EP2451803A2 - METHOD FOR PREPARING 5-CHLORO-N-({(5S)-2-OXO-3-[4-(5,6-DIHYDRO-4H-[1,2,4]TRIAZIN-1-YL)PHENYL]-1,3-OXAZOLIDIN-5-YL}METHYL)THIOPHEN-2-CARBOXAMIDE DERIVATIVE AND INTERMEDIATE USED THEREIN