An efficient approach for the stereocontrolled construction of the 3,4‐dihydrothiacarbazol‐2(9H)‐one skeleton has been developed. In the presence of a bifunctional squaramide catalyst that was derived from L‐tert‐leucine, the asymmetric tandem Michael/thiolysis reactions of 9‐methylindoline‐2‐thiones and N‐alkynoylphthalimides proceeded efficiently to furnish the desired 3,4‐dihydrothiacarbazol‐2(9H)‐one derivatives in satisfactory yields with high levels of enantioselectivity (up to 98 % ee).

No abstract

Asymmetric Michael addition of 1-acetylindolin-3-ones to β,γ-unsaturated α-ketoesters was investigated for the synthesis of chiral indolin-3-ones with two adjacent tertiary stereogenic centers. Under the catalysis of a chiral bifunctional squaramide derived from l-tert-leucine, a wide range of 1-acetylindolin-3-ones and β,γ-unsaturated α-ketoesters were well-tolerated in this transformation to provide the corresponding novel densely functionalized chiral indolin-3-one derivatives in high yield with excellent diastereo- and enantioselectivity under mild reaction conditions.