prov:value
| - R8 in the formula II as a heterocyclic group is, in particular, a radical of a five-membered heterocyclic ring containing one ring member other than carbon, such as --S--, --O-- or --NH--, for example furan, thiophene, pyrrole, pyrrolidone, pyroglutamic acid, maleimides of the formula ##STR5## (in which R10 and R11, independently of one another, are hydrogen, C1 -C4 alkyl, in particular methyl, or
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