10.1002/anie.201906283
Angewandte Chemie International Edition
COMMUNICATION
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methylbenzaldehyde and 2-bromobenzaldehyde afforded 8b
and 8c. Heterocyclic aldehydes (8d-e) and an enal (8f) were
suitable substrates. Because compounds with F-substituted
quaternary allylic carbon centers that contain only aliphatic
substituents are unstable to chromatography, 8g was obtained
after catalytic hydrogenation. Perhaps even more valuable are
β-fluoroamines, as a β-fluorosubstituent can lower the pKa of a
neighboring improving pharmacological properties.[19] We used
the reaction of 2o with N-trimethylsilyl benzaldimine 9 (Scheme
4c) to generate homoallylic amide 10 in 59% overall yield, >98:2
E:Z ratio, >98:2 d.r., and without any loss in e.r. (98:2).
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In closing, we put forth a bisphosphine–copper-catalyzed
method for -boryl substitution of difluoro-substituted Z- or E-
alkenes. The approach offers facile access to an assortment of
(Z)--monofluoroallylic boronates in high selectivity. The
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Acknowledgements
This work was supported by the Japan Society for the Promotion
of Science (JSPS) through KAKENHI grant 18H03907,
17H06370 and 19K15547 with the Institute for Chemical
Reaction Design and Discovery (ICReDD), and the NIH (GM-
130395). S. A., Q. L. thank the JSPS (grant 18J20858) and
Shanghai Institute of Organic Chemistry for a scholarship and a
postdoctoral fellowship, respectively. Y. Z. is a LaMattina
Graduate Fellow. We are grateful to Dr. T. Seki and T. Sumitani
for their assistance in analyzing the X-ray data, and to Dr. S.
Torker for advice on the DFT studies.
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[12] See the supporting information for details.
Keywords: Boron • Copper • Enantioselective catalysis •
Fluorine • Synthetic methods
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