Facile synthesis of iodopyridines from N-propargylic beta-enaminones via iodine-mediated electrophilic cyclization


KARABIYIKOĞLU S., Kelgokmen Y. , ZORA M.

TETRAHEDRON, vol.71, no.25, pp.4324-4333, 2015 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 71 Issue: 25
  • Publication Date: 2015
  • Doi Number: 10.1016/j.tet.2015.04.070
  • Title of Journal : TETRAHEDRON
  • Page Numbers: pp.4324-4333
  • Keywords: Pyridine, Iodopyridine, N-Propargylic beta-enaminone, Iodocyclization, Electrophilic cyclization, DIELS-ALDER REACTIONS, ONE-POT SYNTHESIS, DE-NOVO SYNTHESIS, C PI-BONDS, REGIOSELECTIVE SYNTHESIS, HETEROCYCLIC AZADIENES, INTRAMOLECULAR CYCLIZATION, POLYSUBSTITUTED PYRIDINES, OXIDATIVE AROMATIZATION, HETEROATOM CYCLIZATIONS

Abstract

A facile, efficient and general synthetic method for iodopyridines is described. When treated with molecular iodine in the presence of sodium bicarbonate, N-propargylic beta-enaminones have underwent electrophilic cyclization to afford iodo-substituted pyridines in good to high yields. Iodocyclization has been found to be general for a broad range of N-propargylic beta-enaminones and tolerated the presence of aliphatic, aromatic and heteroaromatic groups with electron-withdrawing and electron-donating substituents. The starting N-propargylic beta-enaminones have been prepared by conjugate addition of propargylamine to alpha,beta-allcynic ketones, followed by Sonogashira coupling with aryl iodides. (C) 2015 Elsevier Ltd. All rights reserved.