反应详情

To a solution of methyl 1-(phenylsulfonyl)-1H-pyrrole-2-carboxylate (Intermediate 1) (500 mg, 1.885 mmol) in MeOH (7 ml) and THF (7 ml) cooled to 0° C., aqueous 1N KOH (2.827 ml, 2.83 mmol) was added drop-wise and the resulting mixture was stirred at RT for 24 hours. UPLC-MS analysis showed the presence of desired compound in admixture with methyl 1H-pyrrole-2-carboxylate as the main product. The mixture was poured into ice-water and washed with DCM. The aqueous phase was acidified with 37% HCl (pH=2) and extracted with DCM. The organic layer was dried over sodium sulfate, filtered and evaporated to afford a mixture of 1-(phenylsulfonyl)-1H-pyrrole-2-carboxylic acid (Intermediate 2) (MS/ESI+252.0 [MH]+) and methyl 1H-pyrrole-2-carboxylate (MS/ESI+126.0 [MH]+) (234 mg, ratio about 3/7). This mixture was used as such in the next step.