Studies on the rearrangement of ortho-nitrobenzylidenemalonates and their Analogues to 2-aminobenzoate derivatives

2002 ◽  
Vol 80 (2) ◽  
pp. 192-199 ◽  
Author(s):  
Elzbieta Lewandowska ◽  
Stefan Kinastowski ◽  
Stanislaw F Wnuk
Keyword(s):  
Double Bond ◽  
Nitro Group ◽  
Phenyl Ring ◽  
Nitro Compounds ◽  
Trifluoromethyl Group ◽  
Reverse Polarity ◽  
Michael Reactions ◽  
Carbon Double Bond ◽  
Oxidative Rearrangement ◽  
Aromatic Nitro

Reaction of the diethyl 2-nitro-4-(trifluoromethyl)benzylidenemalonate with diethylamine in alcohols resulted in the reduction of the nitro group and the oxidation of the vinylic carbon attached to the phenyl ring. Simultaneous migration of the malonic fragment gave the appropriate 2-amino-4-(trifluoromethyl)benzoate esters. The presence of at least two nitro groups, or one nitro group and trifluoromethyl group on the phenyl ring, attached to the α-carbon and strongly electron withdrawing substituents at the β-carbon (CO2Et, CN) in ortho-nitrobenzylidene systems is necessary for this reductive–oxidative rearrangement to proceed. Reaction of nitrocinnamates with thiols in the presence of triethylamine in tetrahydrofuran gave Michael addition products with different regioselectivity of addition. Ethyl 2-nitrocinnamate undergoes standard β-addition of thiols to a carbon–carbon double bond. However, 2,4-dinitro- and 2,4,6-trinitrocinnamates undergo α-addition of thiols, indicating that the presence of two nitro groups on the phenyl ring can reverse polarity of the carbon–carbon double bond in cinnamate acceptors.Key words: abnormal Michael reactions, aromatic nitro compounds, benzylidene compounds, rearrangements.

scholarly journals Crystal structure of (3E)-3-(2,4-dinitrophenoxymethyl)-4-phenylbut-3-en-2-one

2014 ◽  
Vol 70 (9) ◽  
pp. o1051-o1052 ◽  
Author(s):  
Ignez Caracelli ◽  
Stella H. Maganhi ◽  
Paulo J. S. Moran ◽  
Bruno R. S. de Paula ◽  
Felix N. Delling ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Nitro Group ◽  
Benzene Ring ◽  
Torsion Angle ◽  
Title Compound ◽  
Phenyl Ring ◽  
Aromatic Rings ◽  
Compound C ◽  
The One

In the title compound, C17H14N2O6, the conformation about the C=C double bond [1.345 (2) Å] isE, with the ketone moiety almost coplanar [C—C—C—C torsion angle = 9.5 (2)°] along with the phenyl ring [C—C—C—C = 5.9 (2)°]. The aromatic rings are almost perpendicular to each other [dihedral angle = 86.66 (7)°]. The 4-nitro moiety is approximately coplanar with the benzene ring to which it is attached [O—N—C—C = 4.2 (2)°], whereas the one in theorthoposition is twisted [O—N—C—C = 138.28 (13)°]. The molecules associateviaC—H...O interactions, involving both O atoms from the 2-nitro group, to form a helical supramolecular chain along [010]. Nitro–nitro N...O interactions [2.8461 (19) Å] connect the chains into layers that stack along [001].

Simple Synthesis of Dimethyl Nitrobenzhydrylphosphonates and Heteroarylnitroarylacetonitriles via Vicarious Nucleophilic Substitution (VNS) Reaction

Synthesis ◽  
2020 ◽  
Vol 53 (01) ◽  
pp. 175-181
Author(s):  
Mieczysław Mąkosza ◽  
Małgorzata Bechcicka ◽  
Krzysztof Wojciechowski
Keyword(s):  
Nucleophilic Substitution ◽  
Nitro Group ◽  
Nitro Compounds ◽  
Simple Synthesis ◽  
Para Position ◽  
Crucial Step ◽  
Vicarious Nucleophilic Substitution ◽  
Aromatic Nitro Compounds ◽  
Leaving Group ◽  
Aromatic Nitro

Acetals of dimethyl phenyl- and heteroaryl-α-hydroxymethanephosphonates were deprotonated to generate carbanions, which enter the vicarious nucleophilic substitution (VNS) of hydrogen in aromatic nitro compounds to form 4-nitrobenzhydrylphosphonates and α-heteroaryl-4-nitrobenzylphosphonates. Similarly acetals of cyano­hydrins of heteroaromatic aldehydes (furfural and 2-formylthiophene) react to form heteroaryl 4-nitroarylacetonitriles. The anion of the hemiacetal of acetaldehyde is an efficient leaving group in the base-induced β-elimination step – the crucial step in the VNS reaction. The reaction selectively occurred at the para-position to the nitro group.

A solvent effect on the conformation of aromatic nitro groups

1967 ◽  
Vol 20 (11) ◽  
pp. 2381 ◽  
Author(s):  
ID Rae
Keyword(s):  
Solvent Effect ◽  
Nitro Group ◽  
Nitro Compounds ◽  
Dimethyl Sulphoxide ◽  
Aromatic Nitro Compounds ◽  
Aromatic Nitro

The differences between proton mangetic resonance spectra of aromatic nitro compounds in deuterochloroform and dimethyl sulphoxide solutions are interpreted in terms of increased steric requirements of the nitro group in the latter solvent. In suitably ortho-substituted aromatic nitro compounds this leads to twisting of the nitro group about the Ar- N bond.

STERIC INHIBITION OF RESONANCE: III. CALCULATION OF RESONANCE ENERGIES AND BOND LENGTHS

1959 ◽  
Vol 37 (5) ◽  
pp. 905-914 ◽  
Author(s):  
James Trotter
Keyword(s):  
Nitro Group ◽  
Bond Order ◽  
Electron Distribution ◽  
Resonance Energy ◽  
Nitro Compounds ◽  
X Ray ◽  
Bond Lengths ◽  
Resonance Energies ◽  
Aromatic Nitro ◽  
Steric Inhibition Of Resonance

In many aromatic nitro compounds steric effects prevent the attainment of complete coplanarity and inhibit resonance interaction between the nitro group and the aromatic π-electrons. The variations with nitro group tilt of resonance energy, electron distribution, and π-bond order in this type of molecule have been calculated by molecular orbital methods, and the corresponding bond length variations have been deduced. The calculated bond lengths for 9,10-dinitroanthracene and 9-nitroanthracene are compared with those measured by X-ray analyses.

Reactions of 4-Pyrones with Azomethine Ylides as a Chemo­selective Method for the Construction of Multisubstituted Pyrano[2,3-c]pyrrolidines

Synthesis ◽  
2021 ◽  
Author(s):  
Dmitrii L. Obydennov ◽  
Vyacheslav D. Steben’kov ◽  
Konstantin L. Obydennov ◽  
Sergey A. Usachev ◽  
Vladimir S. Moshkin ◽  
...  
Keyword(s):  
Double Bond ◽  
Ring Opening ◽  
Azomethine Ylides ◽  
Azomethine Ylide ◽  
Dipolar Cycloaddition ◽  
Computational Studies ◽  
Carbon Double Bond ◽  
Reactivity Indexes ◽  
Reaction Proceeds

Abstract4-Pyrones bearing electron-donating and electron-withdrawing groups react with nonstabilized azomethine ylides to form pyrano[2,3-c]pyrrolidines in moderate to good yields. The reaction proceeds chemoselectively as a 1,3-dipolar cycloaddition of the azomethine ylide at the carbon–carbon double bond of the pyrone activated by the electron-withdrawing substituent. The reactivity of 4-pyrones toward azomethine ylides was rationalized by computational studies with the use of reactivity indexes. The pyrano[2,3-c]pyrrolidine moiety could be modified, for example by a ring-opening transformation under the action of hydrazine to provide pyrazolyl-substituted pyrrolidines.

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