SYNTHESIS OF A FLUORINE ANALOG OF HEMATOPORPHYRIN BY RING-CLOSURE

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.