关键词: 叶绿素-a, 光动力疗法, 脱镁叶绿酸, 焦脱镁叶绿酸, 1,3-偶极环加成反应

From methyl pheophorbide-a (MPa, 1), the pheophorbide-a derivative substituted with hydro-pyrazol 2 was obtained by the 1,3-dipolar cycloaddition of vinyl group at 3-position with diazomethane. Ring opening of this chlorin was performed by heating to rearrange the hydropyrzaol ring into the cyclopropyl group. In basic condition the cyclopropyl-substituted chlorin 3 was converted into pyropheophorbide 4 by demethoxyformylation. The diazoethane was chosen as another dipole and reacted with chlorin 1 in 1,3-dipolar cycloaddition style to give 2-methylcyclopropyl-substituted stereoisomer chlorin 5. The treatment for demethoxyformylation like chlorin 2 yielded pyropheophorbide 6. The structures of all new chlorophyll-a deriva-tives 2～6 were characterized by elemental analysis, UV, IR and ¹H NMR spectra.

Key words: pheophorbide, chlorophyll-a, pyropheophorbide, photodynamic therapy, 1,3-dipolar cycloaddition