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5a (239 mg, 1 mmol), and 4-fluoroaniline (134 mg, 1.2 mmol)were added to ethanol and the resulting heterogeneous solutionwas reuxed for 24 h. The mixture was cooled to room temperatureand ltered through a pad of celite and the ltrate was concen-trated under reduced pressure. The residue was puried by ashchromatography on silica-gel with 20% ethyl acetate in hexane.Yielding 80% compound 10a (348 mg) as a white solid. Compounds10b-g were synthesized following the procedure of preparation10a.