PROCESS FOR THE PREPARATION OF BETA-(BENZOTHIAZOLYLTHIO) AND BETA (BENZIMIDAZOLYLTHIO)CARBOXYLIC-ACID DERIVATIVES

The reaction of 2-mercapto-benzothiazole or -benzimidazole with alpha , beta -unsaturated carboxylic acid derivatives in a strongly acid reaction medium gives compounds of the formula I I in which X is sulfur or NH, each radical R independently of one another is H, alkyl, halogenalkyl, alkoxy, alkylthio, alkylsulfonyl, phenyl, alkylphenyl, phenylalkyl, cycloalkyl, halogen, NO2, CN, COOH, COOalkyl or a tertiary amino or carbamoyl group and R1, R2 and R3 independently of one another are H, alkyl, halogenalkyl, hydroxyalkyl, alkoxyalkyl unesterified or esterified carboxyl or carboxylalkyl, carbamyol, carbamyolalkyl or unsubstituted or substituted aryl or aralkyl, or R1 and R2 together are straight-chain or branched alkylene, which can be substituted by 1 or 2 carboxyl groups, R4 is unsubstituted or substituted amino, alkoxy, cycloalkoxy, aryloxy or aralkyloxy, or R2 and R4 together are CH2-CO-O- or -CH2CO-NR5- or R3 and R4 together are -CO-O- or -CO-NR5-, forming an anhydride or imide ring, wherein R5 is unsubstituted or substituted alkyl, cycloalkyl, aryl, aralkyl or hydrogen.