[F:1][C:2]1[CH:10]=[C:9]([F:11])[CH:8]=[CH:7][C:3]=1[C:4]([OH:6])=[O:5].[Cl:12][S:13](O)(=[O:15])=[O:14]>>[Cl:12][S:13]([C:8]1[C:9]([F:11])=[CH:10][C:2]([F:1])=[C:3]([CH:7]=1)[C:4]([OH:6])=[O:5])(=[O:15])=[O:14]A mixture of chlorosulfonic acid (200 mL) and 2,4-difluorobenzoic acid (40 g, 253 mmol, 1 equiv) was heated to 155° C. for 3 h. The reaction was cooled to RT and poured slowly over ice. The product was extracted into ether and the organics dried over MgSO4, filtered and concentrated to give 5-(chlorosulfonyl)-2,4-difluorobenzoic acid 6a as brown solid (61 g, 94% yield).
Wird geladen…