10.1002/anie.202008138
Angewandte Chemie International Edition
COMMUNICATION
underwent cyclization to the more thermodynamically stable
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mixture was determined as ~1:2 (Scheme 3C). On the basis of
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the above results,
a
plausible mechanism for the
decarboxylative borylation is illustrated (Scheme 3A). The
transformation is initiated by the irritation of photocatalyst Ir(III)
to Ir(III)* and the activation of NHBC ester releases benzonitrile,
chloride, CO2 and generates trifluormethyl cyclobutyl radical.
The HMPA binds to the boron centers of B2cat2 and forms a
heteroleptic complex. This species captures the alkyl radical to
generate the desired boronic ester 7 and cleavage of the B–B
bond forms the HMPA-stabilized boryl radical. This intermediate
is then oxidized to a neutral complex and terminates the radical
chain. Further Stern-Volmer quenching experiment is performed
and quantum yield measurement shows that a radical chain
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Acknowledgements
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We gratefully acknowledge the financial support from the
National Natural Science Foundation of China (Nos. 21772085,
21971107) and the Fundamental Research Funds for the
Central Universities (Nos. 020514380220, 020514380131,
020514913412, 020514913214). We also thank Collaborative
Innovation Center of Advanced Microstructures and Jiangsu
Provincial Key Laboratory of Photonic and Electronic Materials
at Nanjing University for support.
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Keywords: borylation • photoredox • inert radicals• imidoyl
chloride
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