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.