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