Ethyl 4-(difluoromethyl)-3-methoxy-2-nitropyridine-6-carboxylate
Ethyl 4-(difluoromethyl)-6-methoxy-2-nitropyridine-3-carboxylate
Ethyl 4-(difluoromethyl)-6-methoxy-3-nitropyridine-2-carboxylate
Ethyl 4-(difluoromethyl)-2-methoxy-3-nitropyridine-6-carboxylate