Microwave-Assisted Solid-Acid-Catalyzed Friedel-Crafts Alkylation and Electrophilic Annulation of Indoles Using Alcohols as Alkylating Agents

Alcohols are considered environmentally benign alkylating agents since the only by-product generated in their reactions is water. Herein, we report a microwave-assisted Friedel-Crafts alkylation and electrophilic annulation of indoles using alcohols as alkylating agents. Alkylation of indoles using tert-butyl alcohol gives 3-substituted tert-butylindoles. A domino electrophilic annulation/aromatization of indoles using hexane-2,5-diol results in the formation of substituted carbazoles. The reaction is catalyzed by a strong, solid-acid catalyst montmorillonite K-10. The products were obtained in good yields and high selectivities.