A highly efficient chiral N,N'-dioxidenickel(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 as well as the absolute configuration of the product, a catalytic model was proposed to explain the stereocontrol process.Keywords: asymmetric catalysis; N,N'-dioxidenickel complex; spirooxindoles; tetrahydrothiophenes Among the various classes of organic sulfur compounds, optically active polysubstituted tetrahydrothiophenes have attracted considerable attention in the past decades, owing to their prevalence in natural products with a large spectrum of biological activities. [1,2] Recently, many strategies have been developed for the synthesis of this structure. [2][3][4] For the construction of chiral tetrahydrothiophenes, catalytic asymmetric domino [5] thia-Michael/aldol and thia-Michael/Michael reactions between mercaptoacetaldehyde analogues and a,b-unsaturated compounds belong to the most efficient and straightforward processes. The Jørgensen [6] and Wang [7] groups have applied chiral diarylprolinol ethers as organocatalysts to realize these reactions.A spirocyclic oxindole moiety as the core structure appears in many natural molecules.[8] As a result, enormous efforts were devoted to building this scaffold, [9] especially the chiral 3,3'-spirocyclic oxindoles fused with a heterocycle structure. Several enantioselectively synthetic approaches such as 1,3-dipolar cycloaddition [11a,b] or NHC-catalyzed formal [3+2] annulation, [10d,e,f] have been designed to synthesize spiro oxa [10] and spiro aza [11] heterocycle oxindoles. However, only few asymmetric routes to synthesize the spiro tetrahydrothiophene oxindoles have been disclosed. [12,13] Xiaos group recently reported the first domino thia-Michael/aldol reaction between 1,4-dithiane-2,5-diol and 3-alkenyloxindoles catalyzed by an organo-Cinchona-based squaramide, delivering the desired spirocyclic oxindole fused-tetrahydrothiophenes in a good result. However, the substrate scope is limited to the strong electron-deficient ester group Scheme 1. Catalytic asymmetric thia-domino cyclization of 1,4-dithiane-2,5-diol with 3-alkenyloxindoles. These are not the final page numbers! ÞÞ COMMUNICATIONS