B环对位取代异黄酮化合物的核磁共振研究

~1H NMR Studies on Synthetic Isoflavones with p-Substituents on B Ring

对 1 4个合成的 B环对位取代异黄酮化合物核磁共振氢谱进行了研究 .利用超导核磁共振归属了 B环无取代异黄酮质子的化学位移 ,根据取代基化学位移的变化影响规律考察了取代基对分子的影响方式 .研究结果表明 ,2 ( 6 ) ,3 ( 5 )位质子共振迁移分别与取代基参数σp 和 So 线性相关 ,说明 4 位取代基主要通过电子效应影响其间位质子 ,其磁各向异性仅影响邻位质子 ,该取代基对 A环质子影响不大 ,而对 C环尤其是对 2 -H影响较明显 .

In this paper, 1H NMR study on fourteen isoflavones with various p substituents on B ring is reported. The effects of substituents on the chemical shifts of A, B and C ring protons are discussed. Unambiguous assignments of unsubstituted B ring 1H resonance spectra were made with the aid of superconductive NMR spectroanalysis. There is a linear relationship between the chemical shifts of B ring protons and the substituent parameters. The chemical shifts of 2(6) 1H and 3(5) 1H show a linear correlation with Hammett constants σ p and substituent parameter S 0 respectively. The resonance shifts of 3(5) 1H arise from the electron and magnetic anisotropy effects, while the resonance shifts of 2(6) 1H respond to the electron effects of the substituents primarily.