DETERMINATION OF Z-CONFIGURATION AND E-CONFIGURATION IN TRIFLUOROMETHYLATED VINYL COMPOUNDS - 3J(CF) COUPLING-CONSTANTS AS A CRITERION FOR CONFIGURATIONAL ASSIGNMENTS

被引:44
作者
BEGUE, JP [1 ]
BONNETDELPON, D [1 ]
MESUREUR, D [1 ]
OUREVITCH, M [1 ]
机构
[1] CNRS,CERCOA,2 RUE H DUNANT,F-94320 THIAIS,FRANCE
关键词
H-1; NMR; C-13; F-19; T1 AND NOE MEASUREMENTS; TRIFLUOROMETHYLATED VINYL COMPOUNDS;
D O I
10.1002/mrc.1260290707
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
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 beta-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 F-19 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'.
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页码:675 / 678
页数:4
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