Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• continuous-flow photochemistry a sustainable alternative approach being applied already by the chemical and pharmaceutical industries. Porphyrinoid is the term given for a class of organic compounds containing four pyrrole rings connected by four methylene bridges, and include porphyrin, chlorin

• , bacteriochlorin, and isobacteriochlorin. The cores of the porphyrin and chlorin scaffolds contain respectively 22 π and 20 π electrons, whereas bacteriochlorins and isobacteriochlorins contain 18 π electrons (Figure 1). The 18 π electron aromatic system (Figure 1, in bold) of the porphyrinoids confers stability

• such as tetrakis(pentafluorophenyl)porphyrin (TPFPP) is more efficient in an oxidative quenching compared to an electron-rich (e.g., TPP) remained to be elucidated. In this regard, our research group has contributed in the last 10 years with new porphyrin/chlorin synthetic methodologies, and

Fluorinated maleimide-substituted porphyrins and chlorins: synthesis and characterization

• Valentina A. Ol’shevskaya,
• Elena G. Kononova and
• Andrei V. Zaitsev

Beilstein J. Org. Chem. 2019, 15, 2704–2709, doi:10.3762/bjoc.15.263

• prepared based on the reaction of Zn(II) or Ni(II) complexes of 5,10,15,20-tetrakis(4-amino-2,3,5,6-tetrafluorophenyl)porphyrin and chlorin with maleic anhydride. Porphyrin maleimide derivatives were also prepared by the reaction of 5,10,15,20-tetrakis(4-azido-2,3,5,6-tetrafluorophenyl)porphyrinato Zn(II

• ) or Ni(II) with N-propargylmaleimide via the CuAAC click reaction to afford fluorinated porphyrin–triazole–maleimide conjugates. New maleimide derivatives were isolated in reasonable yields and identified by UV–vis, 1H NMR, 19F NMR spectroscopy and mass-spectrometry. Keywords: chlorin; maleimide

• widely used to generate singlet oxygen for PDT applications [9][23]. We intend here to combine within one molecule the structural specificity of a meso-fuorinated porphyrin/chlorin macrocycle and maleimide units to develop novel multifunctional compounds with improved properties for various applications

Introduction of an isoxazoline unit to the β-position of porphyrin via regioselective 1,3-dipolar cycloaddition reaction

• Xiujun Liu,
• Xiang Ma and
• Yaqing Feng

Beilstein J. Org. Chem. 2019, 15, 1434–1440, doi:10.3762/bjoc.15.143

• -dipoles to furnish the chlorin or bacteriochlorin analogues [26][27][28][29][30][31][32][33][34][35][36][37]. On the other hand, the formed heterocycles are also very important. For example, isoxazoline derivatives are not only significant intermediates in organic synthesis, e.g., masked aldols [38][39

• -generated nitrile oxide, which showed inferior selectivity and afforded regio-/stereoisomers [43]. NMR analysis assisted the identification of various isomeric isoxazoline-linked chlorin products. Here, we would like to report an artificial vinylporphyrin 2, which has been designed to control the

p-Nitrophenyl carbonate promoted ring-opening reactions of DBU and DBN affording lactam carbamates

• Madhuri Vangala and
• Ganesh P Shinde

Beilstein J. Org. Chem. 2016, 12, 2086–2092, doi:10.3762/bjoc.12.197

• products [12]. Subsequently, Ma and Dolphin isolated chlorin-e6 lactams from the reaction of methyl pheophorbide with DBU and DBN promoted by trialkyl triflates [13]. Additionally, the conjugate addition reaction of DBU to diarylpyrone [14] and Baylis–Hillman acetates [15] also gave caprolactam products. A

From porphyrin benzylphosphoramidate conjugates to the catalytic hydrogenation of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin

• Marcos C. de Souza,
• Leandro F. Pedrosa,
• Géssica S. Cazagrande,
• Vitor F. Ferreira,
• Maria G. P. M. S. Neves and
• José A. S. Cavaleiro

Beilstein J. Org. Chem. 2014, 10, 628–633, doi:10.3762/bjoc.10.54

• of the catalytic hydrogenation to TPPF20 with 10% Pd/C was then studied with a variety of solvents. The results showed that ethanol/DMF is the solvent of choice to produce chlorin TPCF20 and an ethanol/DMF/NEt3 mixture is more adequate to produce isobacteriochlorin (TPIF20). Keywords: catalytic

• hydrogenation; chlorin; isobacteriochlorin; phosphoramidate; porphyrin; Introduction The use of porphyrin derivatives as photosensitizers is considered for the photodynamic therapy (PDT) of malignant tumors and the treatment of age-related macular degeneration in several countries [1][2]. It is already known

• reduction of the macrocycle, thereby affording chlorin and other derivatives (Scheme 1). Considering the importance of TPPF20 as a template for further functionalizations [7] and the better suitability of chlorins for PDT compared to porphyrins due to their enhanced red-shifted Q bands [2], we decided to