Syngas Instead of Hydrogen Gas as a Reducing Agent─A Strategy To Improve the Selectivity and Efficiency of Organometallic Catalysts
Catalytic reduction reactions play a major role in modern chemistry and are often based on hydrogen gas as a reducing agent. However, the high reactivity of hydrogen is often accompanied by low selectivity on the simple catalysts. Herein, we showed that the usage of syngas as a reducing agent can be a more efficient and selective strategy. Based on control experiments, a plausible mechanism was proposed to explain the superior performance of syngas. The versatility of this approach was demonstrated by successful application to three reactions using different metal catalysts: direct reductive amination, reductive esterification, and the tandem CH-reductive alkylation-hydrolysis-decarboxylation. Catalyst turnover numbers up to 30,000 were achieved. Moreover, the developed strategy showed improved selectivity and functional group compatibility as compared to the use of hydrogen gas.