Ethyl Acetate → 3-[2-methyl-5-(4-trifluoromethoxy-phenyl)-2H-pyrazol-3-yl]-propionic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

A solution of lithium diisopropylamide (16.5 ml of a 2 M solution in tetrahydrofuran/heptane/ethylbenzol, 33 mmol) in tetrahydrofuran (25 ml) was cooled to −78° C. Within 30 min a solution of ethyl acetate (3.77 ml, 38 mmol) in tetrahydrofuran (10 ml) was added. The solution was stirred for 45 min at −78° C., DMPU (6.63 ml, 55 mmol) was added within 20 min and the mixture was kept for additional 30 min at −78° C. Within 20 min a solution of 5-iodomethyl-1-methyl-3-(4-trifluoromethoxy-phenyl)-1H-pyrazole (4.2 g, 11 mmol) in tetrahydrofuran (25 ml) was added. The solution was stirred for 40 min at −78° C., the cooling bath was removed and stirring was continued for 1 h. The reaction mixture was poored onto aqueous NH4Cl solution/ice water and extracted two times with ethyl acetate. The combined extracts were washed three times with ice water/brine and dried over sodium sulfate. The solvent was removed under reduced pressure to give an orange oil which was purified by column chromatography (silica gel, heptane/AcOEt) to give 1.5 g (4.4 mmol, 40%) of the title compound as yellow oil.

Provenance & Evidence