The electrolysis of isatins and cyclic 1,3-diketones in alcohol in an undivided cell results In the formation of the previously unknown substituted 2-(3-hydroxy-2-oxo-2,3-dihydro-1H-indol-3-yl)cyclohexane-1,3-drones in 70-85% substance yields and 700-850% current efficiency Thus, the simple electrocatalytic system can produce, under mild conditions the new electrochemically induced aldol reaction of isatins and cyclic 1,3-diketones (C) 2009 Elsevier Ltd. All rights reserved