In the methanol solution containing 5% sulfuric acid chlorophyll-b was degraded to produce methyl pheophorbide-b which was converted into methyl pyropheophorbide-b by pyrolysis in diphenyl ether. The methyl 13²-hydroxylpheophorbide-b and methyl 13²-hydroxylpyropheophorbide-b were obtained by allomerization in acetic acid from methyl pheophorbide-b. In alkaline condition, pheophorbide-b continued to react with air to give relevant oxidized products. The 1,3-dipolar cycloaddition of C³-vinyl group with diazomethane and pyrolysis produced C³-pyrazolinyl- or C³-cyclopropyl-substituted chlorines. The Wittig reaction of C⁷-formyl group with benzyltriphenylphosphonium bromide formed C⁷-styrylchlorin derivatives. The structures of all new chlorin derivatives were charac-terized by elemental analysis, UV, IR and ¹H NMR spectra. The possible mechanisms about corresponding reactions were tentatively proposed.

Key words: chlorophyll-b, (pyro)pheophorbide, purpurin-18, chemical modification, chlorin, synthesis