Stereodivergent Synthesis of 3-Aminooxindole Derivatives Containing Vicinal Tetrasubstituted Stereocenters via the Mannich Reaction

J Org Chem. 2018 Aug 17;83(16):8936-8952. doi: 10.1021/acs.joc.8b01020. Epub 2018 Jul 23.

Abstract

A highly enantioselective stereodivergent synthesis of 3-aminooxindole derivatives was accomplished via asymmetric Mannich reaction between 2-substituted benzofuran-3-one and isatin-derived ketimines. Both anti and syn-selective chiral 3,3-disubstituted amino oxindoles bearing two adjacent tetrasubstituted stereogenic centers with high yield and excellent enantioselectivities were obtained using readily available cinchona-alkaloid derived organocatalysts. The control experiment revealed that oxygen atom present in the benzofuran ring played an important role in switching diastereodivergence. The obtained Mannich product was further transformed into a biologically important 2,3-dihydrobenzofuran derivative having three contiguous stereocenters with no loss of enantioselectivity.

Publication types

  • Research Support, Non-U.S. Gov't