Ethyl 4-amino-3-(difluoromethyl)-2-hydroxypyridine-6-carboxylate
Ethyl 4-amino-3-(difluoromethyl)-2-hydroxypyridine-5-carboxylate
Ethyl 4-amino-6-(difluoromethyl)-2-hydroxypyridine-3-carboxylate
Ethyl 4-amino-2-(difluoromethyl)-6-hydroxypyridine-3-carboxylate