BENZAZOLE DERIVATIVES WITH ANTIPARASITIC ACTION

The invention relates to a process for the manufacture of novel benzazole derivatives of the formula I (I) in which R1 represents an optionally 4-substituted piperazino group or a group of the formula R2-alk-X2-, R2 represents optionally esterified carboxy or represents hydroxymethyl, alk represents lower alkylene or lower alkylidene, X1 and X2, independently of one another, each represents oxygen or sulphur, Ph represents 1,2-phenylene optionally substituted as well as by the group R1-C(=X1)-NH-, X3 represents oxygen, sulphur or optionally substituted imino, and R3 represents optionally fluorine-substituted lower alkyl or cycloalkyl, and their salts. The compounds of the formula I, which have proved to be excellent micro- and macrofilaricides and schistosomacides, are manufactured according to methods known per se.