초록
Chemical shift values of ${\alpha}$-proton of trans- and cis-methyl cinnamates are well correlated with ${\sigma}({\sigma}_1,\; {{\sigma}_R}^{\alpha})$, and (F, R) (r=0.999-0.879). It is observed that (1) the degree of variation of ${\delta}H_{\alpha}$ value by varying the substituents in trans-cinnamates is similar to that of cis-cinnamates $({\rho}_{trans}=0.296,\;{\rho}_{cis}=0.2840, (2) resonance contribution is larger in the trans-cinnamates than that in the cis-cinnamates, but inductive contribution is reversed, (3) for m-substitued derivatives, resonance contribution is very small compared to that for p-substituted derivatives.