Conformational studies of d(AAAAATTTTT)2 using constraints from nuclear Overhauser effects and from quantitative analysis of the cross-peak fine structures in two-dimensional proton nuclear magnetic resonance spectra

Biochemistry ◽  
1989 ◽  
Vol 28 (4) ◽  
pp. 1462-1471 ◽  
Author(s):  
Bernardo Celda ◽  
Hans Widmer ◽  
Werner Leupin ◽  
Walter J. Chazin ◽  
William A. Denny ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Quantitative Analysis ◽  
Magnetic Resonance ◽  
Proton Nuclear Magnetic Resonance ◽  
Two Dimensional ◽  
Conformational Studies ◽  
Nuclear Magnetic Resonance Spectra ◽  
Fine Structures ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects

Assignments of configuration by nuclear Overhauser effects in some dibenzthiepin derivatives

1970 ◽  
Vol 48 (4) ◽  
pp. 633-640 ◽  
Author(s):  
Robert R. Fraser ◽  
Francis J. Schuber
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Lone Pair ◽  
Remarkable Similarity ◽  
Nuclear Magnetic Resonance Spectra ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects ◽  
Sulfoxide Group ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The configuration of the benzylic protons responsible for each absorption in the nuclear magnetic resonance spectra of 1,11-dimethyl-5,7-dihydrodibenz(c,e)thiepin and its S-oxide and S-dioxide have been determined by nuclear Overhauser experiments. Successful application of the method was achieved by using partially deuterated derivatives for the purpose of removing undesirable relaxation mechanisms between protons. Triple irradiation of doublets was also usefully employed. The sulfoxide assignments arrived at herein reverse the tentative assignments put forth by us (1). It is noteworthy that all experiments on the sulfoxide failed when CDCl3 was used as solvent. In DMSO normal nuclear Overhauser effects were seen, presumably since sulfoxide dimers are not formed in this solvent. The sulfonium perchlorate derivative of the thiepin was also synthesized. The remarkable similarity of its n.m.r. spectrum to that of the sulfoxide is interpreted as evidence that the effect of the sulfoxide group on the shifts of neighboring protons is due primarily to the "lone pair" on sulfur.

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