Strategies for Corrole Functionalization

Abstract

This review covers the functionalization reactions of meso-arylcorroles, both at the inner core, as well as the peripheral positions of the macrocycle. Experimental details for the synthesis of all known metallocorrole types and for the N-alkylation reactions are presented. Key peripheral functionalization reactions such as halogenation, formylation, carboxylation, nitration, sulfonation, and others are discussed in detail, particularly the nucleophilic aromatic substitution and the participation of corroles in cycloaddition reactions as 2π or 4π components (covering Diels-Alder and 1,3-dipolar cycloadditions). Other functionalizations of corroles include a large diversity of reactions, namely Wittig reactions, reactions with methylene active compounds, formation of amines, amides, and imines, and metal catalyzed reactions. At the final section, the reactions involving oxidation and ring expansion of the corrole macrocycle are described comprehensively.

Cancer, Photodynamic Therapy and Porphyrin-Type Derivatives

“…Corroles are also a group of tetrapyrrolic derivatives strongly related with porphyrins which are also playing a special role in PDT medicinal applications (Barata et al 2017). In such way, the strategy of conjugation of a CD to a corrole derivative in order to increase the PS solubility, contributing to an efficient delivery of the drug to the tumoral cell, was also reported by the same research group.…”

Magnetite–Corrole Hybrid Nanoparticles

“…Recent developments on chemical functionalization approaches of corroles have given new impetus to the application of these compounds in several areas [1][2][3][4][5][6]. For example, they are used in the therapeutic field as inactivation agents for bacteria, viruses, and fungi; contrast agents for biomedical imaging; photosensitizers for photodynamic therapy to fight cancer [7][8][9][10][11][12][13][14][15][16]; and also as catalysts [5] and sensors [4].…”

One‐Pot Synthesis of Contracted and Expanded Porphyrins with meso‐CF3 Groups

“…[2] This coincided with the isolation of 5,10,15-tris-(pentafluorophenyl)corrole,the first free-base corrole that is truly stable (owing to its electron-withdrawing meso-C 6 F 5 groups). [3] Still, in contrast with the non-substituted porphyrin (porphine), [4] thec orresponding "naked" corrole and sapphyrin (the expanded pentapyrrolic macrocycle) were not yet reported;a nd the access to derivatives with no b-pyrrole substituents and only alkyl substituents on their corresponding meso-C atoms remains very limited. [3] Still, in contrast with the non-substituted porphyrin (porphine), [4] thec orresponding "naked" corrole and sapphyrin (the expanded pentapyrrolic macrocycle) were not yet reported;a nd the access to derivatives with no b-pyrrole substituents and only alkyl substituents on their corresponding meso-C atoms remains very limited.…”

“…[2b] Large efforts on developing modified and new synthetic methods led to the current stage:c orroles with almost any meso-aryl substituents are nowadays accessible in quite straightforward fashions. [3,5] Hemes present in numerous enzymes do not have any meso-C-substituents and the cobalt complexes of porphine, and 5,10,15,20-tetramethylporphyrin are among the most efficient electrocatalysts. [3,5] Hemes present in numerous enzymes do not have any meso-C-substituents and the cobalt complexes of porphine, and 5,10,15,20-tetramethylporphyrin are among the most efficient electrocatalysts.…”

“…[12] Ghosh and his co-workers were however able to produce minute quantities (6.0-6.6 mg,0 .60-0.65 %yield) of TFC-H 3 ,v ia the one-pot reaction of pyrrole with either the hydrate or the hemiacetal of trifluoroacetaldehyde,w ith trifluoromethanesulfonic acid as catalyst. [3,15] Thefirst step was to check whether the reported synthesis of TFC-H 3 may be improved, by changing reaction conditions or additives.T he results summarized in the Supporting Information, Scheme S1 revealed that:1 )substituting the atmosphere from aerobic to anaerobic (Ar) increased the isolated yield from 5.9 mg (0.58 %) of TFC-H 3 ,p ractically identical to the previous report, [13] to 9.4 mg (0.93 %); 2) replacing trifluoromethanesulfonic acid by Sc-and Inbased Lewis acids did not improve the results and the same holds for employing the hydrate rather than the hemiacetal of the aldehyde;3 )another potentially interesting green compound was also formed, but it was not characterized at that stage.T he best result was actually obtained in the absence of any catalyst, but the isolated yield of TFC-H 3 was still only 1.0 %and an attempted fourfold upscale experiment was not successful. Based on these interesting results,wehave now decided to tackle the challenge of producing adequate amounts of TFC-H 3 that would allow for the development of metal complexes of this corrole in the many applications where metallocorroles excel.…”