Synthesis of Bisspiro(oxindole)s by DMAP‐Catalyzed [3+2] Annulation of Isatin‐Derived Morita‐Baylis‐Hillman Carbonates

Abstract

This study presents a straightforward [3 + 2] annulation method for synthesizing bisspiro(oxindole) derivatives using isatin‐derived Morita–Baylis–Hillman carbonates and p‐quinone methides (p‐QMs) with 4‐dimethylaminopyridine (DMAP) as the catalyst. The optimized protocol in dichloromethane (DCM) solvent achieves good yields (up to 87%) and diastereoselectivity (>20:1). The method's versatility is shown through the synthesis of various derivatives, including chiral variants with up to 82% ee. The intermediates were captured by HRMS, and a plausible reaction pathway was proposed.