3,4-Dichlorophenyl isocyanate → Ethyl 5-(3,4-dichlorophenylcarbamoyl)-4,5,6,7-tetrahydroisoxazolo[4,5-c]pyridine-3-carboxylate

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Reaction Steps

Ethyl 4,5,6,7-tetrahydroisoxazolo[4,5-c]pyridine-3-carboxylate (A-06) (for synthesis see above) (0.5 g, 2.55 mmol) was dissolved in toluene (25 ml), and 1,2-dichloro-4-isocyanatobenzene (0.48 g, 2.55 mmol) was added. The reaction mixture was refluxed for 2 h. Toluene was removed in vacuo, the residue was taken up in ethyl acetate and sat. sodium hydrogen carbonate solution, and the phases were separated. The aqueous phase was extracted with ethyl acetate, and then the combined organic phases were washed with sat. sodium chloride solution, dried over sodium sulfate and concentrated in vacuo. Purification of the crude product was carried out by column chromatography (silica gel, diethyl ether/hexane 2:1). Yield: 1.2 g (>99%)

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