51030-59-2Relevant academic research and scientific papers
Visible-light-induced Beckmann rearrangement by organic photoredox catalysis
Tang, Li,Wang, Zhi-Lv,Wan, Hai-Lan,He, Yan-Hong,Guan, Zhi
supporting information, p. 6182 - 6186 (2020/09/01)
A facile and general strategy for efficient direct conversion of oximes to amides using an inexpensive organic photocatalyst and visible light is described. This radical Beckmann rearrangement can be performed under mild conditions. Various alkyl aryl ketoximes and diaryl ketoximes can be effectively converted into the corresponding amides in excellent yields.
An Electrochemical Beckmann Rearrangement: Traditional Reaction via Modern Radical Mechanism
Tang, Li,Wang, Zhi-Lv,He, Yan-Hong,Guan, Zhi
, p. 4929 - 4936 (2020/08/21)
Abstract: Electrosynthesis as a potential means of introducing heteroatoms into the carbon framework is rarely studied. Herein, the electrochemical Beckmann rearrangement, i. e. the direct electrolysis of ketoximes to amides, is presented for the first time. Using a constant current as the driving force, the reaction can be easily carried out under neutral conditions at room temperature. Based on a series of mechanistic studies, a novel radical Beckmann rearrangement mechanism is proposed. This electrochemical Beckmann rearrangement does not follow the trans-migration rule of the classical Beckmann rearrangement.
Direct synthesis of secondary amides from ketones through Beckmann rearrangement using O-(mesitylsulfonyl)hydroxylamine
Chandra, Dinesh,Verma, Saumya,Pandey, Chandra Bhan,Yadav, Ajay K.,Kumar, Puneet,Tiwari, Bhoopendra,Jat, Jawahar L.
supporting information, (2020/03/23)
The Beckmann rearrangement is a versatile method for the preparation of secondary amides from ketones via oxime intermediates and has been widely used in the synthesis of bioactive natural products and pharmaceuticals. Herein, we have developed a highly efficient direct method for the preparation of secondary amides and lactams from ketones using O-(mesitylsulfonyl)hydroxylamine (MSH). The reactions proceed rapidly at room temperature under mild condition without requiring any additive, and tolerate multiple functional groups. A simple aqueous work-up often furnished the products in excellent yield with high purity.
Mild, calcium catalysed Beckmann rearrangements
Kiely-Collins,Sechi,Brennan,McLaughlin
supporting information, p. 654 - 657 (2018/02/06)
A mild calcium catalysed Beckmann rearrangement has been realised, which forgoes the more traditional harsh reactions conditions associated with the transformation. The catalyst system is shown to be tolerant towards a wide variety of functional groups relevant to natural product synthesis and medicinal chemistry and the synthetic utility of the reaction has also been investigated. A preliminary mechanistic investigation was performed to understand the nature of the incoming nucleophile and a possible reaction pathway is described.
Scope and mechanism of a true organocatalytic beckmann rearrangement with a boronic acid/perfluoropinacol system under ambient conditions
Mo, Xiaobin,Morgan, Timothy D. R.,Ang, Hwee Ting,Hall, Dennis G.
supporting information, p. 5264 - 5271 (2018/04/24)
Catalytic activation of hydroxyl functionalities is of great interest for the production of pharmaceuticals and commodity chemicals. Here, 2-alkoxycarbonyl- and 2-phenoxycarbonyl-phenylboronic acid were identified as efficient catalysts for the direct and chemoselective activation of oxime N-OH bonds in the Beckmann rearrangement. This classical organic reaction provides a unique approach to prepare functionalized amide products that may be difficult to access using traditional amide coupling between carboxylic acids and amines. Using only 5 mol % of boronic acid catalyst and perfluoropinacol as an additive in a polar solvent mixture, the operationally simple protocol features mild conditions, a broad substrate scope, and a high functional group tolerance. A wide variety of diaryl, aryl-alkyl, heteroaryl-alkyl, and dialkyl oximes react under ambient conditions to afford high yields of amide products. Free alcohols, amides, carboxyesters, and many other functionalities are compatible with the reaction conditions. Investigations of the catalytic cycle revealed a novel boron-induced oxime transesterification providing an acyl oxime intermediate involved in a fully catalytic nonself-propagating Beckmann rearrangement mechanism. The acyl oxime intermediate was prepared independently and was subjected to the reaction conditions. It was found to be self-sufficient; it reacts rapidly, unimolecularly without the need for free oxime. A series of control experiments and 18O labeling studies support a true catalytic pathway involving an ionic transition structure with an active and essential role for the boronyl moiety in both steps of transesterification and rearrangement. According to 11B NMR spectroscopic studies, the additive perfluoropinacol provides a transient, electrophilic boronic ester that is thought to serve as an internal Lewis acid to activate the ortho-carboxyester and accelerate the initial, rate-limiting step of transesterification between the precatalyst and the oxime substrate.
Rapid access to N-(indol-2-yl)amides and N-(indol-3-yl)amides as unexplored pharmacophores
Reekie, Tristan A.,Wilkinson, Shane M.,Law, Vivian,Hibbs, David E.,Ong, Jennifer A.,Kassiou, Michael
, p. 576 - 580 (2017/01/25)
Preparation of N-(indol-2-yl)amides and N-(indol-3-yl)amides are scarce in the scientific literature due to unstable intermediates impeding current reported syntheses. We have employed cheap and readily available substrates in the Curtius rearrangement of
The first isocyanide of plant origin expands functional group diversity in cruciferous phytoalexins: Synthesis, structure and bioactivity of isocyalexin A
Pedras, M. Soledade C.,Yaya, Estifanos E.
, p. 3613 - 3616 (2012/06/18)
Although isocyanides are not rare amongst terrestrial microbes and marine organisms, despite tens of thousands of natural products isolated from plants, isocyanides are still missing. Isocyalexin A is the first isocyanide of plant origin. Isocyalexin A was isolated from UV-irradiated rutabaga roots and shown to be a new cruciferous phytoalexin. Its chemical structure was proven by analysis of NMR spectroscopic data and chemical synthesis.
An efficient catalytic method for the Beckmann rearrangement of ketoximes to amides and aldoximes to nitriles mediated by propylphosphonic anhydride (T3P)
Augustine, John Kallikat,Kumar, Rajesha,Bombrun, Agnes,Mandal, Ashis Baran
scheme or table, p. 1074 - 1077 (2011/03/22)
An efficient method for the Beckmann rearrangement of ketoximes to amides mediated by a catalytic amount (15 mol %) of propylphosphonic anhydride (T3P) is described. Aldoximes underwent second order Beckmann rearrangement to provide the corresponding nitriles in excellent yields on reacting with T3P (15 mol %) at room temperature. The main advantages of this environmentally friendly protocol include procedural simplicity, and particularly ease of isolation of the products.
Nitroethane in polyphosphoric acid: A new reagent for acetamidation and amination of aromatic compounds
Aksenov, Alexander V.,Aksenov, Nicolai A.,Nadein, Oleg N.,Aksenova, Inna V.
experimental part, p. 2628 - 2630 (2010/12/18)
A new method of acetamidation of aromatic compounds based on their reaction with nitroethane in polyphosphoric acid has been developed. Upon the hydrolysis of acetamides during the reaction mixture workup, the corresponding amines can be obtained. Georg Thieme Verlag Stuttgart New York.
Convenient synthesis of masked aminoindoles by indium mediated one-pot reductive acylation of 3- and 2-nitroindoles
Roy, Sujata,Gribble, Gordon W.
, p. 51 - 56 (2007/10/03)
Unstable 3- and 2-aminoindoles arc generated in situ by indium mediated reduction of 3- and 2-nitroindoles and capped as the stable amides (or carbamate) in moderate to high yields under mild conditions in a one-pot procedure.
