ABSTRACT
A cobalt catalyst, under oxidative conditions, facilitates the single electron transfer process in N-pyridyl arylacetamides to form α-carbon-centered radicals that readily react with molecular oxygen, giving access to mandelic acid derivatives. In contrast to the known benzylic hydroxylation approaches, this approach enables chemo- and regioselective hydroxylation at a benzylic position adjacent to (N-pyridyl)amides. Mild conditions, broad scope, excellent selectivity, and wide synthetic practicality set up the merit of the reaction.
ABSTRACT
Herein, we report metal- and photocatalyst-free room-temperature amidation for α-ketoamide synthesis from feedstock phenacyl bromides and amines using molecular oxygen as an oxidant as well as a source of oxygen in the amide segment. Visible light-mediated base-promoted one-pot sequential C-N/CâN/CâO bond formation takes place in a tandem manner to afford the desired product. Functional group tolerance (benzylic alcohol, keto, cyano, nitro, halo, etc.), a broad substrate scope, and gram-scale synthesis make this synthetic methodology more attractive. We have observed that electron-rich aromatic amines, aliphatic amines, and phenacyl bromide derivatives proceeded the present transformation with marginally superior reactivity in comparison to electron-deficient aromatic amines and phenacyl bromide derivatives. Moreover, several control experiments, in situ isolation of secondary amine and imine as key intermediates, and 18O-labeling experiments provide complete insight into the mechanism of the tandem pathway.
ABSTRACT
Magnetite (Fe3O4) nanoparticles coated with dextrose and gluconic acid possessing both super-paramagnetism and excellent optical properties have been productively synthesized through a straightforward, efficient and cost-efficient hydrothermal reduction route using Fe3+ as sole metal precursor acquired from accumulated iron ore tailings-a mining waste that usually represents a major environmental threat. Fe3O4/C nanocomposites were fully elucidated by FEGSEM and TEM, revealing a combination of platelets (<1 µm) capped by particles (<10 nm) and magnetite which was verified by XPS, which demonstrated also oxygen deficiency. A dextrose/gluconic acid coating was elucidated by Fourier transform-infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). The Fe3O4/C nanocomposites were found to be superparamagnetic at room temperature. Meanwhile, their optical properties were investigated by UV-visible diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence (PL) spectroscopy; an Eg of 1.86 eV was determined, and emissions at 612 and 650 nm (ex. 250 nm) were consistent with the XPS identification of oxygen vacancies. The efficacy of the as-synthesized magnetically recoverable magnetite/carbon (Fe3O4/C) nanocomposites has been exhibited in the photocatalytic degradation of the toxic textile (industrial) dye bodactive red BNC-BS.