Supernucleophiles—I

Klopman, Gilles; Tsuda, Kazuhiko; Louis, Jeffry; Davis, Robert Earl

doi:10.1016/s0040-4020(01)93101-1

Cited by 72 publications

(25 citation statements)

References 10 publications

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“…[1,2] The origin of the a-effect has been a matter of debate for many years. There are several proposed explanations for the origin of a-effect, including 1) groundstate destabilization of the nucleophile due to the lone-pair repulsion, [3][4][5] 2) transition-state (TS) stabilization due to the favorable interaction between the a-atom and the positively charged reaction center, [6][7][8] and 3) solvent effect differences between a normal nucleophile and the corresponding a-nucleophile, [9][10][11] for example, HO À is more solvated than HOO À in the case of aqueous reactions. However, the factor that controls the size of the a-effect is not yet fully understood.…”

Section: Introductionmentioning

confidence: 99%

G2(+) Investigation on the α‐Effect in the S_N2 Reactions at Saturated Carbon

Ren

Yamataka

2006

Chemistry A European J

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As a continuing theoretical study on the alpha-effect in the S(N)2 reactions at saturated carbon centers, 28 gas-phase reactions have been examined computationally by using the high-level G2(+) method. The reactions include: Nu(-)+CH(3)X-->CH(3)Nu+X(-) (X=F and Cl; Nu(-)=HO(-), HS(-), CH(3)O(-), Cl(-), Br(-), HOO(-), HSO(-), FO(-), ClO(-), BrO(-), NH(2)O(-), and HC(==O)OO(-)). It was found that all alpha-nucleophiles examined exhibit downward deviations from the correlation line between the overall barriers and proton affinities for normal nucleophiles, indicating the existence of the alpha-effect in the gas phase. The transition states (TS) for the alpha-nucleophiles are characterized by less advanced C--X bond cleavages than the normal nucleophiles, leading to smaller deformation energies and overall barriers. The size of the alpha-effect is related to the electron density on the alpha-atom, and increases when the position of alpha-atom is changed from left to right and from bottom to top in the periodic table. The reaction with CH(3)F exhibits a larger alpha-effect than that with CH(3)Cl, which can be explained by a later TS and a more positively charged methyl group at the TS for CH(3)F, [NuCH(3)F](- not equal). Thus, a higher electron density on the alpha-atom and a more positive methyl moiety at the TS result in a larger alpha-effect.

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Section: Introductionmentioning

confidence: 99%

G2(+) Investigation on the α‐Effect in the S_N2 Reactions at Saturated Carbon

Ren

Yamataka

2006

Chemistry A European J

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“…Although compound 2 has two reactive groups which may react with Kryptofix 22 (the -COCl and the -Cl substituent, both activated by the presence of the two nitro groups on the aromatic ring) the acid chloride group is far more reactive and allows the chemoselective synthesis of compounds 3 and 4. These compounds were not isolated but the reaction mixture was directly treated with the supernucleophile methoxyamine 24 affording the final compounds 5 and 6 (Scheme 1). The structures of the new compounds 5 and 6 were confirmed by spectroscopic methods.…”

Section: Resultsmentioning

confidence: 99%

New mono- and di-branched derivatives of Kryptofix K22 with N-(4-methoxyamino-3,5-dinitrobenzoyl) substituents. Synthesis and properties

Tudose¹,

Cãproiu²,

Badea³

et al. 2011

Arkivoc

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Starting from the Kryptofix 22 azacrown compound, mono-and di-branched derivatives have been synthesized, by coupling with one or two 4-chloro-3,5-dinitrobenzoyl chloride units and then substituting the chlorine(s) on the aromatic ring(s) with methoxyamine. The two new compounds were characterized by IR, NMR, and UV-Vis spectra; they are soluble in organic solvents, yielding a yellow color, which is changing to blue in the presence of a base (such as alkali metal hydroxides), thus acting as colorimetric chemosensors. The ratios of complexation and extraction constants with alkali metal cations were measured.

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“…3) and following an S N mechanism, compounds 2-10 have been synthesized by the following procedures: (i) compounds 2 and 10 have been obtained through an S N Ar process in a single step (using H 2 N-O-R as nucleophilic reactants, where R is methyl or trityl; these reagents are known as super-nucleophiles [34][35][36]); (ii) compounds 3 and 9 have been obtained via a S N 2 process, as well in a single step; (iii) compound 5 has been obtained by a combination of S N 2 and S N Ar processes, in three steps, or using a similar procedure, starting from 2 and isopropyl alcohol, under acidic catalysis, and (iv) compound 4 has been obtained starting from 2 via condensation with the corresponding crown ether-amine, in the presence of dicyclohexyl-carbodiimide (DCC), Fig. 3.…”

Section: Synthesismentioning

confidence: 99%

N-Alkoxy-3,5-dinitro-4-aminobenzoic acid derivatives with controlled physico-chemical properties

Tudose¹,

Badea

Ioniţă³

et al. 2010

Struct Chem

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Starting from 4-chloro-3,5-dinitrobenzoic acid 1, compounds 2-10 (N-alkoxy-3,5-dinitro-4-aminobenzoic acid esters where alkoxy stands for methoxy, carboxymethoxy, triphenylmethoxy, or corresponding amides) have been obtained, from which compounds 3-5 and 7-10 are new, and for the known compounds 2 and 6 the synthetic procedure has been improved. The new derivatives have been characterized by appropriate means (IR, UVVis, 1 H-and 13 C-NMR, fluorescence) and their properties were studied. Thus, depending on their structure, the compounds have acid properties, fluorescence and complexing properties with alkaline cations.

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Supernucleophiles—I

Cited by 72 publications

References 10 publications

G2(+) Investigation on the α‐Effect in the S_N2 Reactions at Saturated Carbon

G2(+) Investigation on the α‐Effect in the S_N2 Reactions at Saturated Carbon

New mono- and di-branched derivatives of Kryptofix K22 with N-(4-methoxyamino-3,5-dinitrobenzoyl) substituents. Synthesis and properties

N-Alkoxy-3,5-dinitro-4-aminobenzoic acid derivatives with controlled physico-chemical properties

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Supernucleophiles—I

Cited by 72 publications

References 10 publications

G2(+) Investigation on the α‐Effect in the SN2 Reactions at Saturated Carbon

G2(+) Investigation on the α‐Effect in the SN2 Reactions at Saturated Carbon

New mono- and di-branched derivatives of Kryptofix K22 with N-(4-methoxyamino-3,5-dinitrobenzoyl) substituents. Synthesis and properties

N-Alkoxy-3,5-dinitro-4-aminobenzoic acid derivatives with controlled physico-chemical properties

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Product

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G2(+) Investigation on the α‐Effect in the S_N2 Reactions at Saturated Carbon

G2(+) Investigation on the α‐Effect in the S_N2 Reactions at Saturated Carbon