Atom transfer carbonylation using ionic liquids as reaction media

Article abstract of DOI:10.1016/j.jorganchem.2006.08.072

Photo-induced ATC reactions of RI, CO, and amines to produce amides, were examined using ionic liquids, such as [bmim]PF₆ and [bmim]NTf₂, as reaction media in the presence of a catalytic amount of a Pd-carbene complex. When the primary alkyl iodide was used, the yield of the amide was lowered due to competing S_N2 reactions between RI and amines, whereas the reaction of the tertiary alkyl iodides was dependent on the structure of the substrates. ATC reactions of a wide variety of secondary RI proceeded smoothly when ionic liquids were used as reaction media. The Pd-catalyst and ionic liquid could also be recycled.

Full text of DOI:10.1016/j.jorganchem.2006.08.072

Journal of Organometallic Chemistry 692 (2007) 685–690
www.elsevier.com/locate/jorganchem
Atom transfer carbonylation using ionic liquids as reaction media
*
Takahide Fukuyama, Takaya Inouye, Ilhyong Ryu
Department of Chemistry, Graduate School of Science, Osaka Prefecture University Sakai, Osaka 599-8531, Japan
Received 28 February 2006; accepted 20 March 2006
Available online 30 August 2006
Abstract
Photo-induced ATC reactions of RI, CO, and amines to produce amides, were examined using ionic liquids, such as [bmim]PF6 and
[bmim]NTf2, as reaction media in the presence of a catalytic amount of a Pd–carbene complex. When the primary alkyl iodide was used,
the yield of the amide was lowered due to competing SN2 reactions between RI and amines, whereas the reaction of the tertiary alkyl
iodides was dependent on the structure of the substrates. ATC reactions of a wide variety of secondary RI proceeded smoothly when
ionic liquids were used as reaction media. The Pd-catalyst and ionic liquid could also be recycled.
Ó 2006 Elsevier B.V. All rights reserved.
Keywords: Atom transfer carbonylation; Ionic liquids; Carbon monoxide; Amide; Palladium
1. Introduction
the addition of Pd(0)-complexes accelerates photo-irradia-
tive ATC reactions [8], we were interested as to whether
the Pd-catalyst can be immobilized effectively in ionic liq-
uids, allowing for the recycling of both the catalyst and
reaction medium. In this paper, we report on a systematic
study of some ATC reactions involving a wide range of
alkyl iodides leading to amides using ionic liquids and a
Pd–carbene complex (Scheme 1).
Ionic liquids have recently attracted considerable inter-
est as potent reaction media, replacing volatile organic sol-
vents without sacrificing the function as a solvent [1]. A
wide range of reactions using ionic liquids have been exam-
ined to date, including transition-metal catalyzed cross-
coupling reactions [2,3], enzyme-reactions [4], to mention
a few. Although radical polymerization using ionic liquids
has been extensively studied [5], an examination of their
feasibility for ordinary radical reactions in organic synthe-
sis is yet to be sufficient. Yorimitsu and Oshima previously
reported that iodine atom transfer reaction of alkynes can
be effectively carried out using [bmim]PF6 as a reaction
medium [6]. We became interested in the use of ionic liq-
uids for atom transfer carbonylation (ATC) reactions [7]
for two reasons. Since ATC reactions of alkyl iodides in
organic solvents proceeds in the presence of nucleophilic
reagents such as amines, the issue of whether such a reac-
tion system containing both alkyl iodides and nucleophiles
would proceed in highly polar ionic liquids or not was of
our primary concern. Since the recent study, revealing that
2. Results and discussion
We examined the atom transfer carbonylation of 2-
iodooctane (1a) with diethylamine (2a) under irradiation
conditions (Xenon, Pyrex) using the Pd–carbene complex
3 [3b], which is readily soluble in ionic liquids, as a catalyst
(Scheme 2). When the reaction of 1a with 2a (3 equiv.) was
carried out using [bmim]NTf2 (1-butyl-3-methylimidazo-
lium bis(trifluoromethanesulfonyl)imide) as a solvent for
16 h, the mono carbonylation product, 4a was obtained
in 87% yield, along with a small amount of double carbon-
ylation product 5a (4%) [9]. The direct nucleophilic substi-
tution product, diethyl(1-methylheptyl)amine, was not
formed in this case. When [bmim]PF6 was used, the yield
of 4a was 73%. In these two cases, the amount of ketoa-
mide 5a that was formed was relatively small, compared
with the case of the reaction using benzene as a solvent
*
Corresponding author. Tel./fax: +81 72 254 9696.
E-mail address: ryu@c.s.osakafu-u.ac.jp (I. Ryu).
0022-328X/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.08.072

686
T. Fukuyama et al. / Journal of Organometallic Chemistry 692 (2007) 685–690
as hexyl amine and benzyl amine, react with 1a and CO
O
hν
R
NR'2
R
Pd catalyst 3
to give the corresponding amides 4b and 4c in 58% and
62% yield, respectively (entries 4 and 5). The reaction of
secondary alkyl iodides, 1b, 1c, and 1d, also gave the corre-
sponding amides 4e, 4f, and 4g in good yields (entries 7–9).
Interestingly, the reaction of iodocyclohexane (1e) gave a
significant amount of ketoamide 5h, along with 4h (entry
10). The efficiency of tertiary alkyl iodides in ATC reac-
tions conducted in [bmim]NTf2 was dependent on their
structures. The reaction of 1-iodoadamantane (1f) gave a
mixture of single and double carbonylation products 4i
and 5i in 38% and 33% yield, respectively (entry 11),
whereas the carbonylation of tert-butyl iodide (1g) pro-
duced pival amide 4j in 61% yield as the sole carbonylation
product (entry 11).
+
+
I
+
NR'2
R
CO
R'2NH
Ionic Liquids
O
O
1
2
4
5
+
N
R = primary alkyl
Bu
secondary alkyl
tertiary alkyl
N
NTf2
PF6
N
N
Bu
[bmim]NTf2
Ph3P Pd Cl
Cl
+
N
Bu
N
3
[bmim]PF6
Scheme 1. Atom transfer carbonylation of alkyl iodides in a Pd/hm system
using ionic liquids.
In contrast, 5-methyl-5-iodononane (1h), gave the antic-
ipated amide 4k in only 22% yield (Eq. (2)). In this case, a
mixture of olefins arising from 1h via the elimination of HI
was formed as the major products. We also examined the
reaction of a primary alkyl iodide 1i, which gave low yields
of carbonylated products (Eq. (3)). The reaction suffered a
competing SN2 reaction with diethylamines to give diethy-
loctylamine. This is consistent with previously reported
observations that ionic liquids accelerate the nucleophilic
substitution of alkyl halides and sulfonates in terms of their
highly polar characteristics [11].
hν (Xe, Pyrex)
Pd cat. 3 (5 mol %)
CO
HNEt2
16 h
I
1a
0.1 M
75 atm 2a 3 equiv
O
NEt2
NEt2
O
O
4a
5a
[bmim]NTf2
[bmim]PF6
C6H6
87%
73%
69%
4%
2%
12%
hν (Xe, Pyrex)
Pd cat. (5 mol %)
HNEt2
+
CO
+
Scheme 2. Atom transfer carbonylation of 2-iodooctane.
[bmim]NTf2, 16 h
I
1h 0.1 M
75 atm 3 equiv
[10]. The reaction in the absence of Pd complex 3 using
[bmim]NTf2 was also examined, which gave a complex
mixture. Thus, amide 4a, SN2 product 6a, elimination
products, 1-octene and 2-octene, were obtained in 11%,
17%, 9%, and 13% (cis/trans = 24/76) yields, respectively,
together with a significant amount of unreacted 1a (20%)
(Eq. (1)). These results clearly demonstrate that the Pd–car-
bene complex 3 effectively promotes the ATC reaction in
ionic liquids.
ð2Þ
+
+
NEt2
O
4k 22%
68% (
Et2NH
E:Z
= 30:70)
8%
hν (Xe, Pyrex)
Pd-cat. (5 mol %)
CO
I
[bmim]NTf2, 16 h
1i 0.1 M
75 atm 3 equiv
hν (Xe, Pyrex)
ð3Þ
CO
Et2NH
I
[bmim]NTf2
16 h
O
1a 0.1 M
75 atm
3 equiv
NEt2
NEt2
O
NEt2
O
4l 15%
5l 9%
25%
4a
1-octene
9%
2-octene
1a
In all of the reactions described above, the products can
be separated from the catalyst solution of the ionic liquid
by biphasic workup using organic solvents. Therefore, we
checked the solubility of [bmim]NTf2 and [bmim]PF6 with
several common organic solvents, including ether, benzene,
toluene, diisopropyl ether (IPE), and cyclohexane and the
results are summarized in Fig. 1. When [bmim]NTf2
(895.4 mg) was treated with 5 mL of ether three times,
6.3% (56.6 mg) of [bmim]NTf2 was isolated from the ether
layer after evaporation, whereas [bmim]NTf2 had a low
NEt2
11%
6a 17%
13%
(cis/trans=24/76)
20%
ð1Þ
The reaction of a variety of secondary and tertiary alkyl
iodides with amines and CO was conducted using
[bmim]NTf2 as the reaction medium and the results are
summarized in Table 1. The ionic liquid containing the
Pd catalyst can be reused (entry 2). Primary amines, such

T. Fukuyama et al. / Journal of Organometallic Chemistry 692 (2007) 685–690
687
Table 1
Atom transfer carbonylation of alkyl iodides with amines in the Pd/hm systema
O
hν (Xe, pyrex)
R
NR'R"
R
Pd-cat. 3 (5 mol %)
NR'R"
+
+
+
R
I
CO
HNR'R"
[bmim]NTf2, 16 h
O
4
O
5
1
2
75 atm
Entry
1
R–1 1
Amine 2
Amide 4
Yield (%)b
Ketoamide 5
Yield (%)b
4
HNEt2 2a
87
O
NEt2
I
NEt2
1a
4a
5a
5b
2c
76
73
5
2
O
O
3d
4
5
6
1a
1a
1a
H2NC6H13 2c
H2NBn 2c
58
62
44
14
O
O
O
NHC6H13
NHBn
N
NHC6H13
NHBn
N
4b
4c
4d
O
O
O
O
O
O
9
5c
5d
4
N
H
2d
O
7
8
2a
80
74
Trace
NEt2
NEt2
NEt2
I
1b
1c
O
O
4e
4f
5e
2a
Ph
Ph
I
O
9
10
11
12
2a
2a
2a
63
53
38
61
NEt2
PhS
I
PhS
4g
O
1d
O
32
33
NEt2
NEt2
I
1e
O
O
4h
5h
O
NEt2
I
NEt2
O
O
1f
4i
5i
Ph
Ph
N
H
N
I
1g
2e
O
4j
a
Reaction conditions; 1 (0.5 mmol), 2 (1.5 mmol), Pd-cat. 3 (5 mol %), CO (75 atm), [bmim]NTf2 (5 mL), hm (Xe, Pyrex), 16 h.
Isolated yield.
The ionic liquid solution recovered from entry 1 was used.
[bmim]PF6 was used as a solvent.
b
c
d
solubility in cyclohexane. It was found that amide 3a can
3. Conclusion
be extracted nearly quantitatively with six portions of
cyclohexane (5 mL) from the [bmim]NTf2 (5 mL). Com-
pared to [bmim]NTf2, [bmim]PF6 showed a low solubility
in all solvents examined.
The ATC reaction of alkyl iodides leading to amides
was examined using ionic liquids, [bmim]NTf2, as a
solvent and a Pd–carbene complex 3 as a catalyst. The

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T. Fukuyama et al. / Journal of Organometallic Chemistry 692 (2007) 685–690
pared from the corresponding alcohols. Ionic liquids
[bmim]NTf2, [bmim]PF6 was prepared according to a pre-
viously reported procedure [12]. The Pd–carbene complex
3 was prepared using a previous reported procedure [3b].
Amides 4a and 4h are commercially available. Amides 4b,
4c, and ketoamide 5h are known product. Amides 4i and
4l, ketoamides 5a, 5i, and 5k are previously reported [8b].
These compounds were identified by comparison with lit-
erature data.
4.2. Typical procedure for the atom transfer carbonylation of
alkyl iodides with an amine using an ionic liquid
In the photoreactions, a magnetic stirring bar, 2-iodooc-
tane (1a, 124 mg, 0.52 mmol), diethylamine (2a, 122 mg,
1.5 mmol), Pd-complex (3, 15 mg, 0.025 mmol) and
[bmim]NTf2 (5.2 mL) were placed in a stainless steel auto-
clave in which a Pyrex glass liner was inserted. The auto-
clave was purged four times with carbon monoxide,
pressurized with 75 atm of CO and then irradiated with a
xenon arc lamp (500 W) with stirring. After 16 h, excess
CO was discharged at room temperature. The product
was extracted from the reaction mixture with cyclohexane.
The residue was subjected to silica gel column chromatog-
raphy using hexane/EtOAc = 2/1 as the eluent, to afford
N,N-diethyl-2-methyloctanamide (4a, 97 mg, 87%) and
N,N-diethyl-3-methyl-2-oxononanamide (5a, 5 mg, 4%).
Fig. 1. Solubility of [bmim]NTf2 and [bmim]PF6 in several common
organic solvents.
reaction of secondary alkyl iodides proceeded well,
whereas primary alkyl iodides were not suitable for the
present system because of competing SN2 reactions. Con-
cerning tertiary alkyl iodides, the course of the reaction
was dependent on the structures of substrates. The ionic
liquid, containing the Pd catalyst could be recycled.
Cyclohexane was found to be an excellent solvent for
extracting the products from the ionic liquids without
being contaminated by the ionic liquid.
4. Experimental
4.3. Recycling of Pd catalyst and [bmim]NTf2
4.1. General
After the reaction, the product was extracted from the
reaction mixture with cyclohexane, and the ammonium
salts were removed by washing with water, in which both
the cyclohexane and water were degassed by N2 bubbling
prior to use. Excess cyclohexane and water were removed
under reduced pressure, and the remaining ionic liquid
layer, containing the Pd catalyst, was used in the next
reaction.
1H NMR spectra were recorded with a JEOL JMN
ECP-500 (500 MHz) spectrometer in CDCl3. Chemical
shifts are reported in parts per million (d) downfield from
internal TMS at 0.00. 13C NMR spectra were recorded
with a JEOL JMN ECP-500 (125 MHz) spectrometer
and referenced to the solvent peak at 77.00 ppm. Infrared
spectra were obtained on a JASCO FT/IR 4100 spectrom-
eter; absorption data are reported in reciprocal centime-
ters. Conventional mass spectra were obtained on a
JEOL MS700 spectrometer or SHIMADZU GCMS-QP
5050A instrument. High-resolution mass spectra were
obtained on a JEOL MS700 spectrometer. Analytical
GC was SHIMADZU GC-17A using J&W DB-1 column
(30 m/0.32 mm i.d.). Benzene was distilled from benzo-
phenone/Na prior to use. The products were purified by
flash chromatography on silica gel (NACALAI TESQUE
Inc., Silica Gel 60, 70–230 mesh) and, if necessary, were
further purified by recycling preparative HPLC (Japan
Analytical Industry Co. Ltd., LC-908) on GPC columns
using CHCl3 as the eluent. Photolysis experiments were
conducted using a stainless steel autoclave with quartz
glass windows lined with a Pyrex glass liner and using a
500 W xenon short arc lamp (Ushio Co. Ltd., lamp
house: SX-UI500XQ, xenon short arc lamp: UXL-
500SX, power supply: BA-X500). Alkyl iodides were pre-
4.4. Reaction of the atom transfer carbonylation without Pd
catalyst using an ionic liquid
A magnetic stirring bar, 2-iodooctane (1b) (0.119 g,
0.50 mmol), diethylamine (0.109 g, 1.5 mmol) and
[bmim]NTf2 (5.0 mL) were placed in a stainless steel auto-
clave in which a Pyrex glass liner was inserted. The auto-
clave was purged four times with carbon monoxide,
pressurized with 75 atm of CO and then irradiated with a
xenon arc lamp (500 W) with stirring. After 16 h, excess
CO was discharged at room temperature. The product
was extracted from the reaction mixture with cyclohexane.
The products were identified from GC, GC–MS, and
NMR data. The yields were determined by GC (internal
standard: nonane) and 1H NMR (internal standard:
1,1,2,2-tetrachloroethene): 4a (11%; NMR), olefins (21%;
GC), diethyl-(1-methyl-heptyl)amine (17%; GC), 1a (20%;
GC).

T. Fukuyama et al. / Journal of Organometallic Chemistry 692 (2007) 685–690
689
4.5. Determination of solubility of ionic liquids to organic
solvents
24.49, 25.48, 26.42, 27.08, 29.33, 31.40, 31.75, 42.45,
42.88, 46.84, 166.20, 204.60; IR (neat) 1447 cmꢀ1
,
1641 cmꢀ1, 1709 cmꢀ1; MS (relative intensity) m/z 253
(M+, 15), 113 (29), 112 (100), 71 (66), 69 (89), 57 (73);
HRMS (EI) calc. for C15H27NO2 m/z 253.2042, found:
253.2034.
A mixture of [bmim]NTf2 (895.4 mg) and ether (5 mL)
was vigorously stirred at room temperature for 5 min.
After standing for 5 min, the ether layer was decanted. This
was repeated an additional two times. The combined ether
layer was evaporated and the residue weighed to give
56.6 mg (6.3 wt%) of [bmim]NTf2.
4.10. N,N-diethyl-2-butylhexanamide (4e)
1H NMR (CDCl3, 500 MHz) d 3.41–3.32 (m, 4H),
2.53–2.48 (m, 1H), 1.65–1.58 (m, 3H), 1.46–1.39 (m,
2H), 1.32–1.20 (m, 10H), 1.18 (t, J = 7.1 Hz, 3H), 1.11
(t, J = 7.1 Hz, 3H), 0.88 (t, J = 7.1 Hz, 3H); 13C NMR
(CDCl3, 125 MHz) d 13.09, 13.97, 14.00, 14.91, 22.99,
29.94, 33.07, 40.37, 41.32, 41.83, 175.60; IR (neat)
1460 cmꢀ1, 1638 cmꢀ1; MS (relative intensity) m/z 227
(M+, 2), 184 (23), 171 (50), 128 (30), 128 (100), 115
(49), 100 (53), 73 (34), 71 (45), 58 (66), 57 (37), 44 (48),
43 (64), 41 (49); HRMS (EI) calc. for C14H29NO m/z
227.2249, found: 227.2235.
4.6. N-hexyl-3-methyl-2-oxononanamide (5b)
1H NMR (CDCl3, 500 MHz) d 6.94 (s, 1H), 3.98–3.53
(m, 1H), 3.29 (q, J = 6.7 Hz, 2H), 1.67 (m, 1H), 1.56–
1.51 (m, 3H), 1.34–1.25 (m, 16H), 1.10 (d, J = 6.9 Hz,
3H), 0.90–0.86 (m, 6H); 13C NMR (CDCl3, 125 MHz) d
14.05, 14.13, 15.68, 15.71, 22.58, 22.64, 26.59, 27.18,
29.30, 31.45, 31.72, 32.56, 38.91, 39.44, 160.03, 202.71; IR
(neat) 1461 cmꢀ1, 1677 cmꢀ1, 1716 cmꢀ1, 3330 cmꢀ1; MS
(relative intensity) m/z 269 (M+, 7), 85 (26), 81 (22), 71
(71), 57 (100), 55 (44); HRMS (EI) calc. for C16H31NO2
m/z 269.2355, found: 269.2357.
4.11. N,N-diethyl-2-methyl-4-phenylbutylamide (4f)
4.7. N-benzyl-3-methyl-2-oxononanamide (5c)
1H NMR (CDCl3, 500 MHz) d 7.27–7.26 (m, 3H), 7.18
(d, J = 7.8 Hz, 2H), 3.47–3.40 (m, 2H), 3.35–3.24 (m,
2H), 3.28–3.14 (m, 2H), 2.60–2.55 (m, 1H), 2.07–2.00 (m,
1H), 1.74–1.07 (m, 1H), 1.14 (d, J = 6.4 Hz, 3H), 1.12 (t,
J = 7.1 Hz, 3H), 1.07 (t, J = 7.3 Hz, 3H); 13C NMR
(CDCl3, 125 MHz) d 13.21, 14.89, 33.62, 34.79, 35.98,
40.43, 128.37, 128.41, 128.45, 142.07, 175.57; IR (neat)
1454 cmꢀ1, 1939 cmꢀ1; MS (relative intensity) m/z 233
(M+, 1), 129 (100), 114 (25), 91 (55), 72 (24), 58 (34), 44
(28); HRMS (EI) calc. for C15H23NO m/z 233.1780, found:
233.1779.
1H NMR (CDCl3, 500 MHz) d 7.42–7.24 (m, 5H), 4.49
(s, 2H), 1.73–1.68 (m, 1H), 1.56 (s, 1H), 1.35–1.26 (m,
9H), 1.12 (d, J = 5.9 Hz, 3H), 0.88 (t, J = 6.6 Hz, 3H);
13C NMR (CDCl3, 125 MHz) d 14.15, 15.71, 22.66,
27.20, 29.34, 31.74, 32.57, 39.12, 43.52, 127.93, 128.91,
159.94, 202.36; IR (neat) 1455 cmꢀ1
,
1679 cmꢀ1
,
1716 cmꢀ1, 3340 cmꢀ1; MS (relative intensity) m/z 275
(M+, 2), 141 (27), 91 (100), 71 (74), 57 (79); HRMS
(EI) calc. for C17H25NO2 m/z 275.1885, found: 275.1879.
4.8. 1-(2-Methyl-1-oxooctyl)piperidine (4d)
4.12. N, N-diethyl-2-methyl-4-phenylsulfanylbutylamide
(4g)
1H NMR (CDCl3, 500 MHz) d 3.63-3.41 (m, 4H), 2.68
(sext, J = 6.8 Hz, 1H), 1.69–1.64 (m, 3H), 1.57–1.52 (m,
4H), 1.37–1.26 (m, 9H), 1.09 (d, J = 6.9 Hz, 3H), 0.87
(t, J = 6.6 Hz, 3H); 13C NMR (CDCl3, 125 MHz) d
14.12, 17.71, 22.68, 24.79, 25.82, 26.89, 27.53, 29.46,
31.83, 34.22, 35.26, 42.88, 46.62, 175.00; IR (neat)
1434 cmꢀ1, 1643 cmꢀ1; MS (relative intensity) m/z 225
(M+, 8), 154 (62), 142 (31), 141 (100), 140 (36), 112
(66), 86 (35), 85 (71), 84 (77), 71 (32), 70 (33), 69 (70),
57 (26), 56 (45), 55 (30), 44 (40), 43 (70), 42 (55), 41
(82); HRMS (EI) calc. for C14H27NO m/z 225.2093,
found: 225.2081.
1H NMR (CDCl3, 500 MHz) d 7.31 (t, J = 8.0 Hz, 2H),
7.27 (d, J = 6.4 Hz, 1H), 7.10 (t, J = 7.3 Hz, 2H), 3.41–3.25
(m, 4H), 3.02–2.97 (m, 1H), 2.92–2.81 (m, 2H), 2.11 (sext,
J = 7.0 Hz, 1H), 1.69 (sext, J = 6.8 Hz, 1H), 1.18 (t,
J = 7.1 Hz, 3H), 1.13–1.08 (m, 6H); 13C NMR (CDCl3,
125 MHz) d 13.21, 15.02, 18.05, 31.40, 33.32, 34.20,
40.47, 41.97, 125.84, 128.95, 128.97, 136.47, 175.00; IR
(neat) 1439 cmꢀ1, 1635 cmꢀ1; MS (relative intensity) m/z
265 (M+, 43), 156 (74), 129 (100), 123 (28), 100 (35);
HRMS (EI) calc. for C15H23NOS m/z 265.1500, found:
265.1506.
4.9. 1-(3-Methyl-1,2-dioxononyl)piperidine (5d)
4.13. N-benzyl-N-ethyl-2,2-dimethylpropionamide (4j)
1H NMR (CDCl3, 500 MHz) d 3.58 (t, J = 5.5 Hz,
2H), 3.31 (t, J = 5.5 Hz, 2H), 3.08 (sext, J = 6.7 Hz,
1H), 1.77–1.66 (m, 2H), 1.64–1.57 (m, 5H), 1.36–1.28
(m, 9H), 1.12 (d, J = 6.9 Hz, 3H), 0.88 (t, J = 6.9 Hz,
3H); 13C NMR (CDCl3, 125 MHz) d 14.13, 14.57, 22.66,
1H NMR (CDCl3, 500 MHz) d 7.32 (t, J = 7.6 Hz, 2H),
7.26–7.24 (m, 1H), 7.19 (d, J = 6.9 Hz, 2H), 4.66 (s, 2H),
3.38 (s, 2H), 1.38 (s, 9H), 1.13–1.11 (m, 3H); 13C NMR
(CDCl3, 125 MHz) d 28.71, 28.74, 39.16, 41.69, 127.15,

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T. Fukuyama et al. / Journal of Organometallic Chemistry 692 (2007) 685–690
128.65, 177.55; IR (neat) 1453 cmꢀ1, 1628 cmꢀ1; MS (rela-
tive intensity) m/z 219 (M+, 41), 92 (22), 91 (100), 57 (86);
HRMS (EI) calc. for C14H21NO m/z 219.1623, found:
219.1627.
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1H NMR (CDCl3, 500 MHz) d 3.40 (br.s, 4H), 1.71–1.65
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40.11, 41.37, 46.75, 175.05; IR (neat) 1466 cmꢀ1
,
1626 cmꢀ1; MS (relative intensity) m/z 241 (M+, 2), 185
(100), 184 (22); HRMS (EI) calc. for C15H31NO m/z
241.2406, found: 241.2393.
(b) T. Biedron, P. Kubisa, Macromol. Rapid Commun. 22 (2001)
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Acknowledgements
IR acknowledges a Grant-in-Aid for Scientific Research
on Priority Areas (A) ‘‘Reaction Control of Dynamic
Complexes’’ from MEXT, Japan for financial support.
TF thanks the Japan Science and Technology Agency for
financial support.
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