Ether ethyl isopentenyl

The couplings of vicinal protons in 1,2-disubstituted alkenes lie in the range 6- 12 Hz for cis protons (dihedral angle O ) and 12-17 Hz for trans protons (dihedral angle 180°), thus also following the Karplus-Conroy equation. Typical ejtamples are the alkene proton AB systems of coumarin (16a) (cis) and irans-cinnamic acid (16b), and of the cis-trans isomers 17a and b of ethyl isopentenyl ether, in addition to those in problems 3, 4, 9, 11 and 29. 

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