Organocatalytic Enantioselective aza-Friedel-Crafts Reactions of Pyrazolinone Ketimines with Hydroxyindoles and Electron-Rich Phenols

A variety of enantioenriched indole derivatives substituted in the benzene ring were synthesised via an organocatalytic asymmetric aza-Friedel-Crafts reaction of pyrazolinone ketimines with hydroxyindoles. This reaction was also applicabled to electron-rich phenols, yielding the desired products in high yields (up to 99%) and excellent stereo-selectivities (91-99% ee). Moreover, this method presents its potential in the synthesis of structurally novel indole-pyrazolinone conjugate derivatives.