Chemical shift nonequivalence in proton magnetic resonance spectra of glycyl peptides

1967 ◽  
Vol 89 (13) ◽  
pp. 3107-3111 ◽  
Author(s):  
Vito J. Morlino ◽  
Robert Bruce. Martin
Keyword(s):  
Magnetic Resonance ◽  
Chemical Shift ◽  
Proton Magnetic Resonance ◽  
Magnetic Resonance Spectra

Proton Magnetic Resonance Spectra of Some Substituted 2-Acylamino-3-arylamino-1,4-naphthoquinones

1976 ◽  
Vol 31 (2) ◽  
pp. 261-263 ◽  
Author(s):  
N. L. Agarwal ◽  
R. L. Mttal
Keyword(s):  
Magnetic Resonance ◽  
Chemical Shift ◽  
Proton Magnetic Resonance ◽  
Substitution Pattern ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of a number of substituted 2-acylamino-3-arylamino-1,4-naphthoquinones have been measured and discussed. The effect of various substitution pattern and hetero atoms on the chemical shift values of N-acylmethyl protons have been studied and explained.

Sulfur-free penicillin derivatives. VII. Multiple functionalization of 2-azetidinyl-3-methyl-2-butenoates

1982 ◽  
Vol 60 (2) ◽  
pp. 144-153 ◽  
Author(s):  
Saul Wolfe ◽  
Chia-Cheng Shaw
Keyword(s):  
Magnetic Resonance ◽  
Chemical Shift ◽  
Nitrogen Atom ◽  
Proton Magnetic Resonance ◽  
Methylene Chloride ◽  
Methyl Groups ◽  
Reliable Criterion ◽  
Geometrical Isomers ◽  
Methoxycarbonyl Group ◽  
Magnetic Resonance Spectra

The title compounds, substituted with chlorine in the 4′-position and with phthalimido, 2,2,2-trichloroethoxycarbonylamino, or phenoxycarbonylamino in the 3′-position of the azetidinone ring, have been converted to bis-allylic formates via bromination of both methyl groups with excess N-bromosuccinimide, and displacement of both bromines by formate ions in methylene chloride solvent. The diformates react smoothly with a deficit of a boron halide to form E/Z mixtures of halogeno-formates, in which the E-isomer predominates. Depending on the 3′-azetidinyl substituent, these halogeno-formates undergo a second displacement with acetate either with retention of olefinic geometry or inversion of olefinic geometry. The mechanisms of these reactions are discussed, along with further transformations leading to hydroxylactones, halogenolactones, halogenohydrins, and other compounds. Examination of the proton magnetic resonance spectra of twenty-one compounds reveals that methylene protons cis to the β-lactam nitrogen atom of a methyl 2-azetidinyl-2-butenoate are found at higher field than methylene protons cis to the methoxycarbonyl group. This observation appears to provide a more reliable criterion for the assignment of configuration to geometrical isomers than one based on the magnitude of the chemical shift nonequivalence of the E and Z methylene protons.

Effect of N-acylamino groups on the chemical shift of the ortho proton in biphenyls

1969 ◽  
Vol 47 (7) ◽  
pp. 1151-1156 ◽  
Author(s):  
F. K. Hess ◽  
K. H. Pook
Keyword(s):  
Magnetic Resonance ◽  
Chemical Shift ◽  
Proton Magnetic Resonance ◽  
Lower Field ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of several acylamino biphenyls were determined. Evidence was obtained that the proton adjacent to the acylamino group was shifted to lower field relative to the remaining ring protons.

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