An Efficient Solvent-Free Synthesis of 2-Hydroxy-2-trifluoromethyl-2H-chromenes Using Silica-Immobilized L-ProlineReportar como inadecuado




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School of Science, Henan Agricultural University, Zhengzhou 450002, China.





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Abstract An efficient synthesis of 2-hydroxy-2-trifluoromethyl-2H-chromene-3-carboxylates was carried out under solvent-free conditions in an oven or microwave oven via the Knoevenagel condensation of salicylaldehydes with ethyl trifluoroacetoacetate followed by intramolecular cyclization in the presence of silica-immobilized L-proline. The structures of the title compounds were characterized by IR, 1H-NMR, 13C-NMR, HRMS and X-ray single crystal diffraction. The improved method described herein is economical, easily-operated and environmentally friendly. Furthermore, the catalyst can be recovered conveniently and reused without obvious loss of activity. View Full-Text

Keywords: solvent-free; 2-hydroxy-2-trifluoromethyl-2H-chromene-3-carboxylates; synthesis; Knoevenagel condensation; silica-immobilized L-proline solvent-free; 2-hydroxy-2-trifluoromethyl-2H-chromene-3-carboxylates; synthesis; Knoevenagel condensation; silica-immobilized L-proline





Autor: Cuilian Xu * , Guoyu Yang, Caixia Wang, Sufang Fan, Lixia Xie and Ya Gao

Fuente: http://mdpi.com/



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