ACS Catalysis
Letter
signal appeared at δ = 8.31 (Figure 2, b), indicating the
formation of formoxysilane intermediate, in agreement with
that previously reported.22 This means that the IL catalyzed the
reaction of CO2 with (EtO)3SiH to form the formoxysilane
intermediate. After 2-aminothiophenol was added into the
above solution, excitingly, benzothiazole was obtained in a yield
of 94%. From the above findings, it is clear that the IL served as
a multifunctional catalyst, activating CO2, (EtO)3SiH, and the
substrate simultaneously, and that the formoxysilane from CO2
and (EtO)3SiH was the key intermediate, which could further
react with 2-aminothiophenol easily, producing the final
product.
ACKNOWLEDGMENTS
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We thank the National Natural Science Foundation of China
(Nos. 21533011, 21125314, 21403252, 21503239).
REFERENCES
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On the basis of the experimental results and previous
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in Scheme 2. CO2 was activated by the IL to form intermediate
Scheme 2. Possible Reaction Mechanism
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A. The Si−H bond of (EtO)3SiH was activated by the IL, thus
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under mild conditions, and a series of benzothiazoles were
obtained in high yields. [Bmim][OAc] was the most effecive
catalyst that can simultaneously activate CO2, triethoxysilane
and 2-aminothiophenols. We believe that this simple, metal-free
route to produce benzothiazoles has the potential of various
applications, and more reactions forming the C−S bond may be
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ASSOCIATED CONTENT
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S
* Supporting Information
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The Supporting Information is available free of charge on the
Experimental procedures and characterization data
AUTHOR INFORMATION
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(15) Zhang, Z. F.; Xie, Y.; Li, W. J.; Hu, S. Q.; Song, J. L.; Jiang, T.;
Han, B. X. Angew. Chem., Int. Ed. 2008, 47, 1127−1129.
(16) (a) Jiang, T.; Ma, X. M.; Zhou, Y. X.; Liang, S. G.; Zhang, J. C.;
Han, B. X. Green Chem. 2008, 10, 465−469. (b) Zhang, Z. F.; Wu, C.
Y.; Ma, J.; Song, J. L.; Fan, H. L.; Liu, J. L.; Zhu, Q. G.; Han, B. X.
Green Chem. 2015, 17, 1633−1639.
Corresponding Author
Notes
The authors declare no competing financial interest.
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ACS Catal. 2015, 5, 6648−6652