Triphenylphosphine → 1-(4-tert-butoxyethoxyphenyl)-5-methyl-1H-pyrazole-4-carboxylic acid ethyl ester

Participants

Reaction Steps

To a solution of 1-(4-Hydroxyphenyl)-5-methyl-1H-pyrazole-4-carboxylic acid ethyl ester (500 mg) in Reference Example 39 (2), 2-tert-butoxyethanol (480 mg) and triphenylphosphine (1.06 g) in tetrahydrofuran (20 ml) was added dropwise a solution of 40% azodicarboxylic acid diisopropylester in toluene (2.14 ml) under ice-cooling, and then stirred at room temperature overnight. After completion of the reaction, water was added thereto, extracted with ethyl acetate, the organic layer was dried over anhydrous sodium sulfate, and the solvent was evaporated in vacuo. The obtained residue was purified with silica gel chromatography (n-hexane/ethyl acetate) to give 1-(4-tert-butoxyethoxyphenyl)-5-methyl-1H-pyrazole-4-carboxylic acid ethyl ester (870 mg) as a pale yellow oil.

Provenance & Evidence