ACS Catalysis
Research Article
The product (RuL) was obtained by adding of petroleum ether
to CH2Cl2 solution. RuL: Yellow solid, yield: 64%. H NMR
General Procedure for Ru/Si-8 Recycling Use. According to
the general procedure for DKR of 1-phenylethanol, the first run
reaction was carried out. After completion of the reaction, the
solids were filtrated, washed by CH2Cl2 and water, and then
vacuum-dried. The recovered catalyst was used for consecutive
reactions under same condition, and 6 mg of Novozym-435 was
added each time.
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(CDCl3, 400 MHz): δ 7.04 (s, 2H, NCHCHN), 5.39 (d, J =
22.2 Hz, 2H, Phcymene), 5.08 (d, J = 29.2 Hz, 2H, Phcymene), 4.84
(m, 1H, CHCy), 4.62 (br, 1H, CH2N), 3.90 (br, 1H, CH2N),
2.91−2.83 (m, 1H, CHcymene), 2.06 (s, 3H, CH3cymene), 2.05−
1.08 (m, 14H, CH2Bu,Cy), 1.27, 1.26 (s, 6H, CH3cymene), 0.95 (m,
3H, CH3Bu). 13C NMR (CDCl3): δ 172.32, 121.63, 119.51,
106.75, 98.86, 85.31, 85.23, 82.13, 82.11, 59.72, 51.31, 33.89,
30.96, 26.26, 26.23, 25.53, 25.40, 25.37, 23.87, 21.87, 20.89,
18.83, 14.08.
ASSOCIATED CONTENT
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S
* Supporting Information
The following file is available free of charge on the ACS
Preparations of Heterogeneous Catalysts. To a 50 mL
Schlenk tube containing 10 mL of toluene was added 1-
cyclohexylimidazole (75 mg, 0.50 mmol) and 3-iodopropyl-
trimethoxysilane (165 mg, 0.54 mmol). The mixture was
refluxed for 24 h before filtration. The precipitates were washed
with diethyl ether and dried under vacuum. SiBuCyImI: White
solid 202 mg, yield: 92%. 1H NMR (CDCl3, 400 MHz): δ 10.0
(s, 1H, NCHN), 7.68 (d, 2H, NCH2CH2N), 7.54 (s, 2H,
NCH2CH2N), 4.42 (m, 1H, CHCy), 3.58 (s, 9H, OCH3), 2.25
(m, 2H, CH2N), 2.04−1.46 (m, 10H, Cy), 1.33 (m, 2H, CH2),
0.67 (m, 2H, SiCH2). 13C NMR (CDCl3): δ 135.0, 122.2,
120.8, 60.0, 51.7, 50.8, 33.5, 24.8, 24.5, 24.2, 5.9. The
imidazolium salt SiBuCyImI (200 mg, 0.45 mmol) was
dissolved in CH2Cl2 (10 mL) and added to a Schlenk vessel
containing activated 4 Å molecular sieves (50 mg) and Ag2O
(63 mg, 0.27 mmol). The reaction mixture was stirred at room
temperature for 12 h in the absence of light. Then [Ru(p-
cymene)Cl2]2 (220 mg, 0.36 mmol) was added, and it was
stirred for another 12 h. After filtration, the filtrate was dried
under vacuum and added into the suspension of 2 g of SBA-15
(8 nm) in toluene (10 mL). After the mixture was refluxed for
48 h, the resulting solid was filtered and washed with CH2Cl2
and ether, and then vacuum-dried to obtain Ru/Si-8.
NMR spectra, solid-state 13C-, 29Si- NMR spectra, N2
sorption−desorption isotherms, chromatograms, and
NMR data of products (PDF)
AUTHOR INFORMATION
Corresponding Author
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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Financial support by the National Science Foundation of China
(grant nos. 20871032, 20971026, and 21271047) and by the
Shanghai Leading Academic Discipline Project (project no.
B108) is gratefully acknowledged.
REFERENCES
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General Procedure for Racemization of (R)-1-Phenyl-
ethanol. To a 25 mL Schlenk tube, catalyst (4 mol % Ru), t-
BuOK (8 mol %), and toluene (2 mL) were added. After 10
min of stirring, (R)-1-phenylethanol (97% ee, 0.50 mmol) was
added to the reaction mixture and stirred at 60 °C for 48 h.
After toluene was removed, the residue was extracted with
petroleum ether. The extract was subjected to chiral GC
analysis.
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ethanol. In a typical reaction, t-BuOK (8 mol %) and catalyst
(4 mol % Ru) was added to a 25 mL Schlenk tube containing 2
mL toluene and stirred for 10 min. Sodium carbonate (0.5
mmol), 1-phenylethanol (0.5 mmol), isopropenyl acetate (2
mmol) were then added, and the mixture was stirred at room
temperature for 4 h. The reaction mixture was concentrated,
and the residue was purified by column chromatography with
petroleum ether.
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General Procedure for DKR of sec-Alcohols. In a typical
reaction, t-BuOK (8 mol %) and catalyst (4 mol % Ru) was
added to a 25 mL Schlenk tube containing 2 mL toluene and
stirred for 10 min. Sodium carbonate (0.5 mmol), sec-alcohol
(0.5 mmol), acylating agent (2−3 mmol), and Novozym-435
(20 mg) were then added. After being stirred at 60 °C for 48 h,
the reaction mixture was filtered and evaporated, then extracted
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with petroleum ether. The extract was subjected to H NMR
and chiral HPLC analysis.
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dx.doi.org/10.1021/cs500988a | ACS Catal. 2015, 5, 27−33