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DOI: 10.1039/C8CC04780D
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Ru to starting material) achieved 100% conversion of the
substrate, led to formation of a single product, and produced
the highest TON values ever reported.3 The reduction of esters
Scheme 4. Possible catalytic cycles for hydrosilylation of HCHO with Me2SiH2 catalyzed by
1
[
ꢀ
G in parentheses (kcal/mol)]. The CO ligands are omitted for clarity.
hydrogenation mechanisms reported earlier,5d Cycle
sensitive towards steric bulkiness of the substrate. Cycle B is
more preferable for the acetophenone reduction mechanism to
Cycle A. See details in ESI (11-3).
A is
experienced problems related to selectivity between the
formation of alkyl ethers and silyl ethers; however, a TON of
10,000 was achieved for reaction of ε-caprolactone to disilyl
ether of 1,6-hexane diol, which is the highest TON reported for
hydrosilane reduction of esters. The DFT calculations
suggested two catalytic cycles to explain such remarkably high
catalytic activity. Activation of the Si-H bonds of hydrosilanes
1
(a) G. L. Larson and J. L. Fry, Ionic and organometallic-
catalyzed organosilane reductions, John Wiley & Sons, 2009.
(b) D. Addis, S. Das, K. Junge and M. Beller, Angew. Chem.
Int. Ed., 2011, 50, 6004-6011. (c) H. Nagashima, Synlett,
2015, 26, 866-890. (d) S. Chakraborty, P. Bhattacharya, H. Dai,
H. Guan, Acc. Chem. Res., 2015, 48, 1995-2003. (e) B. Li, J. B.
occurs on the Ru-Si bond in
1. Perutz and Sabo-Etienne
proposed a σ-CAM mechanism involving activation of H2 on a
transition metal that is assisted by an adjacent main group
element.6 Hydrogenation reactions of alkenes catalyzed by
Sortais, C. Darcel, RSC Adv., 2016, 6, 57603-57625. See also,
additional references described in ESI (references S3-S6).
J. Pesti and G. L. Larson, Org. Process Res. Dev., 2016, 20
1164-1181.
2
3
,
complex
both experimental and theoretical data.5 The present report
suggests that the -CAM mechanism is applicable to
hydrosilane reduction of carbonyl compounds, leading to the
high catalytic performance of
1 are exemplified by 6-8, which are supported by
(a) J. Yang and T. D. Tilley, Angew. Chem. Int. Ed., 2010, 49
,
σ
10186-10188. (b) S. Chakraborty, O. Blacque, T. Fox and H.
Berke, ACS Catal., 2013, , 2208-2217. (c) A. J. Ruddy, C. M.
3
Kelly, S. M. Crawford, C. A. Wheaton, O. L. Sydora, B. L.
Small, M. Stradiotto and L. Turculet, Organometallics, 2013,
32, 5581-5588. (d) M. C. Lipke and T. D. Tilley, J. Am. Chem.
Soc., 2014, 136, 16387-16398. (e) R. J. Trovitch, Acc. Chem.
Res., 2017, 50, 2842-2852.
1.
This work was supported by the Core Research Evolutional
Science and Technology (CREST) program of Japan Science and
Technology Agency (JST), Japan, and
a Grant-In-Aid for
Scientific Research (B) (No. 18H01980 to H.N. and No.
16H04120 to Y.S.) from the Ministry of Education, Culture, and
Sports, Science, and Technology, Japan. Help for DFT
calculations by Ms. Konoka Hoshi is acknowledged.
4
5
For an account on disilametallacyclic chemistry; Y. Sunada
and H. Nagashima, Dalton Trans., 2017, 46, 7644-7655.
(a) Y. Sunada, H. Tsutsumi, K. Shigeta, R. Yoshida, T.
Hashimoto and H. Nagashima, Dalton Trans., 2013, 42
16687-16692. (b) A. Tahara, H. Tanaka, Y. Sunada, Y. Shiota,
K. Yoshizawa and H. Nagashima, J. Org. Chem., 2016, 81
,
,
10900-10911. (c) K. Hoshi, A. Tahara, Y. Sunada, H. Tsutsumi,
R. Inoue, H. Tanaka, Y. Shiota, K. Yoshizawa and H.
Nagashima, Bull. Chem. Soc. Jpn., 2017, 90, 613-626. (d) Y.
Sunada, H. Ogushi, T. Yamamoto, S. Uto, M. Sawano, A.
Tahara, H. Tanaka, Y. Shiota, K. Yoshizawa and H. Nagashima,
J. Am. Chem. Soc., 2018, 140, 4119-4134.
Conflicts of interest
There are no conflicts to declare.
6
R. N. Perutz and S. Sabo-Etienne, Angew. Chem. Int. Ed.,
2007, 46, 2578-2592.
Notes and references
‡ Two interesting aspects were obtained on selectivities for
hydrosilane reduction catalyzed by
ketone 3a, which is faster than aldehyde 2a. Another is two
reaction pathways of esters to form alkyl ethers and silyl
1. One is the reaction of
5
ethers. We added three other examples for the reductions of
esters (7-1, 7-2) and mechanistic considerations in ESI (2-2, 7-3).
§ We also performed both experiment and DFT calculations for
hydrosilylation of acetophenone with Ph2SiH2. Similar to the
4 | J. Name., 2012, 00, 1-3
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