Manganese oxide-catalyzed transformation of primary amines to primary amides through the sequence of oxidative dehydrogenation and successive hydration

Article abstract of DOI:10.1039/c2cc17499e

Manganese oxide octahedral molecular sieves (OMS-2) could act as an efficient, reusable heterogeneous catalyst for transformation of various primary amines to the corresponding primary amides through the sequence of oxidative dehydrogenation and successive hydration. The Royal Society of Chemistry 2012.

Full text of DOI:10.1039/c2cc17499e

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COMMUNICATION
Manganese oxide-catalyzed transformation of primary amines to primary
amides through the sequence of oxidative dehydrogenation and successive
hydrationw
Ye Wang, Hiroaki Kobayashi, Kazuya Yamaguchi and Noritaka Mizuno*
Received 1st December 2011, Accepted 12th January 2012
DOI: 10.1039/c2cc17499e
Manganese oxide octahedral molecular sieves (OMS-2) could act as
an efficient, reusable heterogeneous catalyst for transformation of
various primary amines to the corresponding primary amides through
the sequence of oxidative dehydrogenation and successive hydration.
Amides are one of the most important chemicals that have widely
been used as intermediates in organic synthesis, raw materials for
1
engineering plastics, detergents, and lubricants. The development
of green procedures for synthesis of amides from various starting
materials is a very important subject in modern organic synthesis
(
instead of antiquated procedures using activated carboxylic
acid derivatives and amines). The Beckmann rearrangement of
ketoximes is one of the most commonly utilized procedures for
2
,3
synthesis of N-substituted amides. In particular, the vapor-phase
Beckmann rearrangement of cyclohexanone oxime using high
Fig. 1 Transformation of primary amines to primary amides. Nishinaga’s
9
procedure: (i) reflux in ethanol, (ii) BuOK (or KOH), O . Yoshifuji’s
t
2
3
silica zeolite catalysts has been industrialized. Dehydrogenative
10
procedure: (i) tert-butyl S-4,6-dimethylpyrimidyl-2-thiocarbonate,
synthesis of N-substituted amides directly from alcohols and
4
amines can be realized by using several precious metal complexes.
triethylamine, (ii) RuO
2
ꢀnH
2 4
O, NaIO , (iii) trifluoroacetic acid.
5
6
only one system using the supported ruthenium hydroxide
Hydration of nitriles and rearrangement of aldoximes are two of
the most attractive procedures for synthesis of primary amides.
Quite recently, we have reported that manganese oxide octahedral
x
2 3
catalyst, Ru(OH) /Al O , has previously been reported for
1
1
this dehydrogenation–hydration strategy. Various kinds of
primary amines can be converted into the corresponding amides,
while a large amount of water (reactant) is indispensable because
of the very low catalytic activity of Ru(OH) /Al O for nitrile
7
molecular sieves (OMS-2) can act as an efficient, reusable hetero-
geneous catalyst for synthesis of various kinds of primary amides
8
from alcohols (or aldehydes) and aqueous ammonia.
x
2 3
5a,11
hydration.
We demonstrate herein that it is possible to
With regard to synthesis of primary amides, primary amines
are also desirable starting materials because they are readily
available and inexpensive. However, in general, it is very difficult to
oxygenate primary amines, and reactive stoichiometric reagents are
realize oxygenation of primary amines to primary amides through
the sequence of oxidative dehydrogenation and hydration with
OMS-2, and that the catalytic performance of OMS-2 is much
superior to that of Ru(OH) /Al O (see Table 1).
9
,10
necessary.
For example, Nishinaga’s procedure requires a
x
2
3
First, various kinds of catalysts were applied to the trans-
stoichiometric amount of 2,6-di-tert-butyl-p-benzoquinone
9
Fig. 1). In Yoshifuji’s procedure, amines with the Boc
formation of benzylamine (1a) to benzamide (2a) using air
(
(
(
was the suitable solvent because of the high solubilities of
as an oxidant) and aqueous ammonia (Table 1).z 1,4-Dioxane
Boc = tert-butoxycarbonyl) protection are oxygenated using
in situ-generated RuO , followed by deprotection of the Boc group
4
8
substrates, ammonia, and water. When the transformation
1
0
(
Fig. 1). In contrast, the dehydrogenation–hydration sequence
was carried out with OMS-2, 83% yield of 2a was obtained
with a small amount of benzonitrile (3a, 3% yield). In the
with molecular oxygen (air) as a sole oxidant theoretically
produces only water as a co-product (Fig. 1). As far as we know,
2
presence of commercially available activated MnO (generally
utilized for organic oxidations), 1a was converted into the
corresponding nitrile 3a as a major product (72% yield) with
12% yield of 2a. Other manganese-based oxides such as b-MnO2,
b-MnOOH, and birnessite-type MnO2 gave 3a and 4a in
Department of Applied Chemistry, School of Engineering,
The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku,
Tokyo 113-8656, Japan. E-mail: tmizuno@mail.ecc.u-tokyo.ac.jp;
Fax: +81-3-5841-7220; Tel: +81-3-5841-7272
w Electronic supplementary information (ESI) available: Experimental
details and Table S1. See DOI: 10.1039/c2cc17499e
moderate yields, and 2a was hardly produced. KMnO
4
and
MnSO ꢀH O (precursors for OMS-2) were not effective for
4
2
2
642 Chem. Commun., 2012, 48, 2642–2644
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a
Table 1 Effect of catalysts on the transformation of 1a to 2a
Table 2 Scope of the OMS-2 catalyzed transformation of primary
amines to primary amides
a
Time/ Yield
(%)
Entry Substrate
1
Product
h
Yield (%)
1a
1a
2a 3
2a 3
87
82
b
2
Entry
Catalyst
2a
83
12
5
3a
4a
5a
1
2
3
4
5
OMS-2
Activated MnO
3
1
2
o1
2
b
3
4
1b
1b
2b 3
2b 3
98
90
2
72
63
9
29
37
o1
80
46
b
b-MnO
b-MnOOH
Birnessite-type MnO
KMnO
MnSO
Ru(OH)e
RuHAP
2
19
39
10
22
4
o1
o1
2
2
6
o1
2
c
6
7
4
7
5
6
7
1c
1d
1e
2c 3
2d 3
2e 3
92
89
96
c
4
ꢀH
2
O
o1
o1
o1
o1
d
8
9
x
/Al
2
O
3
13
10
2
1
a
Reaction conditions: catalyst (100 mg), 1a (0.5 mmol), aqueous
ammonia (28 wt%, 100 mL), 1,4-dioxane (1 mL), 130 1C (bath
temperature), air (6 atm), 3 h. Yields were determined by GC using
b
naphthalene as an internal standard. Commercially available (see the
c
ESI). Mn salt (0.5 mmol). 100 mg, Ru: 5 mol%, prepared according
d
e
to ref. 11. 100 mg, Ru: 18 mol%, commercially available (see the ESI).
8
9
1f
2f 3
2g 3
2h 3
82
93
65
the transformation. Supported ruthenium catalysts such as
1
1
12
Ru(OH)
gave 3a as a major product without formation of 2a.
x
/Al
2
O
3
and RuHAP (Ru on hydroxyapatite)y
1g
1h
The results of the OMS-2-catalyzed transformations of
various primary amines to the corresponding primary amides
under optimized conditions are summarized in Table 2. Trans-
formations of benzylamine derivatives (1a–1f), which contain
electron-donating as well as electron-withdrawing substituents
at different positions, efficiently proceeded to give the corres-
ponding benzamide derivatives in high yields. In the present
transformation, the steric effect of substrates was not significant
1
1
0
1
1i
1i
2i 3
2i 3
91
84
b
12
(1c–1e). Heteroatom-containing amines such as thiophene (1g)
and pyridine (1h–1j) methylamines efficiently proceeded to
afford the corresponding heteroaromatic amides. An aliphatic
amine (1k) also gave the corresponding amide in moderate
yield. The large scale transformation (10-fold scaled-up) was
also effective; the transformation of 1b efficiently proceeded
without any decrease in the performance in comparison with
the small-scale transformation given in Table 2, and 2b was
produced in 99% yield (by GC). OMS-2 was separated by
filtration and washed with ethanol and acetone. Evaporation of
the combined filtrate gave a crude product, followed by rinsing
with a mixed solvent of n-hexane and acetone (20 : 1 v/v, ca. 5 mL),
giving 0.65 g of 2b (96% isolated yield, >99% purity by GC
and NMR) [eqn (1)]. The observed catalysis was truly hetero-
geneous,z and the retrieved OMS-2 catalyst could be reused
without a significant loss of its high catalytic performance
13
1j
2j 3
2k 8
90
66
c
4
1
1k
a
Reaction conditions: OMS-2 (100 mg), substrate (0.5 mmol),
aqueous ammonia (28 wt%, 50 mL), 1,4-dioxane (1 mL), 130 1C
(bath temperature), air (6 atm). Yields were determined by GC using
diphenyl or naphthalene as an internal standard. See Table S1 in the
b
c
ESI for more details. Reuse experiment. OMS-2 (200 mg), aqueous
ammonia (28 wt%, 200 mL), 160 1C.
3a (6% yield) and 5a (3% yield) [eqn (2)]. The alkylimine 4a is
possibly produced through hydrolytic decomposition of the
aldimine intermediate to 5a, followed by condensation with 1a
(Scheme 1). When the same reaction was carried out in the
presence of aqueous ammonia (28 wt%, 100 mL), 2a, 3a, and
(
see entries 2, 4, and 12 in Table 2).
4
a were obtained in 10%, 21%, and 52% yields, respectively.
In addition, 4a was also converted into 2a (major product) and
a in 80% and 18% yields, respectively, in the presence of
OMS-2 and aqueous ammonia [eqn (3)].
3
ð1Þ
The reaction of 1a at 100 1C without aqueous ammonia
gave 4a as a major product (75% yield) with small amounts of
ð2Þ
Chem. Commun., 2012, 48, 2642–2644 2643
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The Teflon vessel was attached inside an autoclave, and the reaction was
carried out at 130–160 1C (bath temperature) in 6 atm of air. For safety
reasons, explosion-proof apparatus should be used for the reactions. The
turnover numbers based on OMS-2 were 1.2–3.6 under standard reaction
conditions. After the reaction was completed, the spent OMS-2
catalyst was separated by filtration, washed with ethanol and acetone,
and dried at 150 1C for 1 h prior to being used for the reuse experiment
ð3Þ
ð4Þ
(
>95% catalyst recovery). The products (amides) could simply be
isolated by evaporation of volatiles (combined filtrate), followed by
rinsing with a mixed solvent of n-hexane and acetone (20 : 1 v/v, ca. 5 mL).
The products were confirmed by the comparison of their GC retention
1
13
times, GC-MS spectra, and/or H and C NMR spectra with those of
authentic data.
y The step-by-step synthesis of nicotinamide (2i) from 3-picolylamine
1
2
(
1i) using RuHAP catalyst has been reported.
z We confirmed that no further production of 2a (amide) and 3a
nitrile) proceeded after removal of OMS-2 by hot filtration for the
(
transformation of 1a and that no manganese species was detected in the
filtrate (by inductively coupled plasma atomic emission spectroscopy
analysis, below 0.003%).
1
(a) C. E. Mabermann, in Encyclopedia of Chemical Technology,
ed. J. I. Kroschwitz, John Wiley & Sons, New York, 1991, vol. 1,
pp. 251–266; (b) D. Lipp, in Encyclopedia of Chemical Technology,
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pp. 346–356; (d) The Amide Linkage: Structural Significance in
Chemistry, Biochemistry and Material Science, ed. A. Greenberg,
C. M. Breneman and J. F. Liebman, Wiley, New York, 2000.
Scheme 1 Possible reaction pathway for the OMS-2-catalyzed trans-
formation of primary amines to primary amides.
Therefore, aqueous ammonia plays a crucial role; even if the
side-reaction to the corresponding alkylimine takes place
during the transformation, the alkylimine (undesirable by-product)
can efficiently be decomposed to the aldimine (desirable inter-
mediate to the corresponding amides) in the presence of aqueous
ammonia, resulting in the selective formation of the desired
primary amides. Notably, the reaction rate for the hydration of
2 (a) O. Meth-Cohn and B. Narine, Synthesis, 1980, 133;
b) R. E. Gawley, Org. React., 1988, 35, 1; (c) L. De Luca,
G. Giacomelli and A. Porcheddu, J. Org. Chem., 2002, 67, 6272;
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4, 755; (e) Y. Furuya, K. Ishihara and H. Yamamoto, J. Am.
(
(
4
Chem. Soc., 2005, 127, 11240.
3
4
Y. Izumi, H. Ichihashi, Y. Shimazu, M. Kitamura and H. Sato,
Bull. Chem. Soc. Jpn., 2007, 80, 1280.
(a) C. Gunanathan, Y. Ben-David and D. Milstein, Science, 2007,
3a with aqueous ammonia was larger than that with just water,
317, 790; (b) L. U. Nordstrøm, H. Vogt and R. Madsen, J. Am. Chem.
as shown in eqn (4). We confirmed that the hydration did not
proceed at all with aqueous ammonia alone (in the absence of
OMS-2). Thus, the OMS-2-catalyzed nitrile hydration is also
promoted by the presence of ammonia. The possible reaction
pathway for the OMS-2-catalyzed transformation of primary
amines to primary amides is summarized in Scheme 1.
Soc., 2008, 130, 17672; (c) A. J. A. Watson, A. C. Maxwell and J. M. J.
Williams, Org. Lett., 2009, 11, 2667; (d) D. Milstein, Top. Catal., 2010,
5
3, 915; (e) C. Chen and S. H. Hong, Org. Biomol. Chem., 2011, 9, 20;
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Int. Ed., 2011, 50, 8917; (g) J.-F. Soule, H. Miyamura and
(
´
S. Kobayashi, J. Am. Chem. Soc., 2011, 133, 18550.
5
(a) K. Yamaguchi, M. Matsushita and N. Mizuno, Angew. Chem.,
Int. Ed., 2004, 43, 1576; (b) A. Goto, K. Endo and S. Saito, Angew.
Chem., Int. Ed., 2008, 47, 3607; (c) R. S. Ramon, N. Marion and
´
S. P. Nolan, Chem.–Eur. J., 2009, 15, 8695; (d) T. Mitsudome,
Y. Mikami, H. Mori, S. Arita, T. Mizugaki, K. Jitsukawa and
K. Kaneda, Chem. Commun., 2009, 3258; (e) T. J. Ahmed, S. M. M.
Knapp and D. R. Tyler, Coord. Chem. Rev., 2011, 255, 949.
6 (a) H. Fujiwara, Y. Ogasawara, K. Yamaguchi and N. Mizuno,
Angew. Chem., Int. Ed., 2007, 46, 5202; (b) N. A. Owston,
A. J. Parker and J. M. J. Williams, Org. Lett., 2007, 9, 73;
In summary, OMS-2 could act as an efficient heterogeneous
catalyst for synthesis of primary amides from primary amines in
the presence of aqueous ammonia. The catalyst/product separation
was very easy. The observed catalysis was truly heterogeneous,
and OMS-2 could be reused without an appreciable loss of its
high catalytic performance. The dual catalytic functions of
OMS-2 make oxygenation of primary amines possible through the
sequence of oxidative dehydrogenation and successive hydration.
Aqueous ammonia also plays two important roles, that is,
transforming back alkylimines (by-products) to aldimines
(
c) H. Fujiwara, Y. Ogasawara, M. Kotani, K. Yamaguchi and
N. Mizuno, Chem.–Asian J., 2008, 3, 1715; (d) M. Kim, J. Lee,
H.-Y. Lee and S. Chang, Adv. Synth. Catal., 2009, 351, 1807.
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C.-L. O’Young, S. Levine and J. M. Newsam, Chem. Mater., 1994,
7
(
intermediates) and promotion of nitrile hydration.
We thank Dr Y. Kuroda and Mr T. Oishi (The University of
6, 815; (b) Y.-C. Son, V. D. Makwana, A. R. Howell and S. L. Suib,
Angew. Chem., Int. Ed., 2001, 40, 4280; (c) S. L. Suib, J. Mater. Chem.,
2008, 18, 1623; (d) S. L. Suib, Acc. Chem. Res., 2008, 41, 479;
(e) T. Oishi, K. Yamaguchi and N. Mizuno, ACS Catal., 2011, 1, 1351.
K. Yamaguchi, H. Kobayashi, T. Oishi and N. Mizuno,
Angew. Chem., Int. Ed., 2012, 51, 544.
9 A. Nishinaga, T. Shimizu and T. Matsuura, J. Chem. Soc., Chem.
Commun., 1979, 970.
Tokyo) for their help with preparation of manganese oxides. This
work was supported in part by the Global COE Program
8
(Chemistry Innovation through Cooperation of Science and
Engineering) and Grants-in-Aid for Scientific Research from
Ministry of Education, Culture, Sports, Science and Technology.
1
0 K.-I. Tanaka, S. Yoshifuji and Y. Nitta, Chem. Pharm. Bull., 1988,
3
6, 3125.
Notes and references
1
1 J. W. Kim, K. Yamaguchi and N. Mizuno, Angew. Chem., Int. Ed.,
2008, 47, 9249.
12 K. Mori, K. Yamaguchi, T. Mizugaki, K. Ebitani and K. Kaneda,
z Procedure for transformation of primary amines: OMS-2 (100–200 mg),
amine (0.5 mmol), 1,4-dioxane (1 mL), aqueous ammonia (28 wt%,
50–200 mL) were placed in a Teflon vessel with a magnetic stir bar.
Chem. Commun., 2001, 461.
2
644 Chem. Commun., 2012, 48, 2642–2644
This journal is c The Royal Society of Chemistry 2012