Synthesis of 3,3-Spiroindolines via FeCl 3 -Mediated Cyclisation of Aryl or Alkene-Containing 3-Substituted N-Ac Indoles

“This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Organic Letters, copyright © American Chemical Society after peer review. To access the final edited and published work see http://pubsdc3.acs.org/doi/full/10.1021/acs.orglett.6b00174International audienceWe report the cyclization of 3-substituted N-acetylindoles for the straightforward synthesis of 3,3-spiroindolines via the Friedel–Crafts reaction of an appended aryl group or the formal [2 + 2] cycloaddition of an appended alkene. Our strategy involves an Umpolung of the C2═C3 bond of the indole nucleus during FeCl3-mediated hydroarylation or annulation reactions