Flow electrochemistry is an efficient methodology to generate radical intermediates. An electrochemical flow microreactor has been designed and manufactured to improve the efficiency of electrochemical flow reactions. With this device only little or no supporting electrolytes are needed, making processes less costly and enabling easier purification. This is demonstrated by the facile synthesis of amidyl radicals used in intramolecular hydroaminations to produce isoindolinones. The combination with inline mass spectrometry facilitates a much easier combination of chemical steps in a single flow process.

An efficient and reliable electrochemical generator of hypervalent iodine reagents has been developed. In the anodic oxidation of iodoarenes to hypervalent iodine reagents under flowconditions,the use of electricity replaces hazardous and costly chemical oxidants.U nstable hypervalent iodine reagents can be prepared easily and coupled with different substrates to achieve oxidative transformations in high yields. The unstable,e lectrochemically generated reagents can also easily be transformed into classic bench-stable hypervalent iodine reagents through ligand exchange.T he combination of electrochemical and flow-chemistry advantages largely improves the ecological footprint of the overall process compared to conventional approaches.

A catalyst- and supporting electrolyte-free method for electrochemical dehydrogenative C-S bond formation in continuous flow has been developed. A broad range of N-arylthioamides have been converted to the corresponding benzothiazoles in good to excellent yields and with high current efficiencies. This transformation is achieved using only electricity and laboratory grade solvent, avoiding degassing or the use of inert atmosphere. This work highlights three advantages of electrochemistry in flow, which is (i) a supporting electrolyte-free reaction, (ii) an easy scale-up of the reaction without the need for a larger reactor and, (iii) the important and effective impact of having a good mixing of the reaction mixture, which can be achieved effectively with the use of flow systems. This clearly improves the reported methods for the synthesis of benzothiazoles.

Electrosynthesis is an old method currently moving again in the focus of organic synthesis. Some limitations of conventional electrosynthesis can be overcome by the use of electrochemical flow devices. This perspective indicates where the pitfalls, where the advantages and where the challenges are in implementing flow electrosynthesis as an alternative tool for the synthetic chemist.

Electro-reductive radical cyclisation of aryl halides affords the corresponding hetero-and carbocycles in an undivided flow reactor equipped with steel and carbon electrodes using an organic mediator. A dissolving metal anode is not needed, and the mediator can be employed in a sub-stoichiometric amount (0.05 equiv), increasing the practical utility of cathodic radical cyclisation. The methodology is applied to O-, N-, and C-tethers, yielding tricyclic fused and spiro systems. In the absence of mediator, the major pathway is hydrogenolysis of the CÀ X bond, a 2 e À process occurring at the cathode. Predominance of the radical pathway in presence of a strongly reducing mediator (M) is consistent with homogeneous electron-transfer in a reaction layer detached from the cathode surface, where the flux of M *À leaving the electrode is such that little aryl halide reaches the cathode.