J. Wang et al. / Tetrahedron Letters 53 (2012) 1978–1981
1981
Table 4
Comparison of the cyanosilylation of acetophenone (1c) and benzophenone (1h) with TBDMSCN in the presence of Sn-Mont to those reported in the literature
Substrate
Catalyst (amount)
Time
Yield (%)
TOF (hꢀ1
)
Ref.
20
21
20
1c
1c
1h
1c
1h
P(RNCH2CH2)N (7 mol %)
ZnI2 (3 mol %)
P(RNCH2CH2)N (5 mol %)
Sn-Mont (3.8 mol %)
Sn-Mont (3.8 mol %)
1 h
3 h
1 h
5 min
8 min
90
86
87
>98
>98
12.9
9.7
17.4
309.5
193.4
This work
This work
3. Ladrak, T.; Smulders, S.; Roubeau, O.; Teat, S. J.; Gamez, P.; Reedijk, J. Eur. J.
Inorg. Chem. 2010, 3804–3812.
4. Lv, C.; Cheng, Q.; Xu, D.; Wang, S.; Xia, C.; Sun, W. Eur. J. Org. Chem. 2011, 3407–
3411.
5. Teng, Y.; Toy, P. H. Synlett 2011, 551–554.
6. Hatano, M.; Ikeno, T.; Matsumura, T.; Torii, S.; Ishihara, K. Adv. Synth. Catal.
2008, 350, 1776–1780.
in a chlorobenzene solvent were needed for chalcone (1p) to com-
plete the reaction, but also a mixture of 1,2-addition product (2p)
and 1,4-additon one (2p0) were produced in 50% and 47% yields,
respectively. As expected, cinnamaldehyde (1q) underwent exclu-
sive 1,2-addition to quantitatively give 2q.
It was previously reported that the homogeneous catalysts,
such as P(RNCH2CH2)N20 and ZnI2,21 successfully achieved the
cyanosilylation of acetophenone (1c) and benzophenone (1h) with
TBDMSCN, as shown in Table 4. The average turn-over frequencies
(TOF) of the cyanosilylation of 1c with TBDMSCN catalyzed by
P(RNCH2CH2)N and ZnI2 are 12.9 and 9.7 hꢀ1, respectively, both
of which are far lower than that of 309.5 hꢀ1 by Sn-Mont. The aver-
age TOF of the cyanosilylation of 1h by Sn-Mont was as high as
193.4 hꢀ1, which is far greater than that of 17.4 hꢀ1 for the same
reaction using P(RNCH2CH2)N.37 Moreover, Sn-Mont is superior
to homogeneous catalysts in the way that Sn-Mont can be easily
separated from the products38 and can be used in the fixed-bed
processes.
Compared with the cyanosilylation of various ketones with
TMSCN in the presence of Sn-Mont, that with TBDMSCN proceeded
slightly more slowly, but such a prompt cyanosilylation protocol is
useful without question because the OH groups in the formed cya-
nohydrins are being protected by a tert-butyldimethylsilyl group
and much more robust to acidic conditions which often encounter
multi-step organic synthetic processes.
7. He, B.; Li, Y.; Feng, X. M.; Zhang, G. L. Synlett 2004, 1776–1778.
8. Kurono, N.; Arai, K.; Uemura, M.; Ohkuma, T. Angew. Chem., Int. Ed. 2008, 47,
6643–6646.
9. Yamaguchi, K.; Imago, T.; Ogasawara, Y.; Kasai, J.; Kotani, M.; Mizuno, N. Adv.
Synth. Catal. 2006, 348, 1516–1520.
10. Shen, Z. L.; Ji, S. J.; Loh, T. P. Tetrahedron Lett. 2005, 46, 3137–3139.
11. Wang, X.; Tian, S. K. Tetrahedron Lett. 2007, 48, 6010–6013.
12. Ryu, D. H.; Corey, E. J. J. Am. Chem. Soc. 2005, 127, 5384–5387.
13. Song, J. J.; Gallou, F.; Reeves, J. T.; Tan, Z. L.; Yee, N. K.; Senanayake, C. H. J. Org.
Chem. 2006, 71, 1273–1276.
14. Xiong, Y.; Huang, X.; Gou, S. H.; Huang, J. L.; Wen, Y. H.; Feng, X. M. Adv. Synth.
Catal. 2006, 348, 538–544.
15. Fuerst, D. E.; Jacobsen, E. N. J. Am. Chem. Soc. 2005, 127, 8964–8965.
16. Pawar, G. M.; Buchmeiser, M. R. Adv. Synth. Catal. 2010, 352, 917–928.
17. Iwanami, K.; Choi, J. C.; Lu, B. W.; Sakakura, T.; Yasuda, H. Chem. Commun. 2008,
1002–1004.
18. Procopio, A.; Das, G.; Nardi, M.; Oliverio, M.; Pasqua, L. Chemsuschem 2008, 1,
916–919.
19. Wang, J. C.; Masui, Y.; Watanabe, K.; Onaka, M. Adv. Synth. Catal. 2009, 351,
553–557.
20. Fetterly, B. M.; Verkade, J. G. Tetrahedron Lett. 2005, 46, 8061–8066.
21. Golinski, M.; Brock, C. P.; Watt, D. S. J. Org. Chem. 1993, 58, 159–164.
22. Izumi, Y.; Onaka, M. Adv. Catal. 1992, 38, 245–282.
23. Onaka, M.; Hosokawa, Y.; Higuchi, K.; Izumi, Y. Tetrahedron Lett. 1993, 34,
1171–1172.
24. Kawai, M.; Onaka, M.; Izumi, Y. Bull. Chem. Soc. Jpn. 1988, 61, 2157–2164.
25. Onaka, M.; Higuchi, K.; Nanami, H.; Izumi, Y. Bull. Chem. Soc. Jpn. 1993, 66,
2638–2645.
26. Wang, J. C.; Masui, Y.; Onaka, M. Eur. J. Org. Chem. 2010, 1763–1771.
27. Wang, J. C.; Masui, Y.; Onaka, M. Synlett 2010, 2493–2497.
28. Wang, J. C.; Masui, Y.; Onaka, M. Tetrahedron Lett. 2010, 51, 3300–3303.
29. Wang, J. C.; Masui, Y.; Onaka, M. Acs Catal. 2011, 1, 446–454.
30. General procedure for Sn-Mont-catalyzed cyanosilylation of ketones with
TBDMSCN: The ketone (1.0 mmol) was added to a CH2Cl2 (2 mL) suspension of
Sn-Mont (20 mg, 3.8 mol %), which had been activated in vacuum at 120 °C for
1 h, then cooled to room temperature, followed by the addition of TBDMSCN
(1.05 mmol). The mixture was stirred under a nitrogen atmosphere at 25 °C
controlled by a water bath. The progress of the reaction was monitored by thin
layer chromatography (TLC). After the reaction was complete, Sn-Mont was
filtered off and washed with CH2Cl2. Evaporation of the filtrate in vacuum gave
the crude product which was further purified by column chromatography on
silica gel. The 1H and 13C NMR spectra of the selected products can be found in
the Supplementary data.
In conclusion, tin ion-exchanged montmorillonite (Sn-Mont) as
a heterogeneous acid catalyst demonstrated a high catalytic activ-
ity for the cyanosilylation of various ketones including congested
ones with a bulky cyanide source, tert-butyldimethylsilyl cyanide
(TBDMSCN). The desired products were produced in good to excel-
lent yields (85 to >98%) at room temperature. Compared to the pre-
viously reported catalysts, Sn-Mont is easy to prepare,
environmentally benign, nontoxic, noncorrosive, and recyclable.
Acknowledgments
We are grateful for a Grant-in-Aid for Scientific Research from
the Ministry of Education, Culture, Sports, Science and Technology,
Japan, for support of our research. J.W. thanks the Japan Society for
the Promotion of Science for the financial support (P10082).
31. Masui, Y.; Wang, J.; Watanabe, K.; Teramura, K.; Tanaka, T.; Onaka, M.
submitted for publication.
32. Corma, A.; Navarro, M. T.; Renz, M. J. Catal. 2003, 219, 242–246.
33. Taarning, E.; Saravanamurugan, S.; Holm, M. S.; Xiong, J. M.; West, R. M.;
Christensen, C. H. ChemSusChem 2009, 2, 625–627.
34. Alarcon, E. A.; Correa, L.; Montes, C.; Luz Villa, A. Microporous Mesoporous Mat.
2010, 136, 59–67.
35. Ito, S.; Hayashi, A.; Komai, H.; Kubota, Y.; Asami, M. Tetrahedron Lett. 2010, 51,
4243–4245.
36. Prasomsri, T.; To, A. T.; Crossley, S.; Alvarez, W. E.; Resasco, D. E. Appl. Catal. B:
Environ. 2011, 106, 204–211.
37. The average TOF values were calculated based on the reaction times and yields
reported in Refs. 20,21
Supplementary data
Supplementary data associated with this article can be found, in
References and notes
1. Gregory, R. J. H. Chem. Rev. 1999, 99, 3649–3682.
38. Wang, J. C.; Masui, Y.; Onaka, M. Appl. Catal. B: Environ. 2011, 107, 135–139.
2. North, M.; Usanov, D. L.; Young, C. Chem. Rev. 2008, 108, 5146–5226.