Development of strategies for the regiocontrolled synthesis of meso-5,10,20-triaryl-2,3-chlorins.

Triglycoconjugated photosensitizers show promise for use in the photodynamic therapy-based treatment of cancer. Two different routes have been studied for the regioselective preparation of 5,10,20-meso-triphenyl-2,3-chlorin, 9a, and 5,10,20-meso-tri(4-isopropyloxyphenyl)-2,3-chlorin, 9b. The main issue was to control the placement of the partially reduced pyrrole ring in the more hindered environment in the triarylchlorin products.