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.

Resolution of 4-aminoflavan into its optical isomers; nuclear magnetic resonance spectra of 4-aminoflavan and 3-aminoflavanone derivatives

1970 ◽  
Vol 23 (10) ◽  
pp. 2015 ◽  
Author(s):  
R Bognar ◽  
JW Clark-Lewis ◽  
A Liptakne-Tokes ◽  
M Rakosi
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Fractional Crystallization ◽  
Catalytic Hydrogenation ◽  
Optically Active ◽  
Sulphonic Acid ◽  
Trans Configuration ◽  
Optical Isomers ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra

(�)-2,4-cis-4-Aminoflavan obtained by reduction of 4-oximinoflavan has been resolved into enantiomeric forms by fractional crystallization of its amine salts with (+)-camphor-10-sulphonic acid and with (-)-di-O-benzoyltartaric acid. The pairs of diastereoisomeric salts thus separated were converted into (+)- and (-)-2,4-cis-4-aminoflavan hydrochlorides, from which the free bases and the optically active N-acetyl and N-benzoyl derivatives were prepared. N.m.r. data unequivocally establish the 2,4-cis configuration of all these 4-substituted flavan derivatives. 3-Aminoflavanone prepared by the Neber rearrangement of 4-oximinoflavan, and also by controlled catalytic hydrogenation of 3-oximinoflavanone, is shown from N.M.R. data on suitable derivatives to have the 2,3-trans configuration.

Studies of specifically fluorinated carbohydrates. Part VI. Some pentofuranosyl fluorides

1970 ◽  
Vol 48 (7) ◽  
pp. 1155-1165 ◽  
Author(s):  
L. D. Hall ◽  
P. R. Steiner ◽  
C. Pedersen
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Coupling Constants ◽  
The Other ◽  
Nuclear Magnetic Resonance Spectra ◽  
Ring Conformations ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

Detailed analyses of the 1H and 19F nuclear magnetic resonance spectra of seven pentofuranosyl fluoride derivatives are reported. With the help of 1H-{19F} heteronuclear decoupling experiments, some unexpectedly large 4J couplings have been detected between F and H-4; when these substituents are trans the coupling is 5.5–7.9 Hz while the cis relationship gives couplings of 1.0–1.8 Hz. The 4J couplings between F and H-3 are smaller when these groups are trans (< 0.7 Hz) than when they are cis oriented (1.7–2.4 Hz). These, and the other coupling constants are discussed in terms of the favored conformations of these derivatives. The ring conformations of the anomeric tri-O-benzoyl-D-ribo-furanosyl fluorides differ from each other.

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