benzyl 5'-t.butyloxycarbonyl-4,3'-di(2-methoxycarbonylethyl)-3,4'-bismethoxycarbonylmethyl-2,2'-methylenedipyrrole-5-carboxylate

tert-butyl 3,4'-bis<β-(methoxycarbonyl)ethyl>-4,3'-bis<(methoxycarbonyl)methyl>dipyrrylmethane-5-carboxylate

5'-t-butoxycarbonyl-4,3'-di-(2-methoxycarbonylethyl)-3,4'-bismethoxycarbonylmethyl-2,2'-methylenedipyrrole-5-carboxylic acid