The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Pyrrole Syntheses from Amino Ketones with Ketones and Ketone Esters》. Authors are Piloty, O.; Hirsch, P..The article about the compound:3-Methyl-1H-pyrrolecas:616-43-3,SMILESS:CC1=CNC=C1).Electric Literature of C5H7N. Through the article, more information about this compound (cas:616-43-3) is conveyed.
The following pyrrole derivatives have been prepared by treating aqueous solutions of the HCl salts of amino ketones containing an excess of alk. with a ketone or ketone ester and allowing to stand a long time at a slightly elevated temperature in closed vessels. α-β’-Dimethylpyrrole, from Ac2NH2.HCl and AcMe; yield, 30%. α-Phenyl-β’-methylpyrrole, from 10 g. AcCH2NH2.HCl and 5 g. AcPh, m. 152°; yield, 1 g. α,β,β’-Trimethylpyrrole, from AcEt; yield, 28%. α-Ethyl-β,β’-dimethylpyrrole, b10 77-8° (yield, 0.4 g. from 14 g. AcCH3NH2.HCl and 10 g. Et2CO); picrjate, bright yellow, striated prisms, m. 122.5°. α,β,α’-Trimethylpyrrole, from AcCHMeNH2 and AcMe; yield, 50%. Some tetramethylpyrazine is formed in this reaction. AcCHMeNH2 and AcEt react only slowly and incompletely; the chief product is the pyrazine, but a little α,β,α’,β’-tetramethylpyrrole picrate (cf. Fischer and Bartholomäus, C. A., 7, 780) was isolated. Et α,β’-dimethylpyrrole-β-carboxylate, from AcCH2NH2 and AcCH2CO2Et. Monoethyl β-methylpyrrole-α’,β’-dicarboxylate, from 19 g. HO2CCOCH2CO2Et and 11 g. AcCH2NH2.HCl, monoclinic prisms, m. 196° (yield, 2-3 g.), converted by 20 hrs. b. with excess of 20% KOH into β-methylpyrrole-β’ (or α’)-carboxylic acid, flocks, m. 149°, losing CO2 and forming β-methylpyrrole, b11 45°. Monoethyl α,β-dimethylpyrrole-α’,β’-dicarboxylate, from AcCHMeNH2 and HO2CCOCH2CO2Et, prisms, m. 201° (loss of CO2). α,β-Dimethylpyrrole-β’ (or α’)-carboxylic acid, m. 188°. α,β-Dimethylpyrrole, b11 62°; picrate, bright yellow, felted needles, m. 146-5°; contrary to all other pyrrole derivatives, it has the comp. C18H21O7N5, i. e., 2 mols. pyrrole: 1 mol. picric acid.
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Reference:
Synthesis and Crystal Structure of a Chiral C3-Symmetric Oxygen Tripodal Ligand and Its Applications to Asymmetric Catalysis,
Chiral lanthanide(III) complexes of sulphur–nitrogen–oxygen ligand derived from aminothiourea and sodium D-camphor-β-sulfonate