Access to 3‐Oxindoles from Allylic Alcohols and Indoles

Abstract The site‐selective and regioselective allylation of 2‐substituted indoles was performed by using a ruthenium(IV) precatalyst containing a phosphine–sulfonate chelate. Mono‐, di‐, and triallylated indoles were selectively obtained depending on the reaction conditions with the formation of water as the only byproduct. The preparation of 3‐oxindole derivatives was then successfully performed owing to air oxidation of the corresponding allylated indoles. Diallylated pseudoindoxyls were proven to be good synthons to perform cyclization through a ring‐closing metathesis reaction to afford the corresponding tricyclic adducts. The photophysical properties of the 3‐oxindoles were measured, and some of the compounds showed strong fluorescence in water.