Abstract
Diastereoisomers of the 1,3-dienes RCMeCMeCMeCMeR (2, RCO2CH3; 7, RCH2OCH3) have been prepared. The configurations at the CC bonds (Schemes 2 and 3) and the conformations of these chiral dienes were investigated by several spectroscopic methods. The barriers to partial rotation about the central CC single bond in (E,E)-, (E,Z)-, and (Z,Z)-2 were determined by dynamic 1H NMR in the presence of the ...
Abstract
Diastereoisomers of the 1,3-dienes RCMeCMeCMeCMeR (2, RCO2CH3; 7, RCH2OCH3) have been prepared. The configurations at the CC bonds (Schemes 2 and 3) and the conformations of these chiral dienes were investigated by several spectroscopic methods. The barriers to partial rotation about the central CC single bond in (E,E)-, (E,Z)-, and (Z,Z)-2 were determined by dynamic 1H NMR in the presence of the optically active lanthanide complex (+)-Eu(hfbc)3. The ΔG≠-values (Table 6) allow conclusions to be drawn about the structure of the s-trans transition state of rotation.
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