Selective transfer semihydrogenation of alkynes with nanoporous gold catalysts

Article abstract of DOI:10.1021/jo502313d

A facile, highly chemo- and stereoselective transfer semihydrogenation of alkynes to Z-olefins has been achieved by use of unsupported nanoporous gold (AuNPore) as a heterogeneous catalyst together with formic acid as a hydrogen donor. A variety of terminal/internal and aromatic/aliphatic alkynes were reduced to the corresponding alkenes in high chemical yields with good functional-group tolerance. The catalyst is robust enough to be reused without leaching.

Full text of DOI:10.1021/jo502313d

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Article
Selective Transfer Semihydrogenation of
Alkynes with Nanoporous Gold Catalysts
Yogesh S. Wagh, and Naoki Asao
J. Org. Chem., Just Accepted Manuscript • Publication Date (Web): 18 Dec 2014
Downloaded from http://pubs.acs.org on December 19, 2014
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Selective Transfer Semihydrogenation of Alkynes with Nanoporous
Gold Catalysts
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Yogesh S. Wagh and Naoki Asao*
WPIꢀAdvanced Institute for Materials Research, Tohoku University, Sendai 980ꢀ8577, Japan
Fax: (+)81ꢀ22ꢀ217ꢀ6165
Eꢀmail: asao@m.tohoku.ac.jp
Table of Contents Graphic
20 examples
90-99% yield
H
H
AuNPore cat
R1
R2
R1
R2 excellent chemo-
HCO2H, amine cat
and stereoselectivity
ABSTRACT
A facile, highly chemoꢀ and stereoselective transfer semiꢀhydrogenation of alkynes to Zꢀ
olefins has been achieved by use of unsupported nanoporous gold (AuNPore) as a heterogeneous
catalyst together with formic acid as a hydrogen donor. A variety of terminal/internal and
aromatic/aliphatic alkynes were reduced to the corresponding alkenes in high chemical yields
with good functionalꢀgroup tolerance. The catalyst is robust enough to be reused without
leaching.
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INTRODUCTION
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Semihydrogenation of alkynes is one of the most simple and straightforward synthetic methods
of alkenes in laboratory as well as in industry.1 This transformation has been established well
using Lindlar catalyst with molecular hydrogen, and Zꢀolefins are produced seletively.2
However, it often suffers from many drawbacks. E/Z isomerization occurs to a considerable
extent. The overꢀreduction of the produced alkenes to alkanes is a serious problem due to the
difficulty of the control of a stoichiometric amount of H2. Requirement of toxic lead for
deactivation of Pd is obviously undesirable. Furthermore, H2 is highly flammable and readily
forms explosive mixtures with air. On the other hand, the catalytic transfer hydrogenation using
organic hydrogen donors is attractive because of the operational simplicity and safety.3 Several
protocols with homogeneous catalysts have been reported so far,4 but heterogeneous catalytic
systems are surprisingly quite limited.5 The first example was reported by Heck in 1978 by use
of Pd/C with trialkylammonium formate as a hydrogen source.5a,b Johnstone used a combination
of Pdꢀpoisoned catalysts with Hg or Pb and sodium phosphinate.5c In both cases, however, overꢀ
reduction or E/Z isomerization occurred significantly. Alonso and Yus reported that the nickel
nanoparticles were effective for this reaction although substoichiometric amounts of NiCl2 and
large excess of Li metal were required.5d,e Cuerva, Cadenas, and Oltra developed a new
semihydrogenation system with water as a hydrogen source although excess amounts of Cp2TiCl
was needed.5f Liu reported the semihydrogenation with costly Hantzsch ester 1,4ꢀ
dihydropyridine (HEH) as the hydrogen source.5g Furthermore, the recyclability of all these
heterogeneous catalysts have not been investigated well. To overcome these limitations,
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development of selective and costꢀeffective heterogeneous catalytic system is highly desirable.
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Recently, unsupported nanoporous gold (AuNPore) has emerged as a potentially green and
sustainable catalyst in the chemical process, which can be easily obtained from Au alloys by
selective leaching of less noble metals, such as Ag, Cu, and Al.6,7 It has randomly oriented
ligaments with a hyperboloidꢀlike shape and nanopore channels, possessing a high density of
surface steps and kinks that are active for chemical reactions.8 Since AuNPore has high surface
area, high stability for versatile chemicals, high reusability, and no toxic nature, it has been
successfully applied to the various types of chemical processes in the gas and liquid phases.9,10 In
this context, we recently reported that this material was effective for the transfer
semihydrogenation of alkynes.10h Unfortunately, however, this method required excess amounts
of costly organosilanes as a hydrogen source. Therefore, the formation of stoichiometric amounts
of siloxane was inevitable as a byꢀproduct. Also it fails to achieve higher chemical yield of
desired alkenes in some cases. Particularly, the reaction with 1,2ꢀdialkylꢀsubstituted internal
alkynes does not go well. In continuation with our interest on this material, we herein report a
AuNPoreꢀcatalyzed transfer semihydrogenation of alkynes by use of HCO2H as a hydrogen
donor (Scheme 1). With this method, various terminal as well as internal aromatic/aliphatic
alkynes were reduced to the corresponding cisꢀalkenes with remarkable stereoꢀ and
chemoselectivity in high yields.
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Scheme 1: AuNPore-catalyzed transfer semihydrogenation of alkynes with HCO2H.
RESULT AND DISCUSSION
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The transfer semihydrogenation of 4ꢀethynylꢀ1,1'ꢀbiphenyl (1a) was performed under several
conditions and the results are summarized in Table 1. When 1a was treated with HCO2H (1 eq)
and Et3N (1 eq) in the presence of AuNPore catalyst (5 mol%) in DMF at 70 °C for 6h, the
reaction proceeded smoothly and the corresponding olefin product (2a) was obtained in 99%
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Table 1. Catalytic transfer semihydrogenation of alkyne 1aa
selectivity
entry
solvent
H source
additive
yield (%)b
(2a/3a)
99/1<
99/1
100/ꢀ
100/ꢀ
ꢀ
1
DMF
THF
HCO2H
HCO2H
Et3N (1 eq)
Et3N (1 eq)
Et3N (1 eq)
Et3N (1 eq)
Et3N (1 eq)
Et3N (1 eq)
ꢀ
99
90
48
35
0
2
3
CH3CN HCO2H
4
toluene
DMF
DMF
DMF
DMF
DMF
HCO2H
HCO2H
HCO2H
H2 (1 atm)
HCO2H
HCO2H
5c
6d
7
0
ꢀ
0
ꢀ
8e
9e
Et3N(0.2 eq) 98 (98)
Et3N(0.1 eq) 90
99/1<
99/1<
aReaction condition: 1a (0.3 mmol), AuNPore (5 mol %), H source (1.0 eq),
b
1
additive (0.1ꢀ1.0 eq), 70 °C, 6 h. Determined by H NMR analysis with
dibromomethane as an internal standard. Isolated yield is shown in parentheses.
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d
cReaction was conducted in the absence of AuNPore catalyst. Au30Ag70 alloy
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was used as a catalyst instead of AuNPore. eReaction time is 14 h.
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yield with a trace amount of alkane product (3a) (entry 1). The high chemoselectivity was also
observed with other solvents, such as THF, CH3CN, and toluene, although the chemical yield
was significantly decreased in case of CH3CN and toluene (entries 2ꢀ4). No reactions occurred
without AuNPore or with Au alloy (entries 5ꢀ6). It should be noted that H2 gas (1 atm) is unable
to reduce alkyne under the present reaction condition and the starting material was recovered
quantitatively (entry 7). These results clearly indicated that H2 was not formed from HCO2H in
this chemical process. We found that the reaction proceeded even with 20 mol% of Et3N, and 2a
was obtained in 98% yield with longer reaction time (14 h) (entry 8).11 Further decrease of Et3N
to 10 mol% lowered the chemical yield to 90% (entry 9). Based on these results, we decided to
use the condition of entry 8 [(HCO2H (1 eq), Et3N (20 mol%), DMF] as a standard condition.
The substrate generality of the current reaction was examined and the selected examples are
summarized in Table 2. The reaction of phenylacetylene 1b proceeded much faster than that of
1a under the standard condition, and the corresponding product, styrene (2b), was obtained with
4 h in 91% yield (entry 1). On the other hand, the reaction of orthoꢀmethyphenylacetylene 1c
was sluggish and 8 hours were needed for completion, probably due to the steric hindrance of the
methyl group at the orthoꢀposition (entry 2). Actually, the reactions of metaꢀ and paraꢀisomers
(1d-e) finished with 4 hours (entries 3ꢀ4). Methoxyꢀ and fluoroꢀsubstituted phenylacetylene at
the paraꢀposition (1f-g) gave the corresponding olefin products (2f-g) nearly quantitatively with
high selectivity (entries 5ꢀ6). Based on the results shown in entries 1 and 4ꢀ6, the electronic
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effect of these substituents on the phenyl ring is negligible. Not only aromatic terminal
acetylenes but also aliphatic ones were suitable substrates in the present reaction. For example,
propargylbenzene 1h gave allylbenezene 2h in 90% yield (entry 7). Furthermore, a variety of
functional groups are tolerated in the reaction including nitrile, acetal, and sulphonamide groups
(entries 8ꢀ10). Interestingly, no overꢀreduction products were observed with any of the aliphatic
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Table 2. AuNPore-catalyzed transfer semihydrogenation of alkynesa
selectivity
entry
1
alkyne
time (h)
4
yield (%)b
91
(alkene/alkane)
100/ꢀ
1b
1c
2
3
8
4
92
93
98/2
99/1
1d
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5
96
99
98
99/1
99/1
100/ꢀ
1e
1f
1g
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4
4
90
96
100/ꢀ
100/ꢀ
1h
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98
100/ꢀ
100/ꢀ
1j
10
99 (98)
1k
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11c
12 e
13 e
4
99 (96)
99 (96)
99 (98)
100/ꢀd
100/ꢀf
100/ꢀ d
1l
1m
1n
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19
n-C5H11
n-C5H11
14 e
15 e
16 c
2
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4
99 (95)
98 (95)
99 (98)
100/ꢀd
100/ꢀf
100/ꢀd
1o
1p
1q
17 c
4
99 (98)
100/ꢀd
1r
18 c
19c
2
1
99 (95)
99 (94)
100/ꢀd
100/ꢀd
1s
1t
aReaction conditions: alkyne (0.3 mmol), AuNPore (5 mol%), HCO2H (0.3 mmol), Et3N
(20 mol%), DMF, 70 °C. bDetermined by 1H NMR using dibromomethane as an internal
standard. Isolated yield is shown in parentheses. cHCO2H (0.45 mmol), DMAP (10 mol%).
dZ/E ratio was 100:0. eHCO2NH4 (0.3 mmol) was used instead of HCO2H/Et3N in CH3CN
(0.5M) at 80 °C. fZ/E ratio was 99:1.
alkynes screened (entries 7ꢀ10). Next, we conducted the reaction with internal alkynes. When the
reaction was performed with diphenylacetylene 1l, a mixture of Z/E (95/05) isomers 2l was
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produced. To improve the selectivity, further optimization was carried out, and finally the Z/E
selectivity was increased to 100% by use of 1.5 equivalents of HCO2H and 10 mol% of 4ꢀ
dimethylaminopyridine (DMAP) in DMF as shown in entry 11. However, in the case of
phenylbutyne 1m, the reaction proceeded sluggishly and the corresponding product 2m was
obtained in 75% with the recovery of 1m in 25% even after 36 h. In the further investigation of
other hydrogen sources, we found that the use of ammonium formate gave excellent yield of 2m
with very high selectivity (entry 12). The reaction of dodecꢀ6ꢀyne 1n also proceeded smoothly
with ammonium formate to give Zꢀ2n as a sole product (entry 13). Since the transfer
semihydrogenation of 1n with R3SiH did not proceed well, this is a marked contrast result.10h
Primary propargylic alcohol 1o was also hydrogenated efficiently to Zꢀcinnamyl alcohol 2o
(entry 14). Benzyl ethers are vulnerable for hydrogenolysis of benzyl group under hydrogenation
reaction conditions (H2/PdꢀC). The present transfer semihydrogenation using AuNPore catalyst
allows us to selectively reduce alkyne of benzyl protected propargyl alcohol 1p without
disturbing benzyl group providing excellent selectivity for Zꢀolefin (entry 15). The selective
semihydrogenation was also successfully achieved with electronꢀdeficient internal alkynes1q-t,
bearing electronꢀwithdrawing groups, such as nitrile, ketone, and ester groups, and the
corresponding olefin products 2q-t were obtained in nearly quantitative yields with excellent
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chemoꢀ and stereoselectivity (entries 16ꢀ19). To know the reactivity of alkene for overꢀreduction, the
hydrogenation reaction of cisꢀstilbene 2l was performed under the present reaction conditions (same as
table 2, entry 11). As expected, no reaction occurred and 2l was recovered quantitatively. This result
reveals that the present method is highly selective for semihydrogenation of alkynes.
We next examined the split test to clarify whether the AuNPoreꢀcatalyzed reaction proceeds
heterogeneously or not. The reaction of 1a was performed under the standard condition for 6h.
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At this stage, 2a was formed in 40% yield. Then, half of the supernatant solution was transferred
to another reaction vessel, and it was stirred for a further 10 h in the absence of the catalyst. As
we expected, the amount of 2a remained unchanged in the supernatant. In contrast, the reaction
of the residual mixture containing AuNPore catalyst gave 2a in 98% yield after 10 h (Scheme 2).
Furthermore, only negligible amount of gold leaching (4.7 ppb) into the reaction mixture was
detected by inductively coupled plasma mass spectrometry (ICPꢀMS) analysis. These results
clearly indicated that the current reaction proceeded through a heterogeneous process. The
catalyst can be recovered easily by just filtration without any cumbersome separation technique
like centrifugation, and it can be reused repeatedly. When the reaction of 1e was conducted five
times, the corresponding olefin product 2e was obtained in high yield every time (Figure 1).
SEM analysis revealed that the nanostructure of the catalyst was not changed at all even after
five uses (Figure S1 in the Supporting Information).
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Scheme 2. Leaching experiment by split test for AuNPore catalyzed transfer
semihydrogenation of 1a.
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Figure 1. Reusability of AuNPore for transfer semihydrogenation of 1e.
CONCLUSION
In summary, we have established for the first time that the AuNPore is an effective and reusable
catalyst for the transfer semihydrogenation of various terminal as well as internal
aromatic/aliphatic alkynes by use of HCO2H, leading to Zꢀolefins in high yields with excellent
chemoꢀ and stereoselectivity. HCO2H is a costꢀeffective and easily available hydrogen source. A
variety of reducible functional groups are tolerated in the reaction including nitrile, ketone, and
ester groups. Further studies to elucidate the mechanism of the current transformation and to
extend the scope of synthetic utility are in progress in our laboratory.
EXPERIMENTAL SECTION
General information: Scanning electron microscope (SEM) observation was carried out at an
accelerating voltage of 30 kV. EDX analysis was carried out at an accelerating voltage of 20 kV.
All the reactions were carried out under nitrogen atmosphere. The progress of the reaction was
monitored on GCꢀMS/TLC. GCꢀMS analysis was performed on GC interfaced to massꢀselective
detector (30 m x 0.25 mm capillary column, HPꢀ5MS). NMR spectra were measured at 400 MHz
for 1H and 100 MHz for 13C. Analytical thinꢀlayer chromatography (TLC) was performed on 0.2
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mm precoated plate Kieselgel 60 F254. Column chromatography was carried out employing
silica gel 60 N (spherical, neutral, 40−100 ꢁm).
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Materials: The commercially available alkynes are used as received. Alkyne 1k,12a 1p,12b 1q12c
and 1r12c were prepared following the reported literature procedure. The chemical yield of all
products was determined by 1H NMR analysis with dibromomethane as an internal standard. All
the products are known and their spectral data’s are consistent with previously published
literature values.
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Preparation procedure of AuNPore catalysts:
Au (99.99%) and Ag (99.99%) were melted with electric arcꢀmelting furnace under argon
atmosphere to form Au/Ag alloy (30:70, in at.%), which was rolled down to thickness of 40 ꢁm.
The foil was annealed at 850 °C for 18 h in the electrical muffle furnace. The resulting foil was
cut into small pieces (2 x 2 mm square). Immersion of the resulting several chips (total weight:
50 mg) in excess amount of 70 wt.% nitric acid (50 mL) for 18 h at room temperature resulted in
the formation of the nanoporous structure by selective leaching of silver. The material was
washed with saturated aq. NaHCO3, distilled water, and acetone, successively. Drying of the
material under reduced pressure gave the AuNPore (22.1 mg) and its composition was
determined to be Au99.24Ag0.76 by EDX analysis.
Representative procedure for the AuNPore-catalyzed transfer semihydrogenation of
terminal alkyne 1a (Table 1, entry 8): To a Vꢀshaped vial reactor containing AuNPore (3.0 mg,
5 mol %) and 1a (53.4 mg, 0.3 mmol) were added DMF (1 M, 0.3 mL), HCO2H (11.3 ꢁL, 0.3
mmol), NEt3 (8.4 ꢁL, 20 mol %) subsequently at room temperature. The reaction mixture was
stirred at 70 °C for 14 h and was monitored by TLC and GCꢀMS. The AuNPore catalyst was
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recovered by filtration, and the solution was extracted with ethyl acetate. After washing the
organic layer with water (20 mL X 3), the organic solvent was evaporated under reduced
pressure to give a crude material. The crude material was purified with silica gel chromatography
to afford 2a (53 mg, 98%) as a white solid. All the following products are known and spectral
data is in consistent with authentic samples or previously published literature values: 2a,10h 2b,
2c, 2d, 2e, 2f, 2g, 2h, 2i, 2j, 2k.10h Spectral data for some selected compounds is given below.
4-vinyl-1,1'-biphenyl (2a) : White solid, 52 mg, 98% yield; 1HNMR (400 MHz, CDCl3), δ 7.65ꢀ
7.57 (m, 4H), 7.5ꢀ7.43 (m, 4H), 7.37ꢀ7.33 (m, 1H), 6.77 (dd, J = 17.6, 10.8 Hz, 1H), 5.8 (d, J =
17.6 Hz, 1H), 5.28 (d, J = 10.8 Hz, 1H).
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N-allyl-4-methylbenzenesulfonamide (2k) : White solid, 62 mg, 98% yield; 1HNMR (400 MHz,
CDCl3), δ 7.7 (d, J = 8.4, 2H), 7.27ꢀ7.21 (m, 2H), 5.7ꢀ5.61 (m, 1H), 5.13ꢀ5.01 (m, 2H), 4.84ꢀ4.81
(m, 1H), 3.54ꢀ3.5 (m, 2H), 2.37 (s, 3H).
Representative procedure for the AuNPore-catalyzed transfer semihydrogenation of
internal alkyne 1l (Table 2, entry 11): To a Vꢀshaped vial reactor containing AuNPore (3.0 mg,
5 mol %), 1l (53.4 mg, 0.3 mmol) and DMAP (3.66 mg, 10 mol %) were added DMF (1 M, 0.3
mL) and HCO2H (17 ꢁL, 0.45 mmol) subsequently at room temperature. The reaction mixture
was stirred at 70 °C for 4 h and was monitored by TLC and GCꢀMS. The AuNPore catalyst was
recovered by filtration, and the solution was extracted with diethylether. After washing the
organic layer with water (20 mL X 3), the organic solvents were evaporated under reduced
pressure to give a crude material. The crude material was purified with silica gel chromatography
to afford 2l (52 mg, 96%) as a colorless liquid. All the following products are known and
spectral data is in consistent with authentic samples or previously published literature values: 2l,
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2m,12d 2n,12e 2o,12f 2p12f 2q,12g 2r12g , 2s12g and 2t.10h Spectral data for some selected compound
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(Z)-1,2-Diphenylethene (2l) : colorless liquid, 52 mg, 96% yield; 1HNMR (400 MHz, CDCl3), δ
7.26ꢀ7.16 (m, 10H), 6.6 (s, 2H).
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(Z)-But-1-en-1-ylbenzene (2m): colorless liquid, 38 mg, 96% yield; 1HNMR (400 MHz, CDCl3),
δ 7.34ꢀ7.19 (m, 5H), 6.38 (d, J = 11.6 Hz, 1H), 5.68ꢀ5.62 (m, 1H), 2.39ꢀ2.31 (m, 2H), 1.06 (t, J =
7.6 Hz, 3H).
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(Z)-dodec-6-ene (2n): colorless liquid, 49.4 mg, 98% yield; HNMR (400 MHz, CDCl3), δ 5.36
(tꢀlike m, J = 4.8 Hz, 2 H), 2.05ꢀ2.0 (m, 4 H), 1.38ꢀ1.27 (m, 12 H), 0.90 (t, J = 6.8 Hz, 6 H).
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(Z)-3-Phenylprop-2-en-1-ol (2o): colorless liquid, 38 mg, 95% yield; HNMR (400 MHz,
CDCl3), δ 7.36ꢀ7.19 (m, 5H), 6.57 (d, J = 11.6, 1H), 5.87 (dt, J = 11.6, 6.4 Hz, 1H), 4.45ꢀ4.43 (m,
2H), 1.59ꢀ1.55 (bs, 1H).
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(Z)-3-(Benzyloxy)prop-1-en-1-yl)benzene (2p): colorless liquid, 64 mg, 95% yield; HNMR
(400 MHz, CDCl3), δ 7.39ꢀ7.19 (m, 10H), 6.62 (d, J = 12, 1H), 5.94ꢀ5.88 (m, 1H), 5.53 (s, 2H),
4.2 (dd, J = 6, 1.2 Hz, 2H).
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(Z)-3-Styrylbenzonitrile (2q): white solid, 60 mg, 98% yield; HNMR (400 MHz, CDCl3), δ
7.48 (d, J = 8 Hz, 2H), 7.31 (d, J = 8 Hz, 2H), 7.27ꢀ7.17 (m, 5H), 6.75 (d, J = 12.4, 1H), 6.56 (d,
J = 12.4, 1H).
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(Z)-1-(3-Styrylphenyl)ethan-1-one (2r): white solid, 65 mg, 98% yield; HNMR (400 MHz,
CDCl3), δ 7.81 (d, J = 8 Hz, 2H), 7.33 (d, J = 8 Hz, 2H), 7.26ꢀ7.21 (m, 5H), 6.73 (d, J = 12.4 Hz,
1H), 6.61 (d, J = 12.4 Hz, 1H), 2.57 (s, 3H).
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Ethyl-(Z)-3-phenylacrylate (2s): colorless liquid, 50 mg, 95% yield; HNMR (400 MHz,
CDCl3), δ 7.58ꢀ7.56 (m, 2H), 7.37ꢀ7.31 (m, 3H), 6.94 (d, J = 12.8 Hz, 1H), 5.94 (d, J = 12.8 Hz,
1H), 4.17 (q, J = 7.2 Hz, 2H), 1.24 (t, J = 7.2 Hz, 3H).
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Methyl-(Z)-non-2-enoate (2t): colorless liquid, 48 mg, 94% yield; HNMR (400 MHz, CDCl3),
δ 6.26ꢀ6.19 (m, 1H), 5.6 (dt, J = 11.6, 2 Hz, 1H), 3.69 (s, 3H), 2.67ꢀ2.61 (m, 2H), 1.45ꢀ1.39 (m,
2H), 1.36ꢀ1.28 (m, 6H), 0.87 (t, J = 6.8 Hz, 3H).
Procedure for Leaching experiment by split test (Scheme 2): To a Vꢀshaped vial reactor
containing AuNPore (10.0 mg, 5 mol %) and 1a (178 mg, 1.0 mmol) were added DMF (1 M, 1
mL), HCO2H (38 ꢁL, 1.0 mmol), NEt3 (28 ꢁL, 20 mol %) and 1, 3, 5ꢀtrimethoxybenzene (16.8
mg, 0.1 mmol, internal standard) subsequently at room temperature. The reaction mixture was
stirred at 70 °C for 6h. At this stage, 10 ꢁL of the supernatant solution was picked up for
1
checking the chemical yield of 2a with H NMR (40%). Then, 0.5 mL of the supernatant was
transferred to vesselꢀ2, and it was stirred for 10 h at 70 °C in the absence of the catalyst. The
chemical yield of 2a was checked again by picking up 10 ꢁL of the resulting solution and it
remain unchanged (40%). In contrast, the residual containing the AuNPore catalyst was
completed in 10 h, giving 2a in 98% 1H NMR yield.
ASSOCIATED CONTENT
Supporting Information
SEM images and NMR spectra. This material is available free of charge via the Internet at
http://pubs.acs.org.
AUTHOR INFORMATION
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Corresponding Author
Fax: (+)81ꢀ22ꢀ217ꢀ6165
Eꢀmail: asao@m.tohoku.ac.jp
Notes
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The authors declare no competing financial interest.
ACKNOWLEDGMENT
This work was partially supported by a GrantꢀinꢀAid for Scientific Research (No. 25286012)
from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) (Japan).
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