methyl (E)-4-[(4R)-4-[(1R)-1-iodo-3-phenylmethoxypropyl]-2-oxo-1,3-oxazolidin-3-yl]-2-[2-(2-methyl-1,3-dioxolan-2-yl)ethyl]but-2-enoate 生成 methyl (Z)-2-[(6S,7S,7aS)-3-oxo-7-(2-phenylmethoxyethyl)-5,6,7,7a-tetrahydro-1H-pyrrolo[1,2-c][1,3]oxazol-6-yl]-4-(2-methyl-1,3-dioxolan-2-yl)but-2-enoate