[NH2:1][C:2]1[C:7]([Cl:8])=[C:6](Cl)[N:5]=[C:4]([C:10]([OH:12])=[O:11])[C:3]=1[Cl:13].[C:14]1([OH:20])[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1.[OH-].[Na+].[CH3:23]S(C)=O>O>[NH2:1][C:2]1[C:7]([Cl:8])=[C:6]([O:20][C:14]2[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=2)[N:5]=[C:4]([C:10]([O:12][CH3:23])=[O:11])[C:3]=1[Cl:13]A solution of 4-amino-3,5,6-trichloropyridine-2-carboxylic acid (7.2 g, 0.03 mol), phenol (3.0 g, 0.036 mol) and sodium hydroxide (2.7 g 0.068 mol) in DMSO (60 mL) and water (9 mL) was heated to 130° C. for 18 hr. The reaction was diluted with water (250 mL) and a tacky solid collected. This material was dissolved in methanol (100 mL) and treated with TMSCHN2 (25 mL 2M in hexanes). The reaction was stirred 30 min and concentrated. The resulting oil was chromatographed over silica gel (80% hexane and 20% ethyl acetate) to give methyl 4-amino-3,5-dichloro-6-phenoxypyridine-2-carboxylate (1.2, g, 14%); mp 88-90° C.
Loading…
