Regioselective Synthesis of Heterocycles from 3-Cyclohex-2-enyl-4-hydroxy-1-methylquinolin-2-(1H)-one |
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Authors: | K C Majumdar T Bhattacharyya |
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Institution: | Department of Chemistry , University of Kalyani , Kalyani, 741235, W.B., India |
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Abstract: | 3-Cyclohex-2-enyl-4-hydroxy-1-methylquinolin-2(1H)-one (5) reacts with pyridine hydrotribromide in CH2Cl2 at 0–5°C for 0.75h to give a furo fused heterocycle 6 in 96% yield. Product 6 on treatment with KOH-EtOH eliminates HBr to give compound 8 which on treatement with Pd-C in refluxing diphenyl ether for 0.5h furnishes benzofuro3,2-c]quinolone 9 in 90% yield. Substrate 5 on sequential treatment with Ac2O-AcONa and Br2/AcOH followed by KOH-EtOH, however produces bicyclic product 7 in excllent overall yield. Substrate 5 reacts with 1 equivalent of m-chloroperbenzoic acid in refluxing benzene to furnish bicyclic heterocycle 12 in 80% yield and with cold conc. H2SO4 at 0–5°C for 2h generates the bicyclic heterocycle 14 in 90% yield. |
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