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.