Antiparasitic compounds

Abstract

The invention relates to 1,2,4-thiadiazole derivatives and their use to treat parasites.

1 - 18 . (canceled) 
     
     
         19 . A method for controlling parasites at a locus which comprises applying to the locus an effective amount of a thiadiazole derivative of formula (I) 
       
         
           
           
               
               
           
         
         wherein: 
         A is C═O or SO 2 ; 
         X is R 1  or NHR 1 ; 
         R 1  is: 
         phenyl optionally substituted by from one to three substituents, which are the same or different, each selected from the group consisting of nitro, —NR 3 R 4 , cyano, —NR 3 COR 5 , alkyl, —SO 2 R 5 , —NR 3 SO 2 R 5 , —SO 2 NR 3 R 4 , —CONR 3 R 4 , —CONHC 6 H 5 , hydroxy, alkoxy, aryloxy, aryl, heterocyclyl, haloalkyl, haloalkoxy, mercapto, thioalkyl and halogen; 
         naphthyl optionally substituted by from one to three substituents, which are the same or different, each independently selected from the group consisting of nitro, —NR 3 R 4 , cyano, —NR 3 COR 5 , alkyl, —SO 2 R 5 , —NR 3 SO 2 R 5 , —SO 2 NR 3 R 4 , —CONR 3 R 4 , —CONHC 6 H 5 , hydroxy, alkoxy, aryloxy, aryl, heterocyclyl, haloalkyl, haloalkoxy, mercapto, thioalkyl and halogen; 
         quinoxolinyl optionally substituted by from one to three substituents, which are the same or different, each independently selected from the group consisting of nitro, —NR 3 R 4 , cyano, —NR 3 COR 5 , alkyl, —SO 2 R 5 , —NR 3 SO 2 R 5 , —SO 2 NR 3 R 4 , —CONR 3 R 4 , —CONHC 6 H 5 , hydroxy, alkoxy, aryloxy, aryl, heterocyclyl, haloalkyl, haloalkoxy, mercapto, thioalkyl and halogen; 
         quinolinyl optionally substituted by from one to three substituents, which are the same or different, each independently selected from the group consisting nitro, —NR 3 R 4 , cyano, —NR 3 COR 5 , alkyl, —SO 2 R 5 , —NR 3 SO 2 R 5 , —SO 2 NR 3 R 4 , —CONR 3 R 4 , —CONHC 6 H 5 , hydroxy, alkoxy, aryloxy, aryl, heterocyclyl, haloalkyl, haloalkoxy, mercapto, thioalkyl and halogen; 
         or thionyl or furyl optionally substituted by from one to three substituents which are the same or different, each selected from the group consisting of nitro, —NR 3 R 4 , cyano, —NR 3 COR 5 , alkyl, —SO 2 R 5 , —NR 3 SO 2 R 5 , —SO 2 NR 3 R 4 , —CONR 3 R 4 , —CONHC 6 H 5 , hydroxy, alkoxy, aryloxy, aryl, heterocyclyl, haloalkyl, haloalkoxy, mercapto (—SH), thioalkyl and halogen; 
         R 2  is hydrogen, halogen, alkyl, alkoxy, haloalkyl or haloalkoxy, aminoalkyl, alkylaminoalkyl, aryl, heterocyclyl or —CONR 3 R 4 ; or R 2 , together with two adjacent carbons of the pyridyl ring to which it is attached, forms a saturated or unsaturated ring containing from 4 to 6 ring atoms; 
         R 3  and R 4 , which are the same or different, each independently represent hydrogen or alkyl; or when R 3  and R 4  are each attached to a nitrogen atom, they may form a saturated or unsaturated heterocyclic ring containing from 4 to 6 ring atoms 
         R 5  is alkyl or haloalkyl; 
         or a pesticidally acceptable salt thereof. 
       
     
     
         20 . The method of  claim 19  wherein controlling parasites comprises treating or preventing parasite infection in a subject in need thereof. 
     
     
         21 . The method of  claim 19 , wherein:
 A is C═O;   X is R 1 ;   R 1  is phenyl substituted by from one to three substituents which are the same or different selected from the group consisting of trifluoromethyl, trifluoromethoxy, chloro, fluoro, cyano, methyl, ethyl, methoxy, ethoxy, aryloxy, thiomethyl, —SO 2 CH 3 , —SO 2 NH 2 , —SO 2 NHCH 3 , —SO 2 N(CH 3 ) 2  and —NHSO 2 CH 3 ; and   R 2  is hydrogen, fluoro, methyl, trifluoromethyl, methoxy, trifluoromethoxy, morpholino, aminoalkyl or dimethylaminomethyl.   
     
     
         22 . The method of  claim 19 , wherein:
 A is SO 2 ;   X is R 1 ;   R 1  is phenyl substituted by from one to three substituents which are the same or different selected from the group consisting of trifluoromethyl, trifluoromethoxy, chloro, fluoro, cyano, methyl, ethyl, methoxy, ethoxy, thiomethyl, methanesulfonyl, sulfonamide, methylsulfonamide, dimethylsulfonamide, and methylsulfonanilide; and   R 2  is hydrogen.   
     
     
         23 . The method of  claim 19 , wherein:
 A is C═O or SO 2 ;   X is R 1  or NHR 1 ;   R 1  is:   
       phenyl optionally substituted by from one to three substituents which are the same or different, each selected from the group consisting of nitro, —NR 3 R 4 , cyano, —NR 3 COR 5 , alkyl, alkoxy, aryl, heterocyclyl, aryloxy, haloalkyl, haloalkoxy, mercapto (—SH), thioalkyl and halogen;
 R 2  is hydrogen, fluoro, methyl, trifluoromethyl, methoxy, trifluoromethoxy, morpholino, aminoalkyl or dimethylaminomethyl. 
 
     
     
         24 . The method of  claim 19 , wherein the compound is selected from one or more of:
 1-(4-methoxyphenyl)-3-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]urea;   1-(2-chlorophenyl)-3-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]urea;   1-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-3-[4-(trifluoromethyl)phenyl]urea;   1-(3-methoxyphenyl)-3-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]urea;   1-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-3-[4-(trifluoromethoxy)phenyl]urea;   1-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-3-[3-(trifluoromethyl)phenyl]urea;   4-chloro-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   3-chloro-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-cyano-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   3-fluoro-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]naphthalene-2-carboxamide;   4-trifluoromethoxy-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-chloro-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzenesulfonamide;   2-chloro-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzenesulfonamide;   4-cyano-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzenesulfonamide;   4-methoxy-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzenesulfonamide;   2-methoxy-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzenesulfonamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-3-(trifluoromethyl)benzenesulfonamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzenesulfonamide;   N-[3-(3-fluoro-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(4-morpholino-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-[benzyl(methyl)amino]-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-(dimethylamino)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-[2-methoxyethyl)methyl)amino]-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(5-methoxy-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(4-methoxy-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-(triazolo[4,5-b]pyridin-3-yloxy)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(5-bromo-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   methyl 2-[5-[[4-(trifluoromethyl)benzoyl]amino]-1,2,4-thiadiazol-3-yl]pyridine-4-carboxylate;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]isoquinoline-7-carboxamide;   4-acetamido-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-fluoro-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-nitro-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]quinoxaline-6-carboxamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]thiophene-2-carboxamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]thiophene-3-carboxamide;   N-[3-(4-isopropyl-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(3-isoquinolyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(5-fluoro-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(5-methyl-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   3-chloro-4-fluoro-N-[3-(5-fluoro-2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N-[3-(5-fluoro-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethoxy)benzamide;   4-tert-butyl-N-[3-(5-fluoro-2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N-[3-(5-fluoro-2-pyridyl)-1,2,4-thiadiazol-5-yl]-3,5-bis(trifluoromethyl)benzamide;   N-[3-(5-fluoro-2-pyridyl)-1,2,4-thiadiazol-5-yl]-3-(trifluoromethyl)benzamide;   3,4-dichloro-N-[3-(5-fluoro-2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   3-methylsulfonyl-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]isoquinoline-5-carboxamide;   3-chloro-4-(4-methylpiperazin-1-yl)-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   methyl 4-[[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]carbamoyl]benzoate;   4-(diethylsulfamoyl)-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-methyl-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]thiophene-2-carboxamide;   3-chloro-4-fluoro-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   2-fluoro-3-methoxy-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-3-(trifluoromethyl)benzamide;   2,5-dimethyl-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]furan-3-carboxamide;   4-tert-butyl-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-1,3-benzodioxole-5-carboxamide;   3,4-dichloro-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-3,5-bis(trifluoromethyl)benzamide;   4-methoxy-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-phenoxy-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-fluoro-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-2-(trifluoromethyl)benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-[[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]carbamoyl]benzoic acid;   4-iodo-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-morpholino-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-(morpholine-4-carbonyl)-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   tert-butyl 4-[4-[[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]carbamoyl]benzoyl]piperazine-1-carboxylate;   tert-butyl 4-[[4-[[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]carbamoyl]benzoyl]amino]piperidine-1-carboxylate;   4-(piperidine-1-carbonyl)-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-(piperazine-1-carbonyl)-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N1-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]terephthalamide;   4-(2-pyridylamino)-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   tert-butyl 4-[4-[[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]carbamoyl]anilino]piperidine-1-carboxylate;   4-phenyl-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-piperazin-1-yl-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-(4-piperidylamino)-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   tert-butyl 4-[4-[[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]carbamoyl]phenyl]piperazine-1-carboxylate;   3-chloro-2-fluoro-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-5-(trifluoromethyl)benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(1,1,2,2-tetrafluoroethoxy)benzamide;   2-methoxy-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethoxy)benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-5-(trifluoromethyl)furan-2-carboxamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-5-(trifluoromethyl)thiophene-2-carboxamide;   4-formyl-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-[hydroxy(phenyl)methyl]-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   3-bromo-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-benzyl-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N4-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]terephthalamide;   4-bromo-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   3-chloro-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethoxy)benzamide;   N-[3-(4-phenyl-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   4-(trifluoromethyl)-N-[3-[5-(trifluoromethyl)-2-pyridyl]-1,2,4-thiadiazol-5-yl]benzamide;   N4-phenyl-N1-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]terephthalamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-2-(trifluoromethyl) benzamide;   2-fluoro-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethoxy) benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-2-(trifluoromethoxy) benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-3-(trifluoromethoxy) benzamide;   4-(4-fluorophenoxy)-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl] benzamide;   3-hydroxy-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-5-(trifluoromethyl) thiophene-2-carboxamide;   4-(2,4-difluorophenoxy)-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-[4-(trifluoromethyl)phenoxy] benzamide;   N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]-3-[4-(trifluoromethyl)phenoxy]benzamide;   3-(4-fluorophenoxy)-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   3-phenoxy-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N1-(4-piperidyl)-N4-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]terephthalamide;   N-[3-(5-piperazin-1-yl-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   4-(4-piperidyloxy)-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]pyridine-2-carboxamide;   N-[3-(6-piperazin-1-yl-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   4-(3-pyridyl)-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl] benzamide;   N-[3-(5-phenyl-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   4-(trifluoromethyl)-N-[3-(5-vinyl-2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N-[3-[5-(3,6-dihydro-2H-pyran-4-yl)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(6-phenyl-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[6-(3-pyridyl)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   4-anilino-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   4-(benzylamino)-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   3-anilino-N-[3-(2-pyridyl)-1,2,4-thiadiazol-5-yl]benzamide;   N-[3-[5-(3-pyridylamino)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(5-morpholino-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[5-[2-methoxyethyl(methyl)amino]-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(5-pyrrolidin-1-yl-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[5-(2-pyridylamino)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[5-(4-methylpiperazin-1-yl)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   tert-butyl 4-[6-[5-[[4-(trifluoromethyl)benzoyl]amino]-1,2,4-thiadiazol-3-yl]-3-pyridyl]piperazine-1-carboxylate;   N-[3-[5-(1-piperidyl)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(5-anilino-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[5-(4-hydroxy-1-piperidyl)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[6-(4-methylpiperazin-1-yl)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   tert-butyl 4-[6-[5-[[4-(trifluoromethyl)benzoyl]amino]-1,2,4-thiadiazol-3-yl]-2-pyridyl]piperazine-1-carboxylate;   N-[3-(4-Methyl-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(6-Methyl-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-(dimethylaminomethyl)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-[methyl-[2-(1-piperidyl)ethyl]amino]-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-[methyl(2-morpholinoethyl)amino]-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(4-pyrrolidin-1-yl-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-(4-methylpiperazin-1-yl)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-[2-hydroxyethyl(methyl)amino]-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-[2-(1-piperidyl)ethoxy]-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-(2-methoxyethoxy)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-(2-dimethylaminoethyloxy)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-(2,2-dimethylpropoxy)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-[(1-methyl-4-piperidyl)oxy]-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-(4-tetrahydropyran-4-yloxy-2-pyridyl)-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide;   N-[3-[4-(oxetan-3-yloxy)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide; and   N-[3-[4-(hydroxymethyl)-2-pyridyl]-1,2,4-thiadiazol-5-yl]-4-(trifluoromethyl)benzamide,   or a pesticidally acceptable salt thereof.   
     
     
         25 . The method of  claim 19 , wherein the parasite is a helminth. 
     
     
         26 . The method of  claim 19 , wherein the parasite is  dirofilaria immitis.