Nuclear magnetic resonance spectra of cyclic amines. Shielding of .alpha. protons trans to a lone pair and cis to an N-methyl group in pyrrolidines

1973 ◽  
Vol 38 (8) ◽  
pp. 1601-1602 ◽  
Author(s):  
Eli Breuer ◽  
David Melumad
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Lone Pair ◽  
Methyl Group ◽  
Cyclic Amines ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

A Study of the Proton Nuclear Magnetic Resonance Spectra of Aryl and Mono- and Disubstituted N-Methylazoles

1973 ◽  
Vol 51 (14) ◽  
pp. 2315-2322 ◽  
Author(s):  
Richard Noel Butler
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Structural Characteristics ◽  
Proton Nuclear Magnetic Resonance ◽  
Methyl Group ◽  
Nuclear Magnetic Resonance Spectra ◽  
Azole Ring ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

Proton n.m.r. spectra of 111 substituted azoles are compared. The influence of the azole ring on the chemical shifts of substituent phenyl protons is discussed. A correlation between N-methyl chemical shifts and the structural characteristics of the N-methyl group in mono- and disubstituted azoles is noted.

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.

Nuclear magnetic resonance spectra of α,β,β-trimethylstyrenes

1966 ◽  
Vol 19 (9) ◽  
pp. 1667 ◽  
Author(s):  
GP Newsoroff ◽  
S Sternhell
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Aromatic Ring ◽  
Coupling Constants ◽  
Methyl Group ◽  
Nuclear Magnetic Resonance Spectra ◽  
Benzene Rings ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

N.m.r, data for 14 α,β,β-trimethylstyrenes are given. The aromatic ring shields the β-methyl group cis to it relative to the β-methyl group trans to it. The magnitude of this relative shielding is greatest with ortho-substituted benzene rings. The cisoid homoallylic coupling constants in α,β,β-trimethylstyrenes (and indeed in all examples available from the literature) are smaller than the transoid homoallylic coupling constants.

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