Ammonium Chloride → Ethyl 4,5-dichloro-6-((1-ethoxymethyl-pyrazol-5-yl)-hydroxymethyl)-1,3-benzodioxole-2-carboxylate

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Reaction Steps

1.25 ml of 1.6M n-butyl lithium in n-hexane is added dropwise to a solution of 252 mg of 1-ethoxymethyl-pyrazole in 5 ml of tetrahydrofuran at -60° to -50° C. 0.4 ml of hexamethylphosphoric triamide is added to the mixture and the mixture is stirred at the same temperature for 1 hour. The mixture is added to a solution of 582 mg of ethyl 4,5-dichloro-6-formyl-1,3-benzodioxole-2-carboxylate in 10 ml of tetrahydrofuran at -60° to -50° C. and the mixture is stirred at the same temperature for 5 minutes. An aqueous saturated ammonium chloride solution is added to the mixture and the mixture is extracted with ethyl acetate. The extract is washed, dried and evaporated to remove solvent. The residue is purified by silica gel column chromatography (solvent; chloroform-acetone-ethanol) to give 240 mg of ethyl 4,5-dichloro-6-((1-ethoxymethyl-pyrazol-5-yl)-hydroxymethyl)-1,3-benzodioxole-2-carboxylate.

Provenance & Evidence