title: Practical synthesis of pyrazoles via a copper-catalyzed relay oxidation strategy.
abstract: Various 1,3- and 1,3,4-substituted pyrazoles are smoothly formed via copper-catalyzed cascade reactions of oxime acetates, amines and aldehydes. This relay oxidative process involves copper-promoted N-O bond cleavage and C-C/C-N/N-N bond formations to furnish pyrazolines, and sequential Cu-O2 system-involved oxidative dehydrogenation of pyrazolines to afford pyrazoles. This transformation provides a novel and versatile approach for the synthesis of pyrazoles, with an inexpensive copper catalyst and green oxidants. It is atom- and step-economical, and possesses a good functional group tolerance, as well as operational simplicity.
authors.affiliation: School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China. jianghf@scut.edu.cn.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Tang
authors.forename: Liangbin
authors.initials: L
authors.lastname: Huang
authors.forename: Jidan
authors.initials: J
authors.lastname: Yang
authors.forename: Yanli
authors.initials: Y
authors.lastname: Xu
authors.forename: Wanqing
authors.initials: W
authors.lastname: Wu
authors.forename: Huanfeng
authors.initials: H
authors.lastname: Jiang