Stereocontrolled Synthesis of Bispirooxindole-Based Hexahydroxanthones with Five Contiguous Stereocenters

A bifunctional oxindole-chromone synthon 1 directed tandem reaction is developed, serving as a fruitful strategy for facile access to optically active hexahydroxanthones 3 bearing two spirooxindoles with five contiguous stereocenters. All of the bispirooxindole-based hexahydroxanthones 3 are smoothly obtained with up to 91% yield, >20:1 dr, and >99% ee. Biological evaluation of selected compounds 3 revealed that they exerted good cytotoxic effects on human K562, A549, and PC-3 cells.