Organocatalyzed Enantioselective Allylation of Isatins by Using a Chiral Amino Alcohol Derived Squaramide as Catalyst

A series of new squaramide‐based organocatalysts were synthesized from commercially available 3,4‐dimethoxycyclobut‐3‐ene‐1,2‐dione in two steps. A 2.5 mol‐% loading of the organocatalyst successfully catalyzed the asymmetric allylation of isatins with allyltributyltin to give the corresponding 3‐allyl‐3‐hydroxyoxindoles in high yields and enantioselectivities (up to 98 % ee). A new series of squaramide‐based organocatalysts were developed and successfully applied for the asymmetric allylation reaction of isatins with allyltributltin. The present catalytic system was highly efficient for the allylation of N‐protected isatins giving very good yields (75–95 %) and excellent enantioselectivities (62–98 %) of the allylation products.