反应详情

Ethyl 3,4-dichloro-5-methyl-1H-pyrrole-2-carboxylate (Intermediate 2; 7.765 g, 0.03496 mol) was dissolved in MeOH (80 ml) and DCM (10 ml) and slowly added to a 70° C. solution of 2 N LiOH (105 ml, 0.21 mol). After 2 h, the reaction mixture was cooled to room temperature and then in an ice bath, followed by acidification with 2 N HCl. The mixture was stirred at 0° C. for 1 h, and a purple solid was filtered, washed with water and lyophilized overnight to give 4.314 g (0.0222 mol, 64% yield) of the desired product. MS (ES−): 192.13, 194.13 for C6H5Cl2NO2; NMR: 2.17 (s, 3H).

1. filtrationa purple solid was filtered
2. washwashed with water
3. waitlyophilized overnight