Process for producing alpha-ketoamide derivative

Abstract: There is disclosed an efficient process for producing α-ketoacetamide of the formula: which is useful as an intermediate for the production of various alkoxyiminoacetamide compounds to be used for agricultural fungicides. In this process, a corresponding acid halide is condensed with isocyanide to produced the α-ketoacetamide.

Description: The present invention relates to a process for producing α-ketoamide, which is an intermediate for production of alkoxyiminoacetamides useful as agricultural fungicides. Certain kinds of alkoxyimino compounds have been noted because they are known to have excellent fungicidal activities against microorganisms such as Pyricularia oryzae , Rhizoctonia solani , Pseudoperonospora cubensis and the like. Some of the compounds and their production have been known (JP-A 63-23852 and JP-A 63-30463). The present inventors have already filed patent applications (JP-A 3-246268, JP-A 4-89464 and JP-A 4-182461, etc.) on the alkoxyiminoacetamide compound represented by the general formula (V) : wherein A is a hydrogen atom, a halogen atom, alkyl, alkenyl, alkynyl, alkoxy, alkyl halide, alkenyl halide, alkynyl halide, cycloalkyl, cycloalkenyl, optionally substituted phenyl or optionally substituted heterocyclic group, Z is -CH 2 -, -O-, -S-, -CH(OH)-, -CO-, -NR- (wherein R is a hydrogen atom or alkyl), -CH 2 CH 2 -, -CH=CH-, -C≡C-, -CH 2 O-, -CH 2 S-, -CH 2 S(O)-, -OCH 2 -, -SCH 2 -, -S(O)CH 2 - or epoxy, R 2 and R 3 are the same or different and are a hydrogen atom, alkyl or cycloalkyl, R 4 is alkyl or cycloalkyl, ∼ indicates any configuration of the E isomer, Z isomer and the mixture thereof, and processes for producing it. In these processes, the α-ketoamide of the general formula (III): wherein each symbol is as defined above, is important as a common intermediate for the production of various alkoxyiminoacetamide compounds (V). For example, EP-A 398692 discloses a process for producing the α-ketoamide shown in the following scheme: wherein R a is, for example, lower alkyl, R b , R c and R d are the same meaning as R 2 , R 3 and R 4 , respectively. However, this process employs as the starting material an α-ketocarboxylic acid ester which can be prepared with difficulty. Therefore, an improved production process thereof has been required by which not only the compound (III) but also its starting material can be produced economically and efficiently. Chem. Ber. 94, 1961, 1116-1121 discloses the reaction of acyl halides with specific isocyanides followed by hydrolysis in the presence of bases or organic acids. The main object of the present invention is to provide a process for producing an intermediate for the production of an alkoxyiminoacetamide compound which is useful as agricultural fungicides. The present inventors have paid attention to usefulness of α-ketoamide of the general formula (III) as the common intermediate and have studied its production. As a result, it has been found that the ketoamide can efficiently be obtained by subjecting the corresponding acid halide to condensation with isocyanide followed by hydrolysis. That is, according to the present invention, there is provided a process for producing α-ketoamide of the general formula (III): wherein A is a hydrogen atom, a halogen atom, alkyl, alkenyl, alkynyl, alkoxy, alkyl halide, alkenyl halide, alkynyl halide, cycloalkyl, cycloalkenyl, optionally substituted phenyl or optionally substituted heterocyclic group, Z is -CH 2 -, -O-, -S-, -CH(OH)-, -CO-, -NR- (wherein R is a hydrogen atom or alkyl), -CH 2 CH 2 -, -CH=CH-, -C≡C-, -CH 2 O-, -CH 2 S-, -CH 2 S(O)-, -OCH 2 -, -SCH 2 -, -S(O)CH 2 - or epoxy, R 1 is methyl, which comprises subjecting the acid halide of the general formula (I): wherein X is a halogen atom and the other symbols are as defined above, to condensation with an isocyanide of the formula (II): R 1 -NC wherein R 1 is as defined above, followed by hydrolysis in the presence of a mineral acid, wherein said ccndensation reaction is carried out: (a) in the presence of an inert solvent or in the absence of a solvent, (b) at a reaction temperature of from 20° to 80°C, and (c) the alkyl isocyanide (II) is used in an amount of 1 to 2 mole per 1 mole of the acid halide of formula (I). In the production process of the present invention, preferably, the acid halide of the general formula (I) is obtained by halogenating the carboxylic acid of the general formula (IV): wherein each symbol is as defined above. Examples of the alkyl represented by A, R, R 2 , R 3 and R 4 in the above formula include alkyl having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl and the like. Examples of the alkenyl represented by A include alkenyl having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, for example, vinyl, allyl, crotyl and the like. Examples of the alkynyl represented by A include alkynyl having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, for example, propargyl, ethynyl, butynyl and the like. Examples of the alkoxy represented by A include alkoxy having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, for example, methoxy, ethoxy, propoxy, isopropoxy and the like. Examples of the cycloalkyl represented by A, R 1 , R 2 , R 3 and R 4 include cycloalkyl having 3 to 7 carbon atoms, for example, cyclopropyl, cyclopentyl, cyclohexyl and the like. Examples of the cycloalkenyl represented by A include cycloalkenyl having 3 to 7 carbon atoms, for example, cyclopentenyl, cyclohexenyl and the like. The heterocycle in the heterocyclic group represented by A includes 5 or 6 membered heterocycles containing at least one hetero atom selected from the group consisting of nitrogen, oxygen and sulfur. The heterocycle may form a condensed ring with a benzene ring. Examples of the heterocycles include a pyridine ring, pyrimidine ring, pyrazine ring, thiazole ring, benzothiazole ring, benzofuran ring, benzothiophene ring, oxazole ring, benzoxazole ring, isoxazole ring, pyrazole ring, imidazole ring, quinoline ring and the like. The phenyl represented by A and the above heterocyclic group is non-substituted or substituted with substituent(s) selected from alkyl, alkenyl, alkynyl, alkoxy, alkyl halide, alkynyl halide, cycloalkyl, cycloalkenyl, optionally substituted phenyl, optionally substituted heterocyclic group and a halogen atom. Examples of the alkyl, alkenyl, alkynyl, alkoxy, alkyl halide, alkynyl halide, cycloalkyl, cycloalkenyl, optionally substituted phenyl, optionally substituted heterocyclic group and halogen atom include the same alkyl, alkenyl, alkynyl, alkoxy, alkyl halide, alkynyl halide, cycloalkyl, cycloalkenyl, optionally substituted phenyl and optionally substituted heterocyclic group as those represented by A, respectively. When the phenyl or heterocyclic group represented by A is substituted, the number of the substituent is preferably 1 to 3 and the substituents are the same or different. The substituent may be at any possible position on the ring. Examples of the halogen atom represented by A and X include fluorine, chlorine, bromine and iodine. The alkyl halide, alkenyl halide and alkynyl halide represented by A means the alkyl, alkenyl and alkynyl described above which are substituted with at least one halogen atom described above, respectively. In the production process of the present invention, the α-ketoamide of the formula (III) can be produced, for example, according to the reactions shown in Scheme 1: wherein each symbol is as defined above. That is, the carboxylic acid (IV) is halogenated with a halogenating agent in an amount of 1 to 2 mol, preferably 1.1 to 1.2 mol per 1 mol of the carboxylic acid (IV) to obtain the corresponding acid halide (I). Examples of the halogenating agent include thionyl halide (e.g. thionyl chloride, thinyl bromide), phosphoryl halide (e.g. phosphoryl chloride), phosgene and the like. Examples of the solvent include hydrocarbons (e.g. benzene, toluene), halogenated hydrocarbons (e.g. chloroform, carbon tetrachloride, methylene chloride, 1,2-dichloroethane) and the like. The reaction temperature is 0 to 100°C, preferably 0 to 80°C. The reaction time is 0.5 to 3 hours, preferably 0.5 to 1 hours. Next, the acid halide (I) thus obtained is subjected to a condensation reaction with the isocyanide (II). This reaction is carried out in the absence of a solvent or in an inert solvent such as hydrocarbons (e.g. benzene, toluene), halogenated hydrocarbons (e.g. dichloromethane, 1,2-dichloroethane), ethers (e.g. diethyl ether, tetrahydrofuran), ketones (e.g. acetone) and the like. The reaction temperature is 20 to 80°C. The reaction time is preferably 1 to 10 hours. The alkyl isocyanide (II) is used in an amount of 1 to 2 mol, more preferably 1.1 to 1.2 mol per 1 mol of the acid halide (I). The isocyanide (II) can be prepared according to known methods, for example, the method described in Angew. Chem. Internat. Edit., vol. 4, No. 6, 472-484 (1965). The isolation of the isocyanide (II) used in the condensation is not always required before use. The preparation of the isocyanide (II) according to, for example, the above known method and the condensation can be carried out in one-pot. For example, an alkylformamide (e.g. N-methylformamide) is reacted with phosgene, its dimer (e.g. trichloromethylchloroformate) or its trimer in the presence of a base (e.g. triethyl amine) in an inert solvent (e.g. toluene) to obtain isocyanide (II). The acid halide (I) is added to the reaction mixture containing the resulting isocyanide (II). Then, hydrolysis is carried out in the presence of a mineral acid to provide the desired α-ketoamide (III). Examples of mineral acids for hydrolysis include hydrochloric acid, sulfuric acid, nitric acid. The hydrolysis is preferably carried out at 0 to 100°C for 1 to 20 hours. If necessary, a hydrophilic solvent (e.g., acetone, tetrahydrofuran) is added for the hydrolysis. The α-ketoamide (III) obtained according to Scheme 1 above is subjected to conventional separation and purification techniques to obtain the crude or purified product. The product can be used after conversion into, for example, an oxime for the production of the above alkoxyiminoacetamide (V) which is useful as agricultural fungicides, for example, (E)-2-(2-phenoxyphenyl)-2-methoxyimino-N-methylacetamide useful as fungicides for paddy fields, (E)-2-[2-(2,5-dimethylphenoxymethyl)phenyl]-2-methoxyimino-N-methylacetamide useful as fungicides for vegetables and fruit trees. According to the present invention, the α-ketoacetamide (III) can be obtained efficiently which is highly useful as a common intermediate for the production of various alkoxyiminoacetamide compounds (V) available as agricultural fungicides. The following examples and a reference example further illustrate the present invention in detail but are not to be construed to limit the scope thereof. Example 1 Preparation of N-methyl-2-(2-tolyl)-2-oxoacetamide Methyl isocyanide (0.84 ml) was added to 2-methylbenzoyl chloride (1.55 g). The mixture was stirred at 60°C for 16 hours. Then, 5N hydrochloric acid (1.5 ml) and acetone (2 ml) were added, and the mixture was stirred at room temperature for 1.5 hours for hydrolysis. Then, water was added. The mixture was extracted with methylene chloride, washed with water and dried. The solvent was evaporated under reduced pressure to obtain the title compound as an oil (1.68 g). 1 H-NMR (in CDCl 3 , δ ppm): 2.49 (3H, s), 2.98 (3H, d, J=5.1Hz), 7.06 (1H, brs), 7.26-7.31 (2H, m), 7.43 (1H, td, J=7.4,1.7Hz), 7.92 (1H, dd, J=8.5,1.7Hz). Reference Example 1 Preparation of 2-(2,5-dimethylphenoxymethyl)benzoic acid An aqueous solution (200 ml) of phthalide (134 g) and sodium hydroxide (40 g) was heated. After stirring for 1 hour, the mixture was concentrated under reduced pressure for removal of water to obtain sodium 2-hydroxymethylbenzoate as colorless crystals. p-Cymene (480 ml) and 2,5-xylenol (122 g) were added to the crystals. xzeotropic dehydration was carried out with heating under reflux for 7 hours by using an azeotropic dehydration apparatus. After cooling, ice water was added. Concentrated hydrochloric acid was added dropwise to make the mixture acidic. The precipitates were separated by filtration and recrystallized from ethyl acetate to obtain the title compound (155 g, Yield: 60.5%), mp: 162-163°C. 1 H-NMR (in CDCl 3 , δ ppm): 5.51 (2H, s), 6.71 (1H, d, J=7.3Hz), 7.06 (1H, d, J=7.3Hz), 7.42 (1H, t, J=7.7Hz), 7.63 (1H, td, J=7.7,1.5Hz), 7.88 (1H, d, J=7.7Hz), 8.15 (1H, dd, J=7.7,1.5Hz), 2.31 (6H, s). Example 2 Preparation of N-methyl-2-(2-phenoxyphenyl)-2-oxoacetamide N-Methylformamide (2.36 g, 40.0 mmol) and triethyl amine (8.08 g, 80.0 mmol) were dissolved in toluene (40 ml). Trichloromethylchloroformate (3.96 g, 20.0 mmol) was added dropwise slowly under ice-cooling while maintaining the inner temperature at 10°C or lower. The mixture was stirred at the same temperature for 1 hour. A large amount of insoluble materials were precipitated. To the mixture was added 2-phenoxybenzoyl chloride which was prepared from 2-phenoxybenzoic acid (4.28 g, 20.0 mmol) and thionyl chloride (2.86 g, 24.0 mmol). The resulting mixture was stirred at bath temperature of 40 to 50°C for 26 hours. 5N-Hydrochloric acid (12 ml) and acetone (20 ml) were added, and the mixture was stirred for 12 hours. Water was added to the mixture, which was then extracted with toluene and purified by column chromatography on silica gel to obtain the title compound (3.11 g, Yield: 61.0%). Preferably the alkoxyiminoacetamide produced from using the process of this invention has the general formula (VI) wherein A is a hydrogen atom, a halogen atom, alkyl, alkenyl, alkynyl, alkoxy, alkyl halide, alkenyl halide, alkynyl halide, cycloalkyl, cycloalkenyl, optionally substituted phenyl or optionally substituted heterocyclic group, Z¦ is -CH 2 -,-O-, -S-, -CH(OH)-, -CO-, -NR- (wherein R is a hydrogen atom or alkyl), -CH 2 CH 2 -, -CH=CH-, C≡C-, -CH 2 O-, CH 2 S-, - CH 2 S(O)-, -OCH 2 -, -SCH 2 -, -S(O)CH 2 - or epoxy, R 2 is a hydrogen atom and R 3 is methyl, R 4 is alkyl or cycloalkyl, ∼ indicates any configuration of the E isomer, Z isomer and the mixture thereof, especially (E)-2-(2-phenoxy-phenyl)-2-methoxyimino-N-methylacetamide useful as a fungicide for vegetables and fruit trees.

Claims: A process for producing an α-ketoamide of formula (III): wherein A is a hydrogen atom, a halogen atom, alkyl, alkenyl, alkynyl, alkoxy, alkyl halide, alkenyl halide, alkynyl halide, cycloalkyl, cycloalkenyl, optionally substituted phenyl or optionally substituted heterocyclic group, Z is -CH 2 -, -O-, -S-, -CH(OH)-,-CO-, -NR- (wherein R is a hydrogen atom or alkyl),-CH 2 CH 2 -, -CH=CH-, -C≡C-, -CH 2 O-, -CH 2 S-, - CH 2 S(O)-,-OCH 2 -, -SCH 2 -, -S(O)CH 2 - or epoxy, and R 1 is methyl, which process comprises subjecting an acid halide of the formula (I): wherein X is a halogen atom and the other symbols are as defined above, to a condensation reaction with an alkyl isocyanide of the formula (II): R 1 -NC wherein R 1 is as defined above, followed by hydrolysis in the presence of a mineral acid, wherein said condensation reaction is carried out: (a) in the presence of an inert solvent or in the absence of a solvent, (b) at a reaction temperature of from 20° to 80°C, and (c) the alkyl isocyanide (II) is used in an amount of 1 to 2 mole per 1 mole of the acid halide of formula (I). A process according to claim 1, wherein the acid halide represented by the formula (I) is obtained by halogenating a carboxylic acid of the formula (IV): wherein each symbol is as defined in claim 1 with the halogenation being preferably carried out for 0.5 to 1 hour. A process according to claim 1 or claim 2, wherein A-Z- is phenoxy or 2,5-dimethylphenoxymethyl. A process according to any one of the preceding claims, wherein the amount of the isocyanide of the formula (II) to be used is 1.1 to 1.2 mol per 1 mol of the acid halide of the formula (I). A process according to claim 2, wherein the halogenating agent is a thionyl halide, phosphoryl halide or phosgene. A process according to claim 2 or claim 5, wherein the amount of the halogenating agent to be used is 1.1 to 1.2 mol per 1 mol of the carboxylic acid of the formula (IV). A process according to claim 2, claim 5 or claim 6, wherein the halogenation is carried out for 0.5 to 1 hour. A process as claimed in any one of the preceding claims wherein the hydrolysis is effected in the presence of a hydrochloric acid, sulfuric acid or nitric acid. A process as claimed in any one of the preceding claims, wherein the resulting α-ketoamide of formula (III) is further reacted to provide an alkoxyiminoacetamide having the general formula (VI): wherein A is a hydrogen atom, a halogen atom, alkyl, alkenyl, alkynyl, alkoxy, alkyl halide, alkenyl halide, alkynyl halide, cycloalkyl, cycloalkenyl, optionally substituted phenyl or optionally substituted heterocyclic group, Z¦ is -CH 2 -,-O-, -S-, -CH(OH)-, -CO-, -NR- (wherein R is a hydrogen atom or alkyl), -CH 2 CH 2 -, -CH=CH-, C≡C-, -CH 2 O-, CH 2 S-, -CH 2 S(O)-, -OCH 2 -, -SCH 2 -, -S(O)CH 2 - or epoxy, R 2 is a hydrogen atom and R 3 is methyl, R 4 is alkyl or cycloalkyl, ∼ indicates any configuration of the E isomer, Z isomer and the mixture thereof. A process as claimed in claim 9, wherein the α-ketoamide of formula (III) provides the compound of general formula (VI) which is (E)-2-(2-phenoxy-phenyl)-2-methoxyimino-N-methylacetamide useful as a fungicide for vegetables and fruit trees.

Inventors: KAI HIROYUKI, MURABAYASHI AKIRA, TAKENAKA HIDEYUKI, KAI, HIROYUKI, MURABAYASHI, AKIRA, TAKENAKA, HIDEYUKI
Applicants: SHIONOGI & CO, SHIONOGI SEIYAKU KABUSHIKI KAISHA
Application year: 1992
Main classification: C07C235
IPC codes: C07C317, C07C235, C07C323, C07C231