Electrochemical Annulation-Iodosulfonylation of 1,5-Enyne-containing -Quinone Methides (-QMs) to Access ()-Spiroindenes.

A new electrochemical three-component annulation-iodosulfonylation of 1,5-enyne-containing -quinone methides (-QMs) has been established by using available arylsulfonyl hydrazides and potassium iodide under environmentally benign conditions. The electrosynthesis offers sustainable and efficient access to construct spirocyclohexadienone-containing ()-indenes without any additional catalyst or oxidant through a sulfonyl-radical-triggered 1,6-addition and an I-mediated -cyclization cascade. Notably, potassium iodide plays the triple role of an electrolyte, a redox catalyst, as well as an iodination reagent.