(3aR,5R)-5-[(2S)-tetrahydrofuran-2-yl]-3,3a,4,5-tetrahydro-7H-pyrano[3,4-c][1,2]oxazole 、 7a-(2,4-difluorophenyl)-5-[(1R,2R)-2-methylcyclopropyl]hexahydro-1H-pyrano[3,4-c][1,2]oxazole 生成 (3aR,5R,7aS)-7a-(2,4-difluorophenyl)-5-[(2S)-tetrahydrofuran-2-yl]-3,3a,4,5-tetrahydro-7H-pyrano[3,4-c][1,2]oxazole