scholarly journals Synthesis of trifluoromethylated isoxazoles and their elaboration through inter- and intra-molecular C–H arylation

2016 ◽  
Vol 14 (25) ◽  
pp. 5983-5991 ◽  
Author(s):  
Jian-Siang Poh ◽  
Cristina García-Ruiz ◽  
Andrea Zúñiga ◽  
Francesca Meroni ◽  
David C. Blakemore ◽  
...  
Keyword(s):  
Cycloaddition Reaction ◽  
Building Blocks ◽  
Nitrile Oxide

We report conditions for the preparation of a range of trifluoromethylated isoxazole building blocks through the cycloaddition reaction of trifluoromethyl nitrile oxide and their subsequent derivatisation.

scholarly journals Highly Efficient MOF Catalyst Systems for CO2 Conversion to Bis-Cyclic Carbonates as Building Blocks for NIPHUs (Non-Isocyanate Polyhydroxyurethanes) Synthesis

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 628
Author(s):  
Adolfo Benedito ◽  
Eider Acarreta ◽  
Enrique Giménez
Keyword(s):  
Molar Mass ◽  
Cycloaddition Reaction ◽  
Building Blocks ◽  
Catalyst System ◽  
Cyclic Carbonate ◽  
Ammonium Bromide ◽  
Cyclic Carbonates ◽  
High Molar Mass ◽  
Highly Efficient ◽  
Free Process

The present paper describes a greener sustainable route toward the synthesis of NIPHUs. We report a highly efficient solvent-free process to produce [4,4′-bi(1,3-dioxolane)]-2,2′-dione (BDC), involving CO2, as renewable feedstock, and bis-epoxide (1,3-butadiendiepoxide) using only metal–organic frameworks (MOFs) as catalysts and cetyltrimethyl-ammonium bromide (CTAB) as a co-catalyst. This synthetic procedure is evaluated in the context of reducing global emissions of waste CO2 and converting CO2 into useful chemical feedstocks. The reaction was carried out in a pressurized reactor at pressures of 30 bars and controlled temperatures of around 120–130 °C. This study examines how reaction parameters such as catalyst used, temperature, or reaction time can influence the molar mass, yield, or reactivity of BDC. High BDC reactivity is essential for producing high molar mass linear non-isocyanate polyhydroxyurethane (NIPHU) via melt-phase polyaddition with aliphatic diamines. The optimized Al-OH-fumarate catalyst system described in this paper exhibited a 78% GC-MS conversion for the desired cyclic carbonates, in the absence of a solvent and a 50 wt % chemically fixed CO2. The cycloaddition reaction could also be carried out in the absence of CTAB, although lower cyclic carbonate yields were observed.

scholarly journals Furoic Acid and Derivatives as Atypical Dienes in Diels-Alder Reactions

2021 ◽  
Author(s):  
Razvan Cioc ◽  
Tom Smak ◽  
Marc Crockatt ◽  
Jan Kees Van der Waal ◽  
Pieter C A Bruijnincx
Keyword(s):  
Green Chemistry ◽  
Cycloaddition Reaction ◽  
Building Blocks ◽  
Diels Alder ◽  
Furoic Acid

The furan Diels-Alder (DA) cycloaddition reaction has become an important tool in green chemistry, being central to the sustainable synthesis of many chemical building blocks. The restriction to electron-rich furans...

ChemInform Abstract: Novel Trinitrogen-Containing Triheterocycles via the Intramolecular Nitrile Oxide Cycloaddition Reaction.

ChemInform ◽  
2012 ◽  
Vol 43 (9) ◽  
pp. no-no
Author(s):  
Andrew J. Ferreira ◽  
Danielle M. Solano ◽  
James S. Oakdale ◽  
Mark J. Kurth
Keyword(s):  
Cycloaddition Reaction ◽  
Nitrile Oxide

Pyrido[1,2-a]pyrazine - Startprodukte für regioselektive Ringtransformationen und supramolekulare Architekturen / Pyrido[1,2-a]pyrazines - Starting Materials for Regioselective Ringtransformation Reactions and Supramolecular Architectures

2002 ◽  
Vol 57 (4) ◽  
pp. 471-478 ◽  
Author(s):  
D. Müller ◽  
B. Frank ◽  
R. Beckert ◽  
H. Görls
Keyword(s):  
Cycloaddition Reaction ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Building Blocks ◽  
Ring Transformation ◽  
Supramolecular Architectures ◽  
Cross Coupling Reaction ◽  
Metal Catalyzed

The easily available pyrido[1,2-a]pyrazines of type 1 are versatile building blocks for ring transformation reactions.W ith heterocyclic quinones such as quinoline-2,5,8-triones 4a-c, a highly regioselective [4+2]-cycloaddition reaction takes place in the first step, followed by a ring transformation cascade.T he 1,6-diazaanthracene-2,9,10-triones 5a-e, which possess an additional bipyridine substructure, could be isolated as main products.In order to modify the starting products of type 1, a metal-catalyzed cross-coupling reaction with acetylenic benzoic esters 9a,b has been performed.T he modified pyridopyrazines 10a,b which were obtained in good yields could be transformed by analogy to 1a,b into ring-fused heterocyclic quinones 12a,b.

A Novel Synthesis of Benzopyranyl Isoxazolines: Cycloaddition Reaction of Chromone Nitrile Oxide

Heterocycles ◽  
1988 ◽  
Vol 27 (5) ◽  
pp. 1127 ◽  
Author(s):  
Jagir Singh Sandhu ◽  
Arpan K. Baruah ◽  
Dipan Prajapati ◽  
Jagir S. Sandhu
Keyword(s):  
Cycloaddition Reaction ◽  
Nitrile Oxide ◽  
Novel Synthesis

scholarly journals Design, Characterization and Molecular Modeling of New Fluorinated Paramagnetic Contrast Agents for Dual 1H/19F MRI

2020 ◽  
Vol 6 (1) ◽  
pp. 8 ◽  
Author(s):  
Emilie Hequet ◽  
Céline Henoumont ◽  
Vera Djouana Kenfack ◽  
Vincent Lemaur ◽  
Roberto Lazzaroni ◽  
...  
Keyword(s):  
Contrast Agents ◽  
3D Structure ◽  
Relaxation Times ◽  
Cycloaddition Reaction ◽  
Building Blocks ◽  
Lanthanide Ion ◽  
19F Mri ◽  
Fluorine Magnetic Resonance Imaging ◽  
Magnetic Resonance Imaging Mri ◽  
Dynamics Simulations

One major goal in medical imaging is the elaboration of more efficient contrast agents (CAs). Those agents need to be optimized for the detection of affected tissues such as cancers or tumors while decreasing the injected quantity of agents. The paramagnetic contrast agents containing fluorine atoms can be used for both proton and fluorine magnetic resonance imaging (MRI), and they open the possibility of simultaneously mapping the anatomy using 1H MRI and accurately locating the agents using 19F MRI. One of the challenges in this domain is to synthesize molecules containing several chemically equivalent fluorine atoms with relatively short relaxation times to allow the recording of 19F MR images in good conditions. With that aim, we propose to prepare a CA containing a paramagnetic center and nine chemically equivalent fluorine atoms using a cycloaddition reaction between two building blocks. These fluorinated contrast agents are characterized by 19F NMR, showing differences in the fluorine relaxation times T1 and T2 depending on the lanthanide ion. To complement the experimental results, molecular dynamics simulations are performed to shed light on the 3D-structure of the molecules in order to estimate the distance between the lanthanide ion and the fluorine atoms.

New Strategy of Synthesis of Peramivir Analogues as Potential Neuraminidase Inhibitors

Synthesis ◽  
2019 ◽  
Vol 52 (06) ◽  
pp. 933-941
Author(s):  
Roberta Bartolotta ◽  
Concetta La Rosa ◽  
Donatella Nava
Keyword(s):  
Cycloaddition Reaction ◽  
Nitrile Oxide ◽  
Hydroxyl Group ◽  
Dipolar Cycloaddition ◽  
Carbon Nucleus ◽  
Neuraminidase Inhibitors ◽  
Subsequent Reaction ◽  
New Strategy

Highly functionalised potential neuraminidase (NA) inhibitors, analogues of peramivir, were synthesised via a new and versatile method starting from a stereoselective 1,3-dipolar cycloaddition reaction between the nitrile oxide derived from 2-ethylbutanal and the commercially available and inexpensive cyclopentadiene and 1,3-cyclohexadiene, which afforded the isoxazolino-cyclopentene or cyclohexene intermediates, respectively. The subsequent reaction of the C=C bond in different conditions allowed the functionalisation of the five (or six) membered carbon nucleus. Further functionalised derivatives displaying an amino and a hydroxyl group were achieved via the final opening of the isoxazoline ring.

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