Nickel‐Catalyzed Transfer Hydrogenation of Unactivated Aryl Alkenes with Hydrosilane as Hydrogen Source

Abstract

A nickel‐catalyzed transfer hydrogenation of aryl alkenes has been developed using hydrosilane as the hydrogen source. Sterically hindered disubstituted or trisubstituted alkenes were employed to test the efficiency of this transformation. Mechanism studies showed that hydrogenation took place smoothly with more sterically‐hindered trans‐alkenes. While uncongested cis‐alkenes could hardly convert to the alkanes but hydrosilylation products were generated instead. Moreover, certain amount of water was found to be a promotion for the protonation process and could partly serve as the hydrogen source. Not only for simple stilbenes, this easy handle protocol also showed tolerance for substrates involving other unsaturated groups as well as heterocycles.

Ultrasmall Nickel Nanoparticles on a Covalent Triazine Framework for Ammonia Borane Hydrolysis and Transfer Hydrogenation of Nitroaromatics

“…The chemically stored hydrogen can be released by the use of a catalyst to kinetically favor H 2 evolution under mild experimental conditions up to 3 mol of H 2 per mole of AB (eq ) normalH 3 N − B normalH 3 + 2 normalH 2 O → 3 H 2 ↑ + normalN H 4 normalB O 2 AB is also the reducing agent for a wide range of applications, spanning from the reductive transformation of unsaturated organic compounds to biomass refinement and fuel production up to the synthesis of pharmacologically active compounds and commodities . Most of these reduction processes make use of pressurized molecular hydrogen gas for the direct substrate hydrogenation (DH) or liquid hydrogen sources such as alcohols, formic acid, and hydrosilanes for transfer hydrogenation (TH) processes. Conventionally, reactions carried out with molecular dihydrogen gas (DH) require specialized equipment for pressurized and flammable gas manipulation that poses a number of safety concerns.…”