A novel methodology toward the diversity-oriented asymmetric construction of densely functionalized isoxazole-dispirobisoxindoles was developed.

A highly efficient strategy for stereocontrolled construction of potentially bioactive and structurally rigid isoxazole‐fused spirocyclohexane oxindole‐based hexahydroxanthones via an organocatalytic domino Michael/Michael cycloaddition of multifunctional chromone‐based oxindole as a 4C building block and 3‐methyl‐4‐nitro‐5‐alkenyl‐isoxazole as an activated Michael acceptor is reported. Complex and skeleton‐diversified hexahydroxanthones bearing five continuous stereocenters including one spiro quaternary carton center were smoothly afforded in up to 92% yield, >20:1 d.r. and >99% ee. Further transformation of the product into other potentially bioactive molecules has also been demonstrated. This method could also forge the libraries of medicinally relevant molecules with skeletal diversity, thus to facilitate the search for new bioactive entities.magnified image

No abstract

The first example of bifunctional oxindole‐chromone C3 synthon directed organocatalytic cascade cycloaddition reaction is developed, serving as a fruitful strategy for the facile access of optically active tetrahydrocyclopenta[b]chromanone bearing one spirooxindole with five contiguous stereocenters. All the products are smoothly obtained with up to 83% yield, >20:1 d.r. and >99% ee. This is also the first asymmetric catalytic construction of tetrahydrocyclopenta[b] chromanone and tetrahydrocyclopenta[b]chromanone‐spirooxindole scaffold, thus to facilitate the search for new bioactive entities.magnified image