Highly Active Nickel Catalysts for C–H Functionalization Identified through Analysis of Off-Cycle Intermediates

An
inhibitory role of 1,5-cyclooctadiene (COD) in nickel-catalyzed
C–H functionalization processes was identified and studied.
The bound COD participates in C–H activation by capturing the
hydride, leading to a stable off-cycle π-allyl complex that
greatly diminished overall catalytic efficiency. Computational studies
elucidated the origin of the effect and enabled identification of
a 1,5-hexadiene-derived pre-catalyst that avoids the off-cycle intermediate
and provides catalytic efficiencies that are superior to those of
catalysts derived from Ni­(COD)2.

本研究鉴定并探究了1,5-环辛二烯（1,5-cyclooctadiene，COD）在镍催化C–H官能化反应中的抑制作用。配位结合的COD可通过捕获氢化物配体参与C–H活化过程，生成稳定的脱循环π-烯丙基配合物，大幅降低整体催化效率。计算研究阐明了该抑制效应的起源，并成功筛选出一种1,5-己二烯衍生的预催化剂——该催化剂可规避脱循环中间体，其催化性能优于由Ni(COD)₂衍生得到的催化剂。