Friedel-Crafts Alkylation of Indoles with p-Quinols: The Role of Hydrogen Bonding of Water for the Desymmetrization of the Cyclohexadienone System.

Lewis acid catalyzed Friedel-Crafts alkylation of indoles has been achieved in high yields and selectivities using p-quinols as electrophiles. (S)-Binol-3,3'-(9-anthracenyl)-phosphoric acid was able to catalyze the enantioselective formation of 5-(3-indole)-2-cyclohexenone derivatives. Experimental results and theoretical calculations explained the enantioselectivity based on a transition state where two water molecules act as a tether joining the p-quinol with the phosphoric acid and the NH of indole, thus facilitating the desymmetrization of the prochiral cyclohexadienone framework. The toc/abstract graphic was corrected on April 19, 2016. On May 6, 2016, a missing assignment of the configuration of the catalyst 12h and a mistake in the configuration of compounds in the Supporting Information were corrected. [ABSTRACT FROM AUTHOR]