Enantioselective\nOrganocatalyzed Cascade Dearomatizing\nSpirocycloaddition Reactions of Indole-Ynones

An intramolecular organocatalytic cascade dearomatizing\nspirocycloaddition\nreaction of indole-ynone compounds containing <i>O</i>-silyl-naphthol\nsubstituents has been developed with the use of a chiral bifunctional\nthiourea. This process was able to provide various structurally diverse\npolycyclic spiroindolines in high yields (up to 98%) with excellent\nstereoselectivities (>20:1 dr, up to 98% ee) involving the formation\nof carbonylvinylidene <i>ortho</i>-quinone methide intermediates.