P.M.R. study of intramolecular hydrogen bonding in ortho-amidoanilides and its relation to the spectra of α-acylamidocinnamamide

1973 ◽  
Vol 26 (6) ◽  
pp. 1263 ◽  
Author(s):  
KK Prasad ◽  
RV Venkataratnam
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Convenient Method ◽  
Proton Magnetic Resonance ◽  
Intramolecular Hydrogen Bonding ◽  
Strong Hydrogen Bond ◽  
Normal Position ◽  
Tertiary Amide ◽  
Intramolecular Hydrogen

Proton magnetic resonance spectra of some ortho-amido-benzanilides and -acetanilides have been studied. While the secondary amido substituents in the 2-position have been found to form a strong hydrogen bond with the anilide proton, the tertiary amide function is sterically prohibited from doing so with consequent shielding of H 6 from its normal position in the 2-methoxycarbonyl substituted anilides. The abnormal shielding of Hβ in α-acylamidocinnamamides observed earlier has been discussed in relation to the present findings. A convenient method for the preparation of ortho-amidoanilides has been described.

Selective deshielding of aromatic protons in some ortho-substituted acetanilides

1968 ◽  
Vol 46 (15) ◽  
pp. 2593-2600 ◽  
Author(s):  
James R. Bartels-Keith ◽  
Ronald F. W. Cieciuch
Keyword(s):  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Solvent Effects ◽  
Proton Magnetic Resonance ◽  
Aromatic Proton ◽  
Intramolecular Hydrogen Bonding ◽  
Low Field ◽  
Intramolecular Hydrogen

Certain ortho-substituted acetanilides exhibit proton magnetic resonance signals at unusually low field for the amido proton and the aromatic proton adjacent to the acetamido group. This effect, explicable in terms of intramolecular hydrogen-bonding, has been observed for nitro, carbonyl, sulfamoyl, and sulfonyl substituents. Solvent effects are discussed.

Aromatic amides. VII. Steric hindrance to hydrogen bonding in ortho-substituted acetanilides

1972 ◽  
Vol 25 (3) ◽  
pp. 639 ◽  
Author(s):  
BD Andrews ◽  
AJ Poynton ◽  
ID Rae
Keyword(s):  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Steric Hindrance ◽  
Proton Magnetic Resonance ◽  
Intramolecular Hydrogen Bonding ◽  
Intramolecular Hydrogen ◽  
Magnetic Resonance Spectra

A series of 2-substituted 3,5-dimethylanilines and their N-acetyl derivatives have been synthesized, and their proton magnetic resonance spectra recorded. Intramolecular hydrogen bonding between the amide N-H and the 2-substituent is disturbed by steric hindrance of the 2-substituent only in the case of the 2-nitro, 2-acetyl, and 2-methoxycarbonyl substituents.

Conformations of some dianhydrohexitols

1969 ◽  
Vol 47 (13) ◽  
pp. 2395-2401 ◽  
Author(s):  
F. J. Hopton ◽  
G. H. S. Thomas
Keyword(s):  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Intramolecular Hydrogen Bonding ◽  
Coupling Constants ◽  
Ring Conformation ◽  
Intramolecular Hydrogen ◽  
Magnetic Resonance Spectra

Proton magnetic resonance spectra of three known diastereoisomers 1,4:3,6-dianhydro-D-glucitol, 1,4:3,6-dianhydro-D-mannitol, 1,4:3,6-dianhydro-L-iditol, and their diacetyl and dimesyl derivatives have been analyzed. The coupling constants obtained have been utilized to determine the conformation of the five-membered rings. Constancy of the couplings between ring protons throughout the series of compounds indicates the existence of one conformation common to all, and this appears to be a composite of the Cs and C2 forms. It is significant that intramolecular hydrogen bonding, which occurs in two of the three diastereoisomers, has little or no effect on ring conformation.

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