Pyrroles and related compounds. Part XXIV. Separation and oxidative degradation of chlorophyll derivatives

Abstract

A convenient, large-scale method for separation of the aand b series metal-free chlorophyll derivatives is described, utilising the Girard ‘T’ reagent with subsequent chromatography. Efficient procedures for conversion of phaeophytin-a(3) into rhodoporphyrin-XV dimethyl ester (1) and the corresponding 2-vinyl compound (2), involving the classical oxidation to purpurin derivatives, followed by further degradation, are described: n.m.r. data for several important chlorophyll degradation products are reported. Novel oxidative reactions of the isocyclic ring in methyl mesopyrophaeophorbide-a(19) are also described.