Taking electrodecarboxylative etherification beyond Hofer–Moest using a radical C–O coupling strategy

Abstract

Established electrodecarboxylative etherification protocols are based on Hofer-Moest-type reaction pathways. An oxidative decarboxylation gives rise to radicals, which are further oxidised to carbocations. This is possible only for benzylic or otherwise stabilised substrates. Here, we report the electrodecarboxylative radical-radical coupling of lithium alkylcarboxylates with 1-hydroxybenzotriazole at platinum electrodes in methanol/pyridine to afford alkyl benzotriazole ethers. The substrate scope of this electrochemical radical coupling extends to primary and secondary alkylcarboxylates. The benzotriazole products easily undergo reductive cleavage to the alcohols. They can also serve as synthetic hubs to access a wide variety of functional groups. This reaction prototype demonstrates that electrodecarboxylative C–O bond formation can be taken beyond the intrinsic substrate limitations of Hofer-Moest mechanisms.

Since its discovery, the Hofer-Moest mechanism strongly limits the scope of electrochemical decarboxylative etherification. Here, the authors report the electrochemical conversion of carboxylic acids into alkyl benzotriazole ethers expanding the scope to primary and secondary acids beyond the boundaries of Hofer-Moest-type reactions.