Methyl pheophorbide-a (MP-a) (1) was used as starting material and was oxidized with osmium(VIII) oxide followed by ethylene glycol cleavage with sodium periodate to give 2 and 3 for oxidizing vinyl group at 3-position and for α-hydrogen at 13²-poaition respectively. The chlorin aldehyde 2 was oxidized continually with os-mium(VIII) oxide to give bacteriochlorin aldehyde 4. After eliminating for methyl formate and oxi-dizing with thallium(III) nitrate MP-a (1) was converted into pyropheophorbide derivative 5 which was oxidized again with osmium(VIII) oxide to generate becteriochlorin acetal 6. In the basic condition chlorin aldehyde 2 was converted into chlorin e₆ derivatives 7. The Grignard reaction of 2 with alkyl magnesium bromide afforded pheophorbide alco-hol 9 followed by oxidation with tetrapropylammonium perruthenate (TPAP) and N-methylmorpholine N-oxide to afford chlorin diketoester 10. The conversion of 10 from pheophorbide to pyropheophorbide was completed in acid condition by refluxing to form methyl 3-alkylcarbonyl-3-devinylpyropheophorbide-a 11. The chlorin e₆ 7 and chlorin 11 were oxidized further with osmium(VIII) oxide in the same oxidization condition to yield bateriochlorin 8 and 12, respectively. The effect on the spectra by change in the conjugate region was discussed. The structures of the compounds were characterized by elemental analysis, UV, IR and ¹H NMR spectra.

Key words: bateriochlorin, oxidation, photodynamic therapy, chlorine, chlorophyll-a