title: Relay Visible-Light Photoredox Catalysis: Synthesis of Pyrazole Derivatives via Formal [4 + 1] Annulation and Aromatization.
abstract: A relay visible-light photoredox catalysis strategy has been accomplished. Three successive photoredox cycles (one oxidative quenching cycle and two reductive quenching cycles) are engaged in a single reaction with one photocatalyst. This strategy enables formal [4 + 1] annulation of hydrazones with 2-bromo-1,3-dicarbonyl compounds, which functionalizes three C-H bonds of hydrazones. This method affords rapid access to a complex and biologically important pyrazole scaffold in a step-economical manner with high efficiency under mild conditions.
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210023 P. R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210023 P. R. China.
authors.forename: Weipeng
authors.initials: W
authors.lastname: Li
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210023 P. R. China.
authors.forename: Yingqian
authors.initials: Y
authors.lastname: Duan
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210023 P. R. China.
authors.forename: Yixiang
authors.identifier: 0000-0001-6992-4437
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210023 P. R. China.
authors.forename: Shouyun
authors.identifier: 0000-0003-4292-4714
authors.initials: S
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210023 P. R. China.|Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , Shanghai 200032 P. R. China.
authors.forename: Chengjian
authors.identifier: 0000-0003-4465-9408
authors.initials: C
authors.lastname: Zhu