Process for the preparation of 2-aryl-5-(perfluoroalkyl)pyrrole compounds from N-[1-chloro-1-(perfluoroalkyl)methyl]arylimidoyl chloride compounds

Abstract: There is provided a process for the preparation of 2-aryl-5-(perfluoroalkyl)pyrrole compounds of formula I from N-[1-chloro-1-(perfluoroalkyl)methyl]arylimidoyl chloride compounds. The 2-aryl-5-(perfluoroalkyl)pyrrole compounds are useful for the control of insect and acarid pests, and may also be used to prepare other pesticidal arylpyrrole compounds. In addition, the present invention provides compounds which are useful as intermediates in the preparation of arylpyrrole compounds.

Description: BACKGROUND OF THE INVENTION 2-Aryl-5-(perfluoroalkyl)pyrrole compounds are useful as insecticidal and acaricidal agents. In addition, those compounds are also useful for the preparation of other insecticidal and acaricidal agents. In particular, 2-aryl-5-(perfluoroalkyl)pyrrole compounds are key intermediates in the preparation of arylpyrrole compounds such as chlorfenapyr. Accordingly, there is an ongoing search to discover new methods for the preparation of 2-aryl-5-(perfluoroalkyl)pyrrole compounds. The prior art discloses that 2-aryl-5-(trifluoromethyl)pyrrole compounds may be prepared by reacting an N-(substituted benzyl)-2,2,2-trifluoro-acetimidoyl chloride compound with an α-halo-α,β-unsaturated nitrile, ester or nitro compound in the presence of a base. However, the prior art process is not entirely satisfactory because the required α-halo-α,β-unsaturated nitrile, ester or nitro compound is prepared in a two step -halogenation/dehydrohalogenation - process. The prior art also discloses that 2-aryl-5-(trifluoromethyl)pyrrole compounds may be obtained in several steps from the appropriate aldehyde. These processes require the use of an aminonitrile intermediate which is obtained via the Strecker synthesis from the appropriate aldehyde. However, the use of the Strecker synthesis is not entirely satisfactory because of cyanide containing waste streams. It is, therefore, an object of the present invention to provide a new process for the preparation of 2-aryl-5-(perfluoroalkyl)pyrrole compounds which avoids the use of α-halo-α,β-unsaturated nitrile, ester and nitro compounds and the Strecker synthesis. It is also an object of this invention to provide a new process for the preparation of arylpyrrole compounds such as chlorfenapyr. A further object of the present invention is to provide new intermediate compounds which are useful in the processes described hereinbelow. Those and other objects of the present invention will become more apparent from the detailed description thereof set forth below. SUMMARY OF THE INVENTION The present invention provides a new process for the preparation of 2-aryl-5-(perfluoroalkyl)pyrrole compounds having the structural formula I wherein W is hydrogen or C m F 2m+1 ; Y is CN, NO 2 or CO 2 R; R is C 1 -C 4 alkyl; m and n are each independently an integer of 1, 2, 3, 4, 5, 6, 7 or 8; A is L is hydrogen or halogen; M and Q are each independently hydrogen, halogen, CN, NO 2 , C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 1 -C 4 alkoxy, C 1 -C 4 haloalkoxy, C 1 -C 4 alkylthio, C 1 -C 4 haloalkylthio, C 1 -C 4 alkylsulfinyl, C 1 -C 4 haloalkylsulfinyl, C 1 -C 4 alkylsulfonyl, C 1 -C 4 haloalkylsulfonyl with the proviso than M cannot be hydrogen, or when M and Q are on adjacent positions they may be taken together with the carbon atoms to which they are attached to form a ring in which MQ represents the structure -OCH 2 O-, -OCF 2 O- or -CH=CH-CH=CH-; R 1 , R 2 and R 3 are each independently hydrogen, halogen, NO 2 , CHO or R 2 and R 3 may be taken together with the atoms to which they are attached to form a ring in which R 2 R 3 is represented by the structure R 4 , R 5 , R 6 and R 7 are each independently hydrogen, halogen, CN or NO 2 ; and X is O or S, which process comprises reacting an N-[1-chloro-1-(perfluoroalkyl)methyl]arylimidoyl chloride compound having the structural formula II wherein A and n are as described above with a dieneophile compound having the structural formula III wherein W and Y are as described above and a base in the presence of a solvent. The present invention further provides novel compounds having the structural formulas II, IV and V and wherein n and A are as described hereinabove. DETAILED DESCRIPTION OF THE INVENTION The process of the present invention preferably comprises reacting an N-[1-chloro-1-(perfluoroalkyl)methyl]arylimidoyl chloride compound of formula II with at least about one molar equivalent, preferably about one to four molar equivalents, of a dienophile compound of formula III and at least about one molar equivalent, preferably about one to four molar equivalents, of a base in the presence of a solvent preferably at a temperature range of about 5°C to 100°C to form 2-aryl-5-(perfluoroalkyl)pyrrole compounds of formula I. . Alternatively, the formula I compounds may be prepared by forming the formula III dienophile compounds in situ . This process comprises reacting an N-[1-chloro-1-(perfluoroalkyl)methyl]arylimidoyl chloride compound of formula II with preferably about one to four molar equivalents of a substituted haloethane compound having the structural formula VI wherein W and Y are as described hereinabove and Z is Cl, Br or I, and at least about two molar equivalents, preferably about two to five molar equivalents, of a base in the presence of a solvent preferably at a temperature range of about 5°C to 100°C to form 2-aryl-5-(perfluoroalkyl)pyrrole compounds of formula I. Advantageously, the present invention provides new processes for the preparation of 2-aryl-5-(perfluoroalkyl)pyrrole compounds which avoid the use of α-halo-α,β-unsaturated nitrile, ester and nitro compounds and the Strecker synthesis. The formula I compounds of this invention may be isolated by conventional procedures such as dilution of the reaction mixture with water and filtration or, alternatively, extraction with a suitable solvent. Suitable extraction solvents include water-immiscible solvents such as ether, ethyl acetate, toluene, methylene chloride and the like. Bases suitable for use in this invention include tri-(C 1 -C 6 alkyl)amines such as trimethylamine, triethylamine, tripropylamine, tributylamine, diisopropylethylamine and the like; alkali metal carbonates such as potassium carbonate and sodium carbonate; alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; alkali metal acetates such as potassium acetate and sodium acetate; and heterocyclic tertiary amines including, but not limited to, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU); 1,5-diazabicyclo[4.3.0]non-5-ene (DBN); 1,4-diazabicyclo[2.2.2]octane; pyridine; substituted pyridines such as 2,6-dimethylpyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine and the like; quinoline; and substituted quinolines. Preferred bases include tri-(C 1 -C 6 alkyl) amines, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, 1,4-diazabicyclo[2.2.2]octane, potassium carbonate and sodium carbonate. Solvents suitable for use in the present invention include, but are not limited to, carboxylic acid amides such as N,N-dimethylformamide, N,N-dimethylacetamide and the like; N-substituted pyrrolidinones such as N-methylpyrrolidinone and the like; nitriles such as acetonitrile, propionitrile and the like; halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride and the like; ethers such as tetrahydrofuran, dioxane and the like; sulfoxides such as dimethyl sulfoxide and the like; and mixtures thereof. Preferred solvents include carboxylic acid amides and nitriles and mixtures thereof. N,N-dimethylformamide and acetonitrile and mixtures thereof are especially preferred for use in the present invention. Exemplary of halogen hereinabove are fluorine, chlorine, bromine and iodine. The terms "C 1 -C 4 haloalkyl", "C 1 -C 4 haloalkoxy", "C 1 -C 4 haloalkylthio", "C 1 -C 4 haloalkylsulfinyl" and "C 1 -C 4 haloalkylsulfonyl" are defined as a C 1 -C 4 alkyl, C 1 -C 4 alkoxy, C 1 -C 4 alkylthio, C 1 -C 4 alkylsulfinyl or C 1 -C 4 alkylsulfonyl group substituted with one or more halogen atoms, respectively. When used herein the term alkyl, used as a group or part of a group, includes straight and branched alkyl groups, e.g. methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl and t-butyl. When used herein the term haloalkyl, used as a group or part of a group, includes straight and branched haloalkyl groups, e.g. trifluoromethyl and trichloromethyl. Moiety A is preferably 4-chlorophenyl, 4-bromophenyl, 3,5-dichloro-phenyl, 3,4,5-trichlorophenyl or 4-trifluoromethylphenyl. The present invention is especially useful for the preparation of formula I compounds wherein W is hydrogen; Y is CN; n is 1 or 2; A is L is hydrogen or halogen; and M and Q are each independently hydrogen, halogen, C 1 -C 4 haloalkyl or C 1 -C 4 haloalkoxy, with the proviso that M is not hydrogen. In particular, the present invention is useful for the preparation of 2-( p -chlorophenyl)-5-(trifluoromethyl)pyrrole-3-carbonitrile; 2-( p -bromophenyl)-5-(trifluoromethyl)pyrrole-3-carbonitrile; 2-(3,5-dichlorophenyl)-5-(trifluoromethyl)pyrrole-3-carbonitrile; 2-(3,4,5-trichlorophenyl)-5-(trifluoromethyl)pyrrole-3-carbonitrile; and 2-[4-(trifluoromethyl)phenyl]-5-(trifluoromethyl)pyrrole-3-carbonitrile, among others. The present invention also relates to N-[1-chloro-1-(perfluoroalkyl)methyl]arylimidoyl chloride compounds having the structural formula II wherein n is an integer of 1, 2, 3, 4, 5, 6, 7 or 8; A is L is hydrogen or halogen; M and Q are each independently hydrogen, halogen, CN, NO 2 , C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 1 -C 4 alkoxy, C 1 -C 4 haloalkoxy, C 1 -C 4 alkylthio, C 1 -C 4 haloalkylthio, C 1 -C 4 alkylsulfinyl, C 1 -C 4 haloalkylsulfinyl, C 1 -C 4 alkylsulfonyl, C 1 -C 4 haloalkylsulfonyl with the proviso that M cannot represent hydrogen or when M and Q are on adjacent positions they may be taken together with the carbon atoms to which they are attached to form a ring in which MQ represents the structure -OCH 2 O-, -OCF 2 O- or -CH=CH-CH=CH-; R 1 , R 2 and R 3 are each independently hydrogen, halogen, NO 2 , CHO or R 2 and R 3 may be taken together with the atoms to which they are attached to form a ring in which R 2 R 3 is represented by the structure R 4 , R 5 , R 6 and R 7 are each independently hydrogen, halogen, CN or NO 2 ; and X is O or S. Preferred formula II compounds of this invention are those wherein n is 1 or 2; A is L is hydrogen or halogen; and M and Q are each independently halogen, C 1 -C 4 haloalkyl or C 1 -C 4 haloalkoxy. Formula II compounds which are particularly useful in the processes of this invention include N-[1-chloro-(2,2,2-trifluoroethyl)]-4-chlorobenzimidoyl chloride; N-[1-chloro-(2,2,2-trifluoroethyl)]-4-bromobenzimidoyl chloride; N-[1-chloro-(2,2,2-trifluoroethyl)]-3,5-dichlorobenzimidoyl chloride; N-[1-chloro-(2,2,2-trifluoroethyl)]-3,4,5-trichlorobenzimidoyl chloride; and N-[1-chloro-(2,2,2-trifluoroethyl)]-4-(trifluoromethyl)benzimidoyl chloride, among others. Starting N-[1-chloro-1-(perfluoroalkyl)methyl]arylimidoyl chloride compounds of formula II may be prepared, as shown in Flow Diagram I, by reacting an arylamide compound having the structural formula VII with a (perfluoroalkyl)aldehyde C 1 -C 6 alkyl hemiacetal compound having the structural formula VIII to form an N-[1-hydroxy-1-(perfluoroalkyl)methyl]arylamide compound having the structural formula IV, and reacting the formula IV compound with phosphorus pentachloride. Alternatively, N-[1-chloro-1-(perfluoroalkyl)methyl]arylimidoyl chloride compounds of formula II may be prepared, as shown in Flow Diagram II, by reacting an N-[1-hydroxy-1-(perfluoroalkyl)methyl]arylamide of formula IV with phosphorus trichloride to form an N-[1-chloro-1-(perfluoroalkyl)methyl]arylamide compound having the structural formula V, and reacting the formula V compound with phosphorus pentachloride. The present invention also relates to the formula IV and V compounds which are used to prepare the formula II compounds. In particular, the present invention provides N-[1-hydroxy-1-(perfluoroalkyl)methyl]arylamide compounds having the structural formula IV and N-[1-chloro-1-(perfluoroalkyl)methyl]arylamide compounds having the structural formula V and wherein n is an integer of 1, 2, 3, 4, 5, 6, 7 or 8; A is L is hydrogen or halogen; M and Q are each independently hydrogen, halogen, CN, NO 2 , C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 1 -C 4 alkoxy, C 1 -C 4 haloalkoxy, C 1 -C 4 alkylthio, C 1 -C 4 haloalkylthio, C 1 -C 4 alkylsulfinyl, C 1 -C 4 haloalkylsulfinyl, C 1 -C 4 alkylsulfonyl, C 1 -C 4 haloalkylsulfonyl with the proviso that M cannot represent hydrogen or when M and Q are on adjacent positions they may be taken together with the carbon atoms to which they are attached to form a ring in which MQ represents the structure -OCH 2 O-, -OCF 2 O- or -CH=CH-CH=CH-; R 1 , R 2 and R 3 are each independently hydrogen, halogen, NO 2 , CHO or R 2 and R 3 may be taken together with the atoms to which they are attached to form a ring in which R 2 R 3 is represented by the structure R 4 , R 5 , R 6 and R 7 are each independently hydrogen, halogen, CN or NO 2 ; and X is O or S. Preferred formula IV and V compounds of this invention are those wherein n is 1 or 2; A is L is hydrogen or halogen; and M and Q are each independently halogen, C 1 -C 4 haloalkyl or C 1 -C 4 haloalkoxy. Formula IV compounds which are particularly useful for the preparation of arylpyrrole compounds include N-(1-hydroxy-2,2,2-trifluoroethyl)-4-chlorobenzamide; N-(1-hydroxy-2,2,2-trifluoroethyl)-4-bromobenzamide; N-(1-hydroxy-2,2,2-trifluoroethyl)-3,5-dichlorobenzamide; N-(1-hydroxy-2,2,2-trifluoroethyl)-3,4,5-trichlorobenzamide; and N-(1-hydroxy-2,2,2-trifluoroethyl)-4-(trifluoromethyl)-benzamide, among others. Formula V compounds which are particularly useful for the preparation of arylpyrrole compounds include N-(1-chloro-2,2,2-trifluoroethyl)-4-chlorobenzamide; N-(1-chloro-2,2,2-trifluoroethyl)-4-bromobenzamide; N-(1-chloro-2,2,2-trifluoroethyl)-3,5-dichlorobenzamide; N-(1-chloro-2,2,2-trifluoroethyl)-3,4,5-trichlorobenzamide; and N-(1-chloro-2,2,2-trifluoroethyl)-4-(trifluoromethyl)-benzamide, among others. The formula I compounds are useful for the control of insect and acarid pests. In addition, the formula I compounds may be used to prepare other arylpyrrole insecticidal and acaricidal agents having the structural formula IX wherein Y is CN, NO 2 or CO 2 R; R is C 1 -C 4 alkyl; n is an integer of 1, 2, 3, 4, 5, 6, 7 or 8; A is L is hydrogen or halogen; M and Q are each independently hydrogen, halogen, CN, NO 2 , C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 1 -C 4 alkoxy, C 1 -C 4 haloalkoxy, C 1 -C 4 alkylthio, C 1 -C 4 haloalkylthio, C 1 -C 4 alkylsulfinyl, C 1 -C 4 haloalkylsulfinyl, C 1 -C 4 alkylsulfonyl, C 1 -C 4 haloalkylsulfonyl or when M and Q are on adjacent positions they may be taken together with the carbon atoms to which they are attached to form a ring in which MQ represents the structure -OCH 2 O-, -OCF 2 O- or -CH=CH-CH=CH-; R 1 , R 2 and R 3 are each independently hydrogen, halogen, NO 2 , CHO or R 2 and R 3 may be taken together with the atoms to which they are attached to form a ring in which R 2 R 3 is represented by the structure R 4 , R 5 , R 6 and R 7 are each independently hydrogen, halogen, CN or NO 2 ; X is O or S; Hal is a halogen atom; and J is hydrogen or C 1 -C 6 alkoxymethyl. The present invention is especially useful for the preparation of arylpyrrole compounds of formula IX wherein Y is CN; n is 1 or 2; A is L is hydrogen or halogen; M and Q are each independently hydrogen, halogen, C 1 -C 4 haloalkyl or C 1 -C 4 haloalkoxy, with the proviso that M is not hydrogen; Hal is Br or Cl; and J is hydrogen or ethoxymethyl. In particular, the present invention is useful for the preparation of formula IX arylpyrrole compounds such as 4-bromo-2-( p -chlorophenyl)-1-(ethoxymethyl)-5-(trifluoromethyl)pyrrole-3-carbonitrile, (chlorfenapyr); 4-bromo-2-(3,5-dichlorophenyl)-1-(ethoxymethyl)-5-(trifluoromethyl)pyrrole-3-carbonitrile; 4-bromo-2-(3,5-dichlorophenyl)-5-(trifluoromethyl)pyrrole-3-carbonitrile; and 4-bromo-2-( p -chlorophenyl)-5-(trifluoromethyl)pyrrole-3-carbonitrile, among others. Advantageously, formula IX arylpyrrole compounds may be prepared by a process which comprises: (a) reacting an N-[1-chloro-1-(perfluoroalkyl)methyl]arylimidoyl chloride compound of formula II with a dienophile compound having the structural formula X wherein Y is as described above and a base in the presence of a solvent to form a 2-aryl-5-(perfluoroalkyl)pyrrole compound having the structural formula XI (b) halogenating the formula XI compound to form the arylpyrrole compound of formula IX wherein J is hydrogen; and (c) optionally alkoxymethylating the formula IX compound wherein J is hydrogen to form the formula IX arylpyrrole compound wherein J is C 1 -C 6 alkoxymethyl. Alternatively, arylpyrrole compounds of formula IX may be prepared by a process which comprises: (a) reacting an N-[1-chloro-1-(perfluoroalkyl)methyl]arylimidoyl chloride compound of formula II with a substituted haloethane compound having the structural formula XII wherein Y is as described above and Z is Cl, Br or I, and at least about two molar equivalents of a base in the presence of a solvent to form a 2-aryl-5-(perfluoroalkyl)pyrrole compound having the structural formula XI (b) halogenating the formula XI compound to form the arylpyrrole compound of formula IX wherein J is hydrogen; and (c) optionally alkoxymethylating the formula IX compound wherein J is hydrogen to form the formula IX arylpyrrole compound wherein J is C 1 -C 6 alkoxymethyl. Halogenation methods may be any known methods such as those described in U.S. Pat. Nos. 5,010,098 and 5,449,789. Alkoxymethylation procedures suitable for use in this invention include conventional procedures known in the art (see, e.g., U.S. Pat. Nos. 5,010,098 and 5,359,090). In a preferred embodiment of this invention, the alkoxymethylation procedure comprises reacting a formula IX compound wherein J is hydrogen with a di-(C 1 -C 6 alkoxy)methane compound, N,N-dimethylformamide and phosphorous oxychloride in the presence of an aprotic solvent to form a reaction mixture and treating the reaction mixture with a tertiary amine. In order to facilitate a further understanding of this invention, the following examples are presented primarily for the purpose of illustrating more specific details thereof. The scope of the invention should not be deemed limited by the examples, but encompasses the entire subject matter defined in the claims. EXAMPLE 1 Preparation of N-(1-Hydroxy-2,2,2-trifluoroethyl)-4-chlorobenzamide A solution of 4-chlorobenzamide (22.0 g, 0.141 mol) and trifluoroacetaldehyde ethyl hemiacetal (25.0 g as is, 22.5 g real, 0.156 mol) in dioxane (200 mL) is treated with anhydrous sodium sulfate (10 g, to dry the 10% water in the hemiacetal) and refluxed for 60 hours. The solids are filtered and the filtrate is evaporated to a solid. The solids are dissolved in about 200 mL of 15% ethyl acetate in heptane. Unreacted starting material (5.6 g) crystallizes out and is filtered. The title product is obtained from the mother liquors as a white crystalline solid (22.1 g, 82.9% based on recovery of starting material) : mp 139.5-140.5°C; characterized by 1 H and 19 F NMR and Mass spectra. 1 H NMR (DMSO-d 6 ) δ 9.45 (d, J = 8.7 Hz, NH), 7.93, 7.54 ( AB with fine splitting, J = 8.4 Hz, ArH), 7.54 (broad s, OH), 5.90 (m, J = 8.7, 2.9, 5.8 Hz, CH); 19 F NMR δ -80.3 (d, J = 5 Hz). Following essentially the same procedure, but using the appropriately substituted benzamide, the following compounds are obtained: L M Q mp°C Cl H Cl 152.5-153 H Br H 148-148.5 H CF 3 H 124-124.5 EXAMPLE 2 Preparation of N-[1-Chloro-(2,2,2-trifluoroethyl)]-4-chlorobenzimidoyl chloride A mixture of N-(1-hydroxy-2,2,2-trifluoroethyl)-4-chlorobenzamide (22.1 g, 0.087 mol) in phosphorus oxychloride (8 mL) is treated with phosphorus pentachloride (40.0 g, 0.192 mol), heated to and held at 100°C for 15-20 minutes, cooled, and concentrated in vacuo to obtain a residue. The residue is distilled to give the title product as a clear liquid (22.2 g, 87.8% yield): bp 77-78°C (0.1 mm); characterized by IR, 1 H and 19 F NMR, and Mass spectra. 1 H NMR (CDCl 3 ) δ 8.06, 7.44 ( d with fine splitting, J = 8.9 Hz, ArH), 5.92 (q, J = 4.9 Hz, CH); 19 F NMR δ -77.9 (d, J = 5 Hz). A mixture of N-(1-hydroxy-2,2,2-trifluoroethyl)-4-chlorobenzamide (16.3 g, 0.064 mol) in phosphorus oxychloride (10 mL) is treated with phosphorus trichloride (9.3 g, 0.675 mol) and heated to and held at 80°C for 15-20 minutes. 19 F NMR shows clean and complete conversion to N-(1-chloro-2,2,2-trifluoroethyl)-4-chlorobenzamide. The reaction mixture is then cooled to room temperature, treated with phosphorus pentachloride (28.0 g, 0.135 mol), and heated to and held at 100°C for 1 hour. The phosphorus oxychloride is then removed in vacuo and the resultant residue is vacuum distilled to give the title product as a clear liquid (18.5 g, 100% yield): bp 94-96°C (0.5 mm). Following essentially the same procedure as described in Method A, but using the appropriately substituted N-(1-hydroxy-2,2,2-trifluoroethyl)-4-benzamide, the following compounds are obtained: L M Q bp Cl H Cl 114°C (0.3mm) H Br H 95-96°C (0.07mm) H CF 3 H waxy solid EXAMPLE 3 Preparation of 2-( p -Chlorophenyl)-5-(trifluoromethyl)pyrrole-3-carbonitrile A solution of N-[1-chloro-(2,2,2-trifluoroethyl)]-4-chlorobenzimidoyl chloride (5.80 g, 0.02 mol) and acrylonitrile (1.33 g, 0.025 mol) in N,N-dimethylformamide (15 mL) is treated with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, 8.53 g, 0.056 mol) over 1 hour while maintaining the temperature at 45°-50°C. The reaction mixture is then stirred at 50°C for 4 hours, quenched with dilute HCl, and extracted with ethyl acetate. The organic extract is concentrated in vacuo to obtain a residue. Flash chromatography of the residue on silica gel, packed and eluted with 20% ethyl acetate in heptane, and crystallization from heptane and small amount of ethyl acetate gives the title product as a white crystalline solid (2.1 g, 38.9% yield): mp 239-240°C (dec). Following essentially the same procedure, but using the appropriately substituted N-[1-chloro-(2,2,2-trifluoroethyl)]benzimidoyl chloride, the following compounds are obtained: L M Q mp°C Cl H Cl 236.5-237 H Br H 248-249 H CF 3 H 216.5-218.5 EXAMPLE 4 Preparation of Methyl 2-(4-chlorophenyl)-5-(trifluoromethyl)pyrrole-3-carboxylate A solution of N-[1-chloro-(2,2,2-trifluoroethyl)]-4-chlorobenzimidoyl chloride (3.40 g, 0.012 mol) and methyl acrylate (1.26 g, 0.015 mol) in N,N-dimethylformamide (10 mL) is treated with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, 5.0 g, 0.033 mol) over 1 hour. The reaction mixture is then held at 60°C for 15 minutes, quenched with dilute HCl, and extracted with ethyl acetate. The organic extract is concentrated in vacuo to obtain a residue. Flash chromatography of the residue on silica gel, packed and eluted with 20% ethyl acetate in heptane, and crystallization from heptane gives the title product as a yellow solid (0.95 g, 26.0% yield) which is identified by 1 H and 19 F NMR spectral analyses. EXAMPLE 5 Preparation of 4-Bromo-2-(4-chlorophenyl)-5-(trifluoromethyl)pyrrole-3-carbonitrile A solution of N-[1-chloro-(2,2,2-trifluoroethyl)]-4-chlorobenzimidoyl chloride (5.80 g, 0.02 mol) and acrylonitrile (1.33 g, 0.025 mol) in N,N-dimethylformamide (15 mL) under a nitrogen atmosphere is treated with N,N-diisopropylethylamine (DIPEA, 7.8 g, 0.06 mol) over 30 minutes, heated to and held at 45-47°C for 18 hours, cooled to room temperature, treated with bromine (3.2 g, 0.02 mol), stirred at room temperature for 1 hour, quenched with water, and extracted with ethyl acetate. The organic extract is concentrated in vacuo to obtain a residue. Flash column chromatography of the residue on silica gel, packed with 15% ethyl acetate in heptane and eluted with 20% ethyl acetate in heptane, gives the title product as white solid (1.6 g, 22.9% yield) which is identified by 1 H and 19 F NMR spectral analyses. EXAMPLE 6 Preparation of N-(1-Chloro-2,2,2-trifluoroethyl)-4-chlorobenzamide A mixture of N-(1-hydroxy-2,2,2-trifluoroethyl)-4-chlorobenzamide (2.53 g, 0.01 mol) in phosphorus oxychloride (2 mL) is treated with phosphorus trichloride (1.57 g, 0.012 mol), heated to and held at 80°C for 30 minutes, and concentrated in vacuo to obtain a residue. The residue is dissolved in hot heptane, decanted from the waxy phosphorus products, and crystallized to give the title product as a white crystalline solid (2.43 g, 89.3 % yield): mp 119.0-121.0°C; IR (Nujol) 3266, 1668 cm -1 ; 1 H NMR (CDCl 3 ) δ 7.76 and 7.46 (AB with fine splitting, ArH), 6.86 (d, J = 8.5 Hz, NH, moves to 10.24 in DMSO-d 6 ), 6.55(m, CH) ; 19 F NMR δ -77.7(d, J = 5 Hz). Following essentially the same procedure, but using the appropriately substituted N-(1-hydroxy-2,2,2-trifluoroethyl)benzamide, the following compounds are obtained: L M Q mp°C Cl H Cl 163.5-164 H Br H 135-136.5 H CF 3 H 122.5-123.5

Claims: A compound having the formula II, IV or V or wherein n is an integer of 1 to and including 8; A is L is hydrogen or halogen; M and Q are each independently hydrogen, halogen, CN, NO 2 , C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 1 -C 4 alkoxy, C 1 -C 4 haloalkoxy, C 1 -C 4 alkylthio, C 1 -C 4 haloalkylthio, C 1 -C 4 alkylsulfinyl, C 1 -C 4 haloalkylsulfinyl, C 1 -C 4 alkylsulfonyl or C 1 -C 4 haloalkylsulfonyl, with the proviso that M can not be hydrogen, or when M and Q are on adjacent positions they may be taken together with the carbon atoms to which they are attached to form a ring in which MQ represents the structure -OCH 2 O-, -OCF 2 O- or -CH=CH-CH=CH-; R 1 , R 2 and R 3 are each independently hydrogen, halogen, NO 2 or CHO, or R 2 and R 3 may be taken together with the atoms to which they are attached to form a ring in which R 2 R 3 is represented by the structure R 4 , R 5 , R 6 and R 7 are each independently hydrogen, halogen, CN or NO 2 ; and X is O or S. A compound as claimed in claim 1 wherein n is 1 or 2; A is L is hydrogen or halogen; and M and Q are each independently hydrogen, halogen, C 1 -C 4 haloalkyl or C 1 -C 4 haloalkoxy. A compound as claimed in claim 1 or claim 2 which is selected from the group consisting of N-[1-chloro-(2,2,2-trifluoroethyl)]-4-chlorobenzimidoyl chloride; N-[1-chloro-(2,2,2-trifluoroethyl)]-4-bromobenzimidoyl chloride; N-[1-chloro-(2,2,2-trifluoroethyl)]-3,5-dichlorobenzimidoyl chloride; N-[1-chloro-(2,2,2-trifluoroethyl)]-3,4,5-trichlorobenzimidoyl chloride; N-[1-chloro-(2,2,2-trifluoroethyl)]-4-(trifluoromethyl)benzimidoyl chloride; N-(1-hydroxy-2,2,2-trifluoroethyl)-4-chlorobenzamide; N-(1-hydroxy-2,2,2-trifluoroethyl)-4-bromobenzamide; N-(1-hydroxy-2,2,2-trifluoroethyl)-3,5-dichlorobenzamide; N- (1-hydroxy-2,2,2-trifluoroethyl)-3,4,5-trichlorobenzamide; N-(1-hydroxy-2,2,2-trifluoroethyl)-4-(trifluoromethyl)benzamide. N-(1-chloro-2,2,2-trifluoroethyl)-4-chlorobenzamide; N-(1-chloro-2,2,2-trifluoroethyl)-4-bromobenzamide; N-(1-chloro-2,2,2-trifluoroethyl)-3,5-dichlorobenzamide; N-(1-chloro-2,2,2-trifluoroethyl)-3,4,5-trichlorobenzamide; and N-(1-chloro-2,2,2-trifluoroethyl)-4-(trifluoromethyl)benzamide. A process for the preparation of an N-[1-chloro-1-(perfluoroalkyl)methyl]arylimidoyl chloride compound of claim 1 having the formula II which process comprises reacting: an N-[1-hydroxy-1-(perfluoroalkyl)methyl]arylamide compound having the formula IV or an N-[1-chloro-1-(perfluoroalkyl)methyl]arylamide compound having the formula V with phosphorous pentachloride, wherein n and A are as described in claim 1. A process as claimed in claim 4 wherein n is 1 or 2; A is L is hydrogen or halogen; and M and Q are each independently hydrogen, halogen, C 1 -C 4 haloalkyl or C 1 -C 4 haloalkoxy. A process for the preparation of a 2-aryl-5-(perfluoroalkyl)pyrrole compound having the formula I wherein W is hydrogen or C m F 2m+1 ; Y is CN, NO 2 or CO 2 R; R is C 1 -C 4 alkyl; m and n are each independently an integer of 1 to and including 8; and A is as described in claim 1, which process comprises reacting an N-[1-chloro-1-(perfluoroalkyl)methyl]arylimidoyl chloride compound of claim 1 having the formula II wherein A and n are as described above, with a dieneophile compound or a substituted haloethane compound, and a base, in the presence of a solvent, the dieneophile compound having the formula III and the substituted haloethane compound having the formula VI wherein W and Y are as described above, and Z is Cl, Br or I. A process as claimed in claim 6 wherein n is 1 or 2; A is L is hydrogen or halogen; and M and Q are each independently hydrogen, halogen, C 1 -C 4 haloalkyl or C 1 -C 4 haloalkoxy; W is hydrogen; and Y is CN. A process as claimed in claim 6 or claim 7 wherein the base is selected from the group consisting of a tri-(C 1 -C 6 alkyl)amine, an alkali metal carbonate and a heterocyclic tertiary amine. A process as claimed in any one of claims 6 to 8 wherein the solvent is selected from the group consisting of a carboxylic acid amide and a nitrile, and mixtures thereof. A process as claimed in any one of claims 6 to 9 wherein the dieneophile is at about one to four molar equivalents and the base is at about one to four molar equivalents. A process as claimed in any one of claims 6 to 10 wherein the substituted haloethane compound is at about one to four molar equivalents and the base is present in the amount of about two to five molar equivalents. A process for the preparation of an arylpyrrole compound having the formula IX wherein Y is CN, NO 2 or CO 2 R; R is C 1 -C 4 alkyl; n and A are as described in claim 1; Hal is a halogen atom; and J is hydrogen or C 1 -C 6 alkoxymethyl, which process comprises: (a) reacting an N-[1-chloro-1-(perfluoroalkyl)methyl]arylimidoyl chloride compound of claim 1 having the formula II wherein A and n are as described above, with a dieneophile compound or a substituted haloethane compound, and a base, in the presence of a solvent, the dieneophile compound having the formula X and the substituted haloethane compound having the formula XII wherein Y is as described above, and Z is Cl, Br or I, to form a 2-aryl-5-(perfluoroalkyl)pyrrole compound having the formula XI (b) halogenating the formula XI compound to form the arylpyrrole compound of formula IX wherein J is hydrogen; and (c) optionally alkoxymethylating the formula IX compound. A process as claimed in claim 12 wherein step (c) comprises reacting said formula IX compound with a di-(C 1 -C 6 alkoxy)methane compound, N,N-dimethylformamide and phosphorous oxychloride in the presence of an aprotic solvent to form a reaction mixture, and treating the reaction mixture with a tertiary amine.

Inventors: KAMESWARAN VENKATARAMAN, KAMESWARAN, VENKATARAMAN
Applicants: BASF AG, BASF AKTIENGESELLSCHAFT
Application year: 2000
Main classification: C07D207
IPC codes: C07D405, C07C233, C07D207, C07D409, C07C257, C07C251