A SIMPLE SYNTHESIS OF FUNCTIONALIZED RAC-CHLORINS VIA ALLYLBORATION OF PORPHYRIN ALDEHYDES

Chlorins rac-17a, b which bear terminally hydroxy-substituted butyl si de chains were synthesized by allylboration and Claisen rearrangement from readily accessible formylporphyrins 5 and 6. The hydroxyalkyl sid e chain and the photophysical properties of the chlorins rac-17a, b sh ould open a broad access to chlorins suitable for photodynamic therapy having different residues attached to the hydroxy function. The repor ted synthetic pathway also should be useful for the synthesis of natur ally occurring hydroporphyrins containing geminally dialkylated struct ural parts and a propionic acid residue on the saturated pyrrole ring.