Design, Synthesis, and Resolution of Spirocyclic Bisoxindole-Based C2‑Symmetric Diols

A new type of spirocyclic bisoxindole-based C2-symmetric diols (SBIDOLs) was designed and synthesized. A series of racemic SBIDOL derivatives (6a–6g) were readily synthesized from commercially available 2-halo-5-methoxyanilines 1 (X = Cl or Br) through N-mono alkylation, acylation, oxidation, double intramolecular Friedel–Crafts reaction, and demethylation reactions. The optical resolution of racemic 6b was achieved via fractional crystallization of their bis-l-menthoxycarboxylates. Further modifications of SBIDOLs were investigated, leading to 5,5′-diaryl SBIDOL derivatives (11a and 11b) through Pd-catalyzed Suzuki coupling and DM-SBIDOL 12 by Pd/C-catalyzed hydrogenative dechlorination reactions.