论文部分内容阅读
6-取代-1,4-环辛二烯与单重态氧立体有选择地氧化成顺式5,8-和反式5,6-二取代-1,3-环辛二烯的含氧衍生物。依据产物的分子结构推知,6-取代-1,4-环辛二烯发生“ene”反应时的优势构象不同于环辛烷,而是具有角张力的扭曲构象(Ⅰ),这为研究环烯的分子构象提供了一种实验方法。用Monroe法测定了6-取代-1,4-环辛二烯对单重态氧反应的β值。其反应活性顺序为:3>1>4>1,5-环辛二烯>2>5。表明推电子取代基增加了同单重态氧反应的能力,而吸电子取代基则降低了同单重态氧的反应能力。但是不论取代基性质如何,都不能改变“ene”反应的本质。
The oxygen of the 6-substituted-1,4-cyclooctadiene and the singlet oxygen is selectively oxidized to the oxygen of the cis 5,8- and trans 5,6-disubstituted 1,3-cyclooctadiene derivative. According to the molecular structure of the product, the dominant conformation of 6-substituted-1, 4-cyclooctadiene in “ene” reaction is different from that of cyclooctane but with a distorted configuration of angular tension (Ⅰ) The molecular conformation of olefins provides an experimental method. The β value of 6-substituted-1,4-cyclooctadiene for singlet oxygen reaction was measured by Monroe method. The reaction sequence is: 3> 1> 4> 1,5-cyclooctadiene> 2> 5. The electron-donating substituents increase the ability to react singlet oxygen while the electron-withdrawing substituents reduce the ability to react with singlet oxygen. But no matter the nature of the substituent, it can not change the nature of the “ene” reaction.