Hoechst Aktiengesellschaft

Hans-Joachim Ressel

Stephen Lachhein

Hilmar Mildenberger

The invention relates to a process for the preparation of compounds of the formula I ##STR1## in which X and Y denote O or S; R.sup.1 and R.sup.2 denote (substituted) alkyl, R.sup.3 denotes H or a --COR.sup.4 radical in which R.sup.4 is alkyl, halogenoalkyl, alkoxy, halogenoalkoxy, (substituted) phenyl or (substituted) phenoxy, wherein a propanediimidate of the formula II ##STR2## or a salt thereof is reacted, in an inert solvent and in the presence of a base, with a carbonic acid imine derivative of the formula III ##STR3## in which R.sup.5 denotes halogen, alkoxy, alkylthio, phenoxy or phenylthio.

Process for the preparation of pyrimidines

A highly selective, inexpensive and quantitative process is described for the preparation of 5-phenylsulfinyl-1H-2-(methoxycarbonylamino)-benzimidazole (oxfendazole) through reaction of 5-phenylmercapto-1H-2-(methoxycarbonylamino)-benzimidazole with hydrogen peroxide in the presence of one or more aliphatic C.sub.1 -C.sub.6 -alcohols with addition of a strong, nonoxidizing mineral acid.

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Hattersheim am Main, Germany

Hans-Joachim Ressel