ISSN:
0749-1581
Keywords:
1H NMR, 13C NMR, 19F NMR
;
T1 and NOE measurements
;
Trifluoromethylated vinyl compounds
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
NOE and T1 proton measurements were carried out in order to determine unambiguously the Z and E configurations of some CF3-trisubstituted vinylic compounds (HCR—CR′CF3). The β-ethylenic carbon in olefins, enol ethers and enamines is always more strongly coupled to CF3 in the cis compound (CF3 and the vinylic proton cis to each other): |3J(CF)|cis 〉 |3J(CF)|trans. This observation, in addition to the already known higher shielding of 19F NMR signal in the cis isomer, allows the safe assignments of Z and E isomers even when only one is obtained, regardless of the nature of R and R′.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260290707
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