10.1002/anie.202002219
Angewandte Chemie International Edition
COMMUNICATION
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Scheme 4. Proposed catalytic cycle for stereoselective C-F bond alkynylation.
In conclusion, a highly stereoselective Pd-catalyzed C-F
bond alkynylation of tetrasubstituted gem-difluoroalkenes has
been developed. The origin of stereoselectivity presumably stems
from a chelation-assisted oxidative addition of Pd to the C-F bond.
X-ray structure of the monofluorovinyl Pd(II) intermediate has
been obtained for the first time as proof. This method gives
access to a great variety of novel conjugated monofluoroenynes
bearing a tetrasubstituted alkene unit with well-defined geometry.
Their pharmaceutical and materials applications are under
investigation. We are currently exploring other C-C and C-X bond
formations through Pd-catalyzed C-F bond activation involving a
stereoselective oxidative addition process.
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Acknowledgements
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This work was supported by the Research Grants Council of Hong
Kong (CUHK 24301217) and the Chinese University of Hong
Kong (the Faculty Strategic Fund for Research from the Faculty
of Science and the Direct Grant for Research). We also thank the
Key Laboratory of Organofluorine Chemistry, Shanghai Institute
of Organic Chemistry, Chinese Academy of Sciences for funding.
Prof. Jinbo Hu is thanked for the access of some reagents.
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Keywords: C-F bond • palladium • stereoselective • fluoroalkenes
• fluoroenynes
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