A practical approach to orthogonally connected oligopyrrole-peptide conjugates was written by Vazquez, Eugenio;Caamano, Ana M.;Castedo, Luis;Gramberg, Dieter;Mascarenas, Jose L.. And the article was included in Tetrahedron Letters in 1999.Electric Literature of C7H8N2O4 This article mentions the following:
A practical method for synthesizing an orthogonally connected oligopyrrole-peptide conjugate by coupling the oligopyrrole fragment to a selectively deprotected glutamic acid side-chain of a resin-bound peptide is described. For example, oligo(N-methylpyrrole)-peptide conjugate I (X = H3CCO-Asp-Pro-Ala-Ala-Leu-Lys-Arg-Ala-Arg-Asn-Thr-Glu-Ala-Ala-Arg-Arg-Ser-Arg-Ala-) was prepared via standard solid-phase synthesis. These type of compounds may reproduce the DNA binding properties of natural proteins. In the experiment, the researchers used many compounds, for example, Ethyl 4-nitro-1H-pyrrole-2-carboxylate (cas: 5930-92-7Electric Literature of C7H8N2O4).
Ethyl 4-nitro-1H-pyrrole-2-carboxylate (cas: 5930-92-7) belongs to esters. Esters are also usually derived from carboxylic acids. It may also be obtained by reaction of acid anhydride or acid halides with alcohols or by the reaction of salts of carboxylic acids with alkyl halides. Liquid esters of low volatility serve as softening agents for resins and plastics. Esters also include many industrially important polymers. Polymethyl methacrylate is a glass substitute sold under the names Lucite and Plexiglas; polyethylene terephthalate is used as a film (Mylar) and as textile fibres sold as Terylene, Fortrel, and Dacron.Electric Literature of C7H8N2O4
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics