3717-21-3Relevant articles and documents
On the mixed oxides-supported niobium catalyst towards benzylamine oxidation
Granato, álisson Silva,de Carvalho, Gustavo S. Gon?alves,Fonseca, Carla G.,Adrio, Javier,Leit?o, Alexandre A.,Amarante, Giovanni Wilson
, p. 118 - 125 (2020/09/11)
A series of mixed oxides-supported niobium-based catalysts has been synthesized and applied towards oxidation reactions of benzylamine derivatives. Under the optimized reaction conditions, the selectivity to oxime enhanced, leading to the main product with up to 72 %. Moreover, even α-substituted benzylamines were well tolerated and led to oximes in good isolated yields. It is important to mention; four equivalents of the harmless and inexpensive hydrogen peroxide were employed as oxidizing agent. Mechanism hypothesis suggested that the reaction proceed to selective benzylamine oxidation into nitroso intermediate, following by formation of the corresponding oxime tautomer mediated by an unstable water produced by NbOx supported catalyst. This consists the first mixed oxides-supported niobium-based catalyst for selective oxidation of benzylamines to oximes.
Poly(N-vinylimidazole): A biocompatible and biodegradable functional polymer, metal-free, and highly recyclable heterogeneous catalyst for the mechanochemical synthesis of oximes
Fahim, Hoda,Ghaffari Khaligh, Nader,Gorjian, Hayedeh
, p. 2007 - 2012 (2022/01/08)
The catalytic activity of poly(N-vinylimidazole), a biocompatible and biodegradable synthetic functional polymer, was investigated for the synthesis of oximes as an efficient, halogen-free, and reusable heterogeneous catalyst. The corresponding oximes were afforded in high to excellent yields at room temperature and in short times using the planetary ball mill technique. Some merits, such as the short reaction times and good yields for poorly active carbonyl compounds, and avoiding toxic, expensive, metal-containing catalysts, and hazardous and flammable solvents, can be mentioned for the current catalytic synthesis of the oximes. Furthermore, the heterogeneous organocatalyst could be easily separated after the reaction, and the regenerated catalyst was reused several times with no significant loss of its catalytic activity.
Enolate-Based Regioselective Anti-Beckmann C-C Bond Cleavage of Ketones
Jahn, Ullrich,Ma?ek, Tomá?
, p. 11608 - 11632 (2021/09/02)
The Baeyer-Villiger or Beckmann rearrangements are established methods for the cleavage of ketone derivatives under acidic conditions, proceeding for unsymmetrical precursors selectively at the more substituted site. However, the fragmentation regioselectivity cannot be switched and fragmentation at the less-substituted terminus is so far not possible. We report here that the reaction of ketone enolates with commercial alkyl nitrites provides a direct and regioselective way of fragmenting ketones into esters and oximes or ω-hydroxyimino esters, respectively. A comprehensive study of the scope of this reaction with respect to ketone classes and alkyl nitrites is presented. Control over the site of cleavage is gained through regioselective enolate formation by various bases. Oxidation of kinetic enolates of unsymmetrical ketones leads to the otherwise unavailable "anti-Beckmann"cleavage at the less-substituted side chain, while cleavage of thermodynamic enolates of the same ketones represents an alternative to the Baeyer-Villiger oxidation or the Beckmann rearrangement under basic conditions. The method is suited for the transformation of natural products and enables access to orthogonally reactive dicarbonyl compounds.
