1129-50-6Relevant articles and documents
The catalytic activity of titania nanostructures in the synthesis of amides under solvent-free conditions
Nagarajan, Sangaraiah,Ran, Park,Shanmugavelan, Poovan,Sathishkumar, Murugan,Ponnuswamy, Alagusundaram,Suk Nahm, Kee,Gnana Kumar
, p. 1312 - 1319 (2012)
Different shapes and phases of titania nanostructures with the uniform size distribution were synthesized by hydrothermal sol-gel technique. The influence of annealing temperature on the crystalline character, size and phase of the prepared nanomaterials were evidenced from the diffraction analysis. Infrared spectroscopic analysis ensured the structural confirmation of the sulfated titania nanostructures. Catalytic activity of the synthesized nanometric materials in direct amidation of aromatic and aliphatic carboxylic acids with aromatic amines was evaluated. Among the materials studied, sulfated titania nanotubes with the anatase phase exhibited excellent catalytic activity. The employed solvent-free protocol is greener and eradicates the drawbacks associated with the hazardous solvents employed in the prevailing solution phase methodologies.
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Ozaki,Shimada
, (1961)
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Visible-light induced one-pot hydrogenation and amidation of nitroaromatics with carboxylic acids over 2D MXene-derived Pt/N-TiO2/Ti3C2
Jiang, Heyan,Hu, Zujie,Gan, Chuan,Sun, Bin,Kong, Shuzhen,Bian, Fengxia
, (2021/03/03)
Pt nanoparticles supported on N doped titanium dioxide/titanium carbide (MXene) heterojunctions were employed as photocatalysts for the tandem reactions between aromatic nitro compounds and carboxylic acids to produce amide products. The 3%Pt/N-TiO2/Ti3C2 heterojunction was prepared by in situ grew TiO2 on Ti3C2 nanosheets and then N doped TiO2 with melamine, Pt nanoparticles with 3.3 nm mean diameter well dispersed on N-TiO2/Ti3C2. 3%Pt/N-TiO2/Ti3C2 had excellent amidation activity and chemoselectivity under visible-light irradiation. The elevated catalytic performance of 3%Pt/N-TiO2/Ti3C2 was owing to the improvement in photogenerated electron and hole separation efficiency through charge short-range directional transmission caused by the intimate contact between the TiO2 and the conductive Ti3C2. This direct hydrogenation along with amidation between nitroaromatics and carboxylic acids own actual merits in the amides produce with no harmful byproducts. In situ DRIFTS spectra verified that the amidation activation with visible light irradiation at 25 °C was much faster than heating.
Photocatalyzed Triplet Sensitization of Oximes Using Visible Light Provides a Route to Nonclassical Beckmann Rearrangement Products
Zhang, Xiao,Rovis, Tomislav
, p. 21211 - 21217 (2021/12/27)
Oximes are valuable synthetic intermediates for the preparation of a variety of functional groups. To date, the stereoselective synthesis of oximes remains a major challenge, as most current synthetic methods either provide mixtures of E and Z isomers or furnish the thermodynamically preferred E isomer. Herein we report a mild and general method to achieve Z isomers of aryl oximes by photoisomerization of oximes via visible-light-mediated energy transfer (EnT) catalysis. Facile access to (Z)-oximes provides opportunities to achieve regio- and chemoselectivity complementary to those of widely used transformations employing oxime starting materials. We show an enhanced one-pot protocol for photocatalyzed oxime isomerization and subsequent Beckmann rearrangement that enables novel reactivity with alkyl groups migrating preferentially over aryl groups, reversing the regioselectivity of the traditional Beckmann reaction. Chemodivergent N- or O- cyclizations of alkenyl oximes are also demonstrated, leading to nitrones or cyclic oxime ethers, respectively.
Cobalt-Catalyzed Deoxygenative Hydroboration of Nitro Compounds and Applications to One-Pot Synthesis of Aldimines and Amides
Gudun, Kristina A.,Hayrapetyan, Davit,Khalimon, Andrey Y.,Segizbayev, Medet,Slamova, Ainur,Zakarina, Raikhan
, (2021/11/30)
The commercially available and bench-stable Co(acac)2 ligated with bis[(2-diphenylphosphino)phenyl] ether (dpephos) was employed for selective room temperature hydroboration of nitro compounds with HBPin (TOF up to 4615 h?1), tolerating halide, hydroxy, amino, ether, ester, lactone, amide and heteroaromatic functionalities. These reactions offered a direct access to a variety of N-borylamines RN(H)BPin, which were in situ treated with aldehydes and carboxylic acids to produce a series of aldimines and secondary carboxamides without the need for dehydrating and/or coupling reagents. Combination of these transformations in a sequential one-pot manner allowed for direct and selective synthesis of aldimines and secondary carboxamides from readily available and inexpensive nitro compounds.
