Journal of the American Chemical Society
Article
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alkynes. The catalyst is remarkably chemoselective, performing
DHBTA but no other catalytic alkyne transformation under the
same conditions. Moreover, the catalyst showed low or no
activity toward heteroarenes and alkenes. The reactivity of the
catalyst is limited by a decomposition pathway that apparently
stems from a side reaction with the alkyne substrate.
The origins of the high reactivity selectively toward terminal
alkynes and the origins of the decomposition reaction are not
yet clear. In particular, it is not obvious whether all elements of
the rather specific ligand design executed here are critical for
the success of alkyne C−H borylation. The great variety of
accessible pincer ligands promises exciting directions for
exploring this new reaction further.
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ASSOCIATED CONTENT
* Supporting Information
■
S
Crystallographic information in the form of CIF files; general
considerations; computational details; X-ray structural deter-
mination details; ligand synthesis; synthesis of iridium
complexes; optimization of catalytic reactions and control
experiments; optimized catalytic reactions; NMR spectra; and
movie of the hydrogen evolution from the addition of 1-hexyne
to a mixture of (SiNN)IrH(COE) and HBpin in toluene. This
material is available free of charge via the Internet at http://
files is available free of charge from the Cambridge Crystallo-
graphic Data Centre (CCDC 900440 and CCDC 900441).
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́ ́
ez, L. A.; Tomas, M. J.
Am. Chem. Soc. 2007, 129, 14422.
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39, 3101.
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̃
Walsh, P. J. J. Am. Chem. Soc. 2009, 131, 6516.
(24) Auvinet, A.-L.; Harrity, J. P. A. Angew. Chem., Int. Ed. 2011, 50,
2769.
AUTHOR INFORMATION
Corresponding Author
(25) Hussain, M. M.; Toribio, J. H.; Carroll, P. J.; Walsh, P. J. Angew.
Chem., Int. Ed. 2011, 50, 6337.
(26) Nishihara, Y.; Okada, Y.; Jiao, J.; Suetsugu, M.; Lan, M.-T.;
Kinoshita, M.; Iwasaki, M.; Takagi, K. Angew. Chem., Int. Ed. 2011, 50,
8660.
■
Notes
(27) Brown, H. C.; Bhat, N. G.; Srebnik, M. Tetrahedron Lett. 1988,
29, 2631.
The authors declare no competing financial interests.
(28) Vollhardt, K. P. C.; Schore, N. E. Organic Chemistry: Structure
and Function; W. H. Freeman and Company: New York, 2003.
(29) Beletskaya, I.; Pelter, A. Tetrahedron 1997, 53, 4957.
(30) Trost, B. M.; Ball, Z. T. Synthesis 2005, 6, 853.
(31) Vanchura, B. A., II; Preshlock, S. M.; Roosen, P. C.; Kallepalli,
V. A.; Staples, R. J.; Maleczka, R. E., Jr.; Singleton, D. A.; Smith, M. R.,
III Chem. Commun. 2010, 46, 7724.
(32) van der Boom, M. E.; Milstein, D. Chem. Rev. 2003, 103, 1759.
(33) The Chemistry of Pincer Compounds; Morales-Morales, D.,
Jensen, C. M., Eds.; Elsevier: Amsterdam, The Netherlands, 2007.
(34) O’ Murchu, C. Synthesis 1989, 11, 880.
(35) Peters, J. C.; Harkins, S. B.; Brown, S. D.; Day, M. W. Inorg.
Chem. 2001, 40, 5083.
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2001, 1200.
(37) Wada, K.; Mizutani, T.; Kitagawa, S. J. Org. Chem. 2003, 68,
ACKNOWLEDGMENTS
■
We are grateful for the support of this research by the U.S.
National Science Foundation (grant CHE-0944634 to O.V.O.)
and the Welch Foundation (grant A-1717 to O.V.O.). We are
grateful to Prof. T. Don Tilley and Mark Lipke (UC Berkeley)
for advice on and to Dr. Steven K. Silber (Texas A&M) for
experimental assistance with the double quantum filter NMR
experiments. We are also grateful to Dr. Nattamai Bhuvanesh,
Iou-Sheng Ke, Sheng-Hsuan Wei, and Chun-Yu Chen (Texas
A&M) for assistance with X-ray structural determination, to
Ms. Linda Redd for editorial assistance, and to Rafael Huacuja
for assistance with the video capture.
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