Synthesis of Pyrazoles via Cul-Mediated Electrophilic Cyclizations of alpha,beta-Alkynic Hydrazones


ZORA M. , KIVRAK A.

JOURNAL OF ORGANIC CHEMISTRY, vol.76, no.22, pp.9379-9390, 2011 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 76 Issue: 22
  • Publication Date: 2011
  • Doi Number: 10.1021/jo201685p
  • Title of Journal : JOURNAL OF ORGANIC CHEMISTRY
  • Page Numbers: pp.9379-9390

Abstract

Synthesis of pyrazoles via electrophilic cyclization of alpha,beta-alkynic hydrazones by copper(I) iodide is described. When treated with copper(I) iodide in the presence of triethylamine in refluxing acetonitrile, alpha,beta-alkynic hydrazones, prepared readily from hydrazines and propargyl aldehydes and ketones, undergo electrophilic cyclization to afford pyrazole derivatives in good to excellent yields. The reaction appears to be general for a variety of alpha,beta-alkynic hydrazones and tolerates the presence of aliphatic, aromatic, and ferrocenyl moieties with electron-withdrawing and electron-donating substituents.