Novel route for the synthesis of 8-oxa-3-azabicyclo[3.2.1]octane: One-pot aminocyclization of 2,5-tetrahydrofurandimethanol catalyzed by Pt/NiCuAlOx

Article abstract of DOI:10.1016/j.catcom.2014.09.027

2,5-Tetrahydrofurandimethanol (THFDM) was selectively transformed into 8-oxa-3-azabicyclo[3.2.1] octane (OABCO), a valuable building block for the synthesis of bioactive molecules, via one-pot aminocyclization with ammonia catalyzed by Pt/NiCuAlO_x. Under optimized conditions (200 °C, 6-16 h, 0.5 MPa hydrogen, 0.4 MPa ammonia), the OABCO yield reached 58% with 100% THFDM conversion.

Full text of DOI:10.1016/j.catcom.2014.09.027

Catalysis Communications 58 (2015) 195–199
Contents lists available at ScienceDirect
Catalysis Communications
journal homepage: www.elsevier.com/locate/catcom
Short Communication
Novel route for the synthesis of 8-oxa-3-azabicyclo[3.2.1]octane:
One-pot aminocyclization of 2,5-tetrahydrofurandimethanol catalyzed
by Pt/NiCuAlOx
Xinjiang Cui a, Hangkong Yuan a, Jerry-Peng Li b, Floryan De Campo b, Marc Pera-Titus b,
Youquan Deng a, Feng Shi a,
⁎
a
State Key Laboratory for Oxo Synthesis and Selective Oxidation, Center for Green Chemistry and Catalysis, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences,
Lanzhou 730000, China
b
Eco-Efficient Products and Processes Laboratory (E2P2L), UMI 3464 CNRS—Solvay, 3966 Jin Du Road, Xin Zhuang Ind. Zone, 201108 Shanghai, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 21 June 2014
Received in revised form 22 August 2014
Accepted 16 September 2014
Available online 23 September 2014
2,5-Tetrahydrofurandimethanol (THFDM) was selectively transformed into 8-oxa-3-azabicyclo[3.2.1] octane
(OABCO), a valuable building block for the synthesis of bioactive molecules, via one-pot aminocyclization with
ammonia catalyzed by Pt/NiCuAlOx. Under optimized conditions (200 °C, 6–16 h, 0.5 MPa hydrogen, 0.4 MPa
ammonia), the OABCO yield reached 58% with 100% THFDM conversion.
© 2014 Elsevier B.V. All rights reserved.
Keywords:
Tetrahydrofurandimethanol
8-Oxa-3-azabicyclo[3.2.1]octane
Ammonia
Amination
Biomass
1. Introduction
been subjected to amination reactions with promising yields [13,17,
19–21]. These alcohols are commonly separated from biomass and
Direct alcohol amination is an attractive route for clean and econom-
ic amine synthesis, since water is the main by-product. In recent years,
numerous catalytic systems have been developed, operating mainly via
the so-called borrowing hydrogen mechanism. Transition metal com-
plexes relying mostly on Ir and Ru in combination with a wide range
of ligands have been explored and encouraging results were obtained
[1–5]. In a further step, to facilitate the industrial implementation, a se-
ries of supported Ru [6], Pd [7], Pt [8], Au [9–12], Cu [13], Ni [14,15], and
Ni–Cu [16,17] heterogeneous catalysts have been developed with com-
parable performance to homogeneous systems. These catalysts could be
easily separated from the reaction mixture and reused for several runs
without significant deactivation.
extensively used as chemical intermediates. Among biomass-derived
alcohols, tetrahydrofurandimethanol (THFDM) is a common platform
chemical and its further conversion to other fine chemicals has received
increasing attention. However, to our knowledge, no report is available
on the potentials of such diol for direct amination. Relying on our con-
tinuous exploration of alcohol amination reactions with heterogeneous
catalysts [7,17,22,23], we report here the first results on the one-pot
aminocyclization reaction of THFDM with ammonia to synthesize 8-
oxa-3-azabicyclo[3.2.1]octane (OABCO) over a supported Pt catalyst
(Scheme 1). The OABCO ring system constitutes a building block for
the synthesis of analgesics for animals [24,25], anticarcinogenic agents
[26–28], and derivatives for preventing diabetes [29].
The studies reported so far concentrate mainly on the amination of
alcohols produced from fossil resources. However, as of today, biomass
is a large and renewable source for the generation of alcohols, and thus
this could constitute an ideal platform for a sustainable expansion of the
amine chemistry [18]. Indeed, a reduced series of biomass-derived alco-
hols such as furfuryl alcohol, isosorbide, isomannide and piperitol have
Noteworthy, the synthetic approach presented here constitutes an
alternative to the standard process recently optimized by Wyeth [30],
where OABCO hydrochloride can be accessed in a four-step process
starting from 5-hydroxymethylfurfural (HMF): 1) reduction of HMF to
THFDM using Raney Nickel at 60 °C and 4 bar hydrogen pressure in
methanol, 2) conversion of THFDM into a ditosylate by reaction of
THFDM with p-toluenesulfonyl chloride in acetonitrile, 3) cyclization
of the ditosylate with benzylamine in acetonitrile/MTBE (or with
ammonia in methanol [31]) generating the OABCO core, and 4)
⁎
Corresponding author.
E-mail address: fshi@licp.cas.cn (F. Shi).
http://dx.doi.org/10.1016/j.catcom.2014.09.027
1566-7367/© 2014 Elsevier B.V. All rights reserved.

196
X. Cui et al. / Catalysis Communications 58 (2015) 195–199
Scheme 1. OABCO synthesis via aminocyclization of THFDM.
hydrogenolysis of the N-benzyl group at 4 bar H2 over a Pearlman's cat-
alyst (i.e. Pd(OH)2/C) in IPA/heptane/TMSCl to finally obtain OABCO
hydrochloride from a mixture of with a yield of 43–64%.
2.3. Catalytic aminocyclization tests
All the reactions were performed in an 80 mL autoclave containing a
glass tube inside and equipped with a magnetic stirrer. In each catalytic
test, 1.0 mmol of 2,5-THFDM, 30–100 mg of catalyst and 2 mL of the tar-
get solvent were added. The autoclave was sealed and pressurized/
depressurized with either nitrogen or hydrogen (0.1–1.0 MPa) for 3
times. Then, ammonia (0.4 MPa) was introduced and the reaction was
conducted at 200 °C for 6–16 h. After the reaction, the autoclave was
cooled down to room temperature and 40 mg biphenyl and 10 mL
ethanol were added for quantitative analysis (GC-FID, Agilent 6890A).
Specific analyses were performed on an HP 6890/5973 GC-MS to assist
the identification of reaction intermediates.
2. Experimental
2.1. Preparation of Pt/CuNiAlOx catalysts
The different Pt/CuNiOAlx catalysts used in this study were prepared
by the co-precipitation method. Briefly, 1.16 g of Ni(NO3)2·6H2O, 0.97 g
of Cu(NO3)2·3H2O, 2 g of Al(NO3)3·9H2O and variable amounts of
H2PtCl6·6H2O (18.8–27.6 mg) were first dissolved in 30 mL deionized
water. Subsequently, a 20 mL of a Na2CO3 solution (0.95 mol/L) was
added dropwise at room temperature during 30 min under mild stirring
and the system was stirred for further 5 h. After this period, the precip-
itate was separated by centrifugation and washed with deionized water
until neutral pH. The as-obtained solid was dried at 100 °C for 5 h,
calcined at 500 °C for 5 h and reduced under hydrogen flow at 400 °C
for 2 h, obtaining ca. 0.8 g of catalyst for each batch. The Ru/CuNiAlOx
and Pd/CuNiAlOx catalysts were prepared with the same method, but
using RuCl3·xH2O and H2PdCl4 as the metal precursors. The Cu and Ni
content were 28.8 wt.% and 27.6 wt.%, respectively.
3. Results & discussion
3.1. Effect of noble metals on the catalytic performance of NiCuAlOx
The combination of Cu, Ni and Al oxides prepared by co-
precipitation can yield highly versatile catalysts for alcohol amination
[20]. Accordingly, the THFDM amination reaction was first attempted
over a NiCuAlOx catalyst (Ni:Cu:Al = 1:1:1.25). Subsequently, noble
metals were supported over NiCuAlOx by adding the corresponding
RuCl3, H2PdCl4, and H2PtCl6 precursors during co-precipitation. Using
this approach, three catalytic formulations were prepared, i.e. Ru/
NiCuAlOx (0.64 wt.% Ru), Pd/NiCuAlOx (2.84 wt.% Pd) and Pt/NiCuAlOx
(0.11–0.22 wt.% Pt).
2.2. Characterization methods
High-resolution TEM analysis was carried out on a JEM 2010 micro-
scope operating at 200 keV. XRD measurements were conducted on a
STADI P automated transmission diffractometer (STOE) equipped with
an incident beam curved germanium monochromator selecting Cu
Kα1 radiation and a 6° position sensitive detector (PSD). For data inter-
pretation, the software WinXpow (STOE) and the database of Powder
Diffraction File (PDF) of the International Centre of Diffraction Data
(ICDD) were used. The XPS measurements were performed on a VG
ESCALAB 210 instrument provided with a dual Mg/Al anode X-ray
source, a hemispherical capacitor analyzer and a 5 keV Ar+ ion-gun.
All spectra were recorded using non-monochromatic Mg Ka
(1253.6 eV) radiation. Finally, the Cu and Ni contents of the catalyst
were measured by atomic emission spectrometry (ICP-AES) using an
Iris advantage Thermo Jarrel Ash device.
Table 2
Influence of the atmosphere on the catalytic performance of the 0.11wt.%Pt/NiCuAlOx
samplea.
Entry
N2
H2
Conversion%
Yield%
1
2
3
4
5
0.1 MPa
0.05 MPa
–
–
–
–
100
100
100
100
100
20
46
54
52
50
0.05 MPa
0.1 MPa
1.0 MPa
2.0 MPa
a
See footnote in Table 1.
Table 3
Influence of the solvent on the catalytic performance of the 0.11wt.%Pt/NiCuAlOx samplea.
Entry
Solvent
Conversion%
Yield%
TONb
Table 1
Catalyst screening for THFDM aminocyclizationa.
1
2
3
4
5
6
7
8
9
10
Methanol
Tert-butanol
THF
DMF
Acetone
Acetonitrile
Ethyl acetate
Dioxane
Trimethylbenzene
Toluene
0
0
0
0
0
0
0
66
86
100
0
0
0
0
0
0
0
34
38
58
0
0
0
0
0
0
0
81
134
403
Entry
Catalyst
Conversion%b
Yield%b
TONc
1
2
3
4
5
6
CuNiAlOx
95
28
58
52
54
40
48
–
0.11wt.%Pt/CuNiAlOx
0.18wt.%Pt/CuNiAlOx
0.22wt.%Pt/CuNiAlOx
0.64wt.%Ru/CuNiAlOx
2.84wt.%Pd/CuNiAlOx
100
100
100
82
403
197
175
14
6
100
The contribution from CuNiAlOx, i.e. 28% yield, was subtracted for calibration.
a
100 mg THFDM, 100 mg 0.11wt.%Pt/NiCuAlOx, 2 mL toluene, H2 atmosphere (0.1 MPa),
0.4 MPa NH3, 200 °C, 11 h. bDetermined by GC-FID using biphenyl as internal standard. cmol
OABCO produced per mol of Pt, Pd or Ru.
The contribution from CuNiAlOx, i.e. 28% yield, was subtracted for calibration.
a
See the footnote in Table 1; 100 mg 0.11wt.%Pt/CuNiAlOx was used as catalyst. bmol
OABCO produced per mol of Pt.

X. Cui et al. / Catalysis Communications 58 (2015) 195–199
197
Table 4
NiCuAlOx sample (Table 2). Only 20% OABCO was obtained at 100%
THFDM conversion under nitrogen atmosphere (Entry 1). In contrast,
the OABCO yield was significantly enhanced either in the presence of
an equimolar nitrogen/hydrogen mixture (0.05 MPa/0.05 MPa, Entry
2), or under pure hydrogen (0.1 MPa, Entry 3), reaching a value of 54%
in the latter case. A further increase of the hydrogen pressure to 1 and
2 MPa did not exert any remarkable effect on the catalytic performance
(Entries 4 and 5). In line with reported studies on Ni-supported cata-
lysts [14,15,32–35], the presence of hydrogen is expected to help main-
taining the catalyst activity.
Influence of the reaction time on the catalytic performance of the 0.11wt.%Pt/NiCuAlOx
samplea.
Entry
t/h
Conversion%
Yield%
TONb
1
2
3
4
6
8
11
16
100
100
100
100
43
50
58
55
201
296
403
363
The contribution from CuNiAlOx, i.e. 28% yield, was subtracted for calibration.
a
See the footnote in Table 2.
mol OABCO produced per mol of Pt.
b
The catalytic performance of the 0.11wt.%Pt/NiCuAlOx sample was
surveyed as a function of the solvent under 0.1 MPa hydrogen atmo-
sphere (Table 3). Noticeably, no reaction occurred using polar solvents
such as methanol, tert-butanol, THF, DMF, acetone, acetonitrile and
ethyl acetate (Entries 1–7). Conversely, in the presence of dioxane, the
THFDM conversion and OABCO yield reached values of 66% and 34%, re-
spectively (Entry 8). This result points out a possible negative influence
of hydroxyl and carbonyl groups on the catalytic performance. In light of
these results, we further explored the effect of apolar solvents such as
trimethylbenzene or toluene (Entries 9 and 10), the latter providing
the largest OABCO yield (ca. 58%).
Given the higher catalytic performance in the presence of toluene,
we further optimized the catalyst loading for the 0.11wt.%Pt/NiCuAlOx
sample. Only 12% THFDM conversion and ~1% OABCO yield could be
achieved with 30 mg of catalyst. The reaction progressed well by
increasing the catalyst loading to 70 or 100 mg, reaching a OABCO
yield of 51% and 58%, respectively, at full THFDM conversion with corre-
sponding TON values of 441 and 403.
The different formulations were tested in the presence of a 0.1 MPa
hydrogen atmosphere (Table 1). The parent NiCuAlOx catalyst only
afforded OABCO with 28% yield at 95% THFDM conversion (Entry 1).
The addition of Pt (0.11 wt.%) improved the OABCO yield to 58% at full
THFDM conversion (Entry 2). However, the yield declined slightly to
52–54% at higher Pt loading, i.e. 0.18 wt.% and 0.24 wt.% (Entries 3 and
4). The other supported noble metals, i.e. Ru (0.64 wt.%) and Pd
(2.84 wt.%), showed a moderate OABCO yield of 48% and 40%, respec-
tively (Entries 5 and 6). In light of these results, the Pt/NiCuAlOx formu-
lation with the lowest Pt loading (i.e. 0.11 wt.% Pt/NiCuAlOx) was
selected for further optimization.
3.2. Optimization of the reaction conditions for 0.11 wt.% Pt/NiCuAlOx
Additional catalytic tests were performed to assess the influence of
the atmosphere on the catalytic performance of the 0.11 wt.% Pt/
Scheme 2. THFDM and OABCO stability test and compounds observable by GC-MS during the amination reaction of THFDM.

198
X. Cui et al. / Catalysis Communications 58 (2015) 195–199
Fig. 1. From top to bottom, XRD patterns of fresh CuNiAlOx, fresh 0.11wt.%Pt/CuNiAlOx,
and used 0.11wt.%Pt/CuNiAlOx samples.
Finally, we completed our optimization by surveying the effect of the
reaction time on the catalytic performance for the 0.11wt.%Pt/NiCuAlOx
sample (Table 4). The reaction attained full THFDM conversion after 6 h
with an OABCO yield about 43% (Entry 1). The OABCO yield was pro-
moted to 50 and 58% by increasing the reaction time to 8 and 11 h,
respectively (Entries 2 and 3). However, a further increase of the reac-
tion time to 16 h resulted in a decline of the OABCO yield (Entry 4).
Fig. 3. TEM (top) and HR-TEM (bottom) micrographs of the fresh 0.11wt.%Pt/NiCuAlOx
sample.
3.3. Catalyst reusability
3.4. Mechanistic insights
The reusability of the 0.11wt.%Pt/CuNiAlOx catalyst was explored in
two consecutive runs. Only 1% OABCO yield was achieved after the sec-
ond run with ~20% THDFM conversion. Interestingly, almost the same
result was obtained when the parent CuNiAlOx catalyst was used. There-
fore, the observed deactivation in the former sample is not expected to
occur due to a possible Pt leaching, even if ICP-AES analysis revealed a
decrease of the Pt loading from the initial 0.11 wt.% to 0.07 wt.% after
reaction. We attribute the catalyst deactivation to the formation of a car-
bon film covering the active centers, as suggested by the increase of the
surface C concentration from 22.1 atom% to 37.7 atom% on the catalyst
after reaction (XPS). The activity of the catalyst could be partially recov-
ered after air-treatment at 500 °C and further reactivation under hydro-
gen flow at 400 °C, reaching an OABCO yield of 37% after the second run.
To gain insight into the reaction mechanism, the starting material
(THFDM) was tested at the optimized reaction conditions under
hydrogen (0.1 MPa) but with no addition of ammonia (Scheme 2a).
Under such conditions, THFDM was fully decomposed into light prod-
ucts and coke. Furthermore, the desired product (OABCO) was stable
under the reaction conditions with no detectable decomposition
(Scheme 2b). These observations suggest that, in the presence of ammo-
nia (0.4 MPa), THFDM amination can compete with its intrinsic decom-
position due to the high stability of the final product (OABDC).
By tracing the amination reaction with GC-MS, three main com-
pounds were detected (Scheme 2c). In addition, a similar OABCO yield
was achieved using compounds (a) or (d) in Scheme 2c as starting ma-
terial, but at a much faster rate than that in the case of THFDM
(Scheme 2d and Scheme 2e, respectively). In light of these results, a pos-
sible reaction mechanism for OABCO synthesis can be proposed
(Scheme 2f), where compound (a) in Scheme 2c or the corresponding
aminoalcohol (d) might behave as intermediates for OABCO synthesis.
In light of these results, a possible reaction mechanism for OABCO
synthesis can be proposed.
3.5. Catalyst characterization
The XRD patterns of the 0.11wt.%Pt/CuNiAlOx sample revealed the
presence of three characteristic reflections centered at 43.7°, 50.8° and
74.8° (Fig. 1), suggesting the formation of a Cu3.8Ni alloy (PDF09-0205).
The sample also presented a small amount of Cu2O (PDF77-0199) as de-
duced from the reflection appearing at 36.5°. The crystalline structure of
the catalyst kept unchanged before and after the reaction. The presence
of Cu2O was confirmed by XPS analysis (BE = 932.0 eV, Fig. 2A), even if
the presence of reduced Cu cannot be excluded. The XPS analyses also
revealed the formation of a NiO phase (BE = 854.8 eV, Fig. 2B), being
most likely located at the external surface of the Cu3.8Ni particles and
generated during sample handling. In all cases, the TEM and HR-TEM mi-
crographs revealed a high dispersion of the metal phase (Pt, Ru or Pd) on
Fig. 2. XPS spectra for the Cu2p and Ni2p core levels for the fresh and used 0.11wt.%Pt/
CuNiAlOx sample.

X. Cui et al. / Catalysis Communications 58 (2015) 195–199
199
[7] Y. Zhang, X.J. Qi, X.J. Cui, F. Shi, Y.Q. Deng, Tetrahedron Lett. 52 (2011) 1334–1338.
[8] W. He, L.D. Wang, C.L. Sun, K.K. Wu, S.B. He, J.P. Chen, P. Wu, Z.K. Yu, Chem. Eur. J. 17
(2011) 13308–13317.
[9] C.H. Tang, L. He, Y.M. Liu, Y. Cao, H.Y. He, K.N. Fan, Chem. Eur. J. 17 (2011)
7172–7176.
CuNiAlOx as nanoparticles with an average size of about ~5–10 nm with
preferential (111) orientation. Fig. 3 shows an illustrative example for
the 0.11wt.%Pt/CuNiAlOx sample.
[10] N. Zotova, F.J. Roberts, G.H. Kelsall, A.S. Jessiman, K. Hellgardt, K.K. Hii, Green Chem.
14 (2012) 226–232.
4. Conclusions
[11] T. Ishida, R. Takamura, T. Takei, T. Akita, M. Haruta, Appl. Catal. A Gen. 413–414
(2012) 261–266.
[12] Y.S. Demidova, I.L. Simakova, M. Estrada, S. Beloshapkin, E.V. Suslov, K.P. Korchagina,
K.P. Volcho, N.F. Salakhutdinov, A.V. Simakov, D.Y. Murzin, Appl. Catal. A Gen.
464–465 (2013) 348–356.
[13] D. Pingen, O. Diebolt, D. Vogt, ChemCatChem 5 (2013) 2905–2912.
[14] C.F. Winans, H. Adkins, J. Am. Chem. Soc. 54 (1932) 306–312.
[15] K.I. Shimizu, N. Imaiida, K. Kon, S.M.A.H. Siddiki, A. Satsuma, ACS Catal. 3 (2013)
998–1015.
[16] J. Sun, X. Jin, F. Zhang, W. Hu, J. Liu, R. Li, Catal. Commun. 24 (2012) 30–33.
[17] X. Cui, X. Dai, Y. Deng, F. Shi, Chem. Eur. J. 19 (2013) 3665–3675.
[18] A.J.J. Straathof, Chem. Rev. 114 (2014) 1871–1908.
The direct synthesis of 8-oxa-3-azabicyclo[3.2.1]octane via 2,5-
tetrahydrofuran-dimethanol aminocyclization reaction was realized
for the first time with an encouraging yield of 58% at 200 °C for 6–
16 h in the presence of hydrogen (0.1 MPa) and at an ammonia pressure
of 0.4 MPa. Partial catalyst recycling could be achieved after air treat-
ment at 500 °C followed by reactivation under hydrogen at 400 °C.
The direct amination process developed in this study provides a simpli-
fied route at comparable OABCO yield to the benchmark Wyeth's
process.
[19] C. Gunanathan, D. Milstein, Angew. Chem. Int. Ed. 47 (2008) 8661–8664.
[20] J. Luo, M. Wu, F. Xiao, G. Deng, Tetrahedron Lett. 52 (2011) 2706–2709.
[21] S. Imm, S. Bähn, M. Zhang, L. Neubert, H. Neumann, F. Klasovsky, J. Pfeffer, T. Haas,
M. Beller, Angew. Chem. Int. Ed. 50 (2011) 7599–7603.
Acknowledgments
[22] Q.L. Peng, Y. Zhang, F. Shi, Y.Q. Deng, Chem. Commun. 47 (2011) 6476–6478.
[23] X.J. Cui, Y. Zhang, F. Shi, Y.Q. Deng, Chem. Eur. J. 17 (2011) 1021–1028.
[24] A.C. Cope, W.N. Baxter, J. Am. Chem. Soc. 77 (1955) 393–395.
[25] A.D. Miller, US Patent 3,856,783, 1974.
[26] J.C. Verheijen, D.J. Richard, K. Curran, J. Kaplan, K. Yu, A. Zask, Bioorg. Med. Chem.
Lett. 20 (2010) 2648–2653.
The authors would like to express their gratitude to Dr. M. Corbet at
E2P2L for helpful discussion on reaction mechanisms during the prepa-
ration of this paper.
[27] H.-R. Tsou, G. MacEwan, G. Birnberg, N. Zhang, N. Brooijmans, L. Toral-Barza, I.
Hollander, S. Ayral-Kaloustian, K. Yu, Bioorg. Med. Chem. Lett. 20 (2010)
2259–2263.
[28] K.M. Foote, K. Blades, A. Cronin, S. Fillery, S.S. Guichard, L. Hassall, I. Hickson, X. Jacq,
P.J. Jewsbury, T.M. McGuire, J.W.M. Nissink, R. Odedra, K. Page, P. Perkins, A.
Suleman, K. Tam, P. Thommes, R. Broadhurst, C. Wood, J. Med. Chem. 56 (2013)
2125–2138.
Appendix A. Supplementary data
Supplementary data to this article can be found online at http://dx.
doi.org/10.1016/j.catcom.2014.09.027. These data include MOL files
and InChiKeys of the most important compounds described in this
article.
[29] W. Mao, M. Ning, Z. Liu, Q. Zhu, Y. Leng, A. Zhang, Bioorg. Med. Chem. 20 (2012)
2982–2991.
[30] T.J. Connolly, J.L. Considine, Z. Ding, B. Forsatz, M.N. Jennings, M.F. MacEwan, K.M.
McCoy, D.W. Place, A. Sharma, K. Sutherland, Org. Process Res. Dev. 14 (2010)
459–465.
[31] F.H. Newth, L.F. Wiggins, J. Chem. Soc. (1948) 155–158.
[32] A. Fischer, T. Mallat, A. Baiker, J. Mol. Catal. A Chem. 149 (1999) 197–204.
[33] P.S.E. Dai, T.L. Renken, L.D. Neff, US Patent 5,352,835, 1994.
[34] G.A. Vedage, L.A. Emig, H.X. Li, J.N. Armor, US patent 5,917,092, 1998.
[35] T.L. Renken, H.P. Klein, WO2009/114438, 2009.
References
[1] M.H.S.A. Hamid, P.A. Slatford, J.M.J. Williams, Adv. Synth. Catal. 349 (2007)
1555–1575.
[2] G. Guillena, D.J. Ramon, M. Yus, Chem. Rev. 110 (2010) 1611–1641.
[3] G.E. Dobereiner, R.H. Crabtree, Chem. Rev. 110 (2010) 681–703.
[4] S. Bahn, S. Imm, L. Neubert, M. Zhang, H. Neumann, M. Beller, ChemCatChem 3
(2011) 1853–1864.
[5] C. Gunanathan, D. Milstein, Science 341 (2013) 12297121–122971211.
[6] J.W. Kim, K. Yamaguchi, N. Mizuno, J. Catal. 263 (2009) 205–208.