Oxidative Asymmetric Aza-Friedel-Crafts Alkylation of Indoles with 3-Indolinone-2-carboxylates Catalyzed by a BINOL Phosphoric Acid and Promoted by DDQ.

Abstract

An asymmetric aza-Friedel-Crafts alkylation reaction between indoles and indolenines that were derived in situ from 3-indolinone-2-carboxylates has been developed by using 3,3'-bis(triphenylsilyl)-1,1'-binaphthyl-2,2'-diyl hydrogen phosphate as a catalyst. The reaction proceeded under mild conditions and provided chiral indol-3-yl-3-indolinone-2-carboxylate derivatives in good yields with excellent ee values (up to 98.6 %). Similarly, the Mannich-type addition of indoline-3-ones to indolenines provided heterodimers with vicinal chiral quaternary centers. This method was successfully applied to the construction of the core structure of trigonoliimine C.