36298-61-0Relevant academic research and scientific papers
Facile and expedient synthesis of α,β-unsaturated isoxazol-5(4H)-ones under mild conditions
Ghorbani, Fatemeh,Kiyani, Hamzeh,Pourmousavi, Seied Ali
, p. 943 - 959 (2019/11/13)
Abstract: It was found that nano-SiO2–H2SO4 was catalyzed by the three-component cyclocondensation of aryl/heteroaryl aldehydes, hydroxylamine hydrochloride, and β-ketoesters toward the synthesis of α,β-unsaturated?isoxazol-5(4H)-ones under green conditions. The reaction yielded the corresponding heterocycles at room temperature in relatively shorter reaction times. It merits mentioning that the mild conditions allow the synthesis of several α,β-unsaturated?isoxazol-5(4H)-ones using this method. In this study, some new derivatives of isoxazolones were also synthesized and characterized. It is efficient, clean, simple, safe, and ecologically friendly. This straightforward method is cost-effective and requires no preparation of reactants. The three-component annulation was performed without using energy sources, for example, heat, ultrasound wave, and microwave irradiation. Graphic abstract: [Figure not available: see fulltext.].
Enantioselective Synthesis of Functionalized Diazaspirocycles from 4-Benzylideneisoxazol-5(4H)-one Derivatives and Isocyanoacetate Esters
Martínez-Pardo, Pablo,Laviós, Adrián,Sanz-Marco, Amparo,Vila, Carlos,Pedro, José R.,Blay, Gonzalo
supporting information, p. 3564 - 3569 (2020/07/24)
Enantioenriched spirocyclic compounds bearing three contiguous stereocenters and high functionalization were obtained through a formal [3+2] cycloaddition reaction catalyzed by a cooperative system. The spiro compounds were synthesized from 4-arylideneisoxazol-5-ones and isocyanoacetate esters using a bifunctional squaramide/Br?nsted base organocatalyst derived from a Cinchona alkaloid and silver oxide as Lewis acid. This method afforded two out of the four possible diastereomers with good yields and high enantiomeric excess for both diastereomers. (Figure presented.).
Quantum chemical-guided steglich rearrangement of azlactones and isoxazolones
De Castro, Pedro P.,Dos Santos, Juliana A.,De Siqueira, Marcelo M.,Batista, Gabriel M. F.,Dos Santos, Hélio F.,Amarante, Giovanni W.
, p. 12573 - 12582 (2019/10/11)
The theoretical-guided evaluation of the Steglich rearrangement of azlactones and isoxazolones allowed the determination of the reactivity patterns in these heterocycles, including the factors that drive the regioselectivity toward both possible sites. These results allowed the first experimental report on the regioselective Steglich rearrangement of isoxazolones, affording the nitrogen- or carbon-acyloxy adducts.
Synthesis and characterization of nanocrystalline hydroxyapatite and its catalytic behavior towards synthesis of 3,4-disubstituted isoxazole-5(4H)-ones in water
Maleki, Behrooz,Chahkandi, Mohammad,Tayebee, Reza,Kahrobaei, Sepideh,Alinezhad, Heshmatollah,Hemmati, Saba
, (2019/08/02)
In the present work, the nanocrystalline particles of hydroxyapatite (HAp) using an easy alkoxide-based sol–gel technique including triethyl phosphate [PO (OC2H5)3] and Ca (NO3)2·4H2O as P and Ca precursors have been synthesized. The sample characterization was performed by X-ray diffraction, Fourier transform-infrared analysis, scanning electron microscopy, thermal analysis (thermogravimetric analysis/differential thermal analysis), and elemental analysis of energy-dispersive X-ray analysis. It is interesting that single phase of HAp was obtained at a low firing temperature of 500°C. Modified Scherrer equation as the Williamson?Hall method was applied for the measurement of crystallite size distributions and micro-strain of the sample. The determined crystallite size by complementary technique of transmission electron microscopy has good consistency with those obtained from the Scherrer formula. Moreover, we reported the one-pot synthesis of 3,4-disubstituted isoxazole-5(4H)-ones through the aqueous solution reaction of three components of ethyl acetoacetate, hydroxylamine hydrochloride and various aromatic aldehydes at room temperature. This protocol offers several advantages, including a simple work-up procedure, very short reaction times (under 25?min), in accordance with the principles of green chemistry, recyclability, excellent yields (87–98%) and environmentally friendly.
Cooperative Catalysis with Coupled Chiral Induction in 1,3-Dipolar Cycloadditions of Azomethine Ylides
Cayuelas, Alberto,Larra?aga, Olatz,Selva, Verónica,Nájera, Carmen,Akiyama, Takahiko,Sansano, José M.,de Cózar, Abel,Miranda, José I.,Cossío, Fernando P.
supporting information, p. 8092 - 8097 (2018/05/30)
1,3-Dipolar cycloadditions (1,3-DC) between imino esters (as precursors of N-metallated azomethine ylides) and π-deficient alkenes are promoted by cooperative asymmetric Lewis acid/Br?nsted base catalysis. The components of these catalytic pairs are silver salts derived from enantiopure commercially available BINOL-based phosphoric acids and Cinchona alkaloids. Chiral phosphoric silver(I) salts promote HOMO raising of in situ formed 1,3-dipoles, whereas protonated cinchona alkaloids generate a LUMO lowering for the dipolarophiles resulting in a global acceleration of the 1,3-DC. The best results were obtained with BINOL-derived silver phosphate and hydrocinchonine. Matching between both cooperative metallo- and organocatalyst results in an enhanced enantiomeric excess, superior to that reached by both separate components. NOESY experiments and DFT calculations are compatible with a non-covalent interaction (hydrogen bond) between both catalysts, which results in close contacts and mutually coupled chiral environments.
An Aminocatalyzed Stereoselective Strategy for the Formal α-Propargylation of Ketones
Jurberg, Igor D.
, p. 9716 - 9720 (2017/07/25)
A two-step reaction sequence is described for the asymmetric formal α-propargylation of ketones. This approach takes advantage of an aminocatalyzed conjugate addition of ketones to alkylidene isoxazol-5-ones, followed by a controlled nitrosative degradation event. The target compounds can be accessed in broad scope, in moderate to good yields, perfect diastereocontrol and good to excellent enantioselectivity.
One-pot green synthesis of isoxazol-5(4H)-one derivatives using Dowex1-x8OH in water
Setamdideh, Davood
, p. 971 - 978 (2016/11/09)
4-(Arylmethylidene)-3-methylisoxazol-5(4H)-ones and 4-(arylmethylidene)-3-phenylisoxazol-5(4H)-ones were synthesized in a one-pot three-component procedure in the presence of Dowex1-x8OH as catalyst in water. The products were obtained in high yields (90-
Michael Addition of Soft Carbon Nucleophiles to Alkylidene Isoxazol-5-ones: A Divergent Entry to β-Branched Carbonyl Compounds
Capreti, Naylil M. R.,Jurberg, Igor D.
supporting information, p. 2490 - 2493 (2015/05/27)
A novel, divergent strategy toward the synthesis of β-branched (and linear) carbonyl compounds is developed by taking advantage of alkylidene isoxazol-5-ones as key building blocks. The yields obtained range from good to excellent, therefore making the described methods attractive options for building such molecules. (Chemical Equation).
Regioselective catalytic asymmetric C-alkylation of isoxazolinones by a base-free palladacycle-catalyzed direct 1,4-addition
Hellmuth, Tina,Frey, Wolfgang,Peters, Ren
supporting information, p. 2788 - 2791 (2015/03/04)
Isoxazolinones constitute a class of heterocycles utilized for the development of novel drug candidates. The cyclic oxime ester motif is also synthetically useful as it contains functional handles which have previously been used to provide access to an assortment of valuable compound classes not easily accessible by alternative approaches. However, asymmetric methods towards isoxazolinones are notoriously scarce. Herein we report the first catalytic asymmetric alkylations of isoxazolinones forming all-C-substituted quaternary stereocenters. The present studies were driven by the question of how to control the regioselectivity in the competition of different nucleophilic positions. The investigation of a direct 1,4-addition uncovered that a sterically demanding palladacycle catalyst directs the reactivity in the absence of a base nearly exclusively to the nucleophilic C atom, while at the same time it allows for high enantioselectivity and TONs up to 1900.
New pathway to pyrrolidinones and pyrrolizidinones using aryl aldehydes, 3-phenyl-5-isoxazolone and secondary amino acids
Lakshmi, Neelakandan Vidhya,Perumal, Paramasivan T.
, p. 1817 - 1820 (2013/04/23)
A novel and efficient approach to pyrrolidinones and pyrrolizidinones via a one-pot multicomponent reaction of aryl aldehydes, 3-phenyl-5-isoxazolone, sarcosine and l-proline, respectively in methanol under reflux condition is reported.
