GB1122957A - Substituted benzimidazoles and anthelmintic compositions containing them - Google Patents

Abstract

The invention comprises novel compounds of formula I <FORM:1122957/C2/1> where A is (1) an unsubstituted or methyl-substituted monocyclic 5-membered heterocyclic ring bonded to the carbonyl group through one of its carbon atoms, or (2) straight or branched chain alkyl having 2-10 carbon atoms; cycloalkyl or alkylcycloalkyl of 3-10 carbon atoms; straight or branched chain alkenyl of 3 to 10 carbon atoms; straight or branched chain alkynyl of 3-10 carbon atoms; naphthyl; alkylphenyl; or alkoxyphenyl; provided that when A is alkenyl or alkynyl the double or triple bond thereof is not conjugated with the C = X double bond; X is oxygen or sulphur; R is hydrogen, or alkyl or hydroxyalkyl having 1-10 carbon atoms, or benzyl; R1 is hydrogen or alkyl having 1-10 carbon atoms; and Y and Z are hydrogen, alkyl or alkoxy having 1-10 carbon atoms, trifluoromethyl, amino, mono- or di-alkylamino, cyano, acylamino, halo, hydroxy, nitro, alkylthio, carboxy, carbalkoxy, carbamoyl, or mono- or di-alkyl-carbamoyl, all of the undefined substituent alkyl groups having 1 to 4 carbon atoms therein; and pharmaceutically acceptable acid addition salts thereof. Compounds of formula I above may generally be prepared by condensing a 2-aminobenzimidazole with a compound A-CX-Cl, or by reacting cyanamide with an acid chloride in a basic solvent, and reacting the product with an o-phenylenediamine. Compounds in which Y or Z is amino are obtained by reduction of the corresponding nitro compound. Compounds in which R is alkyl, hydroxyalkyl or benzyl may be prepared by reacting 2-aminobenzimidazole with an acid chloride or also by alkylatng or benzylating the final product. When X is sulphur the compounds may be prepared by treating the corresponding compound wherein X is oxygen with phosphorus pentasulphide. When R1 is alkyl and R is hydrogen, the compounds may be obtained by treating o-phenylene diamine with an alkyl isothiocyanate, cyclizing the alkyl o-aminophenyl thiourea obtained, and treating the 2-alkylaminobenzimidazole produced with an acyl halide. Thiophen-2-carboxylic acid chloride and pyrrole 2-carboxylic acid chloride are prepared from the corresponding acid. Anthelmintic compositions which may be administered orally, e.g. as a sheep drench or bolus, or may be formulated into a feed supplement or animal food concentrate or may be added directly to the food, comprise as active ingredient a compound of formula I above.