Iodine → 1-(4-chlorophenyl)-3-[(Z)-3-iodobut-2-enoxy]pyrazole

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Reaction Steps

To 10.0 g (18.6 mmol) 1-(4-chloro-phenyl)-3-((Z)-3-tributylstannanyl-but-2-enyloxy)-1H-pyrazole in 100 ml methylene chloride have been added 4.7 g (18.6 mmol) iodine at ambient temperature with stirring which was continued for 3 h. After removal of the solvents in vacuo the crude product was dissolved in 200 ml MTBE. 100 ml 20% aqueous potassium fluoride solution have been added and the mixture was stirred for 2 h at ambient temperature. The aqueous layer was separated and extracted with 20 ml methyl-tert.-butyl ether twice. The combined organic phases have been washed twice with 20 ml of water each, dried with sodium sulfate, and the solvents were removed in vacuo. The crude product (7.2 g) has been purified by chromatography on 50 g silica with methyl-tert.-butylether/hexane (1:20). Yield 5.9 g, melting point 75-77° C.

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