Electrochemical Conversion of Phthaldianilides to Phthalazin-1,4-diones by Dehydrogenative N-N Bond Formation.

The electrochemical synthesis of 6-membered rings via anodic dianilide N-N coupling is challenging due to concurring benzoxazole co-formation. The rigidity of the a phthalic acid backbone allows a novel access to phthalazin-1,4-diones by N-N bond formation using anodically generated amidyl radicals. Since conventional synthetic routes to phthalazin-1,4-diones require the use of toxic N,N'-diarylhydrazines and generate reagent waste, a safer and more sustainable approach is required. Easy accessible starting materials, a broad scope of applicable functional groups, promising yields, and a very simple set-up elevate this sustainable method.