论文部分内容阅读
环硫乙烷与它的氧类似物环氧乙烷和氮类似物氮杂环丙烷一样,是一类重要的有机合成中间体,在医药和农用化学品工业领域也得到广泛应用。通过开环和异构化反应,还广泛用于制备硫醇和硫醚等含硫化合物。本文总结了常用亲核试剂对非对称环硫乙烷的亲核开环反应及其区域选择性。环硫乙烷的亲核开环反应通常只受空间效应影响,亲核试剂进攻非对称环硫乙烷位阻小的碳原子,对于烯基取代的环硫乙烷有时可以进攻烯基的β碳原子发生SN2’开环反应。强亲核性的亲核试剂容易致使环硫乙烷脱硫生成烯烃,而亲核性相对较弱的亲核试剂容易发生多聚反应生成多硫醚。在Lewis酸存在下,电子效应会对开环反应的区域选择性产生影响,甚至起主导作用。虽然烷基取代环硫乙烷在Lewis酸存在下的开环仍然主要发生在其取代基少的碳原子上(位阻控制),但受电子效应影响,芳基和烯基取代环硫乙烷的亲核开环,其亲核试剂一般倾向于进攻环硫乙烷的芳甲位和烯丙位碳原子(电子效应控制)。
Like its oxygen analogues ethylene oxide and nitrogen aziridine, ethylene sulfide is an important class of organic synthesis intermediates and is widely used in the pharmaceutical and agrochemical industries. Through the ring-opening and isomerization reactions, it is also widely used to prepare sulfur-containing compounds such as mercaptans and thioethers. This review summarizes the nucleophilic ring-opening reactions and regioselectivities of common nucleophiles for asymmetric ethylene sulfide. The nucleophilic ring-opening reaction of ethylene sulfide is usually only affected by the steric effect, and the nucleophilic agent attacks the carbon atom with asymmetric disulfide-resistance. Sometimes it is possible to attack the alkenyl β SN2 ’carbon atom ring opening reaction. Strongly nucleophilic nucleophile easily lead to ethylene sulfide desulfurization to generate olefins, while the nucleophile relatively weak nucleophilic reagents prone to poly-sulfide reaction. In the presence of Lewis acids, the electron effect will have an influence on the regioselectivity of the ring-opening reaction and may even play a leading role. Although the alkyl-substituted ethylene sulfide in the presence of Lewis acid ring opening still occurs mainly in the few substituents on the carbon atoms (steric control), but by the electronic effect, the aryl and alkenyl substituted ethylene sulfide Nucleophilic ring opening, and its nucleophiles generally tend to attack the aryl and allylic carbon atoms of epichlorohydrin (electron effect control).