ORGN 78

Olefin metathesis and cross-metathesis reactions have recently gained prominence in synthetic organic chemistry, but they have seldom been applied to porphyrin chemistry. Here we report the first application of cross-metathesis to chlorins and porphyrins substrates. Ruthenium-based N-heterocyclic carbene catalyst 1 was demonstrated to catalyze the reaction between vinylchlorons/vinylporphyrins and simple olefins efficiently, while catalyst 2 was not active.

Cross-metathesis products were obtained in good yields, together with high stereoselectivity in which the E-isomer is the major one. The impacts of the substituents in functionalized olefins on the reaction were investigated. Zn-complexes of vinylchlorins and vinylporphyrins were found to exhibit higher reactivities than free bases. The successful application of cross-metathesis to the chemistry of vinylchlorins and vinylprophyrins provide new approaches to the direct synthesis of various kinds of olefin-containing chlorins and porphyrins derivatives, which may be useful in searching for potential photodynamic therapy (PDT) candidates.