Electrochemical Synthesis of 2,5‐Disubstituted 1,3,4‐Oxadiazoles from α‐Keto Acids and Acylhydrazines Under Mild Conditions
Fangling Lu, Fengping Gong, Liangsen Li, Kan Zhang, Zhen Li, Xinwei Zhang, Ying Yin, Ying Wang, Ziwei Gao, Heng Zhang, Aiwen Lei
Abstract
1,3,4‐Oxadiazoles are a kind of useful heterocycles which can be frequently found in materials and bioactive molecules. In this study, intermolecular electrochemical cyclization between α‐keto acids and acylhydrazines has been developed for the synthesis of 2,5‐disubstituted 1,3,4‐oxadiazoles with the yield up to 91 %. This transformation can be run under mild reaction conditions in the absence of external oxidant, base and transition metal catalyst. Both symmetrical and unsymmetrical 2,5‐disubstituted 1,3,4‐oxadiazoles could be prepared according to the careful choice of the substrate combination. Gram scale synthesis also illustrates the potential application of this protocol in large preparation.