Low‐Spin and High‐Spin Perferryl Intermediates in Non‐Heme Iron Catalyzed Oxidations of Aliphatic C−H Groups
作者:Alexandra M. Zima、Oleg Y. Lyakin、Konstantin P. Bryliakov、Evgenii P. Talsi
DOI:10.1002/chem.202004395
日期:2021.5.17
The selectivity patterns of iron catalysts of the Fe(PDP) family in aliphatic C−H oxidation with H2O2 have been studied (PDP=N,N′‐bis(pyridine‐2‐ylmethyl)‐2,2′‐bipyrrolidine). Cyclohexane, adamantane, 1‐bromo‐3,7‐dimethyloctane, 3,7‐dimethyloctyl acetate, (−)‐acetoxy‐p‐menthane, and cis‐1,2‐dimethylcyclohexane were used as substrates. The studied catalyst systems generate low‐spin (S=1/2) oxoiron(V)
研究了Fe(PDP)族铁催化剂在脂族CHH氧化H 2 O 2中的选择性模式(PDP = N,N'-双(吡啶-2-基甲基)-2-2,2'-联吡咯烷)。环己烷,金刚烷,1-溴-3-3,7-二甲基辛烷,3,7-二甲基辛基乙酸酯,(-)-乙酰氧基-对-薄荷烷和顺式1,2-二甲基环己烷用作底物。所研究的催化剂体系会生成低旋转(S = 1/2)的氧代铁(V)中间体或高旋转(S= 3/2)氧代铁(V)中间体,取决于吡啶环上远程取代基的供电子能力。根据测得的自衰变常数和二阶速率常数k 1和k 2,低旋转的perferryl中间体显示出比其高旋转的同类物更低的稳定性和更高的对环己烷的脂肪族CH基团的反应性。。出乎意料的是,氧代铁(V)中间体的自旋态与所考虑的底物氧化中相应催化剂体系的化学和区域选择性之间似乎没有统一的相关性。这与相同催化剂体系的不对称环氧化形成对比,在这种情况下,当从具有较高反应性的低旋转p