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 hydroxyl group with a methyl group, 2 was converted t o benzyl 2,2-trifluoro-1-methoxyethyl)-2-pyrrolecarboxylate (9) and be nzyl 5-acetoxymethyl-3-methyl-4-(2,2,2-trifluoro -1-methoxyethyl)-2-py rrolecarboxylate (10). Both esters were condensed to dipyrrylmethane c ompound 11, which was debenzylated, decarboxylated and condensed with a bottom half of the porphyrin to give hexafluorohematoporphyrin deriv ative 14, potentially useful for photodynamic therapy of cancer. Copyr ight (C) 1996 Elsevier Science Ltd.