A Novel Rearrangement of 3-Arylisoxazol-5(4H)-ones: One-Pot Synthesis of New 2,4-Dichloroquinoline-3-carbaldehydes
17. September 2002 (online)
Vilsmeier-Haack reaction, using a specific combination of phosphorus oxychloride and dimethylformamide, on 3-arylisoxazol-5(4H)-ones 1 resulted in 2,4-dichloroquinoline-3-carbaldehydes 6 as the major products along with other minor products, through a novel rearrangement. Oxidation of 6 with alkaline potassium permanganate gave 2,4-dichloroquinoline-3-carboxylic acids 7. Decarbonylation of 6 and decarboxylation of 7 using aqueous sodium hydroxide yielded 2,4-dichloroquinolines 8. All the compounds were characterised by elemental and spectral analysis.