Acetylation of Chlorophyll-a Degradation Products and Synthesis of Chlorin Derivatives

Abstract

Methyl pheophorbide-a (MPa) was used as starting material and converted to Ni(II) complexes by modifying for chemical structures and metallizing with Ni(acac)2. Their Vilsmerier reactions with phosphoryl chloride and 3-(dimethylamino)-acrolein or N,N-dimethylformamide were performed regioselectively to introduce formyl or formylvinyl group on the periphery of chlorin. The formylmethyl group also was established by oxidation reaction of the C(3)-vinyl group with thallium nitrate. The hydroxyalkyloxyl or hydroxyalkylamino group on the macrocycle was constructed based on the chemical activities of the vinyl group at 3-position and ketone group in E-ring and subsequently the hydroxyl group was oxidized with the conbination of tetrapropylammonium perruthenate (TPAP) and N-methylmorpholine N-oxide to the corresponding formyl group, respectively. The structures of all the new chlorins containing acyl structure were characterized by UV, IR, H NMR spectra and elemental analysis.