Cathodic Aromatic C,C Cross-Coupling Reaction via Single Electron Transfer Pathway.

We have successfully developed a novel cathodic cross-coupling reaction of aryl halides with arenes. Utilization of the cathodic single electron transfer (SET) mechanism for activation of aryl halides enables the cross-coupling reaction to proceed without the need for any transition metal catalysts or single electron donors in a mild condition. The SET from a cathode to an aryl halide initiates a radical chain by giving an anion radical of the aryl halide. The following propagation cycle also consists entirely of anion radical intermediates.

An anodic aromatic C,C cross-coupling reaction using parallel laminar flow mode in a flow microreactor.

We have successfully demonstrated an efficient anodic aromatic C,C cross-coupling reaction using parallel laminar flow mode in a two-inlet flow microreactor. The model reaction proceeded effectively even in single flow-through operations and the desired cross-coupling product was obtained in much higher current yields compared to the reaction in a conventional batch type cell.

In situ electrogeneration of o-benzoquinone and high yield reaction with benzenethiols in a microflow system.

We have successfully demonstrated that a microflow reactor is extremely useful in controlling reactions involving an unstable o-benzoquinone. The key features of the method are an effective o-benzoquinone generation and its rapid use for the following reaction without decomposition in a microflow system.

Product selectivity control induced by using liquid-liquid parallel laminar flow in a microreactor.

Product selectivity control based on a liquid-liquid parallel laminar flow has been successfully demonstrated by using a microreactor. Our electrochemical microreactor system enables regioselective cross-coupling reaction of aldehyde with allylic chloride via chemoselective cathodic reduction of substrate by the combined use of suitable flow mode and corresponding cathode material. The formation of liquid-liquid parallel laminar flow in the microreactor was supported by the estimation of benzaldehyde diffusion coefficient and computational fluid dynamics simulation. The diffusion coefficient for benzaldehyde in Bu(4)NClO(4)-HMPA medium was determined to be 1.32 × 10(-7) cm(2) s(-1) by electrochemical measurements, and the flow simulation using this value revealed the formation of clear concentration gradient of benzaldehyde in the microreactor channel over a specific channel length. In addition, the necessity of the liquid-liquid parallel laminar flow was confirmed by flow mode experiments.