Beyond Kolbe and Hofer-Moest: Electrochemical Synthesis of Carboxylic Anhydrides from Carboxylic Acids.

Herein we report a conceptually new non-decarboxylative electrolysis of carboxylic acids to obtain their corresponding anhydrides as highly valuable reagents in organic synthesis. All carbon atoms of the starting material are preserved in the product in an overall redox-neutral reaction. In a broad substrate scope of carboxylic acids the anhydrides are generated with high selectivity, which demonstrates the versatility of the developed method. Beneficially, no dehydrating reagents are required in comparison to conventional methods and the synthesis is based on uncritical starting materials using graphite and stainless steel as very inexpensive and eco-friendly electrode materials.

Electrochemical Formation of 3,5-Diimido-1,2-dithiolanes by Dehydrogenative Coupling.

A synthetic approach to the cyclic disulfide moiety of 3,5-diimido-1,2-dithiolane derivatives starting with readily available precursors including the electrochemical coupling of dithioanilides is developed. The electrochemical key step provides sustainable synthetic access in high yields, using a very simple electrolysis setup.