An efficient organocatalytic Michael-aldol cascade reaction for the asymmetric synthesis of spirocyclic oxindole derivatives fused with tetrahydrothiophenes has been developed through a formal [3+2] annulation strategy.
Asymmetric Synthesis of Spirocyclic Oxindole-Fused Tetrahydrothiophenes<i>via N,N′-</i>Dioxide-Nickel(II) Catalyzed Domino Reaction of 1,4-Dithiane-2,5-diol with 3-Alkenyloxindoles
A highly efficient chiral N,N′‐dioxide–nickel(II) complex system has been developed to catalyze the domino thia‐Michael/aldol reaction of 1,4‐dithiane‐2,5‐diol with 3‐alkenyloxindoles. A series of the desired spirocyclic oxindole‐fused tetrahydrothiophenes was obtained in good yields with excellent ee and dr (up to 97% yield, 98% ee, >19:1 dr). Besides, based on the X‐ray crystal structure of the catalyst