10.1002/anie.201908556
Angewandte Chemie International Edition
COMMUNICATION
In conclusion, we have developed a visible-light-mediated
silane chlorination catalyzed by neutral eosin Y, using DCM as
both
a chlorinating agent and the solvent media. This
transformation accommodates a wide range of silanes, achieving
products with exclusive SiH activation in the presence of
activated CH bonds. This protocol is also distinguished by its
operational simplicity, metal-free character, use of ambient
conditions, green reagents, and delivery of quantitative yields in
most cases, and can be directly streamlined with a sequential
transformation. A highly selective stepwise chlorination of di- and
trihydrosilanes was achieved assisted by the unique advantages
of continuous-flow micro-tubing reactors. More importantly, the
neutral eosin Y-based HAT provides a very convenient and green
approach for the generation of silicon radicals under visible-light
irradiation, which promise to find wide applications in the
synthesis of valuable silicon compounds in both academic and
industrial settings.
Acknowledgements
We are grateful for the financial support provided by the Ministry
of Education (MOE) of Singapore (MOE2017-T2-2-081), GSK-
EDB (R-143-000-687-592), National Natural Science Foundation
of China (Grant No. 21702142, 21871205, 21425313) and the
National University of Singapore (Suzhou) Research Institute.
Scheme 5. Proposed mechanism and supporting evidence.
The synthetic value of this straightforward photo-mediated
silane chlorination was further demonstrated by one-pot synthesis
of various types of valuable compounds. As illustrated in Scheme
6, the crude DCM solution of silane chlorination could be directly
utilized in subsequent transformations for silanol synthesis (path
a), alcohol protection (path b), silyl enol ether formation (path c),
silylation of nitroalkanes (path d), alkyne protection (path e), and
phenyl silylation (path f), achieving products in good to excellent
yields in all cases.
Keywords: hydrogen atom transfer • SiH activation • neutral
eosin Y • silyl chloride • dichloromethane
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