alcohol of formula (V) is preferably used in large molar excess over the compound of formula (XV).
Compounds of formulae (X), (XI), (Xll) and (XV) are novel compounds.
The various organic sulphites employed in the processes hereinbefore described may be obtained by conventional methods of organic chemistry.
Preparation of a typical organic sulphite of formula (III) is carried out as follows:
Thionyl chloride (0.05 mole) is added during 40 minutes to a solution of n-butyl lactate (0.10 mole) in dichloromethane (20 ml) at room temperature under nitrogen. The reaction mixture is set aside for three days at room temperature and then subjected to short-path distillation at 15 mm Hg pressure to remove traces of residual butyl lactate. This afforded a product with an infra red spectrum identical with an authentic sample of (1-n-butoxycarbonylethyl) sulphite [Strong absorption at 1205 cm-' due to S=0] (cf. J.Amer .Chem.Soc., 78, 456).
The yield of material thus obtained is virtually quantitative and it analyses as follows:
Found: C 51.5%; H 8.1%; S 10.5%; C14H2607S requires: C 49.7%; H 7.8%; S 9.5%.
Other intermediates for use in the process of the present invention may be prepared by similar methods or variations thereof. For example compounds of formula (IV) may be pbtained by reaction of approximately equimoiar quantities of alcohol of formula (V) and thionyl chloride to give the chlorosulphite of formula:
wherein R1, R2 and n have the previously defined meanings, which is subsequently reacted with the alcohol
R3.OH.
Compounds of formula (X) may be obtained by reaction of approximately equimolar quantities of a compound of formula (II) and thionyl chloride to give the corresponding chlorosulphite of formula:
wherein Y and Z have the previously defined meanings, followed by reaction of the latter with an alcohol of formula (V), or by reaction ofa compound of formula (XVI) with a compound of formula (II). Similarly compounds of formula (XII) may be obtained by reaction of a compound of formula (XVII) with a compound
Ar.OH, wherein Ar has the previously defined meaning. The reaction of chlorosulphites of formulae (XVI) or (XVII) with alcohols or phenols is generally carried out in the presence of a hydrogen chloride acceptor such as pyridine.
Compounds of formula (XI) may be obtained by reacting a compound of formula (XVII) with a compound of formula (II), or directly be reacting a large excess of a compound of formula (II) with thionyl chloride.
Likewise the compound of formula (XV) may be obtained by reaction of a large excess of hydroquinone with thionyl chloride.
It will be appreciated that when the group R2 in any compound used in the above processes contains substituents which are reactive towards thionyl chloride, sulphites or chlorosulphites, such substituents must be suitably protected before reaction is carried out, the protective group subsequently being removed to give the desired product.
Claims (1)
1. A process for the manufacture of a pyridine compound of the formula:
wherein Z and Y each represent a fluorine, chlorine, bromine, iodine or hydrogen atom, of a trifluoromethyl, difluoromethyl, of chlorodifluoromethyl radical, provided that at least one of Z and Y is a halogeno-methyl radical;R1 represents hydrogen or an alkyl radical of 1 to 4 carbon atoms; and R2 is a cyano group; a carboxyl group; a carbonamido group
wherein R3 is hydrogen or an alkyl radical and R4 is hydrogen, an optionally hydroxy- or phenyl-substituted alkyl radical of 1 to 4 carbon atoms, a phenyl or chlorophenyl radical, an alkoxy radical of 1 to 4 carbon atoms, or a group -NR5R6 wherein R5 is hydrogen or alkyl of 1 to 4 carbon atoms, and R6 is hydrogen, alkyl of 1 to 4 carbon atoms, phenyl or chlorophenyl, or the group -NR3R4 constitutes a pyrrolidino, piperidino, or morpholino radical; a group
wherein R7 is alkyl or phenyl; an alkoxycarbonyl group wherein the alkoxy group may be straight or branched, and which optionally bears one or more hydroxy, alkoxy, or halogen substituents, or bears a substituent of Formula (I) wherein R2 represents a
radical; a group
wherein R8 is an alkyl radical of 1 to 4 carbon atoms and m is an integer from 1 to 5 inclusive; a cyclohexyloxycarbonyl radical optionally substituted by one or more halogen atoms or methyl radicals; and alkenyl-oxycarbonyl radical in which the alkenyl group contains from 3 to 6 carbon atoms; a phenoxycarbonyl radical optionally bearing one or more halogen or methyl substituents; or a benzyl-oxycarbonyl radical, the phenyl group of which optionally bears one or more halogen or methyl substituents; n isO or 2, which comprises reacting together a pyridine compound of the formula:
and an organic sulphite of the formula:
wherein R1, R2, Y, Z and n have the previously defined meanings and R3 represents an optionally substituted hydrocarbon radical.
2. A process forthe manufacture of a pyridine compound of formula (I) as defined in claim 1 which comprises heating a compound oftheformula (X):
our a compound of the formula (Xll):
and an alcohol of formula (V):
R1 R2 - (CH2)n - CK - OH (V) wherein R, R, Y, Z and n have the meanings defined in claim 1 and Ar represents an optionally substituted aryl radical.
4. A process as claimed in claim 3 wherein the alcohol of formula (V) is used in large molar excess over the compound of formula (XI) or (XII).
5. Aprocessforthe preparation of a compound of the formula (XIV):
which comprises reaction of a compound of formula (XV):
with an alcohol of the formula (V):
R1
R2 - (CH2)n - CH - OH (V) wherein R1, R2 and n have the meanings defined in claim 1.
6. A process as claimed in claim 5 wherein the alcohol of formula (V) is used in large molar excess over the compound of formula (XV).
7. A pyridine compound of formula (I) as defined in claim 1 whenever obtained by a process as claimed in any one of claims 1 to 4.
8. A compound of formula (XIV) as defined in claim 5 whenever obtained by a process as claimed in
claim 5 or claim 6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8009568A GB2051778A (en) | 1979-07-05 | 1980-03-21 | Process for the preparation of certain pyridine derivatives having herbicidal properties |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7923414 | 1979-07-05 | ||
| GB8009568A GB2051778A (en) | 1979-07-05 | 1980-03-21 | Process for the preparation of certain pyridine derivatives having herbicidal properties |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2051778A true GB2051778A (en) | 1981-01-21 |
Family
ID=26272076
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8009568A Withdrawn GB2051778A (en) | 1979-07-05 | 1980-03-21 | Process for the preparation of certain pyridine derivatives having herbicidal properties |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2051778A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2123819A (en) * | 1982-06-18 | 1984-02-08 | Dow Chemical Co | Herbicidal pyridyl (oxy/thio) phenoxy compounds |
| EP0136593A2 (en) * | 1983-09-06 | 1985-04-10 | The Dow Chemical Company | Novel halopyridines and methods of making |
| US4585870A (en) * | 1982-06-04 | 1986-04-29 | Bayer Aktiengesellschaft | Substituted pyridyl-phenyl ethers |
-
1980
- 1980-03-21 GB GB8009568A patent/GB2051778A/en not_active Withdrawn
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4585870A (en) * | 1982-06-04 | 1986-04-29 | Bayer Aktiengesellschaft | Substituted pyridyl-phenyl ethers |
| GB2123819A (en) * | 1982-06-18 | 1984-02-08 | Dow Chemical Co | Herbicidal pyridyl (oxy/thio) phenoxy compounds |
| EP0136593A2 (en) * | 1983-09-06 | 1985-04-10 | The Dow Chemical Company | Novel halopyridines and methods of making |
| EP0136593A3 (en) * | 1983-09-06 | 1988-03-30 | The Dow Chemical Company | Novel halopyridines and methods of making |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |