Comparison of Cinchona Catalysts Containing Ethyl or Vinyl or Ethynyl Group at Their Quinuclidine Ring

Nagy, Sándor; Fehér, Zsuzsanna; Dargó, Gergő; Barabás, Júlia; Garádi, Zsófia; Mátravölgyi, Béla; Kisszékelyi, Péter; Huszthy, Péter; Höltzl, Tibor; Balogh, György Tibor; Kupai, József

doi:10.3390/ma12183034

Cited by 6 publications

(19 citation statements)

References 67 publications

(78 reference statements)

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“…Cinchona squaramide modified with a rigid aromatic linker at the quinuclidine ring ( 1 ) was prepared in an azide–alkyne cycloaddition reaction of 1‐aminomethyl‐4‐azidomethylbenzene ( 5 ) and cinchona squaramide derivative containing an ethynyl group on the quinuclidine moiety ( 4 , see Scheme ) …”

Section: Resultsmentioning

confidence: 99%

“…[a] Rounds Solvent [a] Yield [%] [b] ee [%] [c] 1EtOAc97 which is described in the literature (99 %y ield, 85 % ee)i nt he Michael reactionb etween trans-b-nitrostyrene (13)a nd pentane-2,4-dione (14). [18] Therefore, it can be stated that the presence of non-modified PGMA had no effect on the catalytic activity of cinchona catalysts in the studied asymmetric Michael reactions.…”

Section: Roundsmentioning

confidence: 91%

“…Cinchona squaramide modifiedw ith ar igid aromatic linker at the quinuclidine ring (1)w as prepared in an azide-alkyne cycloaddition reactiono f1 -aminomethyl-4-azidomethylbenzene ( 5) [20] and cinchona squaramide derivativec ontaining an ethynyl group on the quinuclidine moiety (4,s ee Scheme 2). [18] In the case of precatalyst 2,am ore flexible and shorter linker,n amely a2 -aminoethyl group, was incorporated into the cinchonas keleton at the quinoline unit. Demethylated cinchona squaramide (6) [4c] was reactedw ith O-toluenesulfonyl-N-Boc-ethanolamine( 7).…”

Section: Catalyst Synthesismentioning

confidence: 99%

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Synthesis and Applications of Cinchona Squaramide‐Modified Poly(Glycidyl Methacrylate) Microspheres as Recyclable Polymer‐Grafted Enantioselective Organocatalysts

Nagy

Fehér

Kárpáti

et al. 2020

Chemistry A European J

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This work presentst he immobilization of cinchona squaramide organocatalysts on poly(glycidyl methacrylate) solid supports. Preparation of the well-definedm onodisperse polymer microspheres was facilitated by comprehensive parameter optimization.B ye xploiting the reactive epoxy groups of the polymer support,t hree amino-functionalized cinchonad erivatives were immobilized on this carrier. To explore the effect of the amino linker,t heses tructurally variedp recatalysts were synthesized by modifying the cinchonas keleton at different positions. The catalytic activities of the immobilized organocatalysts were tested in the Michaela dditiono fp entane-2,4-dione and trans-b-nitrostyrene with excellent yields(up to 98 %) and enantioselectivities (up to 96 % ee). Finally,t he catalysts were easily recovered five times by centrifugationwithout loss of activity.

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Section: Resultsmentioning

confidence: 99%

Section: Roundsmentioning

confidence: 91%

Section: Catalyst Synthesismentioning

confidence: 99%

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Synthesis and Applications of Cinchona Squaramide‐Modified Poly(Glycidyl Methacrylate) Microspheres as Recyclable Polymer‐Grafted Enantioselective Organocatalysts

Nagy

Fehér

Kárpáti

et al. 2020

Chemistry A European J

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“…The C9 hydroxyl group of the commercially available starting materials (Q, HQ, C) was converted to an amino group as reported earlier [31]. In the next step, half squaramide derivatives quininehalf squaramide (Q-HSQ), hydroquinine-half squaramide (HQ-HSQ) and cinchonine-half squaramide (C-HSQ) were obtained by the addition of these amines to dimethyl squarate (DMSQ) [32,33]. Finally, the addition of 1-aza-15-crown-5 or 1-aza-18-crown-6 ethers to the previously mentioned half squaramides afforded the corresponding cinchona-crown ether-squaramide derivatives (Q5, Q6, C5, C6, HQ5).…”

Section: Synthesis Of Crown Ether-squaramide Phase-transfer Catalystsmentioning

confidence: 99%

Synthesis of Novel Crown Ether-Squaramides and Their Application as Phase-Transfer Catalysts

et al. 2021

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This work presents the synthesis of six new phase-transfer organocatalysts in which the squaramide unit is directly linked to the nitrogen atom of an aza-crown ether. Four chiral skeletons, namely hydroquinine, quinine, cinchonine (cinchonas), and α-d-glucopyranoside were responsible for the asymmetric construction of an all-carbon quaternary stereogenic center in α-alkylation and Michael addition reactions of malonic esters. We investigated the effects of these different chiral units and that of crown ethers with different sizes on catalytic activity and enantioselectivity. During extensive parameter investigations, both conventional and emerging green solvents were screened, providing valuable α,α-disubstituted malonic ester derivatives with excellent yields (up to 98%).

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“…The numbers shown are the pK a of the acid (red) and that of the conjugate acid of the basic functional groups (blue) for the quinuclidine-and quinoline-type heterocycles, as calculated by MarvinSketch software (Version 20.14.0; ChemAxon, 2020). Experimental pK a values are 3.49 for aspirin at 25 C (O'Neil, 2006) and 8.52 for the quinuclidine-type heterocycle of quinine in water at 25 C (Nagy et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Mechanochemical synthesis insights and solid-state characterization of quininium aspirinate, a glass-forming drug–drug salt

Harris¹,

Benedict²,

Dickie³

et al. 2021

Acta Crystallogr C

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Quinine (an antimalarial) and aspirin (a nonsteroidal anti-inflammatory drug) were combined into a new drug–drug salt, quininium aspirinate, C20H25N2O2 +·C9H7O4 −, by liquid-assisted grinding using stoichiometric amounts of the reactants in a 1:1 molar ratio, and water, EtOH, toluene, or heptane as additives. A tetrahydrofuran (THF) solution of the mechanochemical product prepared using EtOH as additive led to a single crystal of the same material obtained by mechanochemistry, which was used for crystal structure determination at 100 K. Powder X-ray diffraction ruled out crystallographic phase transitions in the 100–295 K interval. Neat mechanical treatment (in a mortar and pestle, or in a ball mill at 20 or 30 Hz milling frequencies) gave rise to an amorphous phase, as shown by powder X-ray diffraction; however, FT–IR spectroscopy unambiguously indicates that a mechanochemical reaction has occurred. Neat milling the reactants at 10 and 15 Hz led to incomplete reactions. Thermogravimetry and differential scanning calorimetry indicate that the amorphous and crystalline mechanochemical products form glasses/supercooled liquids before melting, and do not recrystallize upon cooling. However, the amorphous material obtained by neat grinding crystallizes upon storage into the salt reported. The mechanochemical synthesis, crystal structure analysis, Hirshfeld surfaces, powder X-ray diffraction, thermogravimetry, differential scanning calorimetry, FT–IR spectroscopy, and aqueous solubility of quininium aspirinate are herein reported.

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Comparison of Cinchona Catalysts Containing Ethyl or Vinyl or Ethynyl Group at Their Quinuclidine Ring

Cited by 6 publications

References 67 publications

Synthesis and Applications of Cinchona Squaramide‐Modified Poly(Glycidyl Methacrylate) Microspheres as Recyclable Polymer‐Grafted Enantioselective Organocatalysts

Synthesis and Applications of Cinchona Squaramide‐Modified Poly(Glycidyl Methacrylate) Microspheres as Recyclable Polymer‐Grafted Enantioselective Organocatalysts

Synthesis of Novel Crown Ether-Squaramides and Their Application as Phase-Transfer Catalysts

Mechanochemical synthesis insights and solid-state characterization of quininium aspirinate, a glass-forming drug–drug salt

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