Nanoporous gold catalyst for highly selective semihydrogenation of alkynes: Remarkable effect of amine additives

Article abstract of DOI:10.1021/ja3087592

We report for the first time the highly selective semihydrogenation of alkynes using the unsupported nanoporous gold (AuNPore) as a catalyst and organosilanes with water as a hydrogen source. Under the optimized reaction conditions, the present semihydrogenation of various terminal- and internal-alkynes affords the corresponding alkenes in high chemical yields and excellent Z-selectivity without any over-reduced alkanes. The use of DMF as solvent, which generates amines in situ, or pyridine as an additive is crucial to suppress the association of hydrogen atoms on AuNPore to form H₂ gas, which is unable to reduce alkynes on the unsupported gold catalysts. The AuNPore catalyst can be readily recovered and reused without any loss of catalytic activity. In addition, the SEM and TEM characterization of nanoporosity show that the AuNPore catalyst has a bicontinuous 3D structure and a high density of atomic steps and kinks on ligament surfaces, which should be one of the important origins of catalytic activity.

Full text of DOI:10.1021/ja3087592

Supporting Information
Nanoporous Gold Catalyst for Highly Selective Semihydrogenation of Alkynes:
Remarkable Effect of Amine Additives
Mei Yan,†, Tienan Jin,*,† Yoshifumi Ishikawa,† Taketoshi Minato,‡ Takeshi Fujita,† LuꢀYang
Chen,† Ming Bao,§ Naoki Asao,† MingꢀWei Chen,† Yoshinori Yamamoto†,§
†WPIꢀAdvanced Institute for Materials Research (WPIꢀAIMR), Tohoku University, Sendai 980ꢀ8577,
Japan
‡Institute for International Advanced Interdisciplinary Research (IIAIR), International Advanced
Research and Education Organization, Tohoku University, Sendai, 980ꢀ8578, Japan
§State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012, China
tjin@m.tohoku.ac.jp
Content
General Information
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References
SEM image and EDX spectra of AuNPore material
Representative procedure of AuNPoreꢀcatalyzed semihydrogenation
Leaching experiment
Synthesis of starting materials
Analytical data of (1 and 2)
NMR spectra
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General Information. GCꢀMS analysis was performed on an Agilent 6890N GC interfaced to
an Agilent 5973 massꢀselective detector (30 m x 0.25 mm capillary column, HPꢀ5MS).
Scanning electron microscope (SEM) observation was carried out using a JEOL JSMꢀ6500F
instrument operated at an accelerating voltage of 30 kV. 1H NMR and 13C NMR spectra were
recorded on JEOL JNM AL 400 (400 MHz) spectrometers. 1H NMR spectra are reported as
follows: chemical shift in ppm (δ) relative to the chemical shift of CDCl3 at 7.26 ppm,
integration, multiplicities (s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet and
br = broadened), and coupling constants (Hz). 13C NMR spectra were recorded on JEOL JNM
AL 400 (100.5 MHz) spectrometers with complete proton decoupling, and chemical shift
reported in ppm (δ) relative to the central line of triplet for CDCl3 at 77 ppm. IR spectra
were recorded on JASCO FT/IRꢀ4100 spectrometer; absorptions are reported in cmꢀ1.
Highꢀresolution mass spectra were obtained on a BRUKER APEXIII spectrometer and
JEOL JMSꢀ700 MStation operator. Column chromatography was carried out employing
silica gel 60 N (spherical, neutral, 40~100 ꢁm, KANTO Chemical Co.). Analytical thinꢀlayer
chromatography (TLC) was performed on 0.2 mm precoated plate Kieselgel 60 F254 (Merck).
Materials. The hydrosilanes and alkynes are commercially available, which are used as
received. Au (99.99%) and Ag (99.99%) are purchased from Tanaka Kikinzoku Hanbai K.K.
and Mitsuwa’s Pure Chemicals, respectively. Alkyne 1f was prepared following the reported
literature.1,2 2a was identified by 1H NMR comparing with the commercially available
styrene. Structures of 2b,3 2c,4 2d,5 2e,6 2f,7 2h,8 2i,9 2k,10 and 2l11 were determined by
comparing with the reported authentic compounds. Products 2g and 2j were confirmed by 1H,
13C NMR and HRMS.
References
1. Okitsu, T.; Sato, K.; Potewar, T. M.; Wada, A. J. Org. Chem. 2011, 76, 3438ꢀ3449.
2. Zhao, L.; Lu, X.; Xu, W. J. Org. Chem. 2005, 70, 4059ꢀ4063.
3. Huang, J.ꢀM.; Lin, J.ꢀQ.; Chen, D.ꢀS. Org. Lett. 2012, 14, 22ꢀ25.
4. Woolven, H.; GonzálezꢀRodríguez, C.; Marco, I.; Thompson, A. L.; Willis, M. C. Org. Lett
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2011, 13, 4876ꢀ4878.
5. Yu, JꢀY.; Kuwano, R. Angew. Chem. Int. Ed. 2009, 48, 7217ꢀ7220.
6. Shen, R.; Chen, T.; Zhao, Y.; Qiu, R.; Zhou, Y.; Yin, S.; Wang, X.; Goto, M.; Han, LꢀB. J.
Am. Chen. Soc. 2011, 133, 17037ꢀ17044.
7. Oppolzer, W.; Stammen, B. Tetrahedron 1997, 53, 3577ꢀ3586.
8. Kim, I. S.; Dong, G. R.; Jung, Y. H. J. Org. Chem. 2007, 72, 5424ꢀ5426.
9. Littke, A. F.; Fu, G. C. J. Am. Chem. Soc. 2001, 123, 6989ꢀ7000
10. Walter C.; Oestreich, M. Angew. Chem. Int. Ed. 2008, 47, 3818ꢀ3820.
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11. Belger, C.; Neisius, N. M.; Plietker, B. Chem. Eur. J. 2010, 16, 12214ꢀ12220
SEM images and EDX spectra of AuNPore catalyst
Figure S1. (a) EDX analysis of fresh AuNPore, Au98Ag2. (b) SEM image of after reaction.
Figure S2. FTIR spectra of (a) pyridine and water in acetonitrile, (b) water in acetonitrile, (c)
pyridine in acetonitrile.
Representative procedure for the AuNPoreꢀcatalyzed semihydrogenation of 1j (Tables 4,
entry 19): method A.
To a DMF solution (1 M, 0.5 mL) of AuNPore (2 mol%, 2.0 mg) were added 1j (84 mg, 0.5
mmol), H2O (18 ꢁl, 1.0 mmol) and PhMe2SiH (116 ꢁl, 0.75 mmol) subsequently at room
o
temperature. The reaction mixture was stirred at 35 C for 5 hours and was monitored by
GCꢀMS analysis. The AuNPore catalyst was recovered by filtration, and the solution was
extracted with diethyl ether and washed by water. The recovered AuNPore catalyst was
washed with acetone and dried under vacuum. After concentration, the residue was purified
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with a silica gel chromatography to afford 2j (81 mg, 95%) as a yellow solid.
Representative procedure for the AuNPoreꢀcatalyzed semihydrogenation of 1d (Tables 4,
entry 8): method B.
To a MeCN solution (1 M, 0.5 mL) of AuNPore (2 mol%, 2.0 mg) were added 1d (89 mg, 0.5
mmol), H2O (18 ꢁl, 1.0 mmol), pyridine (20 ꢁl, 0.25 mmol) and PhMe2SiH (116 ꢁl, 0.75 mmol).
o
The reaction mixture was stirred at 55 C for 8 hours. The reaction was monitored by
GCꢀMS analysis. The mixture was filtered and washed by diethyl ether. The recovered
AuNPore catalyst was washed with acetone and dried under vacuum. After concentration of
the filtrate, the residue was purified with silica gel chromatography, to afford 2d (81 mg,
90%) as a white solid.
Leaching experiment
Phenyl acetylene 1a was treated with PhMe2SiH and water in the presence of AuNPore
o
catalyst (2 mol%) in DMF at 35 C (method A). After 40 min, a part of supernatant was
1
transferred to the other reaction vessel and 2a was produced in 72% H NMR yield at this
time. The supernatant was continuously heated at 35 oC in the absence of the catalyst for 2
1
h, affording 2a in 72% H NMR yield. In contrast, the residual containing the AuNPore
catalyst was completed in 2 h, giving 2a in 90% 1H NMR yield.
Synthesis of starting materials
Synthesis of PhMe2SiD
To a Et2O solution (0.22 M) of LiAlD4 (3 mmol) under argon atmosphere were added
PhMe2SiCl (9 mmol). The reaction mixture was heated to reflux for 10 hours. Aqueous
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sodium hydroxide (10 ml, 10 wt%) was added to the reaction mixture, and extracted by Et2O
and dried over anhydrous sodium sulfate. Filtration and evaporation of the solvent gave the
crude product which was purified by silica gel column chromatography to give PhMe2SiD in
65% yield.
4ꢀMethylꢀ
N
ꢀ(3ꢀphenylpropꢀ2ꢀynꢀ1ꢀyl)benzenesulfonamide (1f)1,2
CBr4 (1.2 equiv) was added in one portion to a solution of 3ꢀphenylpropꢀ2ꢀynꢀ1ꢀol (1 equiv) in
o
o
dry CH2Cl2 (0.6 M) at 0 C, and the reaction was stirred at 0 C. After 10min, a solution of
o
Ph3P (1.5 equiv) in CH2Cl2 (1.5 M) was added via cannula and stirred at 0 C for 10 min.
Then the reaction mixture was allowed to warm at rt and further stirred for 2 h. After
reaction completed, the mixture was evaporated in vacuo. The residue was purified by silica
gel column chromatography to give (3ꢀbromopropꢀ1ꢀynꢀ1ꢀyl)benzene, 82% yield.
To a 50 mL roundꢀbottom flask was added 2.07 g (15 mmol) of K2CO3, TsNHBOC
(
N
ꢀ(2,2ꢀDimethylꢀpropionyl)ꢀ4ꢀmethylꢀbenzenesulfonamide) 2.71 g (10 mmol) and DMF (12
mL). The solution was stirred at room temperature for h. Then
4
(3ꢀbromopropꢀ1ꢀynꢀ1ꢀyl)benzene 1.95 g (10 mmol) was added in one portion. The reaction
was monitored by TLC, after completion, Et2O (100 mL) was added. The solution was
washed with 3 times of 15 mL portions of water. Then the solvent was removed at reduced
pressure, leaving a yellow solid. The crude was dissolved in CH2Cl2 (8 mL), then CF3COOH
(3 mL) was added. The solution was stirred for overnight. The solvent was evaporated and
the residue was purified by silica gel column chromatography to give
4ꢀmethylꢀNꢀ(3ꢀphenylpropꢀ2ꢀynꢀ 1ꢀyl) benzenesulfonamide (1f) 2.6 g, 90 % yield.
4ꢀMethylꢀ
4ꢀMethylꢀ
N
ꢀ(octꢀ2ꢀynꢀ1ꢀyl)benzenesulfonamide (1g)
N
ꢀ(octꢀ2ꢀynꢀ1ꢀyl)benzenesulfonamide (1g) was prepared according to the method of
1h from 2.0 g (10 mmol) of 1ꢀbromoꢀoctꢀ2ꢀyne. Yield: 2.0 g (71%) of 1g after purification of the
crude product by silica gel column chromatography.
1ꢀ(4ꢀ(Hexꢀ1ꢀynꢀ1ꢀyl)phenyl)ethanone (1i)
A mixture of 1ꢀ(4ꢀbromophenyl)ethanone (995 mg, 10 mmol), Pd(PPh3)2Cl2 (140 mg, 0.2
mmol), CuI (19 mg, 0.1 mmol) and hexꢀ1ꢀyne (2.5 g, 30 mmol) in triethylamine (40 mL) was
heated to reflux for 4 h. After then, the mixture was cooled to room temperature. Filtration
through celite and evaporation of the solvent gave the crude product which was purified by
silica gel column chromatography to give 1ꢀ(4ꢀ(hexꢀ1ꢀynꢀ1ꢀyl)phenyl) ethanone (1i) 1.7 g,
85% yield.
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Analytical data of (1 and 2)
PhMe2SiD
Colorless liquid; 1H NMR (400 MHz, CDCl3) δ 7.26ꢀ7.54 (m, 2H), 7.38ꢀ7.36 (m, 3H), 0.35 (s,
6H); 13C NMR (100 MHz, CDCl3) δ 137.3, 133.9, 129.1, 127.8, ꢀ3.8.
N
ꢀAllylꢀ4ꢀmethylbenzenesulfonamide (2c)
White solid; 1H NMR (400 MHz, CDCl3) δ 7.71 (d,
J = 8.0 Hz, 2H), 7.25 (d, J = 8.0 Hz, 2H),
5.70ꢀ5.62 (m, 1H), 5.13ꢀ4.96 (m, 3H), 3.53ꢀ3.49 (m, 2H), 2.37 (s, 3H); 13C NMR (100 MHz,
CDCl3) δ 143.2, 136.7, 132.7, 129.5, 126.9, 117.4, 45.6, 21.4; HRMS (ESI positive) calcd for
C10H13NO2S [M + Na]+: 234.0559, found: 234.0559.
4ꢀPhenylstyrene (2d)
White solid; 1H NMR (400 MHz, CDCl3) δ 7.67ꢀ7.62 (m, 4H), 7.55ꢀ7.47 (m, 4H), 7.42ꢀ7.38 (m,
1H), 6.82 (dd,
J = 17.6 Hz, 11.2 Hz, 1H), 5.86 (d, J = 17.6 Hz, 1H), 5.34 (d, J = 11.2 Hz,
1H);13C NMR (100 MHz, CDCl3) δ 140.5, 140.4, 136.4, 136.2, 128.6, 127.2, 127.1, 126.8, 126.5,
113.8; HRMS (APCI positive) calcd for C14H12 [M + H]+: 181.1012, found: 181.1011.
(Z)ꢀ1,2ꢀDiphenylethene (2e)
Colorless liquid; 1H NMR (400 MHz, CDCl3) δ 7.28ꢀ7.18 (m, 10H), 6.61 (s, 2H); 13C NMR (100
MHz, CDCl3) δ 137.1, 130.1, 128.7, 128.1, 126.9.
4ꢀMethylꢀNꢀ(3ꢀphenylpropꢀ2ꢀynꢀ1ꢀyl)benzenesulfonamide (1f)
Light yellow solid; 1H NMR (400 MHz, CDCl3) δ 7.82 (d,
J
= 7.2 Hz, 2H), 7.29ꢀ7.12 (m, 5H),
= 6.0 Hz, 2H), 2.33 (s, 3H); 13
C
7.11 (d, = 8.4 Hz, 2H), 5.02 (t, = 6.0 Hz, 1H), 4.06 (d,
J
J
J
NMR (100 MHz, CDCl3) δ 143.5, 136.7, 131.4, 129.5, 128.3, 127.9, 127.3, 121.9, 84.5, 83.2,
33.7, 21.4.
(Z)ꢀ4ꢀMethylꢀNꢀ(3ꢀphenylallyl)benzenesulfonamide (2f)
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Colorless viscous liquid; 1H NMR (400 MHz, CDCl3) δ 7.71 (d,
5H), 7.08 (d, = 8.0 Hz, 2H), 6.51 (d, = 11.6 Hz, 1H), 5.58ꢀ5.52 (m, 1H), 4.63 (bs, 1H), 3.84
(dd,
= 7.2, 6.4 Hz, 2H), 2.42 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 143.4, 136.6, 135.6, 132.5,
J = 8.0 Hz, 2H), 7.28ꢀ7.24 (m,
J
J
J
129.6, 128.4, 128.2, 127.3, 127.0, 126.3, 41.3, 21.5; HRMS (ESI positive) calcd for
C16H17NO2S [M + Na]+: 310.0872, found: 310.0872.
4ꢀMethylꢀNꢀ(octꢀ2ꢀynꢀ1ꢀyl)benzenesulfonamide (1g)
Yellow liquid; 1H NMR (400 MHz, CDCl3) δ 7.73 (d,
4.96 (s, 1H), 3.75 (d, = 6.0 Hz, 2H), 2.37 (s, 3H), 1.87 (t,
0.81 (t,
= 6.8 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 143.2, 136.7, 129.3, 127.2, 85.3, 73.9,
33.3, 30.8, 27.9, 22.0, 21.4, 18.3, 13.8.
J
= 8.0 Hz, 2H), 7.25 (d,
J = 8.0 Hz, 2H),
J
J
= 6.8 Hz, 2H), 1.25ꢀ1.14 (m, 6H),
J
(
Z
)ꢀ4ꢀMethylꢀ
N
ꢀ(octꢀ2ꢀenꢀ1ꢀyl)benzenesulfonamide (2g)
1
Colorless liquid; H NMR (400 MHz, CDCl3) δ 7.70 (d,
J
= 8.0 Hz, 2H), 7.25 (d,
= 6.8 Hz, 2H), 2.37 (s, 3H),
= 6.8 Hz, 2H), 1.24ꢀ1.11 (m, 6H), 0.80 (t, J = 6.8 Hz, 3H); 13C NMR (100 MHz,
J = 8.0 Hz,
2H), 5.45ꢀ5.39 (m, 1H), 5.23ꢀ5.17 (m, 1H), 4.45 (s, 1H), 3.52 (t,
1.84 (q,
J
J
CDCl3) δ 143.2, 136.7, 134.6, 129.5, 127.0, 123.5, 40.1, 31.3, 28.9, 27.2, 22.4, 21.5, 14.0;
HRMS (ESI positive) calcd for C15H23NO2S [M + Na]+: 304.1342, found: 304.1341.
1ꢀ(4ꢀ(Hexꢀ1ꢀynꢀ1ꢀyl)phenyl)ethanone (1i)
Brown liquid; 1H NMR (400 MHz, CDCl3) δ 7.87 (d,
2.57 (s, 3H), 2.42 (t, = 7.2 Hz, 2H), 1.61ꢀ1.44 (m, 4H), 0.94 (t,
MHz, CDCl3) δ 197.1, 135.4, 131.5, 129.0, 128.0, 94.2, 80.0, 30.6, 26.5, 22.0, 19.2, 13.6.
J
= 8.0 Hz, 2H), 7.44 (d,
J = 8.0 Hz, 2H),
J
J
= 7.2 Hz, 3H); 13C NMR (100
(Z)ꢀ1ꢀ(4ꢀ(hexꢀ1ꢀenꢀ1ꢀyl)phenyl)ethanone (2i)
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1
Colorless liquid; H NMR (400 MHz, CDCl3) δ 7.91 (d,
J = 8.0 Hz, 2H), 7.34 (d, J = 8.0 Hz,
2H), 6.42 (d,
4H), 0.89 (t,
J
J
= 12.0 Hz, 1H), 5.80ꢀ5.74 (m, 1H), 2.58 (s, 3H), 2.36ꢀ2.30 (m, 2H), 1.48ꢀ1.30 (m,
= 7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 197.3, 142.5, 135.4, 134.8, 128.6,
128.1, 127.7, 31.9, 28.4, 26.5, 22.3, 13.9; HRMS (ESI positive) calcd for C14H18O [M + Na]+:
225.1250, found: 225.1249.
(Z)ꢀMethyl nonꢀ2ꢀenoate (2j)
Yellow liquid; 1H NMR (400 MHz, CDCl3) δ 6.23ꢀ6.17 (m, 1H), 5.74 (d,
J
= 11.6 Hz, 1H), 3.68
= 6.4 Hz, 3H); 13
(s, 3H), 2.65ꢀ2.60 (m, 2H), 1.43ꢀ1.38 (m, 2H), 1.33ꢀ1.27 (m, 6H), 0.86 (t,
J
C
NMR (100 MHz, CDCl3) δ 166.6, 150.8, 118.9, 50.8, 31.6, 29.0, 28.9, 28.9, 22.5, 14.0; HRMS
(ESI positive) calcd for C10H18O2 [M + Na]+: 193.1199, found: 193.1199.
(Z)ꢀEthyl 3ꢀphenylacrylate (2k)
Yellow liquid; 1H NMR (400 MHz, CDCl3) δ 7.55ꢀ7.53 (m, 2H), 7.33ꢀ7.27 (m, 3H), 6.90 (d,
12.4 Hz, 1H), 5.91 (d, = 12.4 Hz, 1H), 4.13 (q, = 7.2 Hz, 2H), 1.20 (t,
= 7.2 Hz, 3H); 13
J
=
J
J
J
C
NMR (100 MHz, CDCl3) δ 166.0, 142.8, 134.7, 129.5, 128.8, 127.8, 119.7, 60.2, 14.0; HRMS
(ESI positive) calcd for C10H12O2 [M + Na]+: 199.0730, found: 199.0729.
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1H and 13C NMR spectra
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D
H3C
CH3
Si
D
H3C
CH3
Si
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Ph
NHTs
1f
Ph
NHTs
1f
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Ph
NHTs
2f
Ph
NHTs
2f
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NHTs
1g
NHTs
1g
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NHTs
2g
NHTs
2g
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H3COC
2i
H3COC
2i
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