1: O,N-dimethyl-hydroxylamine hydrochloride With trimethylaluminum in tetrahydrofuran; n-heptane T=0 - 20°C; 2: (4R,2'R,3'S)-4-benzyl-3-[3-hydroxy-2-methylpent-4-enoyl]-oxazolidin-2-one in tetrahydrofuran; n-heptane T=-40 - 20°C; 2.5 h;