Organocatalytic Asymmetric Synthesis of Bridged Acetals with Spirooxindole Skeleton.

The first highly diastereo- and enantioselective synthesis of bridged O, O-acetals embedded with spirooxindoles has been developed. Dioxindoles and 2-hydroxy cinnamaldehydes were employed as the reaction partners in this method. The desired products were obtained via diaryl prolinol TBS ether catalyzed Michael reaction followed by acetal formation with TFA.