An Electrosynthesis of 1,3,4-Oxadiazoles from N-Acyl Hydrazones
Luke Chen1,2, James D F Thompson1, Craig Jamieson2
1Medicinal Chemistry, GSK, Gunnels Wood Road, Stevenage, SG1 2NY, United Kingdom.
Abstract:
The 1,3,4-oxadiazole is a widely encountered motif in the areas of pharmaceuticals, materials, and agrochemicals. This work has established a mediated electrochemical synthesis of 2,5-disubstituted 1,3,4-oxadiazoles from N-acyl hydrazones. Using DABCO as the optimal redox mediator has enabled a mild oxidative cyclisation, without recourse to stoichiometric oxidants. In contrast to previous methods, this indirect electrochemical oxidation has enabled a broad range of substrates to be accessed, with yields of up to 83 %, and on gram scale. The simplicity of the method has been further demonstrated by the development of a one-pot procedure, directly transforming readily available aldehydes and hydrazides into valuable heterocycles.
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