Organic Letters
Letter
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moieties (e.g., the carboxyl group of 3v) are, again, unaffected by
thioetherification. Overall, the diversity of the thioetherifications
using thiols matched the observed trends with alkylthiolsilicate
1a.15
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In summary, a mild, S-selective method for the thioether-
ifcation of aryl bromides using photoredox/Ni-dual catalysis is
presented. Although alkylthiolsilicates can be used directly, the
reaction scope was extended to include simple thiols by way of an
intermolecular HAT pathway using alkylsilicates as H-atom
abstractors. This base-free, room-temperature reaction tolerates
a variety of aryl and heteroaryl bromides. Additionally, protic
(even those containing acidic moieties) and sterically congested
thiols were all competent toward thioetherification. The broad
tolerance and mild nature of the described reaction could
potentially be employed to prepare sulfides with biological
relevance or for bioconjugation. Moreover, it provides
unprecedented access to new chemical space for thioethers,
unlocking their potential for examination by drug discovery
groups or agroscience.
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́
dez-Rodríguez, M. A.; Shen, Q.; Hartwig, J. F. J. Am.
dez-Rodríguez, M. A.; Hartwig, J.
́
ASSOCIATED CONTENT
* Supporting Information
■
(9) Formation of dinuclear Ni-complexes having bridged thiolate
ligands, which would be mitigated when using dtbbpy, might explain this
observation. See: Louie, J.; Hartwig, J. F. J. Am. Chem. Soc. 1995, 117,
11598.
S
The Supporting Information is available free of charge on the
(10) (a) Peach, M. E. In The Chemistry of the Thiol Group; Patai, S., Ed.;
John Wiley & Sons: London, 1974; pp 721−784. (b) Yin, J.; Pidgeon, C.
Tetrahedron Lett. 1997, 38, 5953. (c) Beletskaya, I. P.; Ananikov, D. P.
Chem. Rev. 2011, 111, 1596. (d) Eichman, C. C.; Stambuli, J. P. Molecules
2011, 16, 590. (e) Bichler, P.; Love, J. A. Top. Organomet. Chem. 2010,
31, 39. (f) Kondo, T.; Mitsudo, T. Chem. Rev. 2000, 100, 3205.
(11) Alternatively, oxidative addition may precede thiyl radical
metalation, but would still lead to a closed cycle; for a detailed
mechanistic analysis of photoredox/Ni dual catalysis. See: Gutierrez, O.;
Tellis, J. C.; Primer, D. N.; Molander, G. A.; Kozlowski, M. C. J. Am.
Chem. Soc. 2015, 137, 4896.
Experimental details and spectral characterization (PDF)
AUTHOR INFORMATION
Corresponding Author
■
Author Contributions
†These authors contributed equally to this work.
Notes
(12) Straathof, N. J. W.; Tegelbeckers, B. J. P.; Hessel, V.; Wang, X.;
The authors declare no competing financial interest.
Noel, T. Chem. Sci. 2014, 5, 4768.
̈
(13) Hartwig, J. F. Angew. Chem., Int. Ed. 1998, 37, 2046.
(14) Vinogradova, E. V.; Zhang, C.; Spokoyny, A. M.; Pentelute, B. L.;
Buchwald, S. L. Nature 2015, 526, 687.
ACKNOWLEDGMENTS
■
We thank Kingson Lin (University of Pennsylvania) for the
preparation of alkylsilicates and Geraint H. M. Davies
(University of Pennsylvania) for helpful discussions/technical
assistance. We thank NIGMS (RO1 GM113878) for financial
support of this research.
(15) Although not explicitly shown in Scheme 5, attempts to employ
electron-rich aryl bromides with these three thiols were not met with
success.
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