The rhodochlorin was synthesized by a series of degradation from pheophorbide-a. The electrophilic substitution of rhodochlorin was performed with N-chlorosuccinimide (NCS) or nitric acid as electrophilic reagent|1,3-polar cycloaddition reactions of C-3-vinyl group of rhodochlorin with p-chlorobenzonitrile oxide or diazomethane constructed isoxazoline and pyrazoline rings on the chlorin chromophore, respectively. The pyrolysis reaction of pyrazolinesubstituted chlorin introduced cyclopropyl group at C-3-position. In acid condition rhodochlorin dimethyl was hydrolyzed to its monoester. After introducing chlorine atom at 20-meso-position the purpurin-7 trimethyl was selectively converted into monochloro-substituted rhodochlorin by decarboxylation to remove functional group at 15-position. The structures of all new compounds were characterized by elemental analysis, UV, IR and ¹H NMR spectra. In same time, the possible mechanisms in the air oxidation and rearrangement reaction were tentatively proposed.

Key words: methyl pheophorbide-a, degradation reaction, rhodochlorin, reaction mechanism, synthesis