Synthesis 2014; 46(18): 2489-2498
DOI: 10.1055/s-0034-1378206
paper
© Georg Thieme Verlag Stuttgart · New York

A Solvent-Free and One-Pot Strategy for Ecocompatible Synthesis of Substituted­ Benzofurans from Various Salicylaldehydes, Secondary Amines, and Nonactivated Alkynes Catalyzed by Copper(I) Oxide Nanoparticles

Hashem Sharghi*
Department of Chemistry, Shiraz University, Shiraz, 71454, Iran   Fax: +98(711)2280926   Email: shashem@chem.susc.ac.ir
,
Pezhman Shiri
Department of Chemistry, Shiraz University, Shiraz, 71454, Iran   Fax: +98(711)2280926   Email: shashem@chem.susc.ac.ir
,
Mahdi Aberi
Department of Chemistry, Shiraz University, Shiraz, 71454, Iran   Fax: +98(711)2280926   Email: shashem@chem.susc.ac.ir
› Author Affiliations
Further Information

Publication History

Received: 03 March 2014

Accepted after revision: 12 May 2014

Publication Date:
25 June 2014 (online)


Abstract

Copper(I) oxide nanoparticles (CONPs) catalyze multicomponent coupling/cycloisomerization reactions between various 2-hydroxybenzaldehydes, secondary amines, and nonactivated alkynes to give 2,3-disubstituted 1-benzofurans. All reactions are carried out under solvent- and ligand-free conditions at 100 °C in air. The combination of copper-catalyzed C–H activation and an O-annulation process is essential for this transformation. This methodology provides rapid access to substituted 1-benzofurans in good to excellent yields with high atom economy and high catalytic efficiency. This procedure eliminates the need for propargylamine derivatives, uncyclized intermediates that make purification difficult. The CONPs and tetrabutylammonium bromide were reused successfully for up to five times.

Supporting Information