S-和R-五味子丙素非对映异构体的圆二色谱研究

园二色谱(CD)是测定有机化合物绝对构型的常用方法。文章用圆二色谱仪对合成的4个联苯类化合物进行了表征(2个非桥键联苯化合物和2个桥键联苯化合物)，得到两对几乎完全对称的圆二色谱谱图。根据其圆二色谱Cotton效应确定了4个化合物的联苯键的绝对构型。化合物3分别在256 nm出现负的Cotton效应，且在220 nm出现正的Cotton效应，表明这个化合物是S-构型;而化合物3’出现了相反的Cotton效应，表明这个化合物是S-构型。由化学相关法可以得知化合物2是R-构型, 化合物2’是R-构型。通过这些数据得出结论, 以S-噁唑啉为手性合成子的Ullmann反应得到的是S-构型联苯类化合物, 而以S-噁唑啉为手性合成子的Ullmann反应得到的是R-构型型联苯类化合物。

Study on the Circular Dichroism of(S)-and(R)-Wuweizisu C

The circular dichroism (CD) is an excellent method for determining the absolute stereochemistry of organic compounds. The CD spectra of four biphenyl compounds were determined by using CD spectrometer, and two pairs of symmetrical CD spectra were obtained. The absolute configuration of biphenyl bond was confirmed by the Cotton effect according to the CD rule. The CD spectrum of compound 3 shows a negative Cotton effect at 256 nm, and a positive Cotton effect at 220 nm, which predicts an S-configuration of biphenyl according to an experimental CD rule. Conversely, the CD spectrum of compound 3＇ displays a positive Cotton effect at 256 nm, and a negative Cotton effect at 219 nm, which predicts an R-configuration of biphenyl. And the regularity of oxazoline-mediated Ullmann reaction was obtained, too.