Methyl chloroformate → HCID 13248998, compound

Participants

Reaction Conditions

Reaction Steps

A solution of 3-(2,5-dimethyl-pyrrol-1-yl)-1-methyl-1H-pyrazole (Intermediate 7, 0.56 g, 3.21 mmol) (Intermediate 7) in tetrahydrofuran (26.8 mL) cooled to −78° C. was treated dropwise with a 2.5M solution of n-butyllithium in hexanes (1.44 mL, 3.60 mmol). The reaction was stirred at −78° C. for 1.5 h. After this time, the reaction was treated dropwise with methyl chloroformate (0.28 mL, 3.63 mmol). After this time, the cooling bath was removed. The reaction continued to stir for 1 h, at which time the reaction was concentrated in vacuo. The residue was then partitioned between water (100 mL) and diethyl ether (3×75 mL). The organics were dried over sodium sulfate, filtered, and concentrated in vacuo. Silica gel column chromatography (ISCO, 40 g, 5-10% ethyl acetate/hexanes) afforded 5-(2,5-dimethyl-pyrrol-1-yl)-2-methyl-2H-pyrazole-3-carboxylic acid methyl ester (0.33 g, 44%) as an off-white solid; ES+-HRMS m/e calcd for C12H15N3O2 [M+H+] 234.1237, found 234.1237.

Provenance & Evidence