A copper-promoted annulative direct coupling of o-alkynylaniline derivatives with 1,3,4-oxadiazoles for the synthesis of C3-azolylindoles has been developed. The copper-based system provides a new protocol for the dehydrogenative construction of indole-oxadiazole conjugations from nonhalogenated and non-metalated starting materials.
Mild and efficient cyclization reaction of 2-ethynylaniline derivatives to indoles in aqueous medium
作者:Kou Hiroya、Shin Itoh、Takao Sakamoto
DOI:10.1016/j.tet.2005.08.098
日期:2005.11
Results of the optimized cyclization reaction of 2-ethynyl aniline derivatives to indoles catalyzed by copper(II) salts are described. The reactions can be carried out in a mixture of H2O and MeOH in the presence of 1-ethylpiperidine at room temperature. These conditions can be applied to a bulky substrate, which is difficult to be cyclized efficiently by existing reaction conditions. Furthermore, this reaction condition was applied to a catalyst recycling reaction system. (c) 2005 Elsevier Ltd. All rights reserved.