A new method is developed for the synthesis of spirooxindoles from amines and isatins via C-H functionalization. The reaction leverages the tert-amino effect to form an enolate-iminium intermediate via [1,5]-hydride shift followed by cyclization. Interestingly the hydride migrates to the N atom of a C═N, which is atypical for hydride additions to imines.
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Recent advances in the reactions of isatin-derived MBH carbonates for the synthesis of spirooxindoles.
Org Biomol Chem
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Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry & Chemical Engineering, Tianjin University of Technology, Tianjin 300384, P. R. China.
As one of the main fragments in medical drugs, spirooxindole has received considerable attention from organic and medicinal chemists. In the past few decades, chemists have been searching for more straightforward and efficient methods to produce compounds containing a spirooxindole fragment. In this regard, isatin-derived Morita-Baylis-Hillman (MBH) carbonates have been widely used as versatile building blocks for the synthesis of spirooxindole structures.
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IICT CSIR: Indian Institute of Chemical Technology, Department of Applied Biology, Hyderabad, INDIA.
An efficient and concise synthesis of highly functionalized bridged coumarins has been developed through a diastereoselective double Michael addition reaction of p-quinols with various 4-hydroxy coumarins under catalyst-free conditions in H2O-DMSO (8:2). The method has been applied to oxindoles for the synthesis of a variety of bridged-oxindoles and bridged-spiroxindoles in presence of a DABCO base using H2O-EtOH (8:2) as solvent medium. The strategy is simple, highly atom economical as there is no by-product and environmentally benign (E-factor = 0.
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Department of Chemistry, Indian Institute of Technology Kanpur, Uttar Pradesh, Kanpur, 208016, India.
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Molecular 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.
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.
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Sichuan Provincial Key Laboratory of Quality and Innovation Research of Chinese Materia Medica, Sichuan Academy of Chinese Medicine Sciences, Chengdu 610041, P. R. China.
Although there have been various reviews on the asymmetric construction of C3-spirooxindoles, there is a scarcity of reviews focusing on the asymmetric organocatalytic synthesis of C3-spiro-cyclopentaneoxindole derivatives. This particular scaffold has garnered significant attention from synthetic chemists due to its relevance in medicinal chemistry. In this review, we provide an overview of recent advancements in the asymmetric organocatalytic synthesis of various C3-spiro-cyclopentaneoxindoles using organic catalysts.
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