10.1021/acscatal.0c01310
The research describes a novel method for the γ-C(sp3)–H oxygenation of free aliphatic amines, utilizing 2-hydroxynicotinaldehyde as a transient directing group and N-fluoro-2,4,6-trimethylpyridinium tetrafluoroborate as a bystanding oxidant. The purpose of this study was to develop a general protocol for the selective oxygenation at the γ-methyl positions of a wide range of aliphatic amines, which could be coupled with various aryl, heteroaryl, and aliphatic acids, as well as primary, secondary, and tertiary alcohols, to afford amine-containing esters and ethers. The conclusions highlight the method's broad applicability, good functional group tolerance, and its potential for late-stage functionalization of natural products and drug molecules, such as ibuprofen, isozepac, fenbufen, and lithocholic acid. This approach provides a more straightforward access to mono-protected amino alcohols and hindered ethers, which are challenging to synthesize using conventional methods.
10.1016/S0968-0896(99)00202-3
The study investigates the biomimetic oxidation of ibuprofen using hydrogen peroxide catalyzed by Horseradish peroxidase (HRP) and specific metalloporphyrins in AOT reverse micelles. The metalloporphyrins involved are 5,10,15,20-tetrakis-(2',6-dichloro-3'-sulphonatophenyl)porphyrinatoiron(III) (ClsTPPS,Fe(III)) and its manganese(III) analogue (ClsTPPS,Mn(III)). These catalysts, along with HRP, facilitate the formation of oxidation products such as 2-(4'-isobutyl-phenyl)ethanol (5) and p-isobutyl acetophenone (6) from ibuprofen. The yields of these products are influenced by factors like pH, water to surfactant ratio (Wo), concentration of the catalysts, and the presence of molecular oxygen in the AOT reverse micelles. The study aims to elucidate the molecular mechanisms of heme peroxidase and related enzymes through this biomimetic oxidation process.
10.1016/j.tetlet.2010.09.007
The research focuses on the development of a simple and robust method for the preparation of 11C-labeled ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID), using Tetrabutylammonium fluoride (TBAF)-promoted α-[11C]methylation of α-arylesters. This method is suitable for remote-controlled synthesis and is advantageous for positron emission tomography (PET) tracer development. The experiments involved the use of TBAF as a base to activate the α-carbon of various α-arylesters, including methyl phenylacetate and its derivatives, under homogeneous conditions. The reactants included the 11C-labeling agent iodo[11C]methane (1), different α-arylesters (2a-e), and TBAF. The analyses used to assess the radiochemical conversion and purity of the products included radiochromatography with analytical high-performance liquid chromatography (HPLC). The study also investigated the influence of electron-withdrawing and donating groups on the [11C]methylation efficiency and confirmed the active base for the reaction to be fluoride, even in a hydrated form. The method was optimized for the synthesis of 11C-labeled ibuprofen, which involved the hydrolysis of the ester 3d to yield the acid form 5, and was amenable to remote-controlled synthesis, demonstrating its potential for PET tracer development.
10.1016/j.phytochem.2009.08.007
The research focused on the isolation and characterization of bioactive compounds from the stem bark of Fagara heitzii, a plant traditionally used in Cameroonian medicine for treating various ailments including cancer and malaria. The study aimed to discover potential antitumoral, anti-inflammatory, antioxidant, and antimalarial agents. Through extraction with methanol and subsequent chromatographic separation, the researchers identified two new amides, heitziamide A and B, and two phenylethanoids, heitziethanoid A and B, along with thirteen known compounds. The structures of these compounds were established using spectroscopic analysis. Nine of these compounds were evaluated for their ability to inhibit oxidative burst activity and their cytotoxicity against PC-3 prostate cancer cells. The results showed that all compounds significantly suppressed the oxidative burst response in a dose-dependent manner, with IC50 values ranging from 2.0 to 6.5 μM, compared to the control Ibuprofen with an IC50 of 12.1 μM. However, none of the compounds exhibited cytotoxic effects on the prostate cancer cells (IC50 > 100 μM).
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