Synthesis of Cyanided Chlorophyllous Chlorin Derivatives and Study on Their Photodynamic Activities

Pyropheophorbide-a methyl ester was used as a starting material, and its oxygenations were carried out by thaillum nitrate and air as oxidizing agent to introduce the formyl group and the formylmethyl group at 3-, 12- or 15-postion of chlorin periphery, respectively. After oximation these aldehyde groups were converted into cyano group under the reaction mediated from N,N-dimethylformamide and 2,4,6-trichloro-1,3,5-triazine. Dicyanomethylene moiety was established by Knoevenagel reaction of malononitrile with formyl group and 13(1)-carbounyl group on the exocyclic ring. Mulcyano-substitutions on the chromophore were accomplished by further structure modifications. A series of unreported chlorins related to chlorophyll substituted with cyano-group were synthesized making use of cyanation at different positions on the periphery of chlorophyll degradation products. Their chemical structures were characterized by elemental analysis, UV, IR and H-1 NMR spectra. The reaction mechanisms on the cyanation for the chlorophyllous chlorins were discussed and in vitro photodynamic activities of some new compounds were determined.