dibenzyl 3,3'-bismethyl-4,4'-bis-(2-hydroxyethyl)pyrromethane-5,5'-dicarboxylate

dibenzyl 4,4'-bis(2-acetoxyethyl)-3,3'-dimethylpyrromethane-5,5'-dicarboxylate

3,3'-dimethyl-4,4'-bis-(2-acetoxyethyl)pyrromethane-5,5'-dicarboxylic acid