Chlorins, glycoconjugated

Scheme 23. Synthesis of the C-glycoconjugated pyrrolidine-fused chlorin 69.

Glycoconjugated isoxazolidine-fused chlorins and bacteriochlorins were also elegantly synthesised using a 1,3-DC approach (Scheme 26). For instance, the galactosylnitrone reacted with porphyrin Id in a small volume of toluene, at 60 °C, to yield chlorin 75, accompanied by a small amount of two related bacteriochlorins <02TL603>. 

Scheme 24. Synthesis of the A -glycoconjugated pyrrolidine-fused chlorin 70.

On the basis of the fact that glycoconjugation of the porphyrin macrocycle appears to create a balance between hydrophobicity and hydrophilicity, Blais et al. prepared tri- and tetra-meta-glucosylated chlorin derivatives [154]. The aim was to assess how the sugar imits linked to chlorin derivatives affect the photoactivity, cell internalization and subcelMar localization in HT29 human adenocarcinoma cells. This was compared with the action due to me50-tetrakis(m-hydroxyphenyl)chlorin, a compound being formulated as a photosensitizer (Foscan ) for palliative treatment of head and neck cancers. 

In 2002, Cavaleiro et al. [38] developed the stereoselective synthesis of glycoconjugated isoxazoUdine-fused chlorines (potential photosensitizers in photodynamic cancer therapy) by 1,3-dipolar cycloadditions of meso-tetrakis(pentafluorophenyl)porphyrin (83) with glycosyl nitrones 41-43 and 84. In all cases of sugar moieties, the configuration of the major products 85 indicated an endo addition, as shown in Fig. 18. 

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