Diversity-Oriented Synthesis of Spirooxindoles via Asymmetric Organocatalytic Regiodivergent Cascade Reactions
Yong-Chao Ming1, Xue-Jiao Lv1, Chen Wang1
1Molecular Synthesis Center & Key Laboratory of Marine Drugs, Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.
Abstract:
A regiodivergent strategy for the asymmetric diversity-oriented synthesis of spirooxindoles via organocatalytic cascade reactions is developed. Two regioselective pathways can be precisely controlled with different aminocatalysts in the reaction of 2-hydroxycinnamaldehydes and β,β-disubstituted 3-alkylidene oxindoles. The cascade vinylogous Michael/oxa-Michael/aldol reactions gave spiro-bridged oxindoles bearing two adjacent quaternary stereocenters, while the cascade oxa-Michael/Michael reactions gave spirooxindoles. Moreover, during the synthetic application studies, an acid-catalyzed rearrangement of spiro-bridged oxindoles was found to yield biologically important 3-alkylidene oxindoles.
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