Ru/C catalyzed cyclization of linear α,ω-diamines to cyclic amines in water

Article abstract of DOI:10.1016/j.tet.2009.12.025

A facile and convenient way to prepare cyclic amines in water was achieved by the catalyst system composed of Ru/C and Al powder. The α,ω-diaminoalkanes, 1,4-diaminobutane, 1,5-diaminopentane, and 1,6-diamino-heptane were converted to corresponding cyclic amines in good yields. The use of D₂O provided a novel route to obtain deuterated cyclic amines in good yields.

Full text of DOI:10.1016/j.tet.2009.12.025

Tetrahedron 66 (2010) 1249–1253
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Tetrahedron
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Ru/C catalyzed cyclization of linear
a
,u
-diamines to cyclic amines in water
*
Thomas M. Ga¨dda, Xiao-Yan Yu, Akira Miyazawa
Nanotechnology Research Institute (NRI), National Institute of Advanced Industrial Science and Technology (AIST), Central 5, Higashi, Tsukuba, Ibaraki 305-8565, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
A facile and convenient way to prepare cyclic amines in water was achieved by the catalyst system
Received 25 August 2009
Received in revised form
4 December 2009
Accepted 5 December 2009
Available online 11 December 2009
composed of Ru/C and Al powder. The a,u-diaminoalkanes, 1,4-diaminobutane, 1,5-diaminopentane, and
1,6-diamino-heptane were converted to corresponding cyclic amines in good yields. The use of D2O
provided a novel route to obtain deuterated cyclic amines in good yields.
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Cyclic amine
Ru/C
Synthesis
Water
Cyclization
Intramolecular
Ring-closure
Deuteration
1. Introduction
gas phase at high temperatures using zeolites as catalysts for the
cyclic amine conversion.6 Also, homogeneous late transition metal
Alkylations of primary and secondary amines to obtain sec-
ondary- or tertiary amines are of considerable importance in or-
ganic synthesis. Conventionally such compounds have been
prepared by reductive amination of the condensation products
from amino compounds and carbonyl compounds or by amino
dehalogenation from amines and halo-alkanes.1 It is also known
that amines themselves can be used as alkylating reagents to pre-
pare secondary- or tertiary amines from primary amines. Mur-
ahashi and his co-workers reported an inter- and intramolecular
coupling reaction of alkyl amines and diamines to secondary-,
tertiary-, and cyclic amines using heterogeneous Pd black as a cat-
catalyst can also catalyze the intramolecular cyclization of a,u-di-
amines in organic solvents.7 Hydroamination can be considered as
a further approach to prepare cyclic amines from alkyl amines
bearing alkenyl- or alkynyl group at the terminal position of the
starting materials. However, achieving control on the selectivity
may be difficult as the addition to the C–C double or triple bonds
usually favors the Markovnikov rule.8 Additionally, there are
a number of other ways to prepare nitrogen containing heterocy-
cles such as intramolecular ring-closure of N-(
u-haloalkyl)imines,
d
- and
g
-alkenylimines, aminoalkanes, and N-chloroalkylamines.9
Thus, most of the above reactions are carried out at high temper-
atures for prolonged reaction times, utilize organic solvents, and
usually convert with less favorable selectivities, despite the use of
transition metals catalyst.
Recently, we reported a novel, environmentally more benign way
to convert primary amines to secondary amines.10 A change of re-
action conditions transforms amines on secondary alkyl groups to
corresponding ketones. Herein, we would like to report the extension
alyst.2 In a similar manner,
prepare heterocyclic amines.3 Some related reports on the transi-
tion metal catalyzed synthesis of cyclic amines from aliphatic
diamines can be found in the literature. Raney nickel catalyzed
a,u-aminoalcohols can also be used to
a,u-
intramolecular cyclization of aliphatic
a,u-diamines have been
investigated in preparations of pyrrolidine and piperidine.4 Kagiya,
Ohtani, and his co-workers reported that TiO2/Pt catalysts in water
can transform
a
,
u
-diamines to cyclic amines upon prolonged UV
of this synthetic method for the conversion of aliphatic a,u-diamines
irradiation.5 Some studies of the same have been carried out in the
to corresponding cyclic amines. Contrary to previous investigations,
our method uses heterogeneous catalysts and water is employed as
a solvent and reagent. The use of water allows a different reaction
pathway, which results in faster, more selective transformations.
* Corresponding author. Tel.: þ81 29 861 9388; fax: þ81 29 861 4566.
E-mail address: a.miyazawa@aist.go.jp (A. Miyazawa).
0040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2009.12.025

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T.M. Ga¨dda et al. / Tetrahedron 66 (2010) 1249–1253
2. Results and discussion
over 88% in all cases (Table 2). While Pd/C gave similar results as Ru/C
in the absence of Al, addition of it significantly slowed the reaction.
Low conversions, less than 3%, of the starting material of 1,4-dia-
minobutane and 1,6-diaminohexane, respectively, were recorded.
We tested four different metal catalysts (Ru/C, Rh/C, Pd/C, and
Pt/C) for the intramolecular catalytic cyclization of
a,u-dia-
minoalkanes, 1,4-diaminobutane and 1,6-daiaminohexane, to their
corresponding cyclic amines, pyrrolidine and azepane, in water at
158 ꢀC (Table 1). These reactions gave the desired cyclic amines
along with side products. In the reactions with 1,4-diaminobutane,
the cyclic imine, 1-pyrroline, was observed as a major side product
together with small amounts of pyrrole and linear oligomeric
products (entries 1–5). Adiponitrile, on the other hand, was ob-
served in the reactions with 1,6-diaminohexane (entries 6–10). The
formations of side products were confirmed by GC and GC–MS
analysis. The results of these preliminary experiments suggested
that Ru/C and Pd/C were effective catalysts for the reaction in terms
of conversion and both showed better selectivity (entries 1, 2, 4, 6,
7, and 9) in comparison to Rh/C (entries 3 and 8). The Pt/C catalyst
gave similar conversions compared to Ru/C and Pd/C, however se-
lectivity of 2 was poor in 1,4-diaminobutane reaction (entry 5).
Comparing Ru/C and Pd/C, the Ru/C catalyst showed higher selec-
tivity than Pd/C in 1,6-diaminohexane cyclization. From above re-
sults we finally chose Ru/C as a suitable catalyst for the cyclization
Table 2
Ru/C catalyzed cyclization of
powder
a,u-diaminoalkane in the presence of aluminum
H2N CH2 CHR (CH2)n NH2
Ru/C
Al powder
1
H
N
(CH2)n
H2O
R
2
158°C
Entry
Diamine 1
Time (h)
Conv.a (%)
Selectivitya 2 (%)
R
n
1
2
3
4
5
6
7
H
H
H
H
Me
H
H
2
2
3
3
3
4
4
0.5
2
0.5
1
1.5
0.5
1
42
99
46
99
98
75
99
95
88
86
98
95
96
95
of a,u-diaminoalkanes under the condition.
Table 1
Catalytic cyclization of
Reaction conditions;
a,u-diaminoalkane (100 mg), catalyst (50 mg, 2.6–2.9 mol %
a,u-diaminoalkane
Ru), water (2 mL), and Al powder (30 mg) were placed in a 10 mL pressure resistant
glass vessel.
H2N CH2 CH2 (CH2)n NH2
a
Conversions and selectivities were determined by GC and GC–MS analysis.
1
H
N
catalysts
(CH2)n
The conversion of 1,4-diaminobutane and 1,4-diaminohexane,
plotted as a function of reaction time are shown in Figure 1. It is
evident that the in-situ generated H2 from the reaction of alumi-
num with water facilitates the hydrogenation of the imine in-
termediates to amines.11 Similarly, dehydrogenation of imine
intermediates were found to have significantly decreased as for-
mation of side products such as adiponitrile were strongly sup-
pressed. No reaction was seen when the reaction was carried out
with aluminum in the absence of catalyst on carbon.
H2O
158°C
2
Entry Diamine 1 n Catalysts (mol %) Time (h) Conv.a (%) Selectivitya 2 (%)
1
2
3
4
5
6
7
8
9
10
2
2
2
2
2
4
4
4
4
4
Ru/C
(2.7)
Ru/C
(2.7)
Rh/C
(2.6)
Pd/C
(2.6)
Pt/C
(1.4)
Ru/C
(2.9)
Ru/C
(2.9)
Rh/C
(2.8)
Pd/C
(2.8)
Pt/C
1
4
1
1
1
1
4
4
4
4
7
18
7
39
90
d
11
8
47
d
100
80
60
40
20
0
31
43
2
89
95
44
72
84
39
37
(1.5)
Reaction conditions;
a,u-diaminoalkane (100 mg), catalyst (50 mg), and water
(2 mL) were placed in a 10 mL pressure resistant glass vessel.
0
1
2
3
4
a
Conversions and selectivities were determined by GC and GC–MS analysis.
Time (h)
As the conversion and the selectivity of the reaction was rela-
tively poor, aluminum powder was added to the reaction mixture.
Previously, the addition of aluminum powder to the reactions where
primary amines were converted to secondary amines has been found
to drastically accelerate the reaction and enhance the selectivity of
the secondary amine formation.10b Therefore we studied the Ru/C
catalyzed cyclizations of 1,4-diaminobutane, 1,5-diaminopentane, 2-
methyl-1,5-diaminopentane, and 1,6-diamino-heptane in the pres-
ence of aluminum powder. The addition of aluminum powder was
found to dramatically facilitate the reaction and improve selectivity
of the cyclization reaction. The starting diamines were almost
completely consumed within 2 h and cyclic amine selectivities were
Figure 1. Plots of conversion of 1,4-diaminobutane (-) and 1,6-diaminohexane (:)
with (- - -) and without aluminum (d) vs reaction time. Conditions are the same as
described in Table 1 and Table 2.
Some reports indicate that the ease of cyclization in the for-
mation cyclic amines follows the order of ring size 5>3>6>7>4.8,12
The results obtained for a,u-diaminobutane, -pentane and -hexane
cyclization in this study seems to disagree with earlier findings. The
results obtained suggest that the reaction follow the order 7>6>5
in ring size. Although the detailed reaction pathway is not clear, the
results suggests that the intramolecular cyclization of
a,u-
diaminoalkane in water run through different reaction
a

T.M. Ga¨dda et al. / Tetrahedron 66 (2010) 1249–1253
1251
intermediate. In previous studies of the cyclization of diamines,
which have been carried out under dry conditions, aminal in-
termediates have been proposed. Such intermediates are formed by
nucleophilic attack by an amine on an imine (Scheme 1, path A),
which in turn are derived from the starting amines by metal cata-
lyzed dehydrogenation. On the other hand, when water is
employed as the reaction media, an imine is immediately hydro-
lyzed to form an aldehyde (Path B). The subsequent dehydration
condensation reaction between aldehydes and amines is in-
stantaneous and affords the unsaturated cyclic imine. The hydro-
genation of it gives desired cyclic amines. Based on the above and
the results, it seems that the ring strain of unsaturated cyclic imines
affect the ease of ring closure. The intermediates in the present
study have unsaturated cyclic imine structures, which have altered
ring strain compared to their saturated analogs. Hence, in the for-
mation process of the unsaturated cyclic imine structure, the for-
mation of a less strained seven-membered ring appears to be more
facile than its equivalent of decreasing ring size.
reduction of the cyclic imine, resulting in faster and more selective
reactions. A related, observation on the benefit of combination of
water and aluminum to produce H2 has been made during its use in
the reduction of acetophenones.15
The dilute conditions and short reaction times, combined with
proper choice of catalyst, largely eliminate the formation of oligo-
meric amines as well as tertiary amines. This interpretation is based
on the absence of signals in 13C NMR spectra resulting from
a
-carbons
to the nitrogen in linear secondary and tertiary amines. For example,
in the case of 1,4-diaminobutane, the -carbons in linear secondary
a
and tertiary amines would be easily distinguished from their pyrro-
lidine and starting diamine counterparts. However, these signals are
not observed.
The reaction using 1,3-diaminopropane did not give the
expected azetidine under our reaction conditions. Instead, 1-ami-
nopropane was obtained as a major product. Similar findings of
1-aminopropane formation have been reported earlier. This in-
dicates insertion of catalyst into the carbon–nitrogen bond and
subsequent b
-elimination to give allylamine.16 In fact, n-butylamine
and n-hexylamine were observed in small amounts in GC-traces of
several reactions. The insertion of metal catalysts to the carbon–
nitrogen bond was confirmed by treating pyrrolidine (100 mg) with
Pt/C (50 mg) and Al (30 mg) at 158 ꢀC for 2 h. A product distribution
of pyrrolidine (42%), butylamine (31%), dibutylamine (14%), and
oligomeric products (13%) was observed. 1,7-diaminoheptane and
1,8-diaminooctane did not give the expected eight- and nine-
membered cyclic amines under the described reaction conditions.
Oligomers formed in intermolecular reactions were obtained along
with recovered starting diamines. From the above results, the re-
sultant ring-strain in the cyclic amine seems to be an important
factor. Heterocycles with high deuterium contents can be obtained
when D2O is used instead of water under the described reaction
conditions. The results are summarized in Table 3. Deuterium
contents calculated from mass spectra of N-acetylated cyclic
amines were 91, 82, 65, and 70 at % for pyrrolidine, piperidine, 3-
methylpiperidine, and azepane, respectively. Determination of
deuterium contents without acetylation was not possible due to
significant Mþꢁ1 peaks that lower the calculated deuterium con-
tent. Acetylation of the reaction products also permit calculation of
deuterium content by 1H NMR peak integration of the acetyl singlet
peak vs non-deuterated protons in the heterocycles. The 1H NMR
spectrum of acetylated pyrrolidines prepared are depicted in
Figure 2. Deuterium contents by MS were close to those calculated
by NMR peak integration. NMR analysis based on integration of the
methylene protons relative to H/D-exchanged protons further
permitted calculation of the deuteration degree of each carbon on
heterocycles.
H2N CH2 CH2 (CH2)nNH2
H
N
path A
H2N
+H2
- NH3
(CH2)n
HN CH CH2 (CH2)nNH2
H
N
(CH2)n
+ H2O
path B
- NH3
+H2
N
H
(CH2)n
O
CH2 (CH2)nNH2
C
- H2O
Scheme 1. Reaction pathways of the formation of cyclic amine.
Based on our previous report concerning to the intermolecular
coupling of primary amines to secondary amines,10b we propose
that the present, unique intramolecular coupling occurs through
a similar mechanism. Scheme 2 depicts a plausible catalytic cycle of
the reaction. The catalytic cycle begins with oxidative removal of
dihydrogen from the starting diamine to give an alkyleneimine.
This imine undergoes hydrolysis to give an aldehyde bearing an
amine functionality. The formation of this intermediate is consid-
ered the key to the improved reaction outcome, compared to pre-
vious investigations. 1H NMR studies have shown that such
transient intermediates possessing the amine and aldehyde func-
tionality, undergo rapid intramolecular condensation under basic
conditions to give a cyclic alkyleneimine.13 The catalytic cycle is
completed by reduction of the cyclic imine to give its corresponding
cyclic amine. It has been shown that hydrogen pressure is essential
in conversion of 1-pyrroline to pyrrolidine,14 which explains the
beneficial effect of aluminum powder. The generation of H2 from
the reaction of water and aluminum powder enhances the
Table 3
Ru/C catalyzed cyclization of
a
,
u
-diaminoalkane in deuterium oxide
O
N
i)
D
(CD2)n
1
H
N
ii)
D
D
H2N CH2 CH2 (CH2)nNH2
(CH2)n
(CH2)n
Ru/C
R
i) Ru/C, Al, D2O, 158°C ii) Ac2O
Entry
R
n
Yielda (%)
D contentb (atom%)
N
[Ru/C][H2]
Overall
aꢁ
b
ꢁ
g
ꢁ
HN CH CH2 (CH2)nNH2
1
2
3
4
D
D
Me
D
2
3
3
4
67
82
66
71
92(91)
83(82)
58(65)
73(70)
94
92
96
95
89
77 (
88
d
b
þ
þ
g
)
)
39
H2O
64 (
b
g
H2O
a
OHC CH2 (CH2)nNH2
Isolated yields are shown.
NH3
b
Deuterium contents were determined by 1H NMR measurement and the values
in parenthesis were derived from GC–MS analysis.
Scheme 2. Plausible catalytic cycle of cyclic amine formation.

1252
T.M. Ga¨dda et al. / Tetrahedron 66 (2010) 1249–1253
Ac
amines in good yields with moderate to high deuterium content.
This protocol is environmentally friendly chemical process to ob-
tain cyclic amines because of the use of water (deuterium oxide) as
a solvent and hydrogen (deuterium) source.
Ac
N
α−
β−
D
D
D
D
D
x
x
D
D D
4. Experimental
4.1. General synthetic procedure
A TeflonÒ covered magnetic stir bar, catalyst on active carbon
support (50 mg, 5 wt % of metal), aluminum powder (30 mg, par-
Ac
N
x
ticle size w425
mm), diamine (100 mg), and 2 mL water (deionized,
<0.1 S) were placed in a 10 mL pressure resistant glass tube. The
m
PPM
0.0
tube was then sealed and immersed in a preheated oil bath at
158 ꢀC for a predetermined time. After the reaction, K2CO3 was
added until the solution was saturated and the aqueous solution
was then extracted once with 2.5 mL diethyl ether. The organic
layer was analyzed with GC and GC–MS. Conversions and relative
yields were calculated from peak areas in the GC chromatograms.
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
Figure 2. 1H NMR of acetylated deuterated and non-deuterated pyrrolidines. Impurity
peaks are denoted (x).
As expected,
(92–96 at %) while
a
-protons displayed highest deuterium contents
-protons were determined to have undergone
H/D-exchange to a slightly lower degree (88–89 at %). Overall
deuterium contents of piperidine, and azepane were somewhat
b
4.1.1. General outline for determination of the degree of
deuteration. A TeflonÒ covered magnetic stir bar, 50 mg of Ru/C
(5 wt % of metal), aluminum powder (30 mg, particle size
lower compared to pyrrolidine as the exchange of the g-protons
w425 mm), diamine (100 mg), and 2 mL D2O were placed in a 10 mL
does not occur readily. Similarly, the methyl group in 3-methyl-
piperidine essentially does not undergo H/D-exchange readily
(11 at % by NMR). The overall deuterium content of 3-methyl-
piperidine was calculated to be 58 at % assuming that the methyl
group at 3-position does not undergo H/D-exchange. This is close to
the value calculated for piperidine, thus providing further confir-
mation for calculated results. Lockley and his co-workers reported
H/D-exchange reactions of various piperidines and dialkylamines
using homogenous ruthenium catalysts with D2O as a deuterium
pressure resistant glass tube. The tube was then sealed and im-
mersed in a preheated oil bath at 158 ꢀC for predetermined time
period. After the reaction, K2CO3 was added and the saturated
aqueous solution was extracted once with 1 mL CDCl3. Acetic an-
hydride (10% molar excess) was added to the CDCl3 solution and the
mixture was stirred for 15 min. Water and K2CO3 was added to
remove unreacted anhydride and to extract the formed acetic acid.
The CDCl3 layer collected was analyzed by NMR and GC–MS.
source, which gave products labeled with deuteriums at the
- positions.17 The results obtained with pyrrolidine suggest that
the - and - positions are labeled almost to an equal degree,
similar that reported by Lockley. However, the data obtained in this
study cannot exclude H/D-exchange at - and other positions as
noted above. The mechanism for deuteration at these positions is
not fully evident. Unreacted diamines of non-acetylated samples
were observed to display increased mass by GC–MS analysis. The
observation of such partially deuterated diamines suggests that
H/D-exchange reaction takes place with the starting diamines, re-
active intermediates, and products. Indeed the reaction of piperi-
dine under the same condition described in Table 3 gave deuterated
piperidine, which showed almost same number of incorporated
deuterium and molecular mass distribution of deuterated products.
a- and
4.1.2. Scaled-up preparation of 3-methylpiperidine using microwave
b
reactor. A TeflonÒ covered magnetic stir bar, 1.0 g of Ru/C (5 wt %
a
b
of metal), aluminum powder (400 mg, particle size w425 mm),
2-methyl-1,5-pentamethyldiamine (2 g), and 40 mL H2O were
placed in a 80 mL pressure resistant glass vessel. The glass vessel
was sealed and placed in a Discovery microwave oven (CEM Corp.)
The reaction was carried out at 150 ꢀC for 2.5 h. After the reaction,
solids were separated by filtration, washed with water and CH2Cl2.
K2CO3 was added to the filtrate to saturate the solution, the organic
layer was removed and the satd aq K2CO3 was washed three times
with CH2Cl2. The combined organic layers were dried over anhyd.
MgSO4 and filtered. Dry HCl gas was bubbled through the CH2Cl2
solution for 0.5–1 h or until the organic layer did not display vol-
atile products by GC. The solvent was removed under reduced
pressure. The residual solid was re-precipitated from MeOH with
excess ether to give 1.9 g (78%) of a white solid mp 174–175 ꢀC (lit.
173 ꢀC).18
g
While the concept of rapid cyclization of aliphatic a,u-diamines
has been proved with small scale reactions and high catalyst
amounts, reactions carried out in larger scale confirm the results.
Reactions with 2-methyl-1,5-diaminopentane were scaled up 20
and 50 times, gram scale preparation, to confirm GC observations
and to assess possibilities for scale-up. In both cases, pure fractions
with over 74% yields of 3-methylpiperidine as its HCl salt could be
isolated.18 The reaction at 20 time scale was carried out in a mi-
crowave reaction using identical chemical quantities as used in the
small scale preparations. Of particular interest was the reaction
carried out in 50 time scale using reduced catalyst (1 mol % of Ru)
and aluminum amounts, suggests that the procedure described
herein may be of significant practical importance.
4.1.3. Scaled-up preparation of 3-methylpiperidine using autocla-
ve. To a glass autoclave with a stir bar, 1.75 g of 5 wt % Ru/C
(1.0 mol % based on substrate), 11.5 mL (86.2 mmol) of 2-methyl-
1,5-diaminopentane, 30 mL of water, and 0.75 g of aluminum
powder (particle size w425 mm) were added successively. The
equipment was sealed and heated at 158 ꢀC for 14 h. After the re-
action mixture had cooled down to room temperature, the solid
materials were filtered and washed with water and CH2Cl2. K2CO3
was added to the aq solution until saturation and then it was
extracted with CH2Cl2 three times. The organic layers were com-
bined and dried over MgSO4. (GC analysis shows that the conver-
sion is 100%.) After filtration, the CH2Cl2 solution was bubbled
through with dry HCl gas for 3 h. Then the solvent was removed
under vacuum to give white solid as a crude product. The crude
product was then re-dissolved in MeOH and re-precipitated with
3. Conclusion
In summary, we have developed a convenient and simple pre-
parative way to fve-, seven- and seven-membered cyclic amines
from
a,u-diaminoalkanes and their deuterium labeled cyclic

T.M. Ga¨dda et al. / Tetrahedron 66 (2010) 1249–1253
1253
excess ether. Yield: 8.63 g (74%). Mp: 175–176 ꢀC, 1H NMR (D2O):
7. (a) Khai, B.-T.; Concilio, C.; Porzi, G. J. Org. Chem.1981, 46,1759–1760; (b) Tsuji, Y.;
Shida, J.; Takeuchi, R.; Watanabe, Y. Chem. Lett.1984,13, 889–890; (c) Doctorovich,
F.; Trapani, C. Tetrahedron Lett. 1999, 40, 4635–4638.
8. See reviews and references cited therein, (a) Mu¨ller, T. E.; Beller, M. Chem. Rev.
1998, 98, 675–703; (b) Mu¨ller, T. E.; Hultzsch, K. C.; Yus, M.; Fuoeblo, F.; Tada, M.
Chem. Rev. 2008, 108, 3795–3892.
9. (a) Stella, L. Angew. Chem., Int. Ed. Engl. 1983, 22, 337–350; (b) Pugin, B.; Ven-
anzi, L. M. J. Organomet. Chem. 1981, 214, 125–133; (c) Di Martino, A.; Galli, C.;
Gargano, P.; Mandolini, L. J. Chem. Soc. Perkin Trans. 2 1985, 1345–1349; (d) De
Kimpe, N.; Boelens, M.; Piqueur, J.; Baele, J. Tetrahedron Lett. 1994, 35, 1925–
1928; (e) De Kimpe, N.; De Smaele, D. Tetrahedron Lett. 1994, 35, 8023–8026.
10. (a) Miyazawa, A.; Tanaka, K.; Sakakura, T.; Tashiro, M.; Tashiro, H.; Prakash, G.
K. S.; Olah, G. A. Chem. Commun. 2005, 2104–2106; (b) Miyazawa, A.; Saitou, K.;
Tanaka, K.; Ga¨dda, T. M.; Tashiro, M.; Prakash, G. K. S.; Olah, G. A. Tetrahedron
Lett. 2006, 47, 1437–1439.
d
ppm 0.98 (d, J¼8 Hz, 3H, CH3); 1.17–1.26 (m, 1H, CH); 1.65–1.77
(m, 1H, CHCH2CH2); 1.80–1.96 (m, 3H, CHCH2CH2); 2.63 (t, J¼12 Hz,
1H, CH2CH2NH); 2.91 (td, J¼4, 12 Hz, 1H, CH2CH2NH); 3.31–3.40
(m, 2H, CHCH2NH).
Acknowledgements
This research was carried out by Development of Microspace
and Nanospace Reaction Environment Technology for Functional
Materials Project under NEDO.
11. Tyman, J. H. J. Appl. Chem. 1970, 20, 179–182.
References and notes
12. (a) Coy, J. H.; Hegarty, A. F.; Flynn, E. J.; Scott, F. L. J. Chem. Soc., Perkin Trans. 2
1974, 53–58; (b) De Angelis, F.; Grgurina, I.; Nicoletti, R. Synthesis 1979, 70–71;
(c) Khai, B.-T.; Concilio, C.; Porzi, G. J. Organomet. Chem. 1981, 208, 249–251; (d)
Arcelli, A.; Khai, B.-T.; Porzi, G. J. Organomet. Chem. 1982, 235, 93–96.
13. Struve, C.; Christophersen, C. Heterocycles 2003, 69, 1907–1914.
14. Serra, M.; Salagre, P.; Cesteros, Y.; Medina, F.; Sueiras, J. E. J. Catal. 2001, 197,
210–219.
15. Miyazawa, A.; Tashiro, M.; Prakash, G. K. S.; Olah, G. A. Bull. Chem. Soc. Jpn. 2006,
79, 791–792.
16. Murahashi, S.-I.; Yano, T.; Hino, K. Tetrahedron Lett. 1975, 16, 4235–4238.
17. Alexakis, E.; Hickey, M. J.; Jones, J. R.; Kingston, L. P.; Lockley, W. J. S.; Mather, A. N.;
Smith, T.; Wilkinson, D. J. Tetrahedron Lett. 2005, 46, 4291–4293.
18. Zacharie, B.; Moreau, N.; Dockendorf, C. J. Org. Chem. 2001, 66, 5264–5265.
1. Challis, B. C.; Butler, A. R. In The Chemistry of the Amino Group; Patai, S., Ed.;
Interscience: London, Great Britain, 1968; Chapter 5, pp 277–347.
2. Yoshimura, N.; Moritani, I.; Shimamura, T.; Murahashi, S.-I. J. Am. Chem. Soc.
1973, 95, 3038–3039.
3. Murahashi, S.-I.; Kondo, K.; Hakata, T. Tetrahedron Lett. 1982, 23, 229–232.
4. Kindler, K.; Matthies, D. Chem. Ber. 1962, 95, 1992–1998.
5. (a) Nishimoto, S.; Ohtani, B.; Yoshikawa, T.; Kagiya, T. J. Am. Chem. Soc. 1983, 105,
7180–7182; (b) Ohtani, B.; Tsuru, S.; Nishimoto, S.; Kagiya, T. J. Org. Chem. 1990,
55, 5551–5553.
6. (a) Reichle, W. T. J. Catal. 1993, 144, 556–568; (b) Radha, R. V.; Srinivas, N.;
Kulkami, S. J.; Raghavan, K. V. Ind. J. Chem. 1999, 38A, 286–290.