- Cycloaddition reactions of diethyl (E)-2-fluoromaleate
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Diethyl E-2-fluoromaleate has been prepared in a pure state in 89% yield by a Horner-Wadsworth-Emmons Wittig procedure. The E configuration was determined by NMR spectroscopy. Diethyl E-2-fluoromaleate undergoes [3+2] cycloadditions with a series of aroma
- Patrick, Timothy B.,Shadmehr, Mehrdad,Khan, Akbar H.,Singh, Rajiv K.,Asmelash, Bethel
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- [3 + 2] Cycloaddition reactions of ethyl (Z)-3-fluoropropenoate with nitrones
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Ethyl (Z)-2-fluoropropenoate reacts stereospecifically and regioselectively in [3 + 2] cycloadditions with aryl N-methylnitrones. The yields of the cycloaddition products range from 61 to 70%.
- Patrick, Timothy B.,Khan, Akbar H.
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Read Online
- Carbamoylation of Azomethine Imines via Visible-Light Photoredox Catalysis
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A versatile and robust photocatalytic methodology to install the amide functional group into azomethine imine ions is described. This protocol is distinguished by its broad scope and mild reaction conditions, which are well suited for the preparation of s
- Correia, José Tiago M.,Matsuo, Bianca T.,Oliveira, Pedro H. R.,Paix?o, Márcio W.
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supporting information
p. 6775 - 6779
(2021/09/13)
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- Diversity Oriented Clicking (DOC): Divergent Synthesis of SuFExable Pharmacophores from 2-Substituted-Alkynyl-1-Sulfonyl Fluoride (SASF) Hubs
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Diversity Oriented Clicking (DOC) is a unified click-approach for the modular synthesis of lead-like structures through application of the wide family of click transformations. DOC evolved from the concept of achieving “diversity with ease”, by combining classic C?C π-bond click chemistry with recent developments in connective SuFEx-technologies. We showcase 2-Substituted-Alkynyl-1-Sulfonyl Fluorides (SASFs) as a new class of connective hub in concert with a diverse selection of click-cycloaddition processes. Through the selective DOC of SASFs with a range of dipoles and cyclic dienes, we report a diverse click-library of 173 unique functional molecules in minimal synthetic steps. The SuFExable library comprises 10 discrete heterocyclic core structures derived from 1,3- and 1,5-dipoles; while reaction with cyclic dienes yields several three-dimensional bicyclic Diels–Alder adducts. Growing the library to 278 discrete compounds through late-stage modification was made possible through SuFEx click derivatization of the pendant sulfonyl fluoride group in 96 well-plates—demonstrating the versatility of the DOC approach for the rapid synthesis of diverse functional structures. Screening for function against MRSA (USA300) revealed several lead hits with improved activity over methicillin.
- Barrow, Andrew S.,Cheng, Yunfei,Gialelis, Timothy L.,Giel, Marie-Claire,Kitamura, Seiya,Li, Gencheng,Moses, John E.,Ottonello, Alessandra,Sharpless, K. Barry,Smedley, Christopher J.,Wolan, Dennis W.
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supporting information
p. 12460 - 12469
(2020/06/10)
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- BPh3-Catalyzed [2+3] Cycloaddition of Ph3PCCO with Aldonitrones: Access to 5-Isoxazolidinones with Exocyclic Phosphonium Ylide Moieties
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A method for the generation of 5-isoxazolidinones with exocyclic phosphonium ylide functionalities via [2+3] cycloaddition of Ph3PCCO and aldonitrones has been developed and applied in the synthesis of 4-alkylidene-5-isoxazolidinones via Wittig olefination. The reaction proceeds by BPh3 catalysis under mild conditions and with a broad substrate scope. A reaction pathway involving the activation of the aldonitrone via interactions with the Lewis acid BPh3 is proposed.
- Brar, Amandeep,Unruh, Daniel K.,Ling, Natalie,Krempner, Clemens
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p. 6305 - 6309
(2019/08/20)
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- (3 + 3) Cycloaddition of Oxyallyl Cations with Nitrones: Diastereoselective Access to 1,2-Oxazinanes
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Oxyallyl cations are prepared in situ from readily available α-tosyloxy ketones and act as transient electrophilic partners in (3 + 3) cycloaddition with nitrones. Under mild conditions, this method provides a chemoselective and diastereoselective route t
- Cordier, Marie,Archambeau, Alexis
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supporting information
p. 2265 - 2268
(2018/04/30)
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- A highly diastereoselective [3+3] annulation reaction of aza-oxyallyl cations and nitrones
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An efficient synthesis of 1,2,4-oxadiazinan-5-ones via [3+3] cycloaddition of in situ generated aza-oxyallyl cations with nitrones has been developed. The protocol features easy operation, excellent yields, excellent diastereo-control, broad substrate sco
- Chen, Rongxing,Sun, Shaofa,Wang, Gangqiang,Guo, Haibin
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supporting information
p. 1916 - 1920
(2018/04/19)
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- One-Pot Sequential [3 + 3] Dipolar Cycloaddition of Aldehyde or Ketone and Hydroxylamine with Spirocyclopropyl Oxindole
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A Sc(OTf)3-catalyzed highly diastereoselective one-pot sequential [3 + 3] dipolar cycloaddition reaction of aldehyde or ketone, N-alkyl hydroxylamine, and spirocyclopropyl oxindole is developed, allowing facile construction of spirocyclic oxind
- Xu, Peng-Wei,Chen, Chen,Liu, Jia-Kuan,Song, Yu-Ting,Zhou, Feng,Yan, Jun,Zhou, Jian
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p. 12763 - 12774
(2018/10/20)
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- Crystal and molecular structure studies of (Z)-N-methyl-C-4-substituted phenyl nitrones by XRD, DFT, FTIR and NMR methods
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(Z)-N-methyl-C-4-substituted phenyl nitrones –O+N(Me)=C(H)R (Z-2a R = 4-ClC6H4, Z-2b R = 4-NO2C6H4, Z-2c R = 4-CH3OC6H4) were synthesized and cha
- Lasri, Jamal,Eltayeb, Naser Eltaher,Haukka, Matti,Alghamdi, Yousef
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- Cooperative Multifunctional Catalysts for Nitrone Synthesis: Platinum Nanoclusters in Amine-Functionalized Metal–Organic Frameworks
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Nitrones are key intermediates in organic synthesis and the pharmaceutical industry. The heterogeneous synthesis of nitrones with multifunctional catalysts is extremely attractive but rarely explored. Herein, we report ultrasmall platinum nanoclusters (PtNCs) encapsulated in amine-functionalized Zr metal–organic framework (MOF), UiO-66-NH2 (Pt@UiO-66-NH2) as a multifunctional catalyst in the one-pot tandem synthesis of nitrones. By virtue of the cooperative interplay among the selective hydrogenation activity provided by the ultrasmall PtNCs and Lewis acidity/basicity/nanoconfinement endowed by UiO-66-NH2, Pt@UiO-66-NH2 exhibits remarkable activity and selectivity, in comparison to Pt/carbon, Pt@UiO-66, and Pd@UiO-66-NH2. Pt@UiO-66-NH2 also outperforms Pt nanoparticles supported on the external surface of the same MOF (Pt/UiO-66-NH2). To our knowledge, this work demonstrates the first examples of one-pot synthesis of nitrones using recyclable multifunctional heterogeneous catalysts.
- Li, Xinle,Zhang, Biying,Tang, Linlin,Goh, Tian Wei,Qi, Shuyan,Volkov, Alexander,Pei, Yuchen,Qi, Zhiyuan,Tsung, Chia-Kuang,Stanley, Levi,Huang, Wenyu
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supporting information
p. 16371 - 16375
(2017/11/28)
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- Methyltrioxorhenium-catalysed oxidation of secondary amines to nitrones in ionic liquids
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Nitrones serve as starting materials for the synthesis of many heterocycles. Oxidation of secondary amines using hydrogen peroxide and the catalytic amount of methyltrioxorhenium in ionic liquids is a useful method for the preparation of nitrones. Ultrasonic irradiation and ionic liquids have a positive influence on the reaction. The nitrones required were isolated in good yields. Corresponding hydroxylamines, which can be easily oxidised to nitrones, often accompanied the main products. Methyltrioxorhenium in ionic liquids was re-used in several reaction cycles without any deteriorating effect on the course of the reaction.
- Meciarova, Maria,Mojzesova, Melinda,Sebesta, Radovan
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p. 51 - 58,8
(2020/08/20)
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- 1,3-Dipolar cycloaddition of nitrones to a nitrile functionality in closo -decaborate clusters: A novel reactivity mode for the borylated C≡N group
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The Z-configured nitrones -O+N(Me)=C(H)C 6H4R2-p (R2 = OMe (2a), Me (2b), NO2 (2c)) react with the nitrile functionality of the closo-decaborate clusters [Bun4N][B10H 9(NCR1)] (R1 = Me (1a), Et (1b), But (1c), Ph (1d)) in CHCl3 solution under mild conditions (20-25 °C, 16-18 h) to afford the products of cycloaddition: viz., the borylated 2,3-dihydro-1,2,4-oxadiazoles [Bun4N][B10H 9{Na=CR1ON(Me)CbH(C 6H4R2-p)}](a-b) (3a-l). This reaction represents the first example of boron-mediated 1,3-dipolar cycloaddition of allyl anion type dipoles, i.e. nitrones, to the nitrile group. Alteration of the lipophilic [Bun4N]+ counterion with the hydrophilic Na+ via the metathetical reaction with NaBPh4 in 3a,b,e,f allows the modification of their hydrophilic-lipophilic properties and, consequently, solubility. Compounds 3a-j and 5a-d were characterized by high-resolution ESI-MS, IR, and 1H, 13C{1H}, and 11B{1H} NMR spectroscopy. The structures of 3a,e,f were determined by single-crystal X-ray diffraction.
- Mindich, Aleksey L.,Bokach, Nadezhda A.,Dolgushin, Fedor M.,Haukka, Matti,Lisitsyn, Leonid A.,Zhdanov, Andrey P.,Zhizhin, Konstantin Yu.,Miltsov, Serguei A.,Kuznetsov, Nikolay T.,Kukushkin, Vadim Yu.
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p. 1716 - 1724
(2012/04/23)
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- Nitrones as dipoles for rapid strain-promoted 1,3-dipolar cycloadditions with cyclooctynes
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Strain-promoted cycloadditions of nitrones with cyclooctynes (k2 = 1.5 M-1 s-1 at 25 °C) are up to 25 times more rapid than comparable reactions of azides. The Royal Society of Chemistry 2010.
- McKay, Craig S.,Moran, Joseph,Pezacki, John Paul
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body text
p. 931 - 933
(2010/06/12)
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- 1,3-Dipolar cycloadditions. Part XVII: Experimental and theoretical spectroscopic investigations of C-aryl-N-methyl nitrones
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Detailed experimental and theoretical spectroscopic studies of C-aryl-N-methyl nitrones have been reported. The optimized geometries have been calculated by DFT/B3LYP level of theory with 6-31+G(d,p) basis set. The theoretically computed frontier orbital
- Acharjee, Nivedita,Banerji, Avijit,Banerjee, Manas,Das, Tapas K.
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body text
p. 1627 - 1637
(2010/06/17)
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- 1,3-Dipolar cycloadditions. Part-XV: Systematic spectroscopic investigations of C-aryl-N-methylnitrones
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Several C-aryl-N-methylnitrones have been synthesised during the course of our work on 1,3-dipolar cycloadditions. Detailed systematic spectroscopic investigations of all these nitrones have been undertaken. These are reported along with some generalisati
- Banerji, Avijit,Acharjee, Nivedita,Biswas, Pizush Kanti
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scheme or table
p. 63 - 67
(2010/05/02)
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- Exploiting microwave-assisted neat procedures: synthesis of N-aryl and N-alkylnitrones and their cycloaddition en route for isoxazolidines
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Microwave irradiation allows increasing the speed of several reactions and also offers the possibility of eliminating poisoning organic solvents. In this work we report the microwave-assisted neat synthesis of α-phenyl-tert-butylnitrone (PBN) and other alkyl and aryl nitrones and also the rapid synthesis of isoxazolidines resulting from 1,3-dipolar cycloaddition of nitrones to ethyl trans-crotonate.
- Andrade, Marta M.,Barros, Maria Teresa,Pinto, Rui C.
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p. 10521 - 10530
(2008/12/23)
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- Oxidation of secondary amines by molecular oxygen and cyclohexanone monooxygenase
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Cyclohexanone monooxygenase from Acinetobacter calcoaceticus catalyzed the oxidation of tertiary and secondary amines to N-oxides and nitrones, respectively. The formation of a hydroxylamine intermediate was involved with secondary amines as starting substrates.
- Colonna, Stefano,Pironti, Vincenza,Carrea, Giacomo,Pasta, Piero,Zambianchi, Francesca
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p. 569 - 575
(2007/10/03)
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- 1,3-Dipolar cycloadditions: Part VIII1-Microwave irradiation assisted synthesis of N-methyl-C-aryl nitrones
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N-Methyl-C-arylnitrones have been synthesized in very high yields within a few minutes from N-methyl-hydroxylamine hydrochloride and aryl aldehydes in presence of sodium hydrogen carbonate in methylene chloride using the microwave irradiation technique.
- Banerji, Avijit,Biswas, Pizush Kanti,Sengupta, Piyali,Dasgupta, Saugandha,Gupta, Maya
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p. 880 - 881
(2007/10/03)
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- Synthesis of functionalized sulfonamides via 1,3-dipolar cycloaddition of pentafluorophenyl vinylsulfonate
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(Matrix presented) An efficient intermolecular 1,3-dipolar cycloaddition of a variety of nitrones to pentafluorophenyl (PFP) vinylsulfonate is described. The transformation produces stable "reversed" cycloadducts of unprecedented stereo- and regioselectiv
- Caddick, Stephen,Bush, Hannah D.
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p. 2489 - 2492
(2007/10/03)
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- Oxidation of N-benzyl-N-methylhydroxylamines to nitrones. A mechanistic study
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Oxidation of various N-(o-, m-, p- substituted benzyl)- N-methylhydroxylamines has been carried out using mercury(II) oxide and p-benzoquinone (p-BQ) as oxidants. Hammett plots have been obtained with negative ρ values, showing the development of a positive centre in the transition state. The unstable E nitrones, which readily isomerize to the more stable Z nitrones, are obtained in appreciable quantities and in some cases as the major product. A considerable deuterium isotope effect is observed in the oxidation process. The overall picture of the mechanistic pathway involves electron transfer from nitrogen to the oxidant followed by hydrogen abstraction.
- Hassan, Azfar,Wazeer, Mohammed I. M.,Ali, Sk. Asrof
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p. 393 - 399
(2007/10/03)
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- Chromium and Tungsten Pentacarbonyl Groups as Reactivity and Selectivity Auxiliaries in Cycloaddition of Alkynyl Fischer Carbene Complexes with N-Alkyl Nitrones
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Alkynyl Fischer carbene complexes were found to undergo chemoselective, regioselective, and rate-enhanced 1,3-dipolar cycloaddition with nitrones to give 2,3-dihydroisoxazole carbene complexes in excellent yields.These alkynyl complexes can serve as synth
- Chan, Kin Shing,Yeung, Ming Lok,Chan, Wai-kin,Wang, Ru-Ji,Mak, Thomas C. W.
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p. 1741 - 1747
(2007/10/02)
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- Selective Rhodium-Catalyzed Insertion of Carbon Monoxide into the Nitrogen-Oxygen Bond of Isoxazolidines. New Reduction, Migration, and Rearrangement Reactions Catalyzed by Iridium Complexes
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Reaction of isoxazolidines with carbon monoxide in benzene, catalyzed by the dimer of chloro(1,5-cyclooctadiene)rhosium, results in the formation of tetrahydro-1,3-oxazin-2-ones as the major or only product, often in fine yields.A novel conversion of 3-ar
- Khumtaveeporn, Kanjai,Alper, Howard
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p. 8142 - 8147
(2007/10/02)
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- Stereochemistry of 1,3-dipolar cycloadditions of nitrones with (E)-1-alkyl-2-nitroethenes
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1,3-Dipolar cycloadditions of the C-aryl-N-alkylnitrones 2a-c and the C,N-dialkylnitrones 2e-g with the (E)-1-alkyl-2-nitroethenes 1a,b afforded predominantly or exclusively the cis-3-substituted 4-nitroisoxazolidines 3a-d and 3f-h. Exceptions are the rea
- Yakura,Nakazawa,Takino,Ikeda
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p. 2014 - 2018
(2007/10/02)
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- A Novel Nitrone Cycloaddition/ Rearrangement
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Adamantanone-derived nitrone 4 and some other keto-nitrones, when reacted with aromatic and aliphatic aldehydes in refluxing toluene or tetrahydrofuran, formed the corresponding aldonitrones (Z)-10, the latter arising from the fragmentation of an initially formed 1,4,2-dioxazolidine 6 to adamantan-2-one and an oxaziridine intermediate 11, which then rearranges to (Z)-10.
- Toder, Bruce H.,Mullen, George B.,Georgiev, Vassil St.
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p. 169 - 173
(2007/10/02)
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