Solvent Effects on Diastereoselective Intramolecular [2 + 2] Photocycloadditions:  Reversal of Selectivity through Intramolecular Hydrogen Bonding

1997 ◽  
Vol 119 (42) ◽  
pp. 10237-10238 ◽  
Author(s):  
Michael T. Crimmins ◽  
Allison L. Choy
Keyword(s):  
Hydrogen Bonding ◽  
Solvent Effects ◽  
Intramolecular Hydrogen Bonding ◽  
Intramolecular Hydrogen

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.

Resonance and solvent effects on absorption spectra of 2-nitroaniline derivatives

1976 ◽  
Vol 29 (7) ◽  
pp. 1469 ◽  
Author(s):  
T Yokoyama
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Spectral Data ◽  
Absorption Spectra ◽  
Long Range ◽  
Solvent Effects ◽  
Intramolecular Hydrogen Bonding ◽  
Intramolecular Hydrogen

Spectral data for N-methyl-2-nitroaniline correlate well with those for N,N-dimethyl-2-nitroaniline in non-hydrogen-bonding, hydrogen-bond-accepting and amphiprotic alcoholic solvents. This same pattern has been reported for N-methyl-2-nitro-p-toluidine. These results indicate that these N-methyl compounds have no hydrogen bonds with any of the solvents studied and intramolecular hydrogen bonding predominates. In the N.M.R. spectra of such amines, long-range coupling between the H5 (ring) and N-H protons is not necessarily evidence for intramolecular hydrogen bonding.� +M substituents at the 4-position increase the twist of the dimethylamino and 2-nitro groups and enhance the C1 → C2 transition, an effect which follows the order of +M abilities of the 4-substituents.

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