New chlorin-terpene conjugates bearing triethylene glycol and cationic tetraalkylammonium fragments

Abstract

Methyl pheophorbide a reacts with terpene alcohols on activation with the Mukaiyama reagent to give the products of the formal transesterification of the C(21)CO₂Me group. To increase hydrophilicity, the synthesized conjugates were modified following two different paths. The first path is the acid-catalyzed transesterification of the C(3)(CH₂)₂CO₂Me moiety of the conjugate with triethylene glycol to give diester with different substituents and different ester groups. The second path is the treatment of terpenyl ester with N,N-dimethylethylenediamine that proceeds via the phorbin exocycle opening to give the porphine derivatives bearing two ester and one carboxamide groups. The dimethylamino groups of these porphine derivatives were quaternized with iodomethane.