Base Induced Chiral Substituted Furans and Imidazoles from Carbohydrate-Derived 2-Haloenones

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• 作者：Kanchan Mal ; Indrajit Das
• 刊名：Journal of Organic Chemistry
• 出版年：2016
• 出版时间：February 5, 2016
• 年：2016
• 卷：81
• 期：3
• 页码：932-945
• 全文大小：825K
• ISSN：1520-6904

文摘

Chiral substituted furans and imidazoles are key intermediates to access biologically important molecules. We describe herein a catalyst/ligand free cascade Michael-type addition/intramolecular cyclization/carbohydrate-ring opening of 2-haloenones with 1,3-dicarbonyl compounds or amidines utilizing K₂CO₃/DMSO at ambient temperature that provides a straightforward approach to a variety of optically active (poly)hydroxy furans and imidazoles containing multiple stereocenters with good yield and excellent regioselectivity. The furan intermediates provide efficient access to synthetically valuable substituted α-benzyloxyvinyl ketones. The NMR spectrum of the substituted 2-methylfurans shows an unusual long-range (⁵J_H–H) ¹H–¹H COSY cross-peak between C₂–CH₃ and C₄–H signals.