Classifications

• • 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
  • C07D213/89—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 with hetero atoms directly attached to the ring nitrogen atom
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D409/00—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms
  • C07D409/02—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms containing two hetero rings
  • C07D409/04—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms containing two hetero rings directly linked by a ring-member-to-ring-member bond
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N43/00—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds
  • A01N43/34—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds having rings with one nitrogen atom as the only ring hetero atom
  • A01N43/40—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds having rings with one nitrogen atom as the only ring hetero atom six-membered rings

Definitions

• the invention disclosed in this document is related to the field of certain functionalized pyridine N-oxides including, for example, 2-substituted-5-(l-alkylthio)alkyl-pyridine N- oxides, and to techniques for preparing and using the same.
• Controlling pest populations is essential to modern agriculture, food storage, and hygiene. There are more than ten thousand species of pests that cause losses in agriculture. The world-wide agricultural losses amount to billions of U.S. dollars each year. Pests, such as termites, are also known to cause damage to all kinds of private and public structures resulting in billions of U.S. dollars in losses each year. Pests also eat and adulterate stored food, resulting in billions of U.S. dollars in losses each year, as well as deprivation of food needed for people.
• U.S. Patent Nos. 7,678,920 and 7,687,634 describe certain pesticidal sulfoximine compounds and U.S. Patent No. 8, 188,292 describes certain pesticidal sulfilimine compounds.
• Some of these sulfoximine and sulfilimine compounds contain a pyridine functional group. It has now been surprisingly discovered that forms of one or more of these compounds where the pyridine functional group has been N-oxidized exhibit pesticidal properties.
• Pyridine N-oxides are commonly prepared from direct oxidation with peracids, such as m-chloroperoxybenzoic acid (mCPBA).
• One embodiment disclosed herein concerns a process for the preparation of certain functionalized pyridine N-oxides including, for example, 2-substituted-5-(l-alkylthio)alkyl- pyridine N-oxides.
• a process is provided for the preparation of a 2-substituted-5-(l-alkylthio)alkyl-pyridine N-oxide according to formula (I),
• L represents a single bond or R 1 , S and L taken together represent a 4-, 5- or 6- membered ring;
• R 1 represents (C1-C4) alkyl
• R 2 and R 3 individually represent hydrogen, methyl, ethyl, flouro, chloro or bromo; n is an integer from 0-3 ;
• Y represents (C1-C4) haloalkyl.
• this process includes condensing an enamine according to formula (II)
• R 1 , R 2 , R 3 , L and n are as previously defined; and R 4 and R 5 independently represent Ci-Cs alkyl, C2-C 8 alkenyl, Ci-Cs arylalkyl, Ci-Cs haloalkyl, Ci-Cs alkoxyalkyl, Ci-Cs alkylaminoalkyl, aryl or heteroaryl, or R 4 and R 5 taken together with N represent a 5- or 6-membered saturated or unsaturated ring;
• X 1 represents halogen, OR 6 , OS0 2 R 6 , SR 6 , SOR 6 , S0 2 R 6 or NR 7 R 8 , where R 6 represents hydrogen, Ci-Cs alkyl, C2-C 8 alkenyl, Ci-Cs arylalkyl, Ci-Cs haloalkyl, Ci-Cs alkoxyalkyl, Ci-Cs alkylaminoalkyl, aryl or heteroaryl, and R 7 and R 8 independently represent hydrogen, Ci-Cs alkyl, C2-C 8 alkenyl, Ci-Cs arylalkyl, Ci-Cs haloalkyl, Ci-Cs alkoxyalkyl, Ci- C 8 alkylaminoalkyl, aryl or heteroaryl or R 7 and R 8 taken together with N represent a 5 -or 6- membered saturated or unsaturated ring;
• R 1 , R 2 , R 3 , R 4 , R 5 , L and n are as previously defined.
• This form of the process further includes cyclizing the intermediate compound according to formula (IV) using an amine nucleophile according to formula (V)
• X 2 represents hydroxyl, alkoxy, cyano, amino or mercaptan, under refluxing conditions to provide a compound according to formula (I).
• this process includes reacting an acetyl chloride compound according to formula (VI)
• R 10 represents C1-C4 alkyl to provide an intermediate compound according to formula (VIII)
• This form of the process further includes condensing the intermediate compound according to formula (VIII) with an enamine according to formula (II)
• R 1 , R 2 , R 3 , L and n are as previously defined;
• R 4 and R 5 independently represent Ci-Cs alkyl, C2-C8 alkenyl, Ci-Cs arylalkyl, Ci-Cs haloalkyl, Ci-Cs alkoxyalkyl, Ci-Cs alkylaminoalkyl, aryl or heteroaryl, or R 4 and R 5 taken together with N represent a 5- or 6-membered saturated or unsaturated ring to provide an intermediate compound according to formula (IV)
• R 1 , R 2 , R 3 , R 4 , R 5 , L and n are as previously defined.
• X 2 represents hydroxyl, alkoxy, cyano, amino or mercaptan, under refluxing conditions to provide a compound according to formula (I).
• L represents a single bond or R 1 , S and L taken together represent a 4-, 5- or 6- membered ring;
• R 1 represents (C 1 -C 4 ) alkyl
• R 2 and R 3 individually represent hydrogen, methyl, ethyl, flouro, chloro or bromo; n is an integer from 0-3 ;
• Y represents (C 1 -C 4 ) haloalkyl is provided.
• alkenyl as used herein, means an acyclic, unsaturated (at least one carbon-carbon double bond), branched or unbranched, substituent consisting of carbon and hydrogen, for example, vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, and decenyl;
• alkoxy means an alkyl further consisting of a carbon-oxygen single bond, for example, methoxy, ethoxy, propoxy, isopropoxy, 1-butoxy, 2-butoxy, isobutoxy, tert-butoxy, pentoxy, 2-methylbutoxy, 1, 1-dimethylpropoxy, hexoxy, heptoxy, octoxy, nonoxy, and decoxy;
• alkyl as used herein, means an acyclic, saturated, branched or unbranched, substituent consisting of carbon and hydrogen, for example, methyl, ethyl, propyl, isopropyl, 1 -butyl, 2-butyl, isobutyl, tert-butyl, pentyl, 2-methylbutyl, 1 , 1 -dimethylpropyl, hexyl, heptyl, octyl, nonyl, and decyl;
• aryl as used herein, means a cyclic, aromatic substituent consisting of hydrogen and carbon, for example, phenyl, naphthyl, and biphenylyl;
• halo as used herein, means fluoro, chloro, bromo, and iodo
• haloalkyl means an alkyl further consisting of, from one to the maximum possible number of, identical or different, halos, for example, fluoromethyl, difluoromethyl, trifluoromethyl, 1 -fluoromethyl, 2-fluoroethyl, 2,2,2-trifluoroethyl, chloromethyl, trichloromethyl, and 1, 1,2,2-tetrafluoroethyl; and
• heteroaryl refers to a 5- or 6-membered aromatic ring containing one or more heteroatoms, viz., N, O or S; these heteroaromatic rings may be fused to other aromatic systems.
• the compounds disclosed herein can exist as one or more stereoisomers.
• the various stereoisomers include geometric isomers, diastereomers and enantiomers.
• the compounds disclosed in this document may include racemic mixtures, individual stereoisomers and optically active mixtures. It will be appreciated by those skilled in the art that one stereoisomer may be more active than the others.
• Individual stereoisomers and optically active mixtures may be obtained by selective synthetic procedures, by conventional synthetic procedures using resolved starting materials or by conventional resolution procedures.
• L represents a single bond or R 1 , S and L taken together represent a 4-, 5- or 6- membered ring;
• R 1 represents (C1-C4) alkyl
• R 2 and R 3 individually represent hydrogen, methyl, ethyl, flouro, chloro or bromo; n is an integer from 0-3; and
• Y represents (C1-C4) haloalkyl is provided.
• R 1 , R 2 , R 3 , L, and n are as previously defined;
• R 4 and R 5 independently represent Ci-Cs alkyl, C2-C 8 alkenyl, Ci-Cs arylalkyl, Ci-Cs haloalkyl, Ci-Cs alkoxyalkyl, Ci-Cs alkylaminoalkyl, aryl, or heteroaryl or R 4 and R 5 taken together with N represent a 5- or 6-membered saturated or unsaturated ring;
• X 1 represents halogen, OR 6 , OS0 2 R 6 , SR 6 , SOR 6 , S0 2 R 6 or NR 7 R 8 , where R 6 represents hydrogen, Ci-Cs alkyl, C2-C 8 alkenyl, Ci-Cs arylalkyl, Ci-Cs haloalkyl, Ci-Cs alkoxyalkyl, Ci-Cs alkylaminoalkyl, aryl or heteroaryl, and R 7 and R 8 independently represent hydrogen, Ci-Cs alkyl, C2-C 8 alkenyl, Ci-Cs arylalkyl, Ci-Cs haloalkyl, Ci-Cs alkoxyalkyl, Ci- C8 alkylaminoalkyl, aryl or heteroaryl, or R 7 and R 8 taken together with N represent a 5 -or 6- membered saturated or unsaturated ring;
• X 2 represents hydroxyl, alkoxy, cyano, amino or mercaptan, under refluxing conditions to provide a compound according to formula (I).
• Enamines according to formula (II) can be conveniently prepared from the addition of a suitably substituted amine to an appropriately substituted aldehyde in the presence of a water adsorbing material, with or without a suitable solvent.
• the appropriately substituted aldehyde is reacted with an anhydrous di-substituted amine at about -20 °C to about 20 °C in the presence of a desiccant such as anhydrous potassium carbonate, and the product is isolated by routine procedures and usually used without further purification.
• a desiccant such as anhydrous potassium carbonate
• the appropriately substituted aldehyde is reacted with pyrrolidine at about -20 °C to about 20 °C in the presence of a desiccant such as anhydrous potassium carbonate, and the resulting product is isolated by routine procedures and usually used without further purification.
• a desiccant such as anhydrous potassium carbonate
• ⁇ , ⁇ -unsaturated ketones according to formula (III) are commercially available or can be prepared from the corresponding vinylogous substrates and acylating agents.
• alkylvinyl ethers can be acylated with haloalkylacetic anhydrides to yield compounds according to formula (III).
• the condensation is conducted at a temperature from about -20 °C to about 35 °C. In another more particular form, temperatures from about -5 °C to about 20 °C are used.
• the condensation of the enamine according to formula (II) with the a, ⁇ -unsaturated ketone according to formula (III) may be conducted in a polar or non-polar solvent, although forms in which it is conducted in solvent-free conditions are also contemplated.
• polar solvents include dichloromethane, tetrahydrofuran, ethyl acetate, acetone, dimethylformamide, acetonitrile, and dimethyl sulfoxide
• non-limiting examples of non- polar solvents include hydrocarbon and aromatic hydrocarbon solvents such as toluene. In one particular but non-limiting form, this condensation is conducted in toluene.
• the a, ⁇ -unsaturated ketone according to formula (III) is added to a preformed mixture of the enamine according to formula (II).
• the enamine according to formula (II) is dissolved in the desired solvent at about -5°C to about 20°C and the a, ⁇ -unsaturated ketone according to formula (III) is continuously added via addition funnel to this solution.
• the mixture is agitated until the enamine according to formula (II) and the a, ⁇ -unsaturated ketone according to formula (III) are consumed.
• a non-polar solvent such as toluene
• the intermediate compound according to formula (IV) can be used as is without further isolation or purification.
• the cyclization of the intermediate compound according to formula (IV) with an amine nucleophile according to formula (V) is performed under refluxing conditions; i.e., at a temperature in the range of 50 °C to 90 °C.
• X 2 may represent hydroxyl, alkoxy, cyano, amino or mercaptan.
• the amine nucleophile used in reaction Scheme A may be present in the form of an acid salt.
• a non-nucleophilic base is also used to neutralize the acid salt analog.
• Non-limiting examples of non-nucleophilic bases include carbonate salts, triethylamine, ⁇ , ⁇ -diisopropylethylamine, and l,8-diazabicycloundec-7-ene.
• X 2 represents hydroxyl
• the compound according to formula (V) is hydroxylamine
• hydroxylamine hydrochloride is used in reaction Scheme A along with triethylamine.
• the cyclization of the intermediate compound according to formula (IV) may be conducted in the same solvent as the condensation of the enamine according to formula (II) and the a, ⁇ -unsaturated ketone according to formula (III).
• This reaction is conducted either in the absence of a solvent, e.g., with excess of the alkyl vinyl ether according to formula (VII), or in the presence of an anhydrous organic solvent.
• suitable solvents are hydrocarbon solvents, including aromatic hydrocarbons such as toluene.
• the reaction may be conducted at a temperature from about -10 °C to about 35 °C. In one particular form, temperatures from about 0 °C to about 20 °C are used.
• the acetyl chloride compound according to formula (VI) is bubbled below the surface of the alkyl vinyl ether compound according to formula (VII), either neat or in the presence of a hydrocarbon solvent, between 0-5 °C.
• the reaction is allowed to warm with stirring for about 1 hour, keeping the temperature no higher than room temperature.
• the crude reaction mixture containing the intermediate compound according to formula (VIII) may be used as is without further isolation or purification of the reaction mixture.
• the intermediate compound according to formula (VIII) is then condensed with an enamine according to formula (II) in the presence of a tertiary amine base to provide an intermediate compound according to formula (IV) where Y represents C1-C4 haloalkyl.
• a tertiary amine base is required in the condensation process; at least one equivalent of tertiary amine base is required with between about 1 and about 2 equivalents being utilized in certain forms.
• This condensation may be conducted at a temperature from about -20 °C to about 35 °C. In one particular form, temperatures from about -5 °C to about 20 °C are utilized.
• This condensation may be conducted in a non-polar or polar aprotic solvent.
• Exemplary non-polar solvents include hydrocarbon solvents and aromatic hydrocarbons.
• Polar aprotic solvents are also a good choice for this chemistry. Either acetonitrile or toluene is used in particular but non-limiting forms.
• the intermediate compound according to formula (VIII) is added to a preformed mixture of the enamine according to formula (II) and a tertiary amine base.
• the enamine according to formula (II) and at least a stoichiometric amount of a tertiary amine base are dissolved in the desired solvent at about - 50 °C to about 200 °C and the intermediate compound according to formula (VIII) is continuously added via addition funnel to this solution.
• the mixture is agitated until the intermediate compound according to formula (VIII) and the enamine according to formula (II) are consumed.
• the intermediate compound according to formula (IV) may be used as is without further isolation or purification. Further details regarding the foregoing steps of the approach of Scheme B are provided in International Patent Publication No. WO
• the 2-substituted-5-(l-alkylthio)alkyl-pyridine N-oxides described herein may be used, for example, in place of corresponding 2-substituted-5-(l-alkylthio)alkyl-pyridine intermediates in the preparation of various N-substituted sulfilimine and sulfoximine pyridine compounds described in, for example, U.S. Patent Nos. 7,678,920, 7,687,634 and 8,188,292, in order to prepare N-substituted sulfilimine or sulfoximine pyridine N-oxide compounds.
• the contents of U.S. Patent Nos. 7,678,920, 7,687,634 and 8,188,292 are hereby incorporated herein by reference in their entirety.
• R 1 , R 2 , R 3 , L, n and Y are as previously defined;
• X 3 is optional and represents O when present
• X 4 represents 0 2 , NCN, NCOOR 9 or NCONH 2 ;
• R 9 represents (C1-C 3 ) alkyl
• Scheme C is representative of the addition of X 4 to a compound according to formula (I) to provide an N-substituted sulfilimine pyridine N-oxide compound, or the addition of both of X 3 and X 4 to a compound according to formula (I) to provide an N-substituted sulfoximine pyridine N- oxide compound.
• preparation of an N-substituted sulfilimine pyridine N-oxide compound where X 4 represents NNO 2 involves the reaction of a compound according to formula (I) with nitramide in the presence of acetic anhydride in Scheme C.
• preparation of an N-substituted sulfilimine pyridine N-oxide compound where X 4 represents NCN involves the oxidation of a compound according to formula (I) with iodobenzene diacetate in the presence of cyanamide in Scheme C. This oxidation can be carried out in a polar aprotic solvent such as CH 2 CI 2 .
• N-substituted sulfoximine pyridine N-oxide compounds according to formula (IX), i.e., where X 3 is present and represents O, may be accomplished by further oxidation of the N-substituted sulfilimine pyridine N-oxide compounds described above.
• an N-substituted sulfilimine pyridine N-oxide compound which includes NCN added by oxidation of a compound according to formula (I) with iodobenzene diacetate in the presence of cyanamide, may be further oxidized with meta- chloroperoxybenzoic acid (mCPBA) in the presence of a base such as potassium carbonate to provide a corresponding N-substituted sulfoximine pyridine N-oxide compound.
• mCPBA meta- chloroperoxybenzoic acid
• This reaction may be carried out in protic polar solvents such as ethanol and water.
• N-oxide compounds according to formula (IX), i.e., where X 3 is present and represents O, may also be accomplished by the stepwise addition of X 3 and X 4 to a compound according to formula (I).
• a compound according to formula (I) may be oxidized with mCPBA in a polar solvent such as dichloromethane below 0 °C to provide a sulfoxide.
• the sulfoxide is subsequently iminated with sodium azide in the presence of concentrated sulfuric acid in an aprotic solvent such as chloroform under heating to provide a sulfoximine.
• this sulfoximine can be either nitrated with nitric acid in the presence of acetic anhydride under mildly elevated temperature, or cyanated with cyanogen bromide in the presence of a base, or carboxylated with alkyl (R 9 ) chloroformate in the presence of base such as 4-dimethylaminopyridine (DMAP) to provide an N-substituted sulfoximine.
• base is required for efficient cyanation and carboxylation and the preferred base is DMAP, whereas sulfuric acid is used as catalyst for efficient nitration reaction.
• N-substituted sulfoximine pyridine N-oxide compounds according to formula (IX) where X 4 represents NCONH 2 can be carried out by acid hydrolyzing a sulfoximine compound according to formula (IX) where NCN has been added, i.e., having the following structur
• Non-limiting examples of acids that may be used in this reaction include sulfuric acid, hydrochloric acid, phosphoric acid, trifluoroacetic acid, and nitric acid.
• the acid hydrolysis reaction is conducted at a temperature from about 50 °C to about 90 °C and at ambient pressure, but the use of higher or lower temperatures and pressures, if desired, is contemplated.
• Non-limiting examples of solvents which can be used in the acid hydrolysis reaction include polar solvents such as dichloromethane, tetrahydrofuran, ethyl acetate, acetone, dimethylformamide, acetonitrile, and dimethyl sulfoxide.
• reaction mixture A small portion of the reaction mixture was purified using preparatory thin layer chromatography by loading 2 mL of the reaction mixture onto a 20 cm by 20 cm plate (1000 microns) and eluting it with a mixture having a ratio of 4: 1 between hexanes and 2-propanol (Rf was about 0.5 to 0.6).
• Rf was about 0.5 to 0.6
• the appropriate band was cut from the plate and extracted off of the silica gel with 20 mL of ethyl acetate. A proton NMR was taken of the best fractions of this separation.
• the reaction mixture was then stirred at room temperature for 12 hours, poured into about 100 mL of water and extracted with three 100 mL volumes of ethyl ether.
• the ether extract was washed with water and saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, filtered and concentrated under vacuum on a rotary evaporator.
• the crude product (6.1 g) was chromatographed on silica gel with a gradient of 100% hexane to 100% ethyl acetate over 20 minutes.
• reaction mixture was analyzed by HPLC using a YMC AQ column (Kyoto, Japan) with a 1.0 mL/min flow rate.
• Acetontitrile (ACN) and water with 0.05% trifluoroacetic acid (TFA) were used as solvents.
• a linear gradient was used starting at 20% ACN/80% water with 0.05% TFA and transitioning to 95% ACN/5% water with 0.05% TFA over 25 minutes.
• the HPLC analysis indicated that the reaction was essentially complete.
• the reaction mixture was then diluted with about 200 mL of ACN and washed with two 100 mL volumes of hexanes to remove the iodobenzene byproduct.

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