Easy α- to β-migration of an enol moiety on a pyrrole ring
作者:Boris A. Trofimov、Ol’ga V. Petrova、Lyubov’ N. Sobenina、Igor’ A. Ushakov、Al’bina I. Mikhaleva、Yurii Yu. Rusakov、Leonid B. Krivdin
DOI:10.1016/j.tetlet.2006.03.148
日期:2006.5
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.