Organic Letters
Letter
Scheme 6. Mechanistic Studies
ACKNOWLEDGMENTS
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We gratefully acknowledge the National Natural Science
Foundation of China (21672098,and21472084) for financial
support.
REFERENCES
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(1) For books and reviews on radical-chain addition of alkenes and
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could be totally terminated by introducing TEMPO into the
reaction mixture. When (−)-β-pinene was employed under
standard conditions, the ring-opening product 10 was obtained
in 77% yield (Scheme 6a). These results suggest that the radical
intermediates are involved in this transformation. Afterward, the
13C-labeled acetylenic triflone 2b′ was used in this reaction
(Scheme 6b). As a result, the 13C-labeled product 11a was
isolated exclusively in 83% yield without detection of any 13C-
migration product 11b. This result supports the notion that α-
addition of radical intermediate A to acetylenic triflone 2b′
occurs predominantly to afford vinyl radical C. β-Elimination of
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•
C produces 11a and CF3SO2 . Therefore, the alternative
pathway of β-addition and subsequent α-elimination to form
the vinylidene carbene E followed by 1,2-migration to give 11b
can be excluded in this radical-chain-addition reaction (Scheme
6c).13
In summary, we have described an electron donor−acceptor
complex initiated radical-chain addition of acetylenic triflones to
alkenes. The alkynyltrifluoromethylation of alkenes can be
achieved under exceptionally mild and operationally simple
conditions. The catalytic amount of EDA complex of Togni’s
reagent and NMM is capable of initiating this transformation
efficiently. The reactivity of silylalkyne- and phenylacetylene-
derived acetylenic triflones with a variety of alkenes, including
aliphatic alkenes, vinyl ethers, enecarbamates, styrenes, and even
acrylates, was extensively discussed. A variety of structurally
diverse β-CF3 alkynes can be easily prepared in a single
operation.
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ASSOCIATED CONTENT
* Supporting Information
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S
(10) (a) Gong, J.; Fuchs, P. L. J. Am. Chem. Soc. 1996, 118, 4486.
(b) Xiang, J.; Jiang, W.; Fuchs, P. L. Tetrahedron Lett. 1997, 38, 6635.
(c) Gong, J.; Fuchs, P. L. Tetrahedron Lett. 1997, 38, 787. (d) Xiang, J.;
Fuchs, P. L. Tetrahedron Lett. 1998, 39, 8597. (e) Xiang, J.; Evarts, J.;
Rivkin, A.; Curran, D. P.; Fuchs, P. L. Tetrahedron Lett. 1998, 39, 4163.
(f) Uenoyama, Y.; Fukuyama, T.; Morimoto, K.; Nobuta, O.; Nagai, H.;
Ryu, I. Helv. Chim. Acta 2006, 89, 2483. (g) Lei, J.; Wu, X.; Zhu, Q. Org.
Lett. 2015, 17, 2322. During preparation of this manuscript, Li and co-
workers reported a nonchain alkynyltrifluoromethylation of alkenes in
three-component fashion: (h) Zhou, S.; Song, T.; Chen, H.; Liu, Z.;
Shen, H.; Li, C. Org. Lett. 2017, 19, 698.
The Supporting Information is available free of charge on the
Full experimental details, characterization of new com-
pounds, and 1H and 13C NMR (PDF)
AUTHOR INFORMATION
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Corresponding Author
ORCID
(11) Liu, W.; Wang, H.; Li, C.-J. Org. Lett. 2016, 18, 2184.
(12) Muller, K.; Faeh, C.; Diederich, F. Science 2007, 317, 1881.
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Notes
(13) Xiang, J. S.; Fuchs, P. L. Tetrahedron Lett. 1996, 37, 5269.
The authors declare no competing financial interest.
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