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

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 <i>anti</i> and <i>syn</i>-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

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

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 <i>anti</i> and <i>syn</i>-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

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

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 <i>anti</i> and <i>syn</i>-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

Diastereo- and Enantioselective Synthesis of 2,2-Disubstituted Benzofuran-3-one Bearing Adjacent Quaternary and Tertiary Stereocenters

The first highly diastereo- and enantioselective synthesis of armeniaspirol analogues was achieved using L-proline derived bifunctional squaramide which outperformed commonly used organocatalysts. Excellent yield (up to 99%) with diastereoselectivity (up to 99:1) and enantioselectivity (up to 99%) were obtained for a wide range of substrates