Synthesis of six-membered spirooxindoles<i>via</i>a chiral Brønsted acid-catalyzed asymmetric intramolecular Friedel–Crafts reaction

Abstract

By means of the direct condensation of <i>N</i>-aminoethylpyrroles and isatins, followed by a chiral phosphoric acid-catalyzed asymmetric intramolecular Friedel-Crafts reaction, a new class of valuable chiral 3',4'-dihydro-2'<i>H</i>-spiro[indoline-3,1'-pyrrolo[1,2-<i>a</i>]pyrazin]-2-ones bearing a quaternary carbon stereocenter were successfully synthesized in good to excellent yields and with moderate to good enantioselectivities under mild reaction conditions.