Synthesis 2019; 51(23): 4487-4497
DOI: 10.1055/s-0037-1610726
paper
© Georg Thieme Verlag Stuttgart · New York

Recyclable Heterogeneous Copper(II)-Catalyzed Oxidative Cyclization of 2-Pyridine Ketone Hydrazones Towards [1,2,3]Triazolo[1,5-a]pyridines

Gan Jiang
a   School of Chemistry & Chemical Engineering, Guangdong Cosmetics Engineering & Technology Research Center, Guangdong Pharmaceutical University, Guangzhou 510006, P. R. of China   Email: zhaohong1001@sina.com
,
Yang Lin
a   School of Chemistry & Chemical Engineering, Guangdong Cosmetics Engineering & Technology Research Center, Guangdong Pharmaceutical University, Guangzhou 510006, P. R. of China   Email: zhaohong1001@sina.com
,
Mingzhong Cai
b   College of Chemistry & Chemical Engineering, Jiangxi Normal University, Nanchang 330022, P. R. of China   Email: mzcai@jxnu.edu.cn
,
Hong Zhao
a   School of Chemistry & Chemical Engineering, Guangdong Cosmetics Engineering & Technology Research Center, Guangdong Pharmaceutical University, Guangzhou 510006, P. R. of China   Email: zhaohong1001@sina.com
› Author Affiliations
We thank the National Natural Science Foundation of China (No. 21462021), the Natural Science Foundation of Jiangxi Province of China (No. 20161BAB203086), and the Key Laboratory of Functional Small Organic Molecules, Ministry of Education (No. KLFS-KF-201704) for financial support.
Further Information

Publication History

Received: 15 June 2019

Accepted after revision: 06 August 2019

Publication Date:
03 September 2019 (online)


Abstract

The heterogeneous copper(II)-catalyzed oxidative cyclization of 2-pyridine ketone hydrazones was achieved in ethyl acetate at room temperature in the presence of an MCM-41-anchored bidentate 2-aminoethylamino copper(II) catalyst [MCM-41-2N-Cu(OAc)2], in the presence of air as the oxidant, yielding a wide variety of [1,2,3]triazolo[1,5-a]pyridines in mostly good to high yields. The present method was also applied to the direct one-pot synthesis of [1,2,3]triazolo[1,5-a]pyridines from 2-acylpyridine derivatives and hydrazine monohydrate. Importantly, this supported copper(II) catalyst could be conveniently obtained via a simple procedure from easily available and inexpensive reagents, recovered by filtration of the reaction mixture, and reused at least seven times without a significant loss of catalytic activity.

Supporting Information