Interaction of heterocycles and nucleophiles. II. Sigma complexes formed from methoxide ion and Methoxy-3,5-dinitropyridines in dimethyl sulphoxide

1970 ◽  
Vol 23 (5) ◽  
pp. 957 ◽  
Author(s):  
MEC Biffin ◽  
J Miller ◽  
AG Moritz ◽  
DB Paul
Keyword(s):  
Dimethyl Sulphoxide ◽  
No Conversion ◽  
Solvation Effects ◽  
Sigma Complexes ◽  
Sigma Complex ◽  
Methoxide Ion ◽  
Rearrangement Reactions

Contrasting behaviour is observed when 2- and 4-methoxy-3,5-dinitropyridine interact with methoxide ion in dimethyl sulphoxide. The 4-methoxy compound affords both methine and acetal sigma complexes, the latter being thermodynamically more stable. The interconversion is catalysed by methanol. Labelling experiments have established that the sigma complex from the 2-methoxypyridine is formed by addition at C6; no conversion into the acetal could be effected. These observations are rationalized in terms of differential steric and solvation effects. Demethylation and rearrangement reactions of 4-methoxy-3,5-dinitropyridine are reported.

scholarly journals Interaction of heterocycles and nucleophiles. III. Interconversion of the methine sigma complexes derived from 3,5-dinitropyridine and methoxide ion in dimethyl sulphoxide

1970 ◽  
Vol 23 (5) ◽  
pp. 963 ◽  
Author(s):  
MEC Biffin ◽  
J Miller ◽  
AG Moritz ◽  
DB Paul
Keyword(s):  
Dimethyl Sulphoxide ◽  
Stable Isomer ◽  
Sigma Complexes ◽  
Methoxide Ion

The conversion of the methine complex (4; R1 = H) into the more stable isomer (5; R1 = R2 = H) is reported.

Interaction of heterocycles and nucleophiles: Sigma complexes formed from methoxide ion and some 5-nitropyrimidines and comparison with those from 2,4,6-trinitroanisole

1969 ◽  
Vol 22 (12) ◽  
pp. 2561 ◽  
Author(s):  
MEC Biffin ◽  
J Miller ◽  
AG Moritz ◽  
DB Paul
Keyword(s):  
Complex Formation ◽  
Aprotic Solvent ◽  
Reaction Coordinate ◽  
Thermodynamic Control ◽  
Sigma Complexes ◽  
Protic Solvents ◽  
Lower Symmetry ◽  
Selective Deuteration ◽  
Sigma Complex ◽  
Methoxide Ion

The sigma complexes formed from the reaction of methoxide ion with 6- nitro-pyrimidine and its monomethoxy derivatives have been examined spectroscopically. Structural ambiguities resulting from the lower symmetry of the nitropyrimidines compared with the trinitrobenzenes have been resolved by selective deuteration. Comparison is made with sigma complex formation from 2,4,6-trinitroanisole and the question of kinetic against thermodynamic control is considered with reference to theoretically derived P.E.-reaction coordinate profiles for protic solvents. The calculations are extended qualitatively to consider reactions in an aprotic solvent.

σ-Complexes as biophysical and biochemical probes. Part II. Transformations of σ-complex intermediates from reaction of 4-nitrobenzofuroxan and methoxide ion

1977 ◽  
Vol 55 (15) ◽  
pp. 2852-2855 ◽  
Author(s):  
Erwin Buncel ◽  
Noemi Chuaqui-Offermanns ◽  
Brian K. Hunter ◽  
Albert R. Norris
Keyword(s):  
Reaction Mechanism ◽  
Dimethyl Sulphoxide ◽  
Antileukemic Activity ◽  
Methoxide Ion ◽  
Transient Intermediates

Reaction of 4-nitrobenzofuroxan with methoxide ion in methanolic dimethyl sulphoxide solution gives rise to 7-hydroxy-4-nitrobenzofurazan (as the anion) and 7-methoxy-4-nitrobenzofurazan (as the methoxide C-7 adduct); the proposed reaction mechanism invokes the formation of several transient intermediates. The results bear on the postulated mechanism for the antileukemic activity of 4-nitrobenzofuroxan.

scholarly journals The Influence of the Solvent on Reaction Velocity. XXXI. The Reaction between Benzyl Chlorides and Methoxide Ion in Dimethyl Sulphoxide-Methanol Mixtures.

1966 ◽  
Vol 20 ◽  
pp. 946-962 ◽  
Author(s):  
Eero Tommila ◽  
Matti Savolainen ◽  
Inkeri Lehtinen ◽  
Bengt von Hofsten ◽  
D. H. Williams ◽  
...  
Keyword(s):  
Dimethyl Sulphoxide ◽  
Reaction Velocity ◽  
Benzyl Chlorides ◽  
Methoxide Ion

Structural Investigation of Sigma Complexes of Aromatic Amines with 1,3,5-Trinitrobenzene

1974 ◽  
Vol 52 (4) ◽  
pp. 630-639 ◽  
Author(s):  
Erwin Buncel ◽  
John G. K. Webb
Keyword(s):  
Dimethyl Sulfoxide ◽  
Aromatic Amine ◽  
Aromatic Amines ◽  
Structural Investigation ◽  
Structural Factors ◽  
Dmso Solution ◽  
Visible Spectroscopy ◽  
Sigma Complexes ◽  
Methoxide Ion ◽  
Characteristic Manner

Reaction of the 1,3,5-trinitrobenzene (TNB) – methoxide ion adduct 1 with a series of substituted arylamines in dimethyl sulfoxide (DMSO) solution yields new 1,3,5-trinitrobenzene – aromatic amine σ-complexes (2). The parent TNB–anilide complex is also obtained in the reaction of TNB with potassium anilide in DMSO. Identification of the complexes is effected by n.m.r. and visible spectroscopy. The n.m.r. parameters of the complexes are influenced in characteristic manner by substituents in the aryl-amine moiety. An analysis of electronic and structural factors in these systems is given, with emphasis on the following aspects: structural implications of NH–Hβ′ coupling; aromatic protons on the arylamine moiety; amino protons in free and complexed arylamines.

Sign in / Sign up

Export Citation Format

Share Document