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.

DOI: 10.1021/acs.orglett.6b03497

Cite this paper

@article{Cheng2017RelayVP, title={Relay Visible-Light Photoredox Catalysis: Synthesis of Pyrazole Derivatives via Formal [4 + 1] Annulation and Aromatization.}, author={Jian Cheng and Weipeng Li and Yingqian Duan and Yixiang Cheng and Shouyun Yu and Chengjian Zhu}, journal={Organic letters}, year={2017}, volume={19 1}, pages={214-217} }