Electrolyte‐Controlled Regiodivergent Continuous Flow Electroselenocyclisations

Supporting electrolytes, beyond traditionally serving as ionic conductors in electrochemistry, can influence regioselectivity in electrochemical synthesis by acting as base. We present a single‐pass continuous flow electrolysis method enabling selective activation of diselenides and oximes to access seleno‐substituted isoquinoline and isoindole derivatives. Mechanistic studies showed a radical pathway via iminoxyl radicals to isoindole N ‐oxides and an ionic mechanism leading to isoquinoline N ‐oxides. This process leverages N ‐activated neutral isoquinolinium products for diverse downstream modifications. Our findings highlight the untapped potential of supporting electrolytes in regiodivergent electrochemical transformations and provide a sustainable and scalable platform for continuous flow approaches for synthesising selenium‐containing heterocycles with biological relevance.