Synthesis of six-membered spirooxindoles via a chiral Br?nsted acid-catalyzed asymmetric intramolecular Friedel–Crafts reaction

摘要

By means of the direct condensation of N -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′ H -spiro[indoline-3,1′-pyrrolo[1,2- a ]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.