Organocatalytic enantioselective Mannich reaction of isoxazol-5(4H)-ones to isatin-derived ketimines

An efficient organocatalytic asymmetric Mannich reaction between isoxazol-5(4H)-ones and isatin-derived ketimines has been developed. A bifunctional squaramide/Bronsted base organocatalyst catalyzed the enantioselective Mannich addition to afford chiral 3-aminooxindoles bearing a tetrasubstituted stereocenter at C3 decorated with an isoxazole moiety in good yields and with excellent enantioselectivities. Additionally, several synthetic transformations were described showing the versatility of the prepared compounds.

Automated summary

An efficient organocatalytic asymmetric Mannich reaction between isoxazol-5(4H)-ones and isatin-derived ketimines has been developed. The reaction is catalyzed by a bifunctional squaramide/Bronsted base organocatalyst, resulting in the synthesis of chiral 3-aminooxindoles. The prepared compounds exhibit good yields and excellent enantioselectivities, and have demonstrated versatile synthetic transformations.