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(mole or mass) amount of biomolecules including amino acids,
nucleosides, oligosaccharides, nucleic acids, or proteins did not
significantly affect the reaction (entries 2−8). We also tested
bacterial cell lysates, which contained various endogenous bio-
molecules, and found the uncompromised alkynylation in 86%
yield (entry 9).
In conclusion, we have developed a visible-light-induced
deboronative alkynylation reaction with the [Ru(bpy)3](PF6)2/
BI−OH catalytic system. This reaction works with primary,
secondary, and tertiary alkyl trifluoroborates or boronic acids
to generate aryl, alkyl, and silyl substituted alkynes. Its broad
substrate scope, excellent chemoselectivity, and mild reaction
conditions bring a useful new addition to C(sp3)−C(sp) bond
coupling reactions. Its compatibility with amino acids, nucleo-
sides, oligosaccharides, nucleic acids, proteins, and cell lysates
suggests future biomolecule applications. The further reactivity
and mechanism of this [Ru(bpy)3](PF6)2/BI−OH catalytic
system is under investigation in our laboratory.
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ASSOCIATED CONTENT
■
S
* Supporting Information
Complete mechanistic experiments, optimization tables,
experimental methods, and additional experimental data. This
material is available free of charge via the Internet at http://
AUTHOR INFORMATION
■
Corresponding Author
(33) Zhdankin, V. V. Curr. Org. Synth. 2005, 2, 121.
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(36) Pure CH2Cl2 or the mixable solvents (MeCN/H2O, DMF/
H2O) did not give good results; however, when boronic acids were
used, either CH2Cl2/H2O or pure CH2Cl2 gave excellent results
(Supporting Information Table S2).
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This paper is dedicated to Professor David R. Liu on the
occasion of his 40th birthday. Financial support was provided by
the National Basic Research Program of China 2014CB910304,
National Natural Science Foundation of China 21272260,
“Thousand Talents Program” Young Investigator Award,
Shanghai Pujiang Investigator Award 12PJ1410700, the start-up
fund from State Key Laboratory of Bioorganic and Natural
Products Chemistry, and Chinese Academy of Sciences.
(37) As BI−OH and BI−alkyne were prepared from o-iodobenzoic
acid, this catalytic alkynylation was sustainable.
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E. J. Am. Chem. Soc. 1986, 108, 8281.
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(42) Frei, R.; Waser, J. J. Am. Chem. Soc. 2013, 135, 9620.
(43) The on−off light experiment alone was not sufficient to indicate
that no radical chain process was occurring. For example, see
Wallentin, C. J.; Nguyen, J. D.; Finkbeiner, P.; Stephenson, C. R. J. J.
Am. Chem. Soc. 2012, 134, 8875. Also see Espelt, L. R.; Wiensch, E.
M.; Yoon, T. P. J. Org. Chem 2013, 78, 4107.
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