Hematoporphyrin ethers--I. Generalized synthesis and chemical properties

A series of hematoporphyrin di-ethers, from methyl to hexyl, has been prepared by a generalized procedure based on reaction of the selected carbinol with the HBr adduct of protoporphyrin, followed by hydrolysis of ester functions and chromatographic purification. Spectroscopic and other properties are reported. They crystallize well. HPLC retention time increases linearly with the number of carbon atoms in the alcohol employed. In previous work we have shown that the more hydrophobic ethers are very efficient photosensitizers of malignant cells.