Chlorophylls make Earth green, are the central constituents in the engine of photosynthesis, and not surprisingly have garnered immense attention. A chlorin, the core chromophore of a chlorophyll, is a dihydroporphyrin macrocycle that contains one pyrroline ring and three pyrrole rings. The dominant method for the synthesis of chlorins has entailed the derivatization of porphyrins. The present review covers the ostensibly simple conversion of porphyrins, regardless of synthetic or biological origin, to chlorins. The period covered encompasses the entire history since the beginnings of chlorin synthetic chemistry in the early 20th century through 2015. Representative transformations include hydrogenation, cycloaddition, annulation, and diverse “breaking and mending” approaches. Altogether, the synthesis of >1000 chlorins or chlorin-like compounds (containing >50 distinct pyrroline motifs) is described. Such diversity animates the question “what structural features are essential for a chlorin to resemble ch...

Synthetic Chlorins, Possible Surrogates for Chlorophylls, Prepared by Derivatization of Porphyrins

Catalysis is a topic of continuous interest since it was discovered in chemistry centuries ago. Aiming at the advance of reactions for efficient processes, a number of approaches have been developed over the last 180 years, and more recently, porphyrins occupy an important role in this field. Porphyrins and metalloporphyrins are fascinating compounds which are involved in a number of synthetic transformations of great interest for industry and academy. The aim of this review is to cover the most recent progress in reactions catalysed by porphyrins in scalable procedures, thus presenting the state of the art in reactions of epoxidation, sulfoxidation, oxidation of alcohols to carbonyl compounds and C-H functionalization. In addition, the use of porphyrins as photocatalysts in continuous flow processes is covered.

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Porphyrins as Catalysts in Scalable Organic Reactions

Photodynamic therapy (PDT) is a well-established treatment option in the treatment of certain cancerous and pre-cancerous lesions. Though best-known for its application in tumor therapy, historically the photodynamic effect was first demonstrated against bacteria at the beginning of the 20th century. Today, in light of spreading antibiotic resistance and the rise of new infections, this photodynamic inactivation (PDI) of microbes, such as bacteria, fungi, and viruses, is gaining considerable attention. This review focuses on the PDI of viruses as an alternative treatment in antiviral therapy, but also as a means of viral decontamination, covering mainly the literature of the last decade. The PDI of viruses shares the general action mechanism of photodynamic applications: the irradiation of a dye with light and the subsequent generation of reactive oxygen species (ROS) which are the effective phototoxic agents damaging virus targets by reacting with viral nucleic acids, lipids and proteins. Interestingly, a light-independent antiviral activity has also been found for some of these dyes. This review covers the compound classes employed in the PDI of viruses and their various areas of use. In the medical area, currently two fields stand out in which the PDI of viruses has found broader application: the purification of blood products and the treatment of human papilloma virus manifestations. However, the PDI of viruses has also found interest in such diverse areas as water and surface decontamination, and biosafety.

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Trends and targets in antiviral phototherapy

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De Novo Synthesis of Gem-Dialkyl Chlorophyll Analogues for Probing and Emulating Our Green World

The utilization of metalloporphyrins as bioinspired oxidation catalysts is an evolving topic of research. By understanding the cytochrome P-450 mechanism of action, chemists have been able to successfully mimic several types of oxidation reactions using metalloporphyrins as catalysts. At first, homogeneous systems presented the most amenable strategy for oxidizing a vast array of substrates; however, current environmental concerns have directed research in this field to the design, synthesis, and application of heterogeneous catalysts, as well as avoiding the use of highly pollutant co-oxidants and/or co-catalysts. Herein, we review the past decade (from 2008) concerning the use of solely molecular oxygen as an environmentally benign oxidant source, in oxidation reactions catalyzed by bioinspired metalloporphyrin analogues. We did not intend to create a comprehensive review; instead we highlight the most important and illustrative examples for this period. We emphasize the application of such catalysts on...

Metalloporphyrins: Bioinspired Oxidation Catalysts

Chlorins: Natural Sources, Synthetic Developments and Main Applications

The first example of enantioselective S-H insertion reactions of sulfoxonium ylides is reported. Under the influence of thiourea catalysis, excellent levels of enantiocontrol (up to 95 % ee) and yields (up to 97 %) are achieved for 31 examples in S-H insertion reactions of aryl thiols and α-carbonyl sulfoxonium ylides.

https://onlinelibrary.wiley.com/doi/epdf/10.1002/anie.202005563

Enantioselective S−H Insertion Reactions of α-Carbonyl Sulfoxonium Ylides

Chemical Transformations and Photophysical Properties of meso‐Tetrathienyl‐Substituted Porphyrin Derivatives

Catalytic Friedel-Crafts Alkylation of Electron Rich Aromatic Derivatives with α-Aryl Diazoacetates Mediated by Brønsted Acids.

For many years diazocarbonyl compounds have been studied due to their versatility and usability in many chemical transformations. In this review, we summarize the traditional methods to prepare these compounds as well as the new methods and recent improvements in experimental procedures. Moreover, emergence of continuous flow techniques has allowed safer and environmentally friendly procedures for the handling of diazomethane and diazo compounds and will also be a topic in this review

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Patrícia B. Momo

Papers

Chlorins: Natural Sources, Synthetic Developments and Main Applications

Enantioselective S−H Insertion Reactions of α-Carbonyl Sulfoxonium Ylides

Chemical Transformations and Photophysical Properties of meso‐Tetrathienyl‐Substituted Porphyrin Derivatives

Catalytic Friedel-Crafts Alkylation of Electron Rich Aromatic Derivatives with α-Aryl Diazoacetates Mediated by Brønsted Acids.

Traditional and New methods for the Preparation of Diazocarbonyl Compounds