Convenient indole synthesis from ethynylanilines with a polymer-supported fluoride

The cyclization reaction of ethynylanilines having phenyl, alkyl, methoxy, cyano, chloro, and ethoxycarbonyl groups with (polystyrylmethyl)trimethylammonium fluoride in dry MeCN under an argon atmosphere at 100°C proceeded in good yields to give the corresponding indoles without affecting these functional groups. Moreover, the polymer-supported fluoride could be reused for the cyclization reaction when the deprotection reaction of the N-substituted indole with the fluoride ion on resin did not occur under the cyclization conditions.