n-π Interaction between an oxygen lone pair and π-electrons in cyclic allylic alcohols and ethers; carbon-13 nuclear magnetic resonance spectra, catalytic hydrogenation, and CNDO/2 calculations

1982 ◽  
pp. 71-76 ◽  
Author(s):  
Jun-ichi Ishiyama ◽  
Yasuhisa Senda ◽  
Shin Imaizumi
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Catalytic Hydrogenation ◽  
Lone Pair ◽  
Allylic Alcohols ◽  
Nuclear Magnetic Resonance Spectra ◽  
Oxygen Lone Pair ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

Diastereoisomeric 2-aryl-6-methyl-3,4 (1,2-piperido)-oxazines

1968 ◽  
Vol 46 (7) ◽  
pp. 1105-1111 ◽  
Author(s):  
G. A. Cooke ◽  
G. Fodor
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Catalytic Hydrogenation ◽  
Optically Active ◽  
The Other ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The alkaloid sedridine (1) is formed stereospecifically by catalytic hydrogenation of optically active α-picolyl methyl carbinol (2). The levorotatory 1 gave on action of p-nitro benzaldehyde two μ-aryl oxazines, one crystalline and levorotatory, the other oily and dextrorotatory. This is the first example where both epimers of a μ-aryl oxazine could be detected. The configurations and the conformations of these isomers (10 and 11) and those of sedridine have been discussed in terms of their nuclear magnetic resonance spectra, with particular reference to spin-decoupling evidence.

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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