Substituent-Dependent Nitration of 9-Substituted 9,10-Dihydro-9,10-ethanoanthracenes

1995 ◽  
Vol 48 (12) ◽  
pp. 1949 ◽  
Author(s):  
MC Harsanyi ◽  
RK Norris ◽  
G Sze ◽  
PK Witting
Keyword(s):  
Nitro Group ◽  
Aromatic Ring ◽  
The Other ◽  
Aromatic Rings

Mononitration of 9-substituted ethanoanthracenes, bearing Me, But, F, Br, I, OMe , NO2, CN, CHO or CO2Me substituents at the bridgehead carbon, was found to occur exclusively at the β-positions of the aromatic ring. The mononitro products were isolated, identified by 1H n.m.r. spectroscopy, and their relative proportions were estimated by quantitative g.l.c . and/or by 1H n.m.r. spectroscopy. For all the above substrates the proportion of nitration at the β-position meta to the bridgehead carbon bearing the substituent [to give compounds of the general form (4)] was greater than the proportion of nitration at the corresponding β-position para to the bridgehead substituent [to give compounds of the general form (3)]. Whilst the preferential nitration at the β-positions of the aromatic rings is consistent with the previously reported nitration of 9,10-dihydro-9,10-ethanoanthracene (2a) itself, no observations of this preferential meta attack have been made previously. No correlation could be made of this behaviour with available substituent parameters for the widely sterically and electronically disparate set of substituents used in this study, and the origin of this preferential attack remains unclear. Dinitration in this system was studied only superficially. The influence of the bridgehead substituent together with that of the nitro group already present on one aromatic ring appear to combine with quite unpredictable results in orienting the position of attack of the incoming nitro group onto the other (non-nitrated) aromatic ring.

scholarly journals Nitrogen NMR shieldings of 2-amino-5-nitro-6-methylpyridines

1997 ◽  
Vol 13 (4) ◽  
pp. 251-256 ◽  
Author(s):  
B. Palasek ◽  
A. Puszko ◽  
Z. Biedrzycka ◽  
W. Sicinska ◽  
M. Witanowski
Keyword(s):  
Nitro Group ◽  
Aromatic Ring ◽  
Steric Hindrance ◽  
Chemical Shifts ◽  
Amino Nitrogen ◽  
Point Of View ◽  
The Other ◽  
Amino Group ◽  
Alkyl Aryl ◽  
Pyridine Nitrogen

Nitrogen NMR shieldings (chemical shifts) of 2-amino-5-nitro-6-methylpyridine derivatives are assessed from the point of view of substituent-induced effects under conditions where alkyl, aryl, nitro, and nitroso moieties are substituents at the amino nitrogen. The nitro nitrogen shielding reveals only little variation upon varying the substituents, and this seems to indicate that steric hindrance which is likely to force the nitro group out of the plane of the aromatic ring reduces theπ-electron conjugation with the latter, and with the amino group as well. On the other side, the pyridine nitrogen shielding shows large effects of substituents at the amino moiety, which suggests a significant conjugation between the ring and the amino group. The latter effects produce a remarkable deshielding of the pyridine nitrogen in the case of nitro and nitroso substituents at the amino group.

Regioselectivity of nucleophilic aromatic photosubstitution in the biphenyl series. Photohydrolysis of some dimethoxynitrobiphenyls

1987 ◽  
Vol 52 (10) ◽  
pp. 2482-2491 ◽  
Author(s):  
Ján Urban ◽  
Petr Kuzmič ◽  
David Šaman ◽  
Milan Souček
Keyword(s):  
Nitro Group ◽  
Steric Hindrance ◽  
The Other ◽  
Quantum Yields ◽  
Hydroxide Anion ◽  
Tert Butanol ◽  
Nitro Derivatives

Anaerobic photolysis of dimethoxynitrobiphenyls IIIa-VIa in aqueous alkaline tert-butanol gave products of nucleophilic photosubstitution of methoxyl by hydroxide anion, while the dimethoxybiphenyls Ia and IIa were found unreactive. Regioselectivity of the reaction was examined in view of a possible “extended meta activation” by the nitro group. The most reactive substrate IIIa gives both C-3 and C-4 substitution products with an unsubstantial preference for the latter, which opposes the “extended meta selectivity” rule. All of the other compounds obey the rule, and 3,4-dimethoxy-3'-nitrobiphenyl (IVa) even displayed absolute selectivity by yielding C-3 substituted compound as the only product. 2,5-Dimethoxy substituted compounds underwent photosubstitution which much lower quantum yields than their 3,4-substituted counterparts, most probably due to some steric hindrance of conjugation. Similarly, 3-nitro-substituted biphenyls exhibited much lower overall reactivity than 4-nitro derivatives.

Photoreaction of N-butyl 3,4-dimethoxy-6-nitrobenzamide with butylamine. A model study for lysine-directed photoaffinity labelling

1987 ◽  
Vol 52 (7) ◽  
pp. 1780-1785 ◽  
Author(s):  
Petr Kuzmič ◽  
Libuše Pavlíčková ◽  
Milan Souček
Keyword(s):  
Nitro Group ◽  
Aromatic Ring ◽  
Ultraviolet Irradiation ◽  
Title Compound ◽  
Reductive Coupling ◽  
Photoaffinity Labelling ◽  
Photolysis Rate ◽  
Model Study ◽  
A Minor

Ultraviolet irradiation of the title compound I in the presence of butylamine gave predominantly products of nucleophilic photosubstitution by the amine, i.e., nitroanilines IIa and IIb. Besides, small amounts of products of hydrolysis (phenol III) and reductive coupling (azoxybenzene IV) were also formed. Comparison of the overall photolysis rate of I with that of 3,4-dimethoxy-1-nitrobenzene (V) indicates a minor loss of reactivity, most probably due to some deviation from coplanarity of the activating nitro group and the aromatic ring.

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].

scholarly journals Methyl 2,4-dihydroxy-5-(4-nitrobenzamido)benzoate

2013 ◽  
Vol 69 (2) ◽  
pp. o207-o207
Author(s):  
Syeda Sohaila Naz ◽  
Nazar Ul Islam ◽  
M. Nawaz Tahir ◽  
Muhammad Raza Shah
Keyword(s):  
Hydrogen Bonds ◽  
Nitro Group ◽  
Dihedral Angle ◽  
Title Compound ◽  
Three Dimensional ◽  
Aromatic Rings ◽  
Compound C ◽  
Dimensional Network

In the title compound, C15H12N2O7, the dihedral angle between the aromatic rings is 4.58 (13)° and the nitro group is rotated from its attached ring by 18.07 (17)°. Intramolecular N—H...O and O—H...O hydrogen bonds generateS(5) andS(6) rings, respectively. In the crystal, molecules are linked by O—H...O hydrogen bonds, generating [001]C(7) chains. The chains are linked by C—H...O interactions, forming a three-dimensional network, which incorporatesR22(7) andR22(10) loops.

scholarly journals N-(4-Ethoxy-2,5-dinitrophenyl)acetamide

IUCrData ◽  
2020 ◽  
Vol 5 (8) ◽  
Author(s):  
Sannihith N. Uppu ◽  
Ogad A. Agu ◽  
Curtistine J. Deere ◽  
Frank R. Fronczek
Keyword(s):  
Hydrogen Bond ◽  
Nitro Group ◽  
Benzene Ring ◽  
Title Compound ◽  
The Other ◽  
Ring Plane ◽  
Torsion Angles ◽  
Compound C ◽  
Bifurcated Hydrogen Bond

In the title compound, C10H11N3O6, the torsion angles about the bonds to the benzene ring are less than 4°, except for the nitro groups, which are twisted out of the ring plane by 25.27 (3) and 43.63 (2)°. The N—H group forms a bifurcated hydrogen bond, with an intramolecular component to a nitro group O atom and an intermolecular component to the other nitro group, thereby forming chains propagating in the [010] direction. Several weak C—H...O interactions are also present.

The Boger Synthesis of (+)-Complestatin

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Nitro Group ◽  
The Other ◽  
Aryl Ether ◽  
Silyl Group ◽  
Model Studies ◽  
La Jolla ◽  
Indole Synthesis ◽  
Modular Nature

(+)-Complestatin 3 shows promising activity against HIV infectivity. Dale L. Boger of Scripps/La Jolla described (J. Am. Chem. Soc. 2010, 132, 7776) an elegant multicomponent assembly of 3, the key step of which was the atropisomer-selective intramolecular Larock cyclization of 1 to 2. The preparation of 1 began with the protected phenethylamine 5, prepared by Sharpless asymmetric aminohydroxylation of the styrene 4. Conversion of 5 to the areneboronic acid followed by coupling with 6 delivered 7. Acylation led to 8, with the stage set for nitro-assisted addition-elimination, to form the first bis-aryl ether of 3. The product was a mixture of atropisomers, subsequently symmetrized to 9 by removal of the nitro group. Acylation of 9 led to 1. The role of the silyl group on the alkyne of 1 was to direct the regioselectivity of the intramolecular Larock indole synthesis. Again, two atropisomers were possible from the cyclization. Earlier model studies had suggested some preference for one over the other. As it turned out, in this case the desired atropisomer was the only one observed. It is particularly striking that the coupling was efficient even in the presence of the readily reduced and unprotected chlorophenols. The modular nature of this route to (+)-complestatin 3 will make it possible to prepare a variety of analogues. As long as only the substituents on the periphery are changed, the atropisomer selectivity in the Larock cyclization should be maintained.

Exploration of relative π-electron localization in naphthalene aromatic rings by C–H⋯π interactions: experimental evidence, computational criteria, and database analysis

CrystEngComm ◽  
2019 ◽  
Vol 21 (42) ◽  
pp. 6432-6445 ◽  
Author(s):  
Ali Samie ◽  
Alireza Salimi ◽  
Jered C. Garrison
Keyword(s):  
Experimental Evidence ◽  
Aromatic Ring ◽  
Electron Localization ◽  
Aromatic Rings ◽  
Database Analysis ◽  
Π Interactions ◽  
Contact Position

In C–H⋯π interaction, the relative π-electron localization in aromatic ring led to the change of contact position from centre to edges of the ring (C–H⋯πe) which was confirmed by experimental evidences, computational criteria, and database analysis.

Polypyridines, Picrates, Lanthanides: A Plethora of Stacks?

2020 ◽  
Vol 73 (6) ◽  
pp. 529
Author(s):  
Eric J. Chan ◽  
Simon A. Cotton ◽  
Jack M. Harrowfield ◽  
Brian W. Skelton ◽  
Alexandre N. Sobolev ◽  
...  
Keyword(s):  
Nitro Group ◽  
The Other ◽  
Molar Ratio ◽  
Lanthanide Ion ◽  
X Ray ◽  
The Third ◽  
Group Oxygen ◽  
Structure Determinations ◽  
Lighter Lanthanides ◽  
Trigonal Prismatic

Reactions of the lanthanide(iii) picrates (picrate=2,4,6-trinitrophenoxide=pic) with 1,10-phenanthroline (phen) and 2,2′:6′,2′′-terpyridine (terpy) in a 1:2 molar ratio have provided crystals suitable for X-ray structure determinations in instances predominantly involving the lighter lanthanides. In all, the aza-aromatic ligands chelate the lanthanide ion, none being found as ‘free’ ligands within the lattice. The complexes of 1,10-phenanthroline have been characterised in two forms, one unsolvated (Ln=La, Sm, Eu; monoclinic, C2/c, Z 8), one an acetonitrile monosolvate (Ln=Gd; monoclinic, P21/a, Z 4), the latter being the only previously known form (with Ln=La). In both forms, the LnIII is nine-coordinate, in an approximately tricapped trigonal-prismatic environment, with two picrate ligands chelating through phenoxide and 2-nitro group oxygen atoms, the third being bound through phenoxide-O only. The 2,2′:6′,2′′-terpyridine complexes, all acetonitrile monosolvates defined for Ln=La, Gd, Er, and Y (monoclinic, C2/c, Z 4), are ionic, one picrate having been displaced from the primary coordination sphere. For Ln=La, the two bound picrates are again chelating, making the LaIII 10-coordinate in a distorted bicapped square-antiprismatic environment but in the other species they are bound through phenoxide-O only, making the LnIII ions eight-coordinate in a distorted square-antiprismatic environment. Stacked arrays of the ligands can be found in both series of complexes, with intramolecular picrate–picrate and picrate–aza-aromatic stacks being prominent features.

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