A two‐step reaction sequence for accessing meso‐(dialkoxyphosphoryl)porphyrins from readily available trans‐A2‐type porphyrins was developed. This approach involves bromination and subsequent palladium‐catalyzed phosphonylation. Optimal conditions for both steps were identified after exploration of various reaction parameters such as solvent, temperature and catalyst. A series of dialkoxyphosphoryl‐substituted A2B‐porphyrins Zn3(a–g) bearing electron‐donating, electron‐withdrawing or sterically bulky substituents at the meso‐aryl groups were prepared in overall yields close to 40 %. These compounds, being air‐stable and soluble in most organic solvents, are valuable synthetic intermediates because they can be readily transformed into functionalized trans‐A2BC‐type porphyrins through regioselective functionalization at the unsubstituted meso position of the macrocycle. Therefore, this approach offers considerable promise for application to the synthesis of trans‐A2BC‐type porphyrins, including water‐soluble derivatives, push‐pull chromophores and bis(porphyrin)s.
International audienceThe synthesis of functionalized porphyrins and their conjugates from meso-tetraarylporphyrins through the acylation and the oxidation of beta-aminoporphyrins was investigated. 2,3-Dioxochlorins were prepared by the oxidation of a variety of beta-aminoporphyrins and subsequently used in a condensation reaction with functionalized aromatic aldehydes and ammonium acetate to form beta-functionalized porphyrins bearing a fused imidazole ring. Under optimized experimental conditions both reactions tolerate various functional groups and afford the products in an appropriate overall yield. The mildness and usefulness of this methodology are illustrated by several examples including the synthesis of porphyrins bearing receptor groups and water-solubilizing moieties
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