Benzyl 3,5-dimethyl-2-pyrrolecarboxylate (1) was converted to 4-(2,2,2
-trifluoro-1-hydroxyethyl) derivative (2) on treatment with trifluoroa
cetaldehyde ethyl hemiacetal in the presence of zinc chloride. After p
rotection of the hydroxy group, 2 was converted to benzyl ,2,2-trifluo
ro-1-methoxyethyl)2-pyrrolecarboxylate (9) and benzyl 2,2-trifluoro-1-
methoxyethyl)-2-pyrrolecarboxylate (10). Both esters were condensed to
a dipyrrolomethane compound (11), which was debenzylated, decarboxyla
ted, and condensed with a bottom half of the porphyrin to give a hexaf
luorohematoporphyrin derivative (14), potentially useful for photodyna
mic therapy of cancer.