Formation of a Cationic Vinylimido Group upon C-H Activation of Nitriles by Trialkylamines in the Presence of TaCl5.
Formation of a Cationic Vinylimido Group upon C-H Activation of Nitriles by Trialkylamines in the Presence of TaCl5.
复制标题
TaCl5 存在下，三烷基胺对腈进行 C-H 活化，形成阳离子乙烯基酰亚胺基团。
作者：
Md. Mamdudur Rahman;Mark D. Smith;D. V. Peryshkov
我们报道了一种新的CH3CN活化模式，其中通过与高刘易斯酸性Ta(V)中心配位的腈去质子化直接形成亚胺基。意想不到的NEt3对TaCl5（CH3CN）的去质子作用导致三乙基乙烯基配合物[HNEt3][Ta(NC(CH2)NEt3)Cl5]的分离。该反应是通过最初的亲核碳离子重排到亲电的氮杂烯/碳阳离子中间体来进行的。使用更具空间阻碍的（i-Pr）CN和弱亲核性的N(i-Pr)2Et分离出由去质子化腈二聚化形成的乙烯基，表明去质子化是转化的第一步。
We report a new CH3CN activation mode where an imido group is directly formed by deprotonation of the nitrile coordinated to the highly Lewis acidic Ta(V) center. The unexpected deprotonation of TaCl5(CH3CN) by NEt3 resulted in isolation of the triethylammonium vinylimido complex [HNEt3][Ta(NC(CH2)NEt3)Cl5]. The reaction is proposed to proceed through rearrangement of the initial nucleophilic carbanion to the electrophilic azaallene/carbocation intermediate. The use of more sterically hindered (i-Pr)CN and weakly nucleophilic N(i-Pr)2Et resulted in the isolation of a vinylimido group formed upon dimerization of deprotonated nitriles, suggesting deprotonation as the first step of the transformation.