Effect of α-fluorination on asymmetric epoxidation of trans-olefins using α-fluorinated cyclohexanone dioxiranes
作者:Arlette Solladié-Cavallo、Loı̈c Jierry、Hassan Norouzi-Arasi、Daryush Tahmassebi
DOI:10.1016/j.jfluchem.2004.04.007
日期:2004.9
Curtin–Hammett principle holds. Conformation K2 with axial fluorine having been found to be more reactive, the inversion of configuration observed for the epoxides obtained with ketones 3e–6e (compared with ketones 3a–6a) could be rationalized from competitive reactions of K2 and K1 conformations leading to simultaneous production of both (−) and (+) epoxides in the case of ketones 3e–6e.
的环氧化反-β -甲基苯乙烯,反式-芪和反式-甲基p -methoxycinnamate使用来自α氟环己酮的两个对映体纯非对映体的手性衍生的双环氧乙烷,(2小号,5 - [R - )3a中-图6a和(2 - [R,5 - [R)-研究并比较了3e – 6e。从(6 S,5 R)-D5a和(2 R,5 R)-D5e构象互转换的HF / 6–31G ∗级别的从头算计算发现二恶英类化合物由于α-氟原子,在(2 S,5 R)-D5a的情况下,构象异构体K1更稳定,而在(2 R,5 R)-的情况下,构象异构体K2更稳定。D5e。但是,在两种情况下,更稳定的构象异构体K1和K2都会经历快速的相互转换。因此,基于缓慢的环氧化反应和六元环二氧杂环己酮的快速环反转,科廷-汉密特原理成立。构型K2在发现轴向氟具有更高的反应性的情况下,可以通过K2和K1构象的竞争反应合理化酮3e - 6e(与酮3a - 6a相