| abstract |
Compounds have the formula (I), in which R stands for straight-chain or branched (C1-C20) alkyl, phenyl or CH2 phenyl, the alkyl group or phenyl group being optionally substituted by halogen, (C1-C4) alkyl, (C1-C4) alkoxy, and R<1>, R<2>, R<3>, R<4> independently represent hydrogen, halogen, OH, NO2, (C1-C6) alkoxy, (C1-C6) alkyl or halogen-substituted (C1-C6)-alkyl. Also disclosed is a process for preparing these compounds. |