Rhodaelectro-Catalyzed\nSynthesis of Pyrano[3,4‑<i>b</i>]indol-1(9<i>H</i>)‑ones via the Double\nDehydrogenative Heck Reaction between Indole-2-carboxylic Acids and\nAlkenes

A rhodaelectro-catalyzed double dehydrogenative Heck\nreaction of\nindole-2-carboxylic acids with alkenes has been developed for the\nsynthesis of pyrano[3,4-<i>b</i>]indol-1(9<i>H</i>)-ones. The weakly coordinating carboxyl group is utilized twice\nas a directing group to activate the C–H bonds throughout the\nreaction. This reaction precedes an acceptorless dehydrogenation under\nexogenous oxidant-free conditions in an undivided cell with a constant\ncurrent.