Synthesis of meso-tetraarylporphyrins using SeO2 as oxidant

A new porphyrin as selective substrate-based inhibitor of breast cancer resistance protein (BCRP/ABCG2)

The ABCG2 transporter plays a pivotal role in multidrug resistance, however, no clinical trial using specific ABCG2 inhibitors have been successful. Although ABC transporters actively extrude a wide variety of substrates, photodynamic therapeutic agents with porphyrinic scaffolds are exclusively transported by ABCG2. In this work, we describe for the first time a porphyrin derivative (4B) inhibitor of ABCG2 and capable to overcome multidrug resistance in vitro. The inhibition was time-dependent and 4B was not itself transported by ABCG2. Independently of the substrate, the porphyrin 4B showed an IC₅₀ value of 1.6 μM and a mixed type of inhibition. This compound inhibited the ATPase activity and increased the binding of the conformational-sensitive antibody 5D3. A thermostability assay confirmed allosteric protein changes triggered by the porphyrin. Long-timescale molecular dynamics simulations revealed a different behavior between the ABCG2 porphyrinic substrate pheophorbide a and the porphyrin 4B. Pheophorbide a was able to bind in three different protein sites but 4B showed one binding conformation with a strong ionic interaction with GLU446. The inhibition was selective toward ABCG2, since no inhibition was observed for P-glycoprotein and MRP1. Finally, this compound successfully chemosensitized cells that overexpress ABCG2. These findings reinforce that substrates may be a privileged source of chemical scaffolds for identification of new inhibitors of multidrug resistance-linked ABC transporters.

Synthesis of dipyroromethanes in water and investigation of electronic and steric effects in efficiency of olefin epoxidation by sodium periodate catalyzed by manganese tetraaryl andtransdisubstituted porphyrin complexes

Condensation of pyrrole with various aldehydes in the presence of BF3•etherate as an acid catalyst in water provides good yield of some dipyrromethanes. Prolongation of the reaction time with aldehydes substituted by electron-donating (mesityl) or electron-withdrawing (2,6-dichlorophenyl) groups on the ortho positions of the phenyl did not lead to decomposition or scrambling. Manganese trans disubstituted porphyrin complexes which derive from various dipyrromethanes and manganese tetraaryl porphyrin complexes including various substituents with different steric and electronic properties show good catalytic activity in epoxidation of alkenes by NaIO4in the presence of imidazole (ImH). The study of steric and electronic effects of the catalysts on the epoxidation of olefins shows that Mn-porphyrin complexes with more bulky and electron-releasing groups on meso phenyls could increase the epoxidation yield of most alkenes.

Synthesis of meso-tetraarylporphyrins using hafnium (IV) bis(perfluorooctanesulfonyl)imide complex in perfluorodecalin medium

This letter presents a non-conventional synthesis of meso-porphyrins in moderate yields, using catalytic quantities of hafnium (IV) bis(perfluorooctanesulfonyl)imide complex in a perfluorodecalin biphasic system. Various meso-tetraarylporphyrins were obtained in good yields. The catalyst is selectively dissolved in perfluorodecalin, and can be recovered simply by phase separation and reused several times without any obvious decrease of activity.

Synthesis and characterization of a new magnetic nanocomposite with metalloporphyrin (Co-TPyP) and sulfated tin dioxide (Fe3O4@SnO2/SO42−), and investigation of its photocatalytic effects in the degradation of Rhodamine B

To achieve the synthesis of (Fe₃O₄@SnO₂/SO₄²⁻), after the preparation of magnetic nanoparticles of Fe₃O₄ (MNP), tin dioxide was supported on the MNP, and it was sulfated using ammonium sulfate.

Developments in Synthetic Application of Selenium(IV) Oxide and Organoselenium Compounds as Oxygen Donors and Oxygen-Transfer Agents

A variety of selenium compounds were proven to be useful reagents and catalysts for organic synthesis over the past several decades. The most interesting aspect, which emerged in recent years, concerns application of hydroperoxide/selenium(IV) oxide and hydroperoxide/organoselenium catalyst systems, as "green reagents" for the oxidation of different organic functional groups. The topic of oxidations catalyzed by organoselenium derivatives has rapidly expanded in the last fifteen years This paper is devoted to the synthetic applications of the oxidation reactions mediated by selenium compounds such as selenium(IV) oxide, areneseleninic acids, their anhydrides, selenides, diselenides, benzisoselenazol-3(2H)-ones and other less often used other organoselenium compounds. All these compounds have been successfully applied for various oxidations useful in practical organic syntheses such as epoxidation, 1,2-dihydroxylation, and α-oxyfunctionalization of alkenes, as well as for ring contraction of cycloalkanones, conversion of halomethyl, hydroxymethyl or active methylene groups into formyl groups, oxidation of carbonyl compounds into carboxylic acids and/or lactones, sulfides into sulfoxides, and secondary amines into nitrones and regeneration of parent carbonyl compounds from their azomethine derivatives. Other reactions such as dehydrogenation and aromatization, active carbon-carbon bond cleavage, oxidative amidation, bromolactonization and oxidation of bromide for subsequent reactions with alkenes are also successfully mediated by selenium (IV) oxide or organoselenium compounds. The oxidation mechanisms of ionic or free radical character depending on the substrate and oxidant are discussed. Coverage of the literature up to early 2015 is provided. Links have been made to reviews that summarize earlier literature and to the methods of preparation of organoselenium reagents and catalysts.

Synthesis of 5,10,15,20-tetrakis[4-(naphthalen-2-yloxycarbonyl)phenyl]porphyrin (TNBP) and its complexes with zinc and cobalt and an investigation of the photocatalytic activity of nanoFe3O4@ZrO2–TNBP

5,10,15,20-Tetrakis[4-(naphthalen-2-yloxycarbonyl)phenyl]porphyrin and its porphyrin complexes with zinc and cobalt and nanoFe₃O₄@ZrO₂–TNBP photocatalysts were synthesized with high yields and the structure and morphology were fully characterized.