Allylic amination of unfunctionalyzed olefins by nitroarenes and CO, catalyzed by Ru3(CO)12/Ph-BIAN (Ph-BIAN=bis(phenylimino) acenaphthenequinone): Extension to the synthesis of allylic amines with strongly electron-withdrawing or el

Article abstract of DOI:10.1016/j.tet.2004.04.034

The allylic amination of unfunctionalyzed olefins by nitroarenes under CO pressure, catalyzed by Ru₃(CO)₁₂/Ph-BIAN (Ph-BIAN=bis(phenylimino)acenaphthenequinone) has been extended to some substrates with strongly electron-withdrawing

Full text of DOI:10.1016/j.tet.2004.04.034

Tetrahedron 60 (2004) 4989–4994
Allylic amination of unfunctionalyzed olefins by nitroarenes
and CO, catalyzed by Ru (CO) /Ph-BIAN
Ph-BIAN5bis(phenylimino)acenaphthenequinone): extension to
3
12
(
the synthesis of allylic amines with strongly electron-withdrawing
or electron-donating groups on the aryl ring
*
Fabio Ragaini, Sergio Cenini, Fabrizio Turra and Alessandro Caselli
Dipartimento di Chimica Inorganica, Metallorganica e Analitica, Universita’ degli Studi di Milano, ISTM-CNR,
via Venezian 21, 20133 Milano, Italy
Received 23 January 2004; revised 22 March 2004; accepted 14 April 2004
3
Abstract—The allylic amination of unfunctionalyzed olefins by nitroarenes under CO pressure, catalyzed by Ru (CO)12/Ph-BIAN
(Ph-BIAN¼bis(phenylimino)acenaphthenequinone) has been extended to some substrates with strongly electron-withdrawing groups on the
nitroarene. Reaction of 1,4-dinitrobenzene selectively affords functionalization of only one nitro group, the other remaining unreacted.
However, the second nitro group can be reduced in one pot by CO/H O in the presence of the same catalytic system employed in the
2
amination reaction, to afford the corresponding 4-amino derivative. Some attempts to render the reaction enantioselective by employing
chiral bis-oxazolines as ligands in place of Ph-BIAN are described. Bis-oxazolines are suitable ligands for the reaction, although not as
efficient as Ph-BIAN, but the allylic amine obtained was found to be racemic.
q 2004 Elsevier Ltd. All rights reserved.
1
. Introduction
(although an higher selectivity can be achieved by purifying
the olefin), the experimental operations are simple, the
selectivity was high (up to 81.9%), and the turnover
numbers were higher than those reported for most C–H
Allylic amines are important building blocks or final
products in organic chemistry and much attention has
been devoted to their synthesis. The most often employed
1
2–4
activation reactions (Scheme 1).
synthetic method involves nucleophilic attack of an amine
on a p-allyl complex. This is in turn generated by reaction
of a suitable metal complex with a prefunctionalized allylic
compound, such as an acetate or an halide. The method
often gives high yields, but has two limitations. The first is
that a prefunctionalized substrate is required, which often
needs preliminary steps to be prepared. The second is that
the amine must be nucleophilic enough to react with the
complex and aromatic amines having electron-withdrawing
substituents on the aryl ring are generally poor substrates in
these reactions. Some years ago, we reported on a new
synthetic way to produce allylic amines, employing a simple
unactivated olefin, cyclohexene, and an aromatic nitro
compound as the aminating reagent, under reducing
conditions (CO pressure). Although the method requires
the use of a high-pressure apparatus, the reagents are bulk,
cheap commercial products which do not need to be purified
Scheme 1.
One feature of this reaction, which is interesting in view of
what said above, apart from the fact of producing CO as the
2
only stoichiometric byproduct, is that nitroarenes bearing
electron-withdrawing substituents were those where the
highest selectivities were obtained. In this work we have
extended the range of nitroarenes for which the reaction
may be performed, employing substrates having strongly
electron-withdrawing groups on the nitroarene.
Keywords: Allylic amines; Nitroarenes; Carbonylation reactions;
Ruthenium; Imines.
*
Corresponding author. Tel.: þ39-2-5031-4373; fax: þ39-2-5031-4405;
e-mail address: fabio.ragaini@unimi.it
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2004.04.034

4990
F. Ragaini et al. / Tetrahedron 60 (2004) 4989–4994
Despite the good results obtained with nitroarenes having
electron-withdrawing substituents, substrates with strong
electron-donating groups such as methoxy or amino are not
suitable substrates for amination reactions of this kind. We
have now found a two step-one pot procedure to the 4-amino
derivative in good yields. The amino group can be an
important entry to a variety of other derivatives. Some
preliminary attempts to make the reaction enantioselective
are further described.
previously shown that the hydrogen atoms necessary for
the aniline formation come from a ruthenium-catalyzed
dehydrogenation of cyclohexene to afford cyclohexadiene
3
and benzene.
Although a complete purification of the allylic amines
required chromatography on silica, almost pure samples
could be obtained by subsequent acidic extraction with HCl
at different concentrations (see Section 4 for details).
Indeed, the byproduct anilines are extracted easily into
1
M aqueous HCl, whereas the allylic amines require a
2
. Results and discussion
more concentrated acid and the presence of methanol as a
co-solvent.
2.1. Nitroarenes with strongly electron-withdrawing
substituents
2.2. Synthesis of N-cyclohex-2-enyl-benzene-1,4-diamine
(2e)
Four nitroarenes bearing strong electron-withdrawing sub-
stituents were employed in this work, 4-MeOC(O)C H NO
2
As alluded to in the introduction, the main limit of this type
of reaction discussed in this paper is that when it is applied
to nitroarenes bearing strongly electron-donating sub-
stituents, only very low conversions and selectivities are
observed. The reason for this is two-fold. First, the evidence
accumulated indicates that the initial reduction of the
nitroarene always proceeds by a single electron transfer
from the complex to the nitroarene and this is disfavored by
6
4
(
1a), 3,5-Cl C H NO (1b), 3,5-(CF ) C H NO (1c), and
2 6 3 2 3 2 6 3 2
4
-O NC H NO (1d), none of which has been previously
2 6 4 2
employed in these reactions. The last contains two nitro
groups both of which may in principle react. However, we
had previously observed that the presence of the strong
electron-donating 4-methoxy group on the aryl ring of the
2
–4
nitroarene led to a very slow reaction.
After one of two
5
nitro groups has reacted, it is converted into an even more
electron-releasing amino group. Thus, we deemed a
selective reaction of only one nitro group could be feasible.
electron-donating substituents on the nitroarene. Moreover,
coupling between the olefin and the nitrogen-containing
complex occurs by a metal catalyzed ene reaction between
the olefin and the intermediately formed nitrosoarene and
1
,6
The results of a series of reactions run under previously
optimized conditions (T¼160 8C, P ¼40 bar, mol ratios
CO
this is also disfavored by the same donating substituents.
Use of a free amino group in a nitroaniline would further
complicate the issue, since the amino group may enter the
3
ArNO /Ph-BIAN/Ru (CO) ¼50:3.75:1) are reported in
2
3
12
5
Table 1. Good selectivities were obtained in all cases and
the 84% selectivity in the allylic amine bearing the
fluorinated groups is the highest obtained to date in these
reactions. As expected, only mono-functionalization was
observed for dinitrobenzene and no byproducts were
observed in which the second nitro group had been
transformed in any way.
reaction via an alternative pathway, to yield diarylureas.
A different catalytic system, reported by Nicholas for the
same reactions, suffers from the same limitations.
7
Molecules having free amino groups are important both as
such and because the amino group can be easily func-
tionalized or transformed (e.g. via an azonium salt) into
many other groups. Thus it would be interesting to prepare
them by our methodology. The system Ru (CO) /Ar-BIAN
When using 4-MeO CC H NO as substrate by lowering
2
6
4
2
3
12
the temperature a very low conversion results, but with the
more reactive 3,5-(CF ) C H NO substrate a significant
reaction was observed even at 100 8C.
is also the most active catalyst known to date for the
,9
8
reduction of nitroarenes to anilines by CO/H O. This
2
3
2
6
3
2
reaction proceeds much more easily than the amination
reaction and the presence of an electron-donating sub-
stituent on the nitroarene is not a major problem here. Since
we have now been able to synthesize the 4-nitro derivative
2d, we effected a two step-one pot reaction from
dinitrobenzene. In the first step, 2d is produced under the
The only observable byproduct was the aniline correspond-
ing to the nitroarene employed, but small amounts of the
corresponding diarylureas are probably also formed, which
could not be detected by gas-chromatography. We have
a
Table 1. Synthesis of allylamines 2 from cyclohexene and different nitroarenes
b
c
c
Run Ru
3
(CO)12 (mmol) Cyclohexene (mL)
Nitroarene
Nitroarene conversion (%)
Allylamine select (%)
Aniline select (%)
1
2
3
4
5
6
0.0306
0.0306
0.0306
0.0102
0.0102
0.0102
30
30
30
10
10
10
3,5-Cl
4-MeO
1,4-(NO
2
C
6
H
3
NO
NO
(1d)
2
(1b)
99.1
100
100
99.9
41.9
39.7
57.2 (2b)
42.1 (2a)
52.7(2d)
83.1 (2c)
84.3 (2c)
52.3 (2c)
12.0
10.4
3.2
14.4
15.7
32.8
2
CC
6
H
4
2
(1a)
2
)
2
C
6
H
4
3,5-(F
3,5-(F
3,5-(F
3
3
3
C)
C)
C)
2
C
6
H
3
NO
2
2
2
(1c)
d
e
2
C
C
6
6
H
H
3
NO
NO
(1c)
(1c)
2
3
a
b
c
d
e
Experimental conditions: mol ratios ArNO /Ph-BIAN/Ru
Calculated with respect to the starting nitroarene by GC analysis (naphthalene as an internal standard).
Calculated with respect to the converted nitroarene by GC analysis (naphthalene as an internal standard).
2
3
(CO)12¼50:3.75:1, T¼160 8C, PCO¼40 bar, t¼6 h.
T¼130 8C.
T¼100 8C.

F. Ragaini et al. / Tetrahedron 60 (2004) 4989–4994
4991
Scheme 2.
same conditions reported in this paper (Table 1). Then the
autoclave was opened and water and methanol (to improve
miscibility) were added. The autoclave was charged again
with CO and the reaction run under the temperature and
pressure conditions previously shown to give a 99%
2.3. Use of chiral bis-oxazolines as ligands
Given the importance chiral allylic amines have in
pharmaceutical chemistry, we attempted to make our
reaction asymmetric by employing a chiral ligand. Since
no chiral Ar-BIAN has to date been reported, we decided to
use bis-oxazolines as ligands. The choice was motivated by
the fact that some years ago we employed similar, although
not chiral, ligands in the Ru (CO) -catalyzed reduction of
selectivity in the reduction of nitrobenzene to aniline
9
(
Scheme 2).
At the end of the reaction, 2d had been completely
consumed to afford the corresponding amine 2e. The total
selectivity in 2e (52.8%) is indistinguishable within
experimental error from the one in 2d in the single step
reaction, indicating that the reduction step occurs in
essentially quantitative yields.
3
12
1
2
nitrobenzene to aniline by CO/H O with good results. In
2
the same work, we had noticed that the central –CH2–
moiety of the bis-oxazoline had to be protected by
alkylation in order for the catalyst to be active. The ligands
employed in this work are shown in Scheme 3.
It should be noted that any amination procedure based on a
reaction of 1,4-diaminobenzene with a functionalized
substrate would surely have to face the problem of multiple
substitution not only on the same nitrogen atom, but even on
the second one, so that up to four products can be expected,
differing in the alkylation extent. On the other hand, with
our strategy only the monosubstituted product can be
obtained.
Two of these, 3a,b, are commercially available, whereas the
methylated indabox 3c is not. Its synthesis from indandiol
and dimethylmalononitrile in a low yield has been briefly
reported in a communication, but the experimental details
and the characterization of the product were not reported.
We preferred to start from the commercially available
1
3
0
p
0
p
0
0
0
(R)-indabox ([3aR-[2(3 aR ,8 aS ),3 ab,8 ab]]-(þ)-2,2 -
methylenebis[3a,8a-dihydro-8H-indeno[1,2-d]oxazole) and
we effected the methylation by deprotonation of the parent
ligand by lithium diisopropylamide, followed by reaction
with methyl iodide (Eq. (1)). The procedure is a modifi-
cation of the one reported in the literature for the alkylation
During the reaction a small amount of unsubstituted aniline
was formed, whose origin is uncertain. Another independent
product was formed (as evidenced by GC-MS analysis),
which does not include the nitroarene-derived fragment,
CyCOOMe. This ester clearly derives from the carboxyla-
tion reaction of cyclohexene, which is still present in the
reaction mixture in large amount, by CO and methanol.
When the reaction was performed by employing ethanol in
place of methanol, the reduction reaction proceeded in the
same way and CyCOOEt was formed in place of the
corresponding methyl ester. This type of carboxylation
reactions are typically catalyzed by palladium complexes.
By searching through the literature we could only find two
examples, both in the patent literature, for ruthenium-
catalyzed olefin carboxylation reactions and in none of these
1
4,15
of the same or of related bis-oxazolines
pure 3c in a 56.2% isolated yield.
and afforded
ð1Þ
1
0,11
examples was a nitrogen ligand present.
Since this
reaction was outside the scope of the present paper, it was
not investigated further at the moment, although it surely
deserves attention.
Scheme 3.

4992
F. Ragaini et al. / Tetrahedron 60 (2004) 4989–4994
a
Table 2. Use of bis-oxazolines 3 as ligands
b
c
c
Run
Ligand
T (8C)
t (h)
Nitroarene
Nitroarene conversion (%)
Allylamine select (%)
Aniline select (%)
1
2
3
4
5
6
7
8
9
3c
3b
3a
3a
3c
3c
3b
3a
3c
3c
160
160
160
130
130
160
160
160
130
100
6
6
6
10
10
6
6
6
10
10
4-MeO
4-MeO
4-MeO
4-MeO
4-MeO
2
2
2
2
2
CC
CC
CC
CC
CC
6
6
6
6
6
H
H
H
H
H
4
4
4
4
4
NO
NO
NO
NO
NO
2
2
2
2
2
80.9
56.4
53.4
46.4
66.2
77.7
99.4
84.4
81.5
12.6
1.9 (2a)
8.0 (2a)
5.9 (2a)
2.6 (2a)
11.1 (2a)
31.0 (2b)
44.5 (2b)
18.3 (2b)
37.3 (2b)
8.9 (2c)
3.0
7.0
13.6
29.1
27.8
13.5
22.3
17.7
32.9
37.4
3,5-Cl
3,5-Cl
3,5-Cl
3,5-Cl
2
2
2
2
C
6
C
6
C
6
C
6
H
H
H
H
3
3
3
3
NO
2
2
2
2
NO
NO
NO
10
3 2 6 3 2
3,5-(CF ) C H NO
a
b
c
23
Experimental conditions: Ru
Calculated with respect to the starting nitroarene; GC analysis.
Calculated with respect to the converted nitroarene; GC analysis.
3
(CO)12¼0.65 mg, 1.0£10 mmol, mol ratio Ru
3
(CO)12/3/ArNO
2
¼1/3/50, PCO¼40 bar, in cyclohexene (1 mL).
The reactions with the oxazolines were run in a similar way
to the ones with Ar-BIAN ligands. However, in order to
be able to perform the reactions on a smaller scale, an
aluminum block having three 12 mm holes was prepared
that could be fitted in the autoclave. Three small test tubes
were placed in the holes (see Section 4 for details), so that
three reactions could be run at the same time, each on a
that carboxylation of cyclohexene is possible using a
ruthenium complex as catalyst and this will be studied in
further depth.
4. Experimental
1
mL scale.
4.1. General procedure
The results of reactions run with the bis-oxazoline ligands
are reported in Table 2.
Cyclohexene, THF and hexane were purified by distillation
over sodium and stored under dinitrogen before use.
1
7
Ru (CO)
3
was synthesized as reported in the literature.
1
12
The desired products were obtained, but reaction rates and
selectivities are in general lower than those achievable with
the use of Ph-BIAN. The two enantiomers of 2a could be
separated by chiral HPLC, employing conditions similar to
8–20
Ph-BIAN was prepared as previously reported,
employing our protocol based on the use of oxalate to
but
2
1
remove the initially present ZnCl2. All other compounds,
except for those mentioned below, were commercial
products and were used as received. Gas chromatographic
analyses were performed on a Perkin Elmer 8420 capillary
gas chromatograph equipped with a PS 255 column. Ri
values (Ri¼response factor, relative to naphthalene as an
internal standard) were determined by the use of solutions of
known concentrations of the compounds. GC-MS analyses
were performed on a Shimadzu GCMS-QP5050A instru-
ment, equipped with an Equity 5 column. NMR spectra
were recorded on a Bruker AC 300 FT, operating at
1
6
the ones reported for the analogous ethyl ester, but the
enantiomers of 2b–d could not be separated by the same
technique, nor by chiral phase gas chromatography.
Unfortunately the reactions corresponding to entries 1–5
in Table 2 all gave a completely racemic product. At 100 8C,
1
a did not react to any detectable extent and even the more
reactive 1c only gave a low conversion and a very low
selectivity in allylic amine. Thus bis-oxazolines are not
suitable ligands for an enantioselective modification of our
amination reaction. Other chiral ligands have to be
developed that also have to impart a reactivity to the
catalytic system at least comparable to the one achievable
with Ar-BIAN ligands, so that the reaction can be performed
at lower temperatures.
1
19
3
00 MHz for H, at 282 MHz for F, and at 75 MHz for
1
3
C. Elemental analyses and mass spectra were recorded in
the analytical laboratories of Milan University.
4.1.1. Synthesis of 3c. The synthesis was performed in
oven-dried glassware working under a dinitrogen atmos-
phere and employing standard Schlenk and cannula
techniques. After the quenching with water, the remaining
operations have been conducted in the air. To a Schlenk tube
3
. Conclusions
0
p
0
p
0
0
In this paper, we have expanded the range of successfully
converted substrates for the amination of cyclohexene by
nitroarenes and CO, including several nitroarenes having
strongly electron-withdrawing substituents. A selective
reaction of only one nitro group in 1,4-dinitrobenzene was
observed. More importantly, a two step-one pot protocol to
an amino substituted derivative has been devised, which
allows the reaction to be extended to previously inaccessible
products, without problems deriving from polysubstitution.
Chiral bis-oxazolines were found to be suitable ligands for
the catalytic system, but results are inferior to the ones
obtainable with Ar-BIAN ligands and the product formed
was found to be racemic. We have also determined
were added (R)-indabox ([3aR-[2(3 aR ,8 aS ),3 ab,8 ab]]-
0
(þ)-2,2 -methylenebis[3a,8a-dihydro-8H-indeno[1,2-d]-
oxazole, 100.0 mg, 0.303 mmol), tetramethylethylen-
diamine (TMEDA, 92 mL, 0.61 mmol) and THF (12 mL).
After the solid was dissolved, the solution was cooled to
278 8C by an acetone–dry ice bath and LiN–iPr2
(0.8 mmol, 0.40 mL of a 2 M solution in THF/heptane/
ethylbenzene) was added. The orange suspension was left to
stir at 278 8C for 30 min, then at 220 8C for 2.5 h. At this
point, the solution was cooled back to 278 8C and MeI
(47 mL, 0.75 mmol) was added. The solution was stirred at
this temperature for 30 min, then at 220 8C for the same
time and finally at room temperature overnight. A saturated

F. Ragaini et al. / Tetrahedron 60 (2004) 4989–4994
4993
solution of NaHCO (7 mL) was added and, after stirring for
3
4.3. Separation and purification of the allylamines 2
1
0 min, 2 more mL water were added to dissolve a white
solid suspended in the aqueous phase. The two phases were
separated, the aqueous phase was extracted with THF
Compounds 2a, 2b. The solution after the withdrawal for the
GC analysis was extracted with 1 M aqueous HCl (3£5 mL)
to remove the byproduct anilines The organic phase was
(
3£10 mL) and the combined extracts were joined to the
organic phase. After drying with sodium sulfate, the organic
solution was evaporated to dryness in vacuo and the
resulting solid, consisting of white and orange crystals,
was recrystallized from hexane (50 mL) to afford 3c as
colorless needle-like crystals (61.1 mg, 56.2% yield). Anal.
Calcd for C H N O : C, 77.07; H, 6.19; N, 7.82. Found:
then extracted with ,3 M H O/MeOH HCl solution,
2
obtained by mixing 1 volume 37% HCl with 1 volume
H O and 2 volumes MeOH (3£5 mL). The combined
2
aqueous phases of the second extraction were made basic
by the addition of NaOH and back extracted with CH Cl
2
2
(3£5 mL). After drying the organic phase with sodium
sulfate, it was evaporated to dryness in vacuo and loaded on
a short (7 cm) silica pad. The mixture is eluted with CH Cl
2
2
3 22 2 2
1
C, 76.80; H, 6.09; N, 8.11. H NMR (300 MHz, CDCl ,
3
2
2
–
5 8C, TMS): d¼1.44 (s, 6H, CH ), 2.97 (d, J ¼17.9 Hz,
3
gem
2
H, –CHC(H)HC), 3.29 (dd, J ¼17.9, J ¼7.1 Hz, 2H,
keeping all the eluate together, until a brown band does not
approach the end of the pad, at which point the elution is
stopped. The eluate is evaporated to dryness to afford the
pure product.
gem
12
CHC(H)HC), 5.29 (pt, 2H, CH–O), 5.54 (d, J ¼7.9 Hz,
1
2
2
H, CH–N), 7.29 (m, 6H, Ar–H), 7.51 (m, 2H, Ar–H). MS
þ
(
70 eV, EI): m/z: 358 [M ].
4
.2. Catalytic reactions
Compounds 2c, 2d. The same procedure was employed as
above, but a ,6 M H O/MeOH HCl solution (obtained by
2
In a typical reaction, the nitroarene, Ru (CO) and the
3
mixing equal volumes of 37% HCl and methanol) was
necessary to efficiently extract these allylic amines.
12
ligand (see Tables 1 and 2) were weighed in a glass liner.
The liner was placed inside a Schlenk tube with a wide
mouth under dinitrogen and was frozen at 278 8C with dry
ice, evacuated and filled with dinitrogen, after which the
solvent was added. After the solvent was also frozen, the
liner was closed with a screw cap having a glass wool-filled
open mouth which allows for gaseous reagents exchange
and rapidly transferred to a 200 mL stainless steel autoclave
with magnetic stirring. The autoclave was then evacuated
and filled with dinitrogen three times. CO was then charged
at room temperature at the required pressure and the
autoclave was immersed in an oil bath preheated at the
required temperature. Other experimental conditions are
reported in Tables 1 and 2. At the end of the reaction the
autoclave was cooled with an ice bath, vented and the
products were analyzed by gas chromatography (naphtha-
lene as an internal standard) and then extracted with acids as
detailed in the following for each compound. In the case of
the synthesis of 2e, after the amination reaction employing
Compound 2e. A clean separation of 2e from 1,4-di-
aminobenzene and aniline could not be achieved by simple
acidic extraction. The amines were thus extracted together
with 3 M H O/MeOH HCl. During the chromatographic
2
separation, a yellow impurity band was first eluted with
CH Cl , after which CHCl was added and the red colored
2
2
3
2e collected. The thus obtained product still contains small
amounts of diaminobenzene and aniline. However, heating
at 60 8C in vacuo the red oil for 3 h, these more volatile
impurity evaporated and the product was shown by GC to
contain about 1% of 1,4-diaminobenzene as the only
contaminant.
4.4. Identification of the organic products of catalysis
The by-products anilines are all commercial products and
were identified by comparison of their CG and CG-MS
spectra with those of authentic samples. Compound 2a is a
colorless solid, 2b and 2c are colorless oils, 2d is a yellow
1
1
d as substrate was over (conditions as in entry 1 of Table
), the autoclave was vented, the glass liner moved to the
2
2
same Schlenk tube employed during the initial preparation
and previously placed under a dinitrogen atmosphere and
opened in a dinitrogen flux. Water (0.3 mL) and methanol
solid, and 2e is a red oil. Compound 2d has been
1
previously reported in the literature. The H NMR spectrum
of our sample was consistent with the one reported in the
1
3
(
1.5 mL) were added. The same procedure described before
literature. The C NMR and mass spectra of 2d are anyway
reported in the following because this data has not been
reported previously. After the chromatographic separation,
was then employed and the second step was run at 180 8C
under 30 bar CO for 4 h. Handling of the reaction solution in
the air should be avoided as much as possible, since the
catalytically active species Ru(Ph-BIAN)(CO)3 (intense
purple color), formed during the reaction, is very air
sensitive. The reactions with bis-oxazolines as ligands were
performed in a similar way, but on a smaller scale. In this
case, three 10 mm wide £40 mm high test tubes were
employed instead of the glass liner, each having a miniature
glass wool-filled screw cap similar to the one of the larger
liner. The three test tubes were located in the holes of an
aluminum block designed to fit the autoclave. Other
operations were analogous to the ones described above
except that stock solutions of Ru (CO) , the ligand and the
1
no impurity could be detected in the GC and H NMR
spectra of the allylamines (except for 2e, as mentioned
above). Thus, the purified compounds are evaluated to be at
least 98% pure.
1
4.4.1. Compound 2a. H NMR (CDCl , 25 8C, TMS):
3
d¼1.65–1.98 (m, 6H, –CH –CH –CH –), 3.87 (s, 3H,
2
2
2
COOCH ), 4.08 (s br, 2H, –CH–NH, 1H exc D O), 5.74
3
2
(m, 1H, –CH –CHvCH–CH–), 5.91 (m, 1H, –CH –
2
2
CHvCH–CH–), 6.57 (d, Jortho¼8.6 Hz, 2H, Ar–H), 7.87
1
3
(d, Jortho¼8.6 Hz, 2H, Ar–H). C NMR (CDCl , 25 8C,
3
TMS): d¼19.59, 25.12, 28.79, 47.58, 51.58, 111.84, 118.17,
3
12
nitroarene were prepared and the reagent amounts measured
by volume to avoid the errors in weighing very small
amounts of materials.
127.64, 131.02, 131.71, 151.01, 167.37. MS (70 eV, EI):
m/z: 231 [M ]. Anal. Calcd for C H NO : C, 72.70; H,
þ
7.41; N, 6.06. Found: C, 72.42; H, 7.50; N, 5.75.
1
4
17
2

4994
F. Ragaini et al. / Tetrahedron 60 (2004) 4989–4994
1
4
.4.2. Compound 2b. H NMR (CDCl , 25 8C, TMS):
3
References and notes
d¼1.60–1.95 (m, 6H, –CH –CH –CH –), 3.82 (s br, 1H,
2
2
2
NH, exc D O), 3.93 (s br, 1H, –CH–NH), 5.70 (m, 1H,
2
1. Johannsen, M.; Jørgensen, K. A. Chem. Rev. 1998, 98,
1689–1708, and references therein.
–
CH–), 6.47 (s 2H, Ar–H), 6.65 (s, 1H, Ar–H). C NMR
CH –CHvCH–CH–), 5.90 (m, 1H, –CH –CHvCH–
2 2
1
3
2. Cenini, S.; Ragaini, F.; Tollari, S.; Paone, D. J. Am. Chem.
Soc. 1996, 118, 11964–11965.
(
CDCl , 25 8C, TMS): d¼19.54, 25.10, 28.69, 47.86, 51.58,
3
111.22, 116.76, 127.48, 131.12, 135.58, 148.87. MS (70 eV,
EI): m/z: 241 [M ]. Anal. Calcd for C H NCl : C, 59.52;
3. Ragaini, F.; Cenini, S.; Tollari, S.; Tummolillo, G.; Beltrami,
R. Organometallics 1999, 18, 928–942.
4. Ragaini, F.; Cenini, S.; Borsani, E.; Domp e´ , M.; Gallo, E.
Organometallics 2001, 20, 3390–3398.
þ
H, 5.41; N, 5.78. Found: C, 59.30; H, 5.57; N, 6.12.
1
2
13
2
1
4
.4.3. Compound 2c. H NMR (CDCl , 25 8C, TMS):
3
5. Cenini, S.; Ragaini, F. Catalytic Reductive Carbonylation of
Organic Nitro Compounds; Kluwer: Dordrecht, 1997; Chapter
6 and references therein.
d¼1.56–1.96 (m, 6H, –CH –CH –CH –), 4.08 (s br, 2H,
2
2
2
–
CH–), 5.96 (m, 1H, –CH –CHvCH–CH–), 6.94 (s, 2H,
CH–NH, 1H exc D O), 5.72 (m, 1H, –CH –CHvCH–
2 2
6. Boger, D. L.; Weinreb, S. N. Hetero Diels–Alder Method-
ology in Organic Synthesis; Academic: New York, 1987; and
references therein.
2
1
3
Ar–H), 7.13 (s, 1H, Ar–H). C NMR (CDCl , 25 8C,
3
TMS): d¼19.79, 25.36, 28.83, 48.15, 110.21, 112.45,
1
23.98 (q, J ¼272.5 Hz), 127.36, 131.81, 132.88 (q,
7. Srivastava, R. S.; Nicholas, K. M. Chem. Commun. 1998,
2705–2706.
C–F
1
9
JC–F¼32.8 Hz), 148.15. F NMR (CDCl , 25 8C, TMS):
3
þ
C H NF : C, 54.37; H, 4.24; N, 4.53. Found: C, 54.00; H,
d¼263.53. MS (70 eV, EI): m/z: 309 [M ]. Anal. Calcd for
8. Ragaini, F.; Cenini, S.; Tollari, S. J. Mol. Catal. 1993, 85,
L1–L5.
9. Ragaini, F.; Cenini, S.; Gasperini, M. J. Mol. Catal. (A) 2001,
1
4
13
6
4
.52; N, 4.80.
1
74, 51–57.
1
4
.4.4. Compound 2d. H NMR (CDCl , 25 8C, TMS):
3
10. Drent, E. Eur. Pat. Appl. EP 310168 A2, 1989. Chem. Abstr.
119, 59984.
d¼1.62–2.02 (m, 6H, –CH –CH –CH –), 4.11 (s br, 1H,
2
2
2
NH, exc D O), 4.49 (s br, 1H, –CH–NH), 5.73 (m, 1H,
2
11. Larkin, J.M. U.S. US 4588834 A, 1986. Chem. Abstr. 105,
42340.
–
CH –CHvCH–CH–), 5.97 (m, 1H, –CH –CHvCH–
2 2
CH–), 6.55 (d, Jortho¼9.2 Hz, 2H, Ar–H), 8.10 (d, J
¼
.2 Hz, 2H, Ar–H). C NMR (CDCl , 25 8C, TMS):
3
12. Ragaini, F.; Pizzotti, M.; Cenini, S.; Abbotto, A.; Pagani,
G. A.; Demartin, F. J. Organomet. Chem. 1995, 489, 107–112.
13. Davies, I. W.; Senanayake, C. H.; Larsen, R. D.; Verhoeven,
T. R.; Reider, P. J. Tetrahedron Lett. 1996, 37, 813–814.
14. Denmark, S. E.; Stiff, C. M. J. Org. Chem. 2000, 65,
5875–5878.
ortho
1
3
9
d¼19.36, 24.92, 28.56, 47.78, 111.34, 126.53, 126.65,
þ
Anal. Calcd for C H N O : C, 66.04; H, 6.47; N, 12.84.
Found: C, 65.77; H, 6.13; N, 13.16.
1
31.79, 137.89, 152.29. MS (70 eV, EI): m/z: 218 [M ].
1
2 14 2 2
1
5. Davies, I. W.; Gerena, L.; Castonguay, L.; Senanayake, C. H.;
Larsen, R. D.; Verhoeven, T. R.; Reider, P. J. Chem. Commun.
1996, 1753–1754.
1
4
.4.5. Compound 2e. H NMR (CDCl , 25 8C, TMS):
3
d¼1.58–1.92 (m, 6H, –CH –CH –CH –), 3.27 (s br, 3H,
2
2
2
NH and NH , exc D O), 3.90 (s br, 1H, –CH–NH), 5.80 (m,
2
16. L o¨ ber, O.; Kawatsura, M.; Hartwig, J. F. J. Am. Chem. Soc.
2001, 123, 436–437.
2
1
3
2
H, –CH –CHvCH–CH–), 6.58 (m, 4H, Ar–H).
2
C
NMR (CDCl , 25 8C, TMS): d¼20.24, 25.65, 29.56, 49.68,
17. Eady, C. R.; Jackson, P. F.; Johnson, B. F. G.; Lewis, J.;
Malatesta, M. C.; McPartlin, M.; Nelson, W. J. J. Chem. Soc.
Dalton Trans. 1980, 383–392.
3
115.89, 117.37, 129.55, 130.04, 138.20, 140.87. MS (70 eV,
EI): m/z: 188 [M ]. Anal. Calcd for C H N : C, 76.56;
þ
H, 8.57; N, 14.88. Found: C, 76.20; H, 8.22; N, 14.60.
1
2 16 2
18. Dvolaitzky, M. C. R. Acad. Sci. Paris, Ser. C 1969, 268,
1
811–1813, Chem. Abstr. 1969, 71, 61566b.
9. Matei, I.; Lixandru, T. Bul. Ist. Politeh. Iasi 1967, 13,
45–255, Chem. Abstr. 1969, 70, 3623m.
1
2
Acknowledgements
20. van Asselt, R.; Elsevier, C. J.; Smeets, W. J. J.; Spek, A. L.;
Benedix, R. Recl Trav. Pays Bas 1994, 113, 88–98.
21. Gasperini, M.; Ragaini, F.; Cenini, S. Organometallics 2002,
21, 2950–2957.
We thank Dr. M. Gasperini and Dr. Chiara Monti for
experimental assistance and the MIUR (Programmi di
Ricerca Scientifica di Rilevante Interesse Nazionale, PRIN
22. Moreno-Ma n˜ as, M.; Morral, L.; Pleixats, R. J. Org. Chem.
1998, 63, 6160–6166.
2
003033857) for financial support.