Methyl pyropheophorbide-a (MPP-a) was used as starting material for the synthesis of new chlorin derivatives. Under the protection of the carbonyl group at 13¹-position with glycol, the carbon-carbon double bond at 3-position was oxidized by OsO₄ and NaIO₄ to give methyl pyropheophorbide-d (MPP-d) derivative 2. The formyl group was converted into the hydroxyalkyl group by the Grignard reaction giving the secondary alcohol 3 which was oxidized with TPAP and N-methyl morphline N-oxide to afford ketone 4. After deprotection 3-alkyloyl derivatives of methyl pyropheophorbide-a 6 were obtained. The addition and rearrangement reactions of MPP-d 7 with excess diazomethane generated rearranged products 6a, 8 and 9. 3-Phenyloxalyl methyl pyropheophorbide-a 11 was obtained by the Wittig and oxidation reactions of 3-formyl group. The structures of these compounds were characterized by elemental analysis, UV, IR and ¹H NMR spectra, and the effect of the peripheral carbonyl groups on the ¹H NMR and the visible spectra was discussed.

Key words: methyl pyropheophorbide-a, chlorin derivative, nuclear magnetic resonance and visible spectra, photodynamic therapy(PDT)