Intermediates in nucleophilic aromatic substitution. II. Temperature-jump study of the interaction of 1,3,5-trinitrobenzene with aliphatic amines in 10% dioxane-90% water. Concurrent nucleophilic attack on the aromatic carbon and on the nitro group

1970 ◽  
Vol 92 (1) ◽  
pp. 129-137 ◽  
Author(s):  
Claude F. Bernasconi
Keyword(s):  
Nitro Group ◽  
Temperature Jump ◽  
Aliphatic Amines ◽  
Nucleophilic Aromatic Substitution ◽  
Nucleophilic Attack ◽  
Aromatic Substitution ◽  
Aromatic Carbon

Nucleophilic aromatic substitution of the nitro-group

1972 ◽  
pp. 385 ◽  
Author(s):  
Francesco Pietra ◽  
Dario Vitali
Keyword(s):  
Nitro Group ◽  
Nucleophilic Aromatic Substitution ◽  
Aromatic Substitution

Trifluoromethylsulfonyl aryl derivatives: competitive nucleophilic attack at an aromatic carbon and at the sulfur atom of an aromatic SO2CF3 group

1980 ◽  
Vol 58 (1) ◽  
pp. 65-71 ◽  
Author(s):  
François Terrier ◽  
Jean Morel ◽  
Marie-José Pouet ◽  
Marie-Paule Simonnin
Keyword(s):  
Nitro Group ◽  
Sulfur Atom ◽  
Negative Charge ◽  
Chemical Shifts ◽  
Nucleophilic Attack ◽  
Aromatic Carbon ◽  
Methoxide Ion ◽  
Aryl Methyl

The reaction of methoxide ion with 2-nitro-4-trifluoromethylsulfonylanisole, 4-nitro-2-triftuoromethylsulfonylanisole and 2,4- bis(trifluoromethylsulfonyl)anisole in DMSO has been studied by 1H and 19F nmr. Evidence for the transient formation of gem-dimethoxy σ-adducts arising from nucleophilic attack at the aromatic C1 carbon is given. Concurrent methoxide ion attack occurs at the sulfur atom of the SO2CF3 group to give the aryl methyl sulfonates ArSO3CH3, which are slowly converted into aryl sulfonates ArSO3−. The 1H chemical shifts of the anisoles are consistent with a greater electron-withdrawing effect of the SO2CF3 group compared to the nitro group. In contrast, a 4-nitro group appears to be more efficient than a 4-SO2CF3 group in delocalizing the negative charge of the σ-adducts.

Carbon versus oxygen nucleophilic selectivity in the reaction of the aryloxide ions, 2,6- and 3,5-di-tert-butylphenoxide, with the 2-[(nitro)\dn6 xaryl]-4,6-dinitrobenzotriazole 1-oxide series of super-electrophiles. Stereoelectronic factors on C-7 Meisenheimer complex formation versus C-1' SNAr displacement

1998 ◽  
Vol 76 (6) ◽  
pp. 662-671 ◽  
Author(s):  
Julian M Dust ◽  
Richard A Manderville
Keyword(s):  
Nmr Spectroscopy ◽  
Nucleophilic Aromatic Substitution ◽  
Nucleophilic Attack ◽  
Aromatic Substitution ◽  
Factors Affecting ◽  
H Nmr ◽  
Sterically Demanding ◽  
Biphenyl Derivative ◽  
First Time ◽  
Electrophilic Site

The 2-[(nitro)xaryl]-4,6-dinitrobenzotriazole 1-oxides (1, Pi-DNBT (x = 3); 2, DNP-DNBT (x = 2); 3, NP-DNBT (x = 1)) are electron-deficient nitro-substituted heteroaromatic substrates that possess two sites for nucleophilic attachment: C-7 and C-1'. Generally, attack at the super-electrophilic C-7 site yields spectroscopically observable anionic sigma -bonded adducts, whereas attack at C-1' leads to displacement products in an overall process of nucleophilic aromatic substitution (SNAr). To gain an understanding of the factors affecting C-1' versus C-7 attack by potentially ambident aryloxide (C- and O-)nucleophiles, we have monitored the reactions of 1-3 with 2,6-di-tert-butylphenoxide (2,6-ArO-) and 3,5-di-tert-butylphenoxide (3,5-ArO-) using 400 MHz 1H NMR spectroscopy (deuterated dimethyl sulfoxide solvent at ambient temperature). The results indicate that 2,6-ArO- acts only as a C-nucleophile with O-attack precluded, presumably by the sterically demanding tert-butyl groups flanking the O-nucleophilic centre. Although 2,6-ArO- reacts preferentially at C-7 of 1-3, the biphenyl derivative that arises from C-1' attack is also observed with 1, the first time that C-nucleophilic attack has been seen at this electrophilic site. In contrast, 3,5-ArO- acts only as an O-nucleophile, also as a consequence of the steric hindrance to the C-4 position; this aryloxide reacts entirely at C-1' of Pi-DNBT but also exclusively at C-7 of 3. However, with DNP-DNBT, 2, both the C-7 O-adduct and C-1' displacement products are noted; attack at C-1' is dominant. The selectivity (C-7 versus C-1') found in these reactions is discussed with emphasis given to stereoelectronic factors that may stabilize the putative C-1' O-adducts.Key words: aryloxides, super-electrophiles, Meisenheimer complexes, 2-[(nitro)xaryl]-4,6-dinitrobenzotriazole 1-oxides.

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