2486-07-9Relevant articles and documents
An efficient strategy for the synthesis of aryl ethers
Wang, Tongen,Love, Jennifer A.
, p. 2237 - 2239 (2007)
An efficient strategy for the construction of aryl ethers using aryl fluorides and silyl ethers is described. This protocol uses a sub-stoichiometric amount of silicon-based reagent and proceeds under milder conditions than previously reported reactions of this type. Georg Thieme Verlag Stuttgart.
Choline Hydroxide as a Versatile Medium for Catalyst-Free O-Functionalization of Phenols
Joo, Seong-Ryu,Kim, Seung-Hoi,Kwon, Gyu-Tae,Park, Soo-Youl
, p. 1200 - 1205 (2020/11/30)
A versatile synthetic protocol for benzyl phenyl ether preparation via O-alkylation of phenolic oxygen with readily available benzyl derivatives was demonstrated. The newly designed procedure was carried out using an eco-friendly medium, room-temperature ionic liquid (choline hydroxide), under metal- and base-catalyst-free aerobic conditions. The reaction platform was also successfully applied to phenol protection strategy.
CoII Immobilized on Aminated Magnetic-Based Metal–Organic Framework: An Efficient Heterogeneous Nanostructured Catalyst for the C–O Cross-Coupling Reaction in Solvent-Free Conditions
Mohammadinezhad, Arezou,Akhlaghinia, Batool
, p. 332 - 352 (2020/01/11)
Abstract: In this paper, we report the synthesis of Fe3O4?AMCA-MIL53(Al)-NH2-CoII NPs based on the metal–organic framework structures as a magnetically separable and environmentally friendly heterogeneous nanocatalyst. The prepared nanostructured catalyst efficiently promotes the C–O cross-coupling reaction in solvent-free conditions without the need for using toxic solvents and/or expensive palladium catalyst. Graphic Abstract: [Figure not available: see fulltext.].
A 2, 4 - dinitro-phenyl ether compounds and the use thereof
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Paragraph 0027-0029, (2018/07/30)
The invention discloses a 2, 4 - dinitro-phenyl ether compounds and the use thereof. This invention said 2, 4 - dinitro-phenyl ether compound, its structure (I) shown in the diimmonium; wherein R is alkyl, cycloalkyl, substituted cycloalkyl, heterocyclyl, substituted heterocyclyl, aryl, substituted aryl, heteroaryl, substituted aryl or substituted heteroaryl in any kind of. The invention is shown 2, 4 - dinitro-phenyl ether compound to the thioredoxin reductase activity has an inhibitory effect, and then can kill tumor cells;
Kinetic study on SNAr reactions of 1-(Y-substituted-phenoxy)-2,4-dinitrobenzenes with Azide ion: Effect of changing nucleophile from hydroxide to Azide ion on reaction mechanism and reactivity
Seo, Hyeon-Ok,Kim, Min-Young,Han, So-Yeop,Um, Ik-Hwan
, p. 1764 - 1768 (2015/07/15)
Second-order rate constants (kN3-) for SNAr reactions of 1-(Y-substituted-phenoxy)-2,4-dinitrobenzenes (2a-2h) with (Formula presented.) in 80 mol % H2O/20 mol % DMSO at 25.0 ± 0.1 °C have been measured spectrophotometrically. The Bronsted-type plot is linear with β1g=-0.38. The Hammett plots correlated with (Formula presented.) constants exhibit highly scattered points. In contrast, the Yukawa-Tsuno plot results in an excellent linear correlation with ρY = 1.02 and r = 0.51, indicating that a negative charge develops partially on the O atom of the leaving Y-substituted-phenoxy moiety in the transition state. Accordingly, the reactions have been concluded to proceed through a stepwise mechanism, in which expulsion of the leaving group occurs in the rate-determining step. Comparison of kN3- with the kOH- values reported previously for the corresponding reactions with OH has revealed that (Formula presented.) is only 6- to 26-fold than OH toward substrates 2a-2h, although the former is over 11 pKa units less basic than the latter. Solvation and polarizability effects have been suggested to be responsible for the unusual reactivity shown by (Formula presented.) and OH. Effects of changing nucleophile from OH to (Formula presented) on reaction mechanism and reactivity are discussed in detail.
The α-effect in the SNAr reaction of 1-(4-nitrophenoxy)-2,4-dinitrobenzene with anionic nucleophiles: Effects of solvation and polarizability on the α-effect
Um, Ik-Hwan,Kim, Min-Young,Cho, Hyo-Jin,Dust, Julian M.,Buncel, Erwin
, p. 1109 - 1114 (2015/10/06)
A kinetic study on SNAr reactions of 1-(4-nitrophenoxy)-2,4-dinitrobenzene (1a) with various anionic nucleophiles in 80 mol% water-20 mol% DMSO at 25.0 °C is reported. The Bronsted-type plot for the reaction of 1a with a series of substituted phenoxides and HOO- results in an excellent linear correlation with βnuc = 1.17. However, OH- exhibits dramatic negative deviation from the Bronsted-type plot, while N3-, C6H5S-, and butane-2,3-dione monoximate (Ox-) deviate positively from linearity. HOO- is 680-fold more reactive than OH- but does not exhibit the α-effect. In contrast, Ox- is 166-fold more reactive than isobasic 4-Cl-C6H4O- and exhibits the α-effect. Differential solvation effects have been suggested to be responsible for the α-effect in this study, i.e., Ox- exhibits the α-effect, since it is 5.7 kcal/mol less strongly solvated than 4-Cl-C6H4O- in the reaction medium, while HOO- does not show the α-effect due to a strong requirement for partial desolvation before nucleophilic attack. The highly enhanced reactivity of polarizable N3- and C6H5S- and extremely decreased reactivity of nonpolarizable OH- are in accord with the hard-soft acid and base principle.
The α-effect in SNar reaction of y-substituted-phenoxy-2, 4-dinitrobenzenes with amines: Reaction mechanism and origin of the α-effect
Cho, Hyo-Jin,Kim, Min-Young,Um, Ik-Hwan
, p. 2448 - 2452 (2014/09/17)
Second-order rate constants (kN) have been measured spectrophotometrically for SNAr reactions of Ysubstituted-phenoxy-2, 4-dinitrobenzenes (1a-1g) with hydrazine and glycylglycine in 80 mol % H 2O/20 mol % DMSO at 25.0 ± 0.1 °C. Hydrazine is 14.6-23.4 times more reactive than glycylglycine. The magnitude of the α-effect increases linearly as the substituent Y becomes a stronger electron-withdrawing group (EWG). The Bronsted-type plots for the reactions with hydrazine and glycylglycine are linear with βlg = -0.21 and -0.14, respectively, which is typical for reactions reported previously to proceed through a stepwise mechanism with expulsion of the leaving group occurring after rate-determining step (RDS). The Hammett plots correlated with so constants result in much better linear correlations than s- constants, indicating that expulsion of the leaving group is not advanced in the transition state (TS). The reaction of 1a-1g with hydrazine has been proposed to proceed through a five-membered cyclic intermediate (TIII), which is structurally not possible for the reaction with glycylglycine. Stabilization of the intermediate TIII through intramolecular H-bonding interaction has been suggested as an origin of the α-effect exhibited by hydrazine.
Kinetic study on SNAr reaction of 1-Y-substituted-phenoxy-2,4- dinitrobenzenes with hydroxide ION: Effect of substituent y on reactivity and reaction mechanism
Kang, Tae-Ah,Cho, Hyo-Jin,Um, Ik-Hwan
, p. 2135 - 2138 (2014/11/08)
A kinetic study is reported for the SNAr reaction of 1-Y-substituted- phenoxy-2,4-dinitrobenzenes (1a-1h) with OH- in 80 mol % H2O/20 mol % DMSO at 25.0 ± 0.1 °C. The second-order rate constant (kOH-) increases as the substituent Y in the leaving group changes from an electron-donating group (EDG) to an electronwithdrawing group (EWG). The Bronsted-type plot for the reactions of 1a-1h is linear with βlg = -0.16, indicating that the reactivity of substrates 1a-1h is little affected by the leaving-group basicity. A linear Bronsted-type plot with βlg = -0.3 ± 0.1 is typical for reactions reported previously to proceed through a stepwise mechanism in which formation of a Meisenheimer complex is the rate-determining step (RDS). The Hammett plot correlated with σY o constants results in a much better correlation than that correlated with σY - constants, implyng that no negative charge is developing on the O atom of the leaving group (or expulsion of the leaving group is not advanced at all in the TS). This excludes a possibility that the SNAr reaction of 1a-1h with OH- proceeds through a concerted mechanism or via a stepwise pathway with expulsion of the leaving group being the RDS. Thus, the current reactions have been concluded to proceed through a stepwise mechanism in which expulsion of the leaving group occurs rapidly after the RDS.
Kinetic study on SNAr reaction of 1-(Y-Substituted-phenoxy)-2,4- dinitrobenzenes with cyclic secondary amines in acetonitrile: Evidence for cyclic transition-state structure
Um, Ik-Hwan,Kim, Min-Young,Kang, Tae-Ah,Dust, Julian M.
, p. 7025 - 7031 (2014/08/18)
A kinetic study is reported for SNAr reactions of 1-(Y-substituted-phenoxy)-2,4-dinitrobenzenes (1a-1h) with amines in MeCN. The plots of pseudo-first-order rate constant versus amine concentration curve upward, indicating that the reactions are catalyzed by a second amine molecule. The Br?nsted-type plots for the reaction of 1-(4-nitrophenyl)-2,4- dinitrobenzene (1a) with secondary amines are linear with βnuc = 1.10 and 0.85 for the uncatalyzed and catalyzed reactions, respectively, while the Yukawa-Tsuno plots for the reactions of 1a-1h with piperidine result in excellent linear correlations with ρY = 1.85 and r = 0.27 for the uncatalyzed reaction and ρY = 0.73 and r = 0.23 for the catalyzed reaction. The catalytic effect decreases with increasing amine basicity or electron-withdrawing ability of the substituent Y in the leaving group. Activation parameters calculated from the rate constants measured at five different temperatures for the catalyzed reaction of 1a with piperidine are ΔH? = 0.38 kcal/mol and ΔS? = -55.4 cal/(mol K). The catalyzed reaction from a Meisenheimer complex (MC ±) is proposed to proceed through a concerted mechanism with a cyclic transition-state rather than via a stepwise pathway with an anionic intermediate, MC-. Deuterium kinetic isotope effects provide further insight into the nature of the concerted transition state.
Alkali-Metal Ion Catalysis and Inhibition in SNAr Displacement: Relative Stabilization of Ground State and Transition State Determines Catalysis and Inhibition in SNAr Reactivity
Um, Ik-Hwan,Cho, Hyo-Jin,Kim, Min-Young,Buncel, Erwin
, p. 13337 - 13344 (2016/02/19)
We report here the first observation of alkali-metal ion catalysis and inhibition in SNAr reactions. The plot of kobsd versus [alkali-metal ethoxide] exhibits downward curvature for the reactions of 1-(4-nitrophenoxy)-2,4-dinitrobenzene with EtOLi, EtONa, and EtOK, but upward curvature for the corresponding reaction with EtOK in the presence of 18-crown-6-ether (18C6). Dissection of kobsd into the second-order rate constants for the reactions with the dissociated EtO- and the ion-paired EtOM (i.e., k EtO - and kEtOM, respectively) has revealed that the reactivity increases in the order EtOLi-+, Na+, and K+ ions but is catalyzed by 18C6 K+ ion. The reactions of 1-(Y-substituted-phenoxy)-2,4-dinitrobenzenes have been proposed to proceed through a stepwise mechanism, in which expulsion of the leaving group occurs after the rate-determining step based on the kinetic result that σo constants exhibit a much better Hammett correlation than σ- constants. Alkali-metal ion catalysis or inhibition has been discussed in terms of differential stabilization of ground-state and transition-state complexes through a qualitative energy profile. A π-complexed transition-state structure is proposed to account for the kinetic results.
