Structural and conformational studies of 5-(1H-pyrrol-2-ylmethylene)-substituted imidazolidine-2,4-diones and thiazolidine-2,4-diones

2002 ◽  
Vol 80 (10) ◽  
pp. 1302-1307 ◽  
Author(s):  
Alfonso de Dios ◽  
Maria Luz de la Puente ◽  
Alfonso Rivera-Sagredo ◽  
Juan Felix Espinosa
Keyword(s):  
Hydrogen Bond ◽  
Double Bond ◽  
Aldol Condensation ◽  
Condensation Reaction ◽  
Trans Form ◽  
Stable Conformer ◽  
Nmr Studies ◽  
Conformational Studies ◽  
Temperature Coefficients ◽  
Intramolecular Hydrogen

Some imidazolidine-2,4-dione (hydantoin) and thiazolidine-2,4-dione (TZD) derivatives with a 1H-pyrrol-2-ylmethylene substituent at the 5-position (1–8) have been synthesized via an aldol condensation reaction. A mixture of Z- and E- stereoisomers was obtained, as confirmed by HPLC and NMR studies. Assignment of the stereochemistry was achieved through chemical shift knowledge, NOE, and 3JH,C data. The conformation of the molecules depends on the configuration at the double bond. While the (NH,C cis) form is the most stable conformer for the E-isomer, the (NH,C trans) form is the preferred conformer for the Z-isomer. The temperature coefficients of the NH pyrrole protons reveal the existence of an intramolecular hydrogen bond for the E-isomers.Key words: hydantoin, TZD, NMR spectroscopy, conformational analysis, temperature coefficient.

scholarly journals Intramolecular hydrogen bond directed stable conformations of benzoyl phenyl oxalamides: unambiguous evidence from extensive NMR studies and DFT-based computations

RSC Advances ◽  
2018 ◽  
Vol 8 (20) ◽  
pp. 11230-11240 ◽  
Author(s):  
P. Dhanishta ◽  
P. Sai Siva kumar ◽  
Sandeep Kumar Mishra ◽  
N. Suryaprakash
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Nmr Studies ◽  
Intramolecular Hydrogen

Hydrogen bond directed stable conformations of benzoyl phenyl oxalamide derivatives.

Theoretical calculations of chemical interactions. VII. SCF-MO conformational studies of substituted 2′-hydroxychalcones

1991 ◽  
Vol 69 (5) ◽  
pp. 865-869 ◽  
Author(s):  
Norma Sbarbati Nudelman ◽  
Jorge Javier P. Furlong
Keyword(s):  
Hydrogen Bond ◽  
Theoretical Calculations ◽  
Slow Step ◽  
Chemical Interactions ◽  
Conformational Studies ◽  
Mndo Calculations ◽  
Indo Calculations ◽  
Intramolecular Hydrogen ◽  
Nmr Signals ◽  
Strong Barrier

INDO calculations have been performed on substituted 2′-hydroxychalcones. The results show that the intramolecularly hydrogen-bonded trans-s-cis conformation is the most stable. The calculations assist in assignment of NMR signals and interpretation of kinetic determinations. The calculated energy of the intramolecular hydrogen bond is compared with IR data when available and with experimentally determined heats of formation of the chalconates. Regarding the isomerization to flavanones, calculations of the ring A rotation in the chalconates show that it is exergonic; on the contrary, complete rotation of the styryl system encounters a strong barrier. MNDO calculations on this process show similar trends. These results indicate that this last rotation is involved in the slow step, which is consistent with kinetic determinations. Key words: chemical interactions, theoretical calculations, substituted hydroxychalcones, flavanones.

1H NMR studies on the solution conformation of contulakin-G and analogues

2002 ◽  
Vol 80 (8) ◽  
pp. 1022-1031 ◽  
Author(s):  
Lill Kindahl ◽  
Corine Sandström ◽  
A Grey Craig ◽  
Thomas Norberg ◽  
Lennart Kenne
Keyword(s):  
Hydrogen Bond ◽  
Chemical Shifts ◽  
Torsional Rigidity ◽  
Peptide Chain ◽  
Random Coil ◽  
Amide Proton ◽  
Solution Conformation ◽  
Nmr Studies ◽  
H Nmr ◽  
Intramolecular Hydrogen

The conformation of contulakin-G, a bioactive 16 amino acid O-linked glycopeptide (ZSEEGGSNAT*KKPYIL) with the disaccharide β-D-Gal(1[Formula: see text]3)α-D-GalNAc attached to the threonine residue in position 10, has been investigated by 1H NMR spectroscopy. The 1H NMR data for the non-glycosylated peptide and for two glycopeptide analogues, one with the monosaccharide α-D-GalNAc at Thr10 and one with the disaccharide β-D-Gal(1–>3)α-D-GalNAc at Ser7, all of lower bioactivity than contulakin-G, have also been collected. The chemical shifts, NOEs, temperature coefficients of amide protons, and 3JNH,αH-values suggest that all four compounds exist mainly in random coil conformations. Some transient populations of folded conformations are also present in the glycopeptides and turns, probably induced by the sugars, are present in the peptide chain around the site of glycosylation. In the two peptides O-glycosylated at Thr10, the rotation of α-D-GalNAc around the linkage between the sugar and the peptide is restricted. There is evidence for a hydrogen bond between the amide proton of α-D-GalNAc and the peptide chain that could contribute to this torsional rigidity. An intramolecular hydrogen bond between the carbohydrate and the peptide chain does not exist in the peptide O-glycosylated at the Ser7 residue. Key words: conformation, contulakin-G, NMR, O-linked glycopeptide.

scholarly journals Crystal structure of (E)-4-methoxy-2-{[(5-methylpyridin-2-yl)imino]methyl}phenol

2015 ◽  
Vol 71 (11) ◽  
pp. o819-o819 ◽  
Author(s):  
Farook Adam ◽  
Md Azharul Arafath ◽  
Rosenani Anwaeul Haque ◽  
Mohd Rizal Razali
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Schiff Base ◽  
Double Bond ◽  
Dihedral Angle ◽  
Compound C ◽  
Benzene Rings ◽  
Schiff Base Compound ◽  
Intramolecular Hydrogen ◽  
Base Compound

The molecule of the title Schiff base compound, C14H14N2O2, displays anEconformation with respect the imine C=N double bond. The molecule is approximately planar, with the dihedral angle formed by the planes of the pyridine and benzene rings being 5.72 (6)°. There is an intramolecular hydrogen bond involving the phenolic H and imine N atoms.

scholarly journals Crystal structure of (E)-9-({[4-(diethylamino)phenyl]imino}methyl)-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-8-ol

2017 ◽  
Vol 73 (1) ◽  
pp. 38-40 ◽  
Author(s):  
Md. Serajul Haque Faizi ◽  
Musheer Ahmad ◽  
Anatoly A. Kapshuk ◽  
Irina A. Golenya
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Title Compound ◽  
Condensation Reaction ◽  
The Other ◽  
Boat Conformation ◽  
Aromatic Rings ◽  
Compound C ◽  
Intramolecular Hydrogen ◽  
Ring Motif

The title compound, C23H29N3O, was synthesized from the condensation reaction of 8-hydroxyjulolidine-9-carbaldehyde andN,N-diethyl-p-phenylenediamine. The hydroxy group forms a intramolecular hydrogen bond to the imine N atom and generates anS(6) ring motif. The conformation about the C=N bond isE, and the aromatic ring of the julolidine moiety is inclined to the benzene ring by 3.74 (14)°. One of the fused non-aromatic rings of the julolidine moiety adopts an envelope conformation and the other has a screw-boat conformation. In the crystal, molecules are linked by C—H...π interactions involving the aromatic julolidine ring, forming slabs parallel to thebcplane. The tricyclic fragment of the julolidine ring and the azomethine C=N bond are disordered over two sets of sites with a refined occupancy ratio of 0.773 (3):0.227 (3).

Diethyl 2-Benzimidazol-1-ylsuccinate–Picric Acid (1/1) – An Inclusion Molecular Complex

1997 ◽  
Vol 53 (6) ◽  
pp. 961-967 ◽  
Author(s):  
P. Zaderenko ◽  
M. S. Gil ◽  
P. López ◽  
P. Ballesteros ◽  
I. Fonseca ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Molecular Complex ◽  
Picric Acid ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
H Nmr ◽  
Intramolecular Hydrogen ◽  
C Nmr

The crystal structure of the diethyl 2-benzimidazol-1-ylsuccinate–picric acid (1/1) molecular complex has been determined by X-ray diffraction analysis. Diethyl 2-benzimidazol-l-ylsuccinate molecules form channels along the a axis, in which the picric acid molecules are located. The benzimidazole moiety and the phenol group are held together by hydrogen bonding between the hydrogen of the phenol and the N3 atom of benzimidazole. Additionally, this hydrogen forms an intramolecular hydrogen bond with one O atom of the ortho-nitro group, thus producing a bifurcated hydrogen bond. 1H NMR spectra in DMSO-d 6 solution and CP/MAS solid 13 C NMR studies of this 2-benzimidazol-1-ylsuccinate–picric acid (1/1) molecular complex, as well as those of dimethyl, diethyl, di-n-butyl and 1-n-butyl-4-ethyl 2-imidazol-1-ylsuccinates, diethyl 2-pyrazol-1-ylsuccinate, ethyl imidazol-1-ylacetate, ethyl pyrazol-1-ylacetate and ethyl pyrazol-l-ylsuccinate, suggest that the picric acid linkage depends on the nature of the azole. Actual proton transfer is deduced for the imidazole derivatives, but only weak hydrogen bonding could be inferred for pyrazole derivatives.

scholarly journals Retention of strong intramolecular hydrogen bonds in high polarity solvents in binaphthalene–benzamide derivatives: extensive NMR studies

RSC Advances ◽  
2019 ◽  
Vol 9 (56) ◽  
pp. 32759-32770 ◽  
Author(s):  
Arun Kumar Patel ◽  
Sandeep Kumar Mishra ◽  
Kiran Krishnamurthy ◽  
N. Suryaprakash
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Strong Hydrogen Bond ◽  
Nmr Studies ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen ◽  
Benzamide Derivatives ◽  
High Polarity

NMR studies reveal very strong hydrogen bond unbreakable even in high polarity solvents.

Reaction of 4-Chloro-3,5-Dinitrobenzotrifluoride with Aniline Derivatives. Substituent Effects

2007 ◽  
Vol 2007 (9) ◽  
pp. 509-512 ◽  
Author(s):  
Hamida O.M. Al-Howsaway ◽  
Magda F. Fathalla ◽  
Ali A. El-Bardan ◽  
Ezzat A. Hamed
Keyword(s):  
Hydrogen Bond ◽  
Transition State ◽  
Positive Charge ◽  
Bond Formation ◽  
Substituent Effects ◽  
Nmr Studies ◽  
H Nmr ◽  
Aniline Derivatives ◽  
Elimination Mechanism ◽  
Intramolecular Hydrogen

N-(2,6-Dinitro-4-trifluoromethylphenyl)aniline derivatives were prepared by anilino-dechlorination of 4-chloro-3, 5-dinitrobenzotrifluoride. IR, UV and 1H NMR studies suggested an intramolecular hydrogen bond between the amino hydrogen and one o-nitro group. An addition-elimination mechanism was suggested based on the second-order kinetics and the dependence of rates on the nature and the position of the substituent in the aniline ring, as well as the high negative values of ρ(-3.14, −3.16, −3.01). Such values indicate a positive charge on the aniline nitrogen in the transition state and that the rate is affected by the polar effect of the substituent. The β value (0.85 at 30°C) indicates an appreciable degree of bond formation in the transition state.

scholarly journals Crystal structures and antioxidant capacity of (E)-5-benzyloxy-2-{[(4-chlorophenyl)imino]methyl}phenol and (E)-5-benzyloxy-2-({[2-(1H-indol-3-yl)ethyl]iminiumyl}methyl)phenolate

2018 ◽  
Vol 74 (4) ◽  
pp. 478-482 ◽  
Author(s):  
Nadir Ghichi ◽  
Chawki Bensouici ◽  
Ali Benboudiaf ◽  
Yacine DJebli ◽  
Hocine Merazig
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Antioxidant Capacity ◽  
Benzene Ring ◽  
Condensation Reaction ◽  
Dihedral Angles ◽  
Compound I ◽  
Π Interactions ◽  
A Charge ◽  
Intramolecular Hydrogen

The title Schiff base compounds, C20H16ClNO2(I) and C24H22N2O2(II), were synthesizedviathe condensation reaction of 2-amino-4-chlorophenol for (I), and 2-(2,3-dihydro-1H-indol-3-yl)ethan-1-amine for (II), with 4-benzyloxy-2-hydroxybenzaldehyde. In both compounds, the configuration about the C=N imine bond isE. Neither molecule is planar. In (I), the central benzene ring makes dihedral angles of 49.91 (12) and 53.52 (11)° with the outer phenyl and chlorophenyl rings, respectively. In (II), the central benzene ring makes dihedral angles of 89.59 (9) and 72.27 (7)°, respectively, with the outer phenyl ring and the mean plane of the indole ring system (r.m.s. deviation = 0.011 Å). In both compounds there is an intramolecular hydrogen bond forming anS(6) ring motif; an O—H...O hydrogen bond in (I), but a charge-assisted N+—H...O−hydrogen bond in (II). In the crystal of (I), molecules are linked by C—H...π interactions, forming slabs parallel to plane (001). In the crystal of (II), molecules are linked by pairs of N—H...O hydrogen bonds, forming inversion dimers. The dimers are linked by C—H...O hydrogen bonds, C—H...π interactions and a weak N—H...π interaction, forming columns propagating along thea-axis direction. The antioxidant capacity of the synthesized compounds was determined by cupric reducing antioxidant capacity (CUPRAC) for compound (I) and by 2,2-picrylhydrazyl hydrate (DPPH) for compound (II).

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