7555-72-8Relevant academic research and scientific papers
Arylboronic Acid-Catalyzed C-Allylation of Unprotected Oximes: Total Synthesis of N-Me-Euphococcine
Kürti, László,Kattamuri, Padmanabha V.,Siitonen, Juha H.,Yousufuddin, Muhammed
, (2020)
O-Unprotected keto-and aldoximes are readily C-allylated with allyl diisopropyl boronate in the presence of arylboronic acid catalysts to yield highly substituted N-α-secondary and tertiary homoallylic hydroxylamines. The method was used in the total synthesis of the trace alkaloid N-Me-Euphococcine.
Chlorotropylium Promoted Conversions of Oximes to Amides and Nitriles
Xu, Jiaxi,Gao, Yu,Li, Zhenjiang,Liu, Jingjing,Guo, Tianfo,Zhang, Lei,Wang, Haixin,Zhang, Zhihao,Guo, Kai
, p. 311 - 315 (2020/01/25)
Chlorotropylium chloride as a catalyst for the transformations of oximes, ketones, and aldehydes to their corresponding amides and nitriles in excellent yields (up to 99 %) and in short reaction times (mostly 10–15 min). Oximes were electrophilically attacked on the hydroxyl oxygen by chlorotropylium. The produced tropylium oxime ethers were the key intermediates, of which the ketoxime ether led to amide through Beckmann rearrangement, and the aldoxime ether led to nitrile by nitrogen base DBU assisted formal dehydration. This chlorotropylium activation protocol offered general, mild, and efficient avenues bifurcately from oximes to both amides and nitriles by one organocatalyst.
Dichloroimidazolidinedione-Activated Beckmann Rearrangement of Ketoximes for Accessing Amides and Lactams
Gao, Yu,Liu, Jingjing,Li, Zhenjiang,Guo, Tianfo,Xu, Songquan,Zhu, Hui,Wei, Fulan,Chen, Siming,Gebru, Hailemariam,Guo, Kai
, p. 2040 - 2049 (2018/02/23)
A novel protocol for the activation of the Beckmann rearrangement utilizing the readily available and economical geminal dichloroimidazolidinediones (DCIDs) on a substoichiometric scale (10 mol %) has been developed. A unique self-propagating mechanism for the substoichiometric dichloroimidazolidinedione-activated transformation was proposed and validated. The substrate scope of the developed protocol has been demonstrated by 23 examples with good to excellent yields (mostly 90-98%) in a short time (mostly 10-30 min), including a substrate for synthesizing the monomer of nylon-12 and a complicated steroidal substrate on a preparative scale. This research not only unveils for the first time the synthetic potential of substoichiometric amounts of dichloroimidazolidinediones in promoting chemical transformation but also offers yet another important illustration of the self-propagating cycle in the context of the Beckmann rearrangement activated by a structurally novel organic promoter.
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.
Synthesis of azaheterocycles from aryl ketone O-acetyl oximes and internal alkynes by Cu-Rh bimetallic relay catalysts
Too, Pei Chui,Chua, Sze Hui,Wong, Siong Heng,Chiba, Shunsuke
experimental part, p. 6159 - 6168 (2011/10/04)
A synthetic method for azaheterocycles from aryl ketone O-acetyl oximes and internal alkynes has been developed by using the Cu(OAc)2- [Cp*RhCl2]2 bimetallic catalytic system. The reactions proceeded with both of anti- and syn-isomers of oximes with a wide scope of substituents. The Cu-Rh bimetallic system could be applied for the synthesis of isoquinolines as well as β-carboline, furo[2.3-c]pyridine, pyrrolo[2,3-c]pyridine, and thieno[2,3-c]pyridine derivatives.
QUINOLINE 4-CARBOXAMIDE DERIVATIVES AND THEIR USE AS NEUROKININ 3 (NK-3) RECEPTOR ANTAGONISTS
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Page/Page column 21-22, (2010/02/10)
The invention relates to novel quinoline derivatives, processes for their preparation, pharmaceutical compositions containing them and their use as medicaments particularly in treating disorders of the central nervous system (CNS).
Thermal Ring-Expansion of N-Acyl Cyclopropyl Imines
Wu, Pei-Lin,Wang, Wen-Shan
, p. 622 - 627 (2007/10/02)
The FVT of N-acyl cyclopropyl imines with methyl, phenyl, and acyl substituents at C-1 or C-2 of the cyclopropyl ring has been studied.The parent N-acyl cyclopropyl imine and N-acyl methylcyclopropyl imines gave no ring-expansion products but ring-opened mixtures, decomposed fragments, and polymerization tars after FVT, whereas N-acyl phenylcyclopropyl imines and N-acyl acylcyclopropyl imines generated ring-expansion products, 2-pyrrolines.It demonstrates the first study on the thermal rearrangement of N-acyl cyclopropyl imines.
