2-O-tert-butyl 4-O-ethyl 5-formyl-3-methyl-1H-pyrrole-2,4-dicarboxylate → 2-O-tert-butyl 4-O-ethyl 5-[cyclopropyl(hydroxy)methyl]-3-methyl-1H-pyrrole-2,4-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

Cyclopropylmagnesium bromide (15 m, 0.5 mol/L) was cooled down to −10° C. in an ice-salt bath under an argon atmosphere. 5-Formyl-3-methyl-1H-pyrrole-2,4-dicarboxylic acid 2-tert-butyl ester 4-ethyl ester 1b (1.26 g, 4.5 mmol) was dissolved in 10 ml of tetrahydrofuran under stirring, the resulting solution was added dropwise to the above solution while maintaining the temperature at −10° C. Upon completion of the addition, the ice-salt bath was removed, and the reaction mixture was stirred for 1 hour at room temperature. After thin lay chromatography showed the disappearance of starting materials, the reaction mixture was quenched with water, added with sulfuric acid solution (20 ml, 10%) and stirred for 30 minutes, and extracted with ethyl acetate (50 ml×3). The combined organic extracts were washed with saturated brine (50 ml), dried over anhydrous magnesium sulfate, filtered to remove the drying agent and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to obtain the title compound 5-(cyclopropyl-hydroxy-methyl)-3-methyl-1H-pyrrole-2,4-dicarboxylic acid 2-tert-butyl ester 4-ethyl ester 60a (576 mg, yield 39.6%) as a white solid.

Provenance & Evidence