C(sp³)–H Selective Benzylic Borylation by In Situ Reduced Ultrasmall Ni Species on CeO₂

Abstract

Herein, we report that highly dispersed Ni hydroxide species supported on CeO2 act as an efficient heterogeneous catalyst for the selective borylation of benzylic C­(sp3)–H bonds of alkylarenes including secondary derivatives, using pinacolborane as the borylating agent. A thorough physicochemical analysis reveals that in situ reduced ultrasmall Ni species on CeO2 during the reaction are the actual active species responsible for the borylation.

Selective Nickel‐Catalyzed Hydrodeacetoxylation of Aryl Acetates

“…However, unexpectedly with 3 b also a significant amount of hydrogen‐deuterium exchange was observed in the propyl chain. Aromatic and benzylic H/D exchange with Ni 0 and HBpin are reported in literature [21, 22] . Benzylic C(sp 3 )−H activation followed by β‐hydride elimination and reinsertion of Ni−H explain the observed methylene deuteration further in the propyl chain.…”

“…Aromatic and benzylic H/D exchange with Ni 0 and HBpin are reported in literature. [21,22] Benzylic C(sp 3 )À H activation followed by β-hydride elimination and reinsertion of NiÀ H explain the observed methylene deuteration further in the propyl chain. These competitive reactions in the alkyl chain offer an explanation for the lower conversion of 3 b compared to conversion of 3 s. Similar results were obtained for 4-propylguaiacyl acetate (3 a) when using DBpin (see Supporting Information section 7).…”

Pd(II)−Catalyzed Non‐Directed Benzylic C(sp3)−H Activation: Cascade C(sp3)−S Bond Cleavage to Access Benzaldehydes from Benzylphenyl Sulfides and Sulfoxides

“…developed a novel protocol for Pd(0)−catalyzed oxidative carbonylation of non‐directed benzylic C(sp 3 )−H bond [5] . Although significant progress has been made on chelation‐induced benzylic C(sp 3 )−H bond functionalization, [6] non‐directed benzylic C(sp 3 )−H bond functionalization is still less explored and a few of them were pioneered by Hiyama, [7a] Li, [7b] Landais, [7c] Chen, [7d] Chirik, [7e] Lei, [7f] Pandey, [7g] Xing, [7h] White, [7i] Takemoto, [7j] Qing, [7k] Shi, [7l] Wu, [7m] Bolm [7n] and Yamaguchi [7o] for Heck‐type couplings with diverse electrophiles (Scheme 1).…”

Contribution of Different Species in Ni‐Ceria Nanorods Catalysts Applied to Steam Reforming of Ethanol

“…These surface effects become more important for low Ni loadings. Recent studies have investigated Ni loadings equal to [44] and less [45] than 3 % supported on CeO 2 for other classes of reactions, and have observed that under oxidizing conditions, the Ni species were very reactive but deactivated quickly due to oxidation.…”