Extreme Projection of a Proton into the π-Cloud of an Aromatic Ring: Record Shielding of an Aromatic Proton in <i>trans</i>-10<i>b</i>-Methyl-10<i>c</i>-(1-naphthyl)-10<i>b</i>,10<i>c</i>-dihydropyrene
作者:Yuhua Ting、Yee-Hing Lai
DOI:10.1021/ja038380m
日期:2004.1.28
respectively. Both exhibit a strong diamagnetic ring current despite the introduction of an internal bulky substituent within the pi-electron cloud. Their electronic spectra suggest interaction between the two near-perpendicular naphthyl and dihydropyrenyl pi systems, resulting in red shift and band broadening. All naphthyl protons are well resolved in their 1H NMR spectra due to a strong shielding effect of
采用二硫代间环芳->间环芳二烯->二氢芘的合成顺序制备反式-10b-甲基-10c-(2-萘基)-和反式-10b-甲基-10c-(1-萘基)-10b,10c-分别为二氢芘5和6。尽管在 pi 电子云中引入了内部庞大的取代基,但两者都表现出强大的抗磁环电流。它们的电子光谱表明两个接近垂直的萘基和二氢芘基 pi 系统之间存在相互作用,导致红移和谱带加宽。由于二氢芘环的强屏蔽作用,所有萘基质子在其 1H NMR 光谱中都得到了很好的分辨。5 和 6 中屏蔽程度最高的质子分别是 delta 2.47 和 1.42 处的 H1' 和 H2',与参考质子的偏移量分别为 5.25 和 5.95 ppm。