A Survey of Acid Catalysis and Oxidation Conditions in the Two-Step, One-Flask Synthesis of Meso-Substituted Corroles via Dipyrromethanedicarbinols and Pyrrole

Abstract

The reaction of dipyrromethanedicarbinols with pyrrole leading to meso-substituted corroles was investigated to determine whether mild acid catalysts [Dy(OTf)(3), Yb(OTf)(3), Sc(OTf)(3), and InCl(3)] known to provide porphyrins from dipyrromethanecarbinol species while suppressing undesired reversibility (resulting in scrambling) are applicable to reactions affording corrole, and to explore the requirements of the oxidation step. We examined a model reaction leading to meso-triphenylcorrole (TPC) to survey the effect of acid catalyst, acid concentration, ratio of pyrrole to dipyrromethanedicarbinol, oxidant, oxidant quantity, and reaction time on the yield of TPC (by UV-vis) in reactions performed at room temperature in CH(2)Cl(2). Key to this survey was a modification of the well-known spectrophotometric method for monitoring reactions leading to porphyrin. The survey revealed that TPC could be prepared via a subset of the mild acid catalysts [Dy(OTf)(3) and Yb(OTf)(3)], and a preparative-scale reaction afforded an isolated yield of TPC of 49%, devoid of porphyrin. Suppression of reversible processes was further demonstrated by the synthesis of three corroles bearing different meso substituents in defined locations in isolated yields ranging from 50% to 80%. The reaction conditions were applicable to a dipyrromethanedicarbinol bearing electron-withdrawing pentafluorophenyl substituents-provided that the reaction time of the condensation step was increased. We identified circumstances under which DDQ can cause severe interference with the detection and isolation of some corroles, we found that the yield and purity of the corrole depend on judicious selection of oxidation conditions, and we assessed the sensitivity toward light of dilute solutions of the corroles prepared in this study.

Constructing Single‐Chain Magnets by Supramolecular π–π Stacking and Spin Canting: A Case Study on Manganese(III) Corroles

“…[30] 5,10,15-tris(pentafluorophenyl)corrole (H 3 tpfc; Scheme 1) bearing electron-withdrawing pentafluorophenyl groups exhibits high stability and has been widely used to stabilize high valent metal intermediates. [31] Although Mn III corroles had been extensively used as catalysts in oxygen and nitrogen atom transfer reactions and potential antioxidant drugs in biological studies, their magnetic properties due to the electron spin states are seldom studied.…”

Study of Structure−Properties Relationship for Lanthanide Tetrapyrrolic Macrocycles Modified with Aminopolycarboxylate Substituents

“…[16] The step of formation of peripheral complexes on the base of ditopic ligands can not be administrated by absorption spectra in contrast to classical systems. Therefore, NMR and…”

Efficient Two‐Step Synthesis of Face‐to‐Face meso‐Substituted Bis(corrole) Dyads

“…As shown in the literature, the choice of the oxidant appears to be critical to the success of the reaction and to the ease of corrole isolation. [17,52] We further decided to investigate the oxidation conditions by replacing DDQ by p-chloranil. Indeed, DDQ oxidation has been generally applied with best success in the preparation of corroles bearing withdrawing groups and/or facially bulky substituents, but, in some cases, oxidation with p-chloranil provided a higher yield.…”