Chemistry of pyrrolic compounds. XLI. The synthesis of the phaeophorbides c₁ and c₂ methyl esters

Abstract

Phaeophorbide c₁, the magnesium-free derivative of chlorophyll c₁, has been synthesized as the methyl ester (1c) by means of the copper acetate cyclization of an appropriately substituted bilene-b salt. Similar syntheses of phaeophorbide c₂ methyl ester (1d) and isophaeophorbide c₁ methyl ester (1g) have been completed. Comparison of these synthetic compounds with natural material both as the metal free derivative and as the magnesium chelate has substantiated the accepted structures for the chlorophylls c.