Octamethylporphyrin was readily obtained from ethyl 3,4,5-trimethylpyrrole-2-carboxylate. Steric control can be overridden by apparent electronic effect is demonstrated by the even bulkier pyrrole derivative, ethyl 3,4,5-trimethylpyrrole-2-carboxylate. The reaction with diazonium salts of theEthyl 3,4,5-trimethylpyrrole-2-carboxylatehas been examined in detail by chromatographic and spectroscopic methods. In the presence of a strong mineral acid, Ethyl 3,4,5-trimethylpyrrole-2-carboxylate reacts with p-nitrobenzenediazonium ions to give a red, chemically labile, azo dye.
