Mechanism of 8-Aminoquinoline-Directed Ni-Catalyzed C(sp<sup>3</sup>)–H Functionalization: Paramagnetic Ni(II) Species and the Deleterious Effect of Carbonate as a Base
作者:Junyang Liu、Samuel A. Johnson
DOI:10.1021/acs.organomet.1c00265
日期:2021.9.13
NMR as [AQpiv]Ni(O2CtBu)L (5·L) and equilibrium reformation of 3 and 6·L. DFT calculations support this equilibrium in solution. Both 3 and 5 undergo C–H activation at temperatures as low as 80 °C and in the presence of PR3 (PR3 = PPh3, PiBu3) to give Ni(C9NH6NCOCMe2CH2-κN,N,C)PR3 (7·PR3). The C–H functionalization reaction orders with respect to 7·PiBu3, iodoarenes, and phosphines were determined.
研究了 8-氨基喹啉导向的镍催化 C(sp 3 )-H 与碘芳烃的芳基化机理,以确定催化剂的静止状态并优化催化性能。顺磁性配合物经历关键的 C-H 激活步骤。发现无处不在的碱 Na 2 CO 3会阻碍催化;在较温和的条件下,用 NaO t Bu替代 Na 2 CO 3提高了催化转化率。使用 NaH 在酰胺氮处对8-氨基喹啉衍生物N- (quinolin-8-yl)pivalamide ( 1a ) 进行去质子化,然后与 NiCl 2 (PPh 3 ) 2 反应允许分离复合物 Ni([AQ piv ]-κ N , N ) 2 ( 3 ) 与螯合 N 供体(其中 [AQ piv ] = C 9 NH 6 NCO t Bu)。配合物3是一个四配位的蝶形高自旋 Ni(II) 配合物,不包括短的 Anagostic Ni-- t Bu 氢相互作用。配合物3与桨轮反应 [Ph 3 PNi(μ-CO 2