The Assembly of Cerium(III)-Containing Silicotungstate with Lewis Acid-Base Sites Enables the Selective -Alkenylation of Oxindole.

A cerium(III)-containing silicotungstate, [HN(CH)]NaK[KCe(SiWO)(HO)]·18.5HO (), was successfully synthesized and characterized. Structure analysis reveals that is composed of two {SiWO} units connected by one cerium(III) cation to form a typical 1:2 sandwich structure, which is further expanding into a 1D chain linked by K ions. The oxygen-enriched surfaces of {SiWO} units and open cerium sites provide abundant Lewis base and acid sites in . As a result, efficiently catalyzed the -alkenylation of oxindoles with aldehydes through the simultaneous activation of both reaction substrates on its crystal framework. Various 3-benzylidene-oxindoles are synthesized with excellent yields and high -selectivity under solvent-free conditions.