Lithiated anions derived from (alkenyl)pentamethyl phosphoric triamides: an accurate study of the carbanion formation mechanism
作者:Claude Grison、Antoine Thomas、Frédéric Coutrot、Philippe Coutrot
DOI:10.1016/j.jorganchem.2004.02.003
日期:2004.5
The mechanism of the formation of lithiated carbanions derived from (alkenyl) pentamethyl phosphoric triamides has been elucidated. Whereas a few initial ambident allylphosphoramide anion was formed with n-BuLi, both reversible α-reprotonation and not reversible γ-reprotonation simultaneously occurred as a result of the reaction between the ambident carbanion formed and the starting enephosphoramide
已经阐明了衍生自(烯基)五甲基磷酸三酰胺的锂化碳负离子形成的机理。正丁基环磷酰胺形成了一些初始的环境型烯丙基磷酰胺阴离子,但由于形成的环境碳负离子与起始的烯磷酰胺之间的反应,可逆的α-质子化和不可逆的γ-质子化同时发生。这种自动催化过程部分地导致转位的烯丙基磷酰胺异构体。在被α-苯基取代的情况下,转位的磷酰胺不是难事,因为它会与n一起在原位进行γ-去质子化。-BuLi仍然存在,最后提供了预期的环境负离子。用α-甲基和α-丙基取代后,在自催化过程中形成的转位烯磷酰胺未进行γ-去质子化,因此不利于目标环境碳负离子的制备。在这些最后的情况下,适应的实验条件避免了自催化过程,并允许制备相应的阴离子。