The Relative Signs of the Nuclear Magnetic Resonance Proton-Proton Coupling Constants in Styrene Sulfide and Styrenimine1

1965 ◽  
Vol 87 (10) ◽  
pp. 2220-2225 ◽  
Author(s):  
Stanley L. Manatt ◽  
Daniel D. Elleman ◽  
Stanley J. Brois
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Coupling Constants ◽  
Proton Proton ◽  
Proton Coupling ◽  
Nuclear Magnetic

scholarly journals Carbon-13 nuclear magnetic resonance spectra of oxazoles

1979 ◽  
Vol 57 (23) ◽  
pp. 3168-3170 ◽  
Author(s):  
Henk Hiemstra ◽  
Hendrik A. Houwing ◽  
Okko Possel ◽  
Albert M. van Leusen
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Proton Coupling ◽  
Nuclear Magnetic Resonance Spectra ◽  
C Nmr ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The 13C nmr spectra of oxazole and eight mono- and disubstituted derivatives have been analyzed with regard to the chemical shifts and the various carbon–proton coupling constants of the ring carbons. The data of the parent oxazole are compared with thiazole and 1-methylimidazole.

A 1H and 13C nuclear magnetic resonance study of nucleosides with methylated pyrimidine bases

1982 ◽  
Vol 60 (24) ◽  
pp. 3026-3032 ◽  
Author(s):  
Frank E. Hruska ◽  
Wayne J. P. Blonski
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Magnetic Resonance Data ◽  
Proton Coupling ◽  
13C Nuclear Magnetic Resonance ◽  
Pyrimidine Bases ◽  
Nuclear Magnetic

Alkylated pyrimidine bases are of interest from the viewpoint of mutagenesis and carcinogenesis. 1H nuclear magnetic resonance data are presented for a series of ribosides and arabinosides alkylated at the O2,O4, N3, and C5 positions of the pyrimidine base. The data provide information about the stereochemical effects of base methylation. The J(5—6) proton coupling constants show that O-alkylation leads to a decrease in the π-bond order of the C5—C6 bond. The 13C chemical shifts are related to the tautomeric changes effected by O-alkylation.

An NMR study of steric and hyperconjugative barriers in benzyl X(CH3)3, X = C, Si, Ge, Sn, Pb

1989 ◽  
Vol 67 (8) ◽  
pp. 1283-1287 ◽  
Author(s):  
Ted Schaefer ◽  
Glenn H. Penner ◽  
Craig S. Takeuchi ◽  
Christian Beaulieu
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Long Range ◽  
Coupling Constant ◽  
Proton Proton ◽  
Proton Coupling ◽  
Nmr Study ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The 1H nuclear magnetic resonance spectra and their analyses are reported for benzyltrimethyl X (X = C, Si, Ge, Sn, Pb) and for the 2,6-dichloro derivatives where X = Si, Ge, Sn, Pb. The steric barrier to rotation about the Csp2—Csp3bond for X = C, based on the long-range proton–proton coupling constant over six bonds, 6J(H,CH2), must be greater than 20 kJ/mol. Unexpectedly, 6J(H,CH2) implies that the barriers for X = Si, Ge, Sn, Pb have relatively minor steric components. If these barriers are dominated by hyperconjugative interactions of the C—X bond with the aromatic π system, then they are probably mainly twofold in nature. Furthermore, their magnitude is likely to be near 9.5 kJ/mol for X = Si, Ge, Sn and may be as high as 12 kJ/mol for X = Pb. Keywords: NMR, benzyl X(CH3)3, X = C, Si, Ge, Sn, Pb; NMR, conformations; NMR, hyperconjugation.

Nucleosides. XLIX. Nuclear magnetic resonance studies of 2′-and 3′-halogeno nucleosides. The conformations of 2′-deoxy-2′-fluorouridine and 3′-deoxy-3′-fluoro-β-D-arabinofuranosyluracil

1968 ◽  
Vol 46 (7) ◽  
pp. 1131-1140 ◽  
Author(s):  
Robert J. Cushley ◽  
John F. Codington ◽  
Jack J. Fox
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Proton Proton ◽  
Pyrimidine Nucleosides ◽  
Magnetic Resonance Data ◽  
Twist Conformation ◽  
Resonance Data ◽  
Nuclear Magnetic

Nuclear magnetic resonance data for a series of 2′-halogeno and 3′-halogeno pyrimidine nucleosides are presented. Using a combination of proton–proton and proton–fluorine couplings vs. dihedral angle values 2′-deoxy-2′-fluorouridine is proposed to have an envelope conformation with C–3′ endo, and 1-(3-deoxy-3-fluoro-β-D-arabinofuranosyl)uracil proposed to have a twist conformation with O-ring endo and C–1′ exo. Correlations between substituent electronegativity and both vicinal coupling constants and internal chemical shifts are discussed.Syntheses of several new 2′-halogeno and 3′-halogeno nucleosides are described.

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