To a solution of 1-{2-[(2-methoxy-ethyl)-methyl-amino]-ethyl}-1H-pyrazole-4-carboxylic acid (467 mg, 1.54 mmol) and phenol (145 mg, 1.54 mmol) in dimethylformamide (8 ml) was added under argon at 0° C. a solution of 4-dimethylaminopyridine (94 mg, 0.77 mmol) and brom-tripyrrolidinophosphonium-hexafluorophosphat (790 mg, 0.70 mmol) in dimethylformamide (8 ml) followed by triethylamine (0.65 ml, 4.6 mmol). After 48 h at ambient temperature, the reaction mixture is treated with saturated aqueous ammonium chloride (25 ml) and extracted three times with ethyl acetate (25 ml each). The combined organic layers are dryed with magnesium sulphate and evaporated to dryness. Flash chromatography (silice, eluent dichloromethane containing 4% methanol) afforded the title compound as colorless oil (55% yield). MS: m/e=304(M+H+).
