Easy α- to β-migration of an enol moiety on a pyrrole ring
摘要:
Functionalized pyrrolic enols, 2-(2,2-dicyano-1-hydroxyethenyl)-1-methylpyrroles, synthesized from 2-ethenylpyrroles by a nucleophilic SEt-OH exchange, upon heating (75-142 degrees C) are readily rearranged to their 3-isomers in near to quantitative yield. The inter or intramolecular auto-protonation of a pyrrole ring by the acidic enol hydroxyl to form a mesomeric pyrrolium cation or zwitterion is suggested to be a key step in the rearrangement. (c) 2006 Elsevier Ltd. All rights reserved.
Facile coupling of 2-(1-ethylthioethenyl)pyrroles with amines: A route to 2-(1-aminoethenyl)pyrroles and 1-amino-3-iminopyrrolizines
作者:Boris A. Trofimov、Lyubov' N. Sobenina、Al'bina I. Mikhaleva、Ol'Ga V. Petrova、Vladislav N. Drichkov、Igor A. Ushakov、Ol'Ga A. Tarasova、Darya-Suren D. Toryashinova、Yuriy Yu. Rusakov、Leonid B. Krivdin
DOI:10.1002/jhet.5570440301
日期:2007.5
2-(2-Cyano-1-ethylthioethenyl)pyrroles are readily coupled (50–55°) with primary and secondary amines at the position 1 of the ethenyl moiety to eliminate ethanethiol and afford 2-(1-amino-2-cyanoethenyl)pyrroles and/or their cyclic isomers - functionalized 1-amino-3-iminopyrrolizines in good to high yields.