General and Scalable Approach to A₂B‐ and A₂BC‐Type Porphyrin Phosphonate Diesters

Abstract

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.

Facile Synthesis and Self‐Assembly of Zinc (2‐Diethoxyphosphorylethynyl)porphyrins

“…[5,15‐Dibromo‐10,20‐bis(4‐cyanophenyl)porphyrinato(2–)]zinc ( Zn10b ) was prepared according standard procedure at –7 °C in 98 % yield. Spectral data were in agreement with those reported in the literature …”

“…Next, the preparation of A 2 B‐type porphyrins bearing the ethynylphosphonate substituent was explored. Selective meso functionalization of the readily available A 2 ‐type tetrapyrrolic macrocycles by transition‐metal‐catalyzed reactions is a challenging task . Two‐steps synthetic procedures involving nonselective bromination of A 2 ‐type porphyrin followed by catalytic functionalization are convenient only when the target cross‐coupling products can be easily isolated by chromatography.…”

Advances in Tetrapyrrolic Chemistry over 2013-2017 of Research group Headed by Full Member of RAS A. Yu. Tsivadze: Highlights on the Occasion of his Anniversary

“…Modern synthetic approaches to phthalonitriles with special emphasis on transition-metal catalyzed cyanation reactions. [3] Synthesis of low-symmetry phthalocyanine analogue annelated with phenanthroline unit was performed, the electronic structure and NH-tautomerism were characterized by 1 H and 13 C NMR spectroscopy and TDDFT calculations ( Figure 2). [4] Synthetic approaches towards meso-RO-appended (R=alkyl, aryl) porphyrins bearing one or two OR substituents at the tetrapyrrolic macrocycle were proposed starting from meso-brominated porphyrins using a S N Ar reaction.…”

“…These compounds, being air-stable and soluble in most organic solvents, are valuable synthetic intermediates because they can be readily transformed into functionalized trans-A 2 BCtype 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-A 2 BC-type porphyrins, including water-soluble derivatives, push-pull chromophores and bis(porphyrin)s. [13,14] Two series of diphosphoryl-substituted porphyrins were synthesized and characterized by electrochemistry and spectroelectrochemistry. The free-base and five metalated porphyrins with nonredox active centers undergo two ring-centered oxidations and two ring-centered reductions, the latter of which is followed by a chemical reaction of the porphyrin dianion to give an anionic phlorin product ( Figure 13).…”

“…General and scalable approach to A 2 B-and A 2 BC-type porphyrin phosphonate diesters. [13] Figure 13. Electrochemical and spectroelectrochemical studies of diphosphorylated metalloporphyrins.…”