Organocatalytic Asymmetric Mannich Reaction of 3‑Hydroxyoxindoles/3-Aminooxindoles with in Situ Generated N‑Boc-Protected Aldimines for the Synthesis of Vicinal Oxindole–Diamines/Amino Alcohols

A highly efficient asymmetric Mannich reaction of 3-monosubstituted 3-aminooxindoles/3-hydroxyoxindoles with in situ generated N-Boc-protected aldimines catalyzed by the chiral bifunctional thiourea–tertiary amine catalyst has been developed. Under mild reaction conditions, a series of structurally diverse vicinal oxindole–diamines/amino alcohols were smoothly obtained in moderate to high yields (up to 99%) with good to excellent diastereoselectivities and enantioselectivities (up to 95:5 dr and 96% ee). The synthetic application of this protocol was also demonstrated by the versatile transformation of chiral vicinal oxindole–diamine/amino alcohol into spirocyclic oxindoles.