Synthesis of ruthenium N-heterocyclic carbene complexes and their catalytic activity for β-alkylation of tertiary cyclic amines

Article abstract of DOI:10.1016/j.jorganchem.2015.10.011

The novel ruthenium N-Heterocyclic carbene complexes are synthesized, and characterized by studying its ¹H, ¹³C, elemental analysis, and X-ray. These complexes have been reported as promising catalyst for β C-H bond functionalization of tertiary cyclic amines through hydrogen autotransfers in the presence of external acidic additive. The new catalytic products were characterized by ¹H NMR, ¹³C NMR spectroscopic methods.

Full text of DOI:10.1016/j.jorganchem.2015.10.011

Journal of Organometallic Chemistry 799-800 (2015) 311e315
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis of ruthenium N-heterocyclic carbene complexes and their
catalytic activity for b-alkylation of tertiary cyclic amines
€
a
,
*
a
a
b
_
Ismail Ozdemir , Serpil Demir Dü s¸ ünceli , Nazan Kalo gꢀ lu , Mathieu Achard ,
b
Christian Bruneau
Catalysis Research and Application Center, In o€ nü University, 44280 Malatya, Turkey
a
b
Universit ꢁe de Rennes 1, UMR6226: Institut des Sciences Chimiques de Rennes, Centre de Catalyse et Chimie Verte, 35042 Rennes, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 3 July 2015
Received in revised form
The novel ruthenium N-Heterocyclic carbene complexes are synthesized, and characterized by studying
1
13
its H, C, elemental analysis, and X-ray. These complexes have been reported as promising catalyst for
b
CeH bond functionalization of tertiary cyclic amines through hydrogen autotransfers in the presence of
18 September 2015
1
13
external acidic additive. The new catalytic products were characterized by H NMR, C NMR spectro-
scopic methods.
Accepted 6 October 2015
Available online xxx
©
2015 Elsevier B.V. All rights reserved.
Keywords:
N-Heterocyclic carbene
Ruthenium
Cyclic amine
Catalysis
1
. Introduction
secondary amine in the presence of a Ru(PNP) precatalyst and
water enable the formation of amides [9]. The transient formation
of enamine intermediates in the presence of ruthenium or iridium
Considering the importance of selective deuteration [1], race-
misation [2] and functionalization [3], to access valuable azahe-
terocycles, oxidant free hydrogen transfer processes enabling either
complexes allowed the access to
b-alkylated products with alde-
hydes acting as electrophiles [10]. To date,
b-alkylation of saturated
a
and/or
b
CeH bonds activation/functionalization adjacent to ni-
tertiary amines involving hydrogen autotransfers have been re-
ported with ruthenium complexes embedded with a phosphine-
sulfonate chelate whereas nothing is known about the use of
NHC ligands or external acidic additive in related transformations.
Since the discovery of stable free N-heterocyclic carbene (NHC)
[11], metal carbene complexes based on imidazol-2-ylidene (imy)
or benzimidazol-2-ylidene (bimy) have received considerable
attention both in organometallic chemistry and homogeneous
catalysis [12]. As regards ruthenium, most of the known NHC-
catalysts have been applied to olefin metathesis [13], CeC alkyne
coupling [14] and hydrogenation [15] reactions. N-Heterocyclic
carbenes are generally derived from imidazoles [16e20], benz-
imidazoles [21e24], triazoles [25e28] and pyrazoles [29e33].
Functionalization on nitrogen atoms enlarge the scope of these
proligands. Owing to these aforementioned tuneable steric and
electronic properties, catalytic activities of the resulted NHC com-
plexes are greatly affected. Our group has prepared a series of
ruthenium-NHC complexes bearing chelating imidazoline or
benzimidazole, bidentate imidazoline-based carbene ligands and
tested their catalytic activities in the metathesis and CeH bond
trogen atom have attracted lot of interest. Selective redox neutral
alkyl exchanges [4] or dehydrogenative hydrolyzes [5] of amines in
the presence of catalytic amount of palladium black were reported
by Murahashi and coworkers. Later on, Shvo and Laine demon-
3 3
strated that homogeneous Ru (CO)12 or Os (CO)12 were efficient
precatalysts for similar alkyl exchanges [6]. The ruthenium catalysts
are well-known for hydrogen transfer from alcohols, they have not
been used for dehydrogenation of cyclic amines except for alkyl-
ation of anilines. We have thus investigated the possibility of per-
forming a sequence of catalytic reactions from cyclic amines with
ruthenium catalysts based on hydrogen transfers according to Fig.1.
Since then, other groups extended these concepts to enable the
a
-alkylation of amines in the presence of platinum(II) [7] whereas
alkynylation, deuteration were successfully achieved in the
presence of Shvo's complex [8]. Replacing tertiary amine by
a,b
*
Corresponding author. Tel./fax: þ90 4223410212.
_
€
E-mail address: ismail.ozdemir@inonu.edu.tr (I. Ozdemir).
http://dx.doi.org/10.1016/j.jorganchem.2015.10.011
022-328X/© 2015 Elsevier B.V. All rights reserved.
0

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I. Ozdemir et al. / Journal of Organometallic Chemistry 799-800 (2015) 311e315
Fig. 1. Functionalization of cyclic amine involving hydrogen transfer processes.
activation reactions [34].
In this paper, we report the synthesis and characterization of a
series of new ruthenium(II) complexes with carbene ligands
bearing hemilabile arene side arm. The influence of the acidic ad-
ditive is evaluated during the non-destructive
b-alkylation of N-
methylpiperidine with various aldehydes as electrophile.
2
. Results and discussion
2
.1. Synthesis of ruthenium NHC complexes
ꢀ
Fig. 2. Molecular structure of complex A. Selected bond lengths [Å] and angles [ ]: Ru-
ꢀ
(
1)-Br(1) 2.540(1), Ru(1)-Br(2) 2.5028(8), Ru(1)-C(9) 2.045(6); Br(2)-Ru(1)-Br(1) 90.9 ;
In this context, the easily accessible and stable Ru dimer [(p-
ꢀ
Br(2)-Ru(1)-C(19) 94.0 .
2 2
cymene)RuCl ] is an easy metallic precursor to handle that is an
ideal starting material for the synthesis of benzimidazolin-2-
ylidene ruthenium catalysts to be further used for alkylation of
cyclic amines. Many synthetic methods for the synthesis of metal-
NHC complexes have been explored. According to these reports, the
most widely used preparation methods can be divided broadly into
five types: (i) reaction of in situ generated free NHCs with metal
precursors [35], (ii) reaction of electron-rich olefin dimers with
organometallic fragments [36], (iii) reaction of imidazolium salts
with suitable basic transition metal salts [37], (iv) reaction of azo-
lium salts with metal precursors under basic phase transfer catal-
ysis (PTC) conditions [38], and (v) transmetallation with Ag(I)e
NHCs [39]. Additionally, Delaude has shown that imidazol(in)ium-
2
.2. Application in
b-alkylation
With these well-defined complexes in hand, we next undertook
their preliminary evaluation in oxidant free CeH bond functional-
ization of tertiary cyclic amines in the presence of electrophile to
rationalized the effect of the hemilabile shielding character of the
side arm of the benzylic moiety toward activity and selectivity. On
the other hand, N-methylated amines represent an interesting class
of biologically active compounds and selective functionalization
keeping intact the methyl group is attractive. However, during b-
alkylation, the competitive formation of exo and endo-cyclic imi-
nium would result in undesired demethylation reaction through
the attack of nucleophile on the resulting exo-cyclic iminium. A
plausible mechanism is depicted for give point to the role of CSA in
Chart 1.
For this purpose we decided to evaluate the challenging N-
methyl piperidine material which can easily undergo hydrolysis of
the methyl group under hydrogen autotransfer conditions. The
screening of our new ruthenium complexes A-C was performed in
toluene with benzaldehyde, in the presence of substoichiometric
2
2
-carboxylates readily lost their CO moiety upon heating or
dissolution and could serve as efficient carbene precursors in
organocatalytic processes or for the synthesis of various transition
metal-NHC complexes [40]. We evaluated two pathways for the
synthesis of our ruthenium NHC complexes. The first method I
(Scheme 1) involved reaction of electron-rich olefin dimers with
organometallic fragments under refluxing toluene allowing the
formation of the chelating complex A. NMR analysis confirmed the
loss of the p-cymene ligand. Selective crystallization by solvent
2 2
diffusion technique (CH Cl /hexane) allowed the formation of
suitable orange-brown crystals for X-ray diffraction analysis. Fig. 2
displays the molecular structure of complex A. The ruthenium
complex displays half sandwich structure where the aromatic
6
moiety of the benzylic arm play the role of
h
-arene ligand. Note-
worthy that selective halogen exchange occurred between the
chloride ligand of the starting metal precursor and the bromide
counteranion of the benzimidazolium bromide. In contrast, under
milder reaction conditions, by using transmetallation methodology
II with Ag(I)eNHCs arising from 2 and 3 and the corresponding
metal precursor [Ru(p-cymene)Cl
p-cymene ligand affording the corresponding [RuCl
2
]
2
prevented the removal of the
(arene)NHC]
2
(
arene ¼ p-cymene) complexes B and C. (Scheme 2).
Scheme 1. Preparation of complex A.
Scheme 2. Preparation of complex B and C.

_
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I. Ozdemir et al. / Journal of Organometallic Chemistry 799-800 (2015) 311e315
313
Chart 1. Proposed mechanism.
amount of complex A-C (2.5 mol%). The addition of formic acid at
the end of the reaction ensure complete conversion of the
lated enamine to the corresponding amines (Table 1).
b-alky-
Firstly, we examined the reactivity of precatalyst A in the
presence of a slight excess of N-methylpiperidine 4 (1.1 eq.) along
with 10 mol% of camphor sulfonic acid (CSA). In this case, formation
of the expected
of the disusbstituted
a:7 (entry 1). Importantly, this result contrasted with the previ-
b
-alkylated product 6a occured but side formation
b-alkylated product reached a 58:42 ratio of
Chart 2. Scope of the b-alkylation of N-methylpiperidine 4.
6
ously reported ruthenium complexes containing phosphinesulfo-
nate chelates which favored the mono alkylation under
stoichiometric reaction conditions. Gratifyingly, the N-methyl
substituent remained intact and only few traces of demethylated
side product were observed.
yielding up to 95% of product 6b. Heteroaromatic aldehydes such as
2-furfural and 2-thiophene carboxaldehyde were compatible and
yields up to 87 and 97% were obtained for 6c and 6e, respectively.
The acetal moiety in piperonal 5d is quite sensitive functional group
under hydrogen autotransfer conditions. Nevertheless, the use of
precatalyst B bearing both an aliphatic side chain and a benzylic
hemilabile side arm gave almost complete conversion to the ex-
pected compound 6d.
To overcome the undesired formation of the dialkylated product
7
we next examined the influence of the CSA amount. Thus,
lowering the catalytic loading of CSA to 5 mol% diminished side
dialkylation reaching complete conversion and 87:13 ratio of 6a:7
(
entry 3). Another strategy to reduce side dialkylation involved the
use of a large excess of piperidine (2.0 eq.) to give a ratio up to 83:17
entry 2). The influence of the ruthenium complex was next
3. Conclusions
(
investigated. Notably, complete conversions were obtained in the
presence of catalytic amount of complex B and C and the best ratio
was observed in the presence of complex C bearing two sterically
hindered benzylic side arms (entries 4 compared to 5).
In summary, we reported new NHC based ruthenium(II) com-
plexes bearing hemilabile arene side arm. Altogether these results
demonstrated the first application and the potential ruthenium
3
bearing NHC ligand in sp CeH functionalization of cyclic amines to
We our best reaction conditions in hands, we next evaluated the
scope of the transformation with various aldehydes (Chart 2).
The reaction appeared to be quite general and good results were
obtained from the reaction of 4 with p-bromobenzaldehyde
access various
b-alkylated N-methylpiperidine derivatives from
easily available aldehydes and amines generating water as the only
side product. This report highlighted the crucial influence on the
acidic additive towards the generation of endo cyclic iminium. Our
Table 1
Ruthenium NHC catalyzed alkylation of N-methyl piperidine.
Entrya
Cat.
Amount of CSA/amount of amine
Ratio 6a/7
Conv.b
1
2
3
4
5
A
A
A
B
C
10 mol%/1.1 eq.
10 mol%/2.0 eq.
5 mol%/1.3 eq.
10 mol%/2.0 eq.
10 mol%/2.0 eq.
58/42
83/17
87/13
79/21
89/11
78%
100%
100%
100%
100%
c
a
All reactions were carried out under an inert atmosphere.
Conversion determined by GC analyses.
b
c
24 h.

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I. Ozdemir et al. / Journal of Organometallic Chemistry 799-800 (2015) 311e315
current effort is to examine the activity of NHC bearing acidic side
arm in similar transformations.
CH
CH
CH
2
-cyclobutane); 5.97 (s, 2H, CH
2
C
6
H
5
); 7.10e7.82 (m, 9H,
). C NMR (75 MHz, CDCl
(ppm) ¼ 18.4 (CH
-cyclobutane); 26.9 (CH , CH -cyclobutane); 36.1 (CH, CH
-cyclobutane); 53.1 (CH ); 134.7, 132.9,
13
2
C
6
H
5
and C
6
H
4
3
)
d
2
,
2
-
2
2
2
4
. Experimental section
cyclobutane); 53.6 (CH
25.8, 123.2, 113.8 and 111.2 (C
88.7 (CH
(CN) ¼ 1408 cm , yield 53%. Anal. Calcd for C19
42.48; H: 3.75; N: 5.21. Found C: 42.45; H: 3.70; N: 5.19%.
2
2 6 5
C H
1
6
H
4
); 100.3, 99.1, 98.9, 98.7, 89.3 and
ꢀ
4.1. Materials and methods
2
C
H
6 5
); 180.3 (Ru-carbene); m.p.¼ 275e276
C,
ꢁ1
n
H
20
N
2
RuBr
2
: C:
All reactions performed to prepare the benzimidazolium salts
and metal complexes were carried out under argon in flame-dried
glassware using standard Schlenk techniques. Glassware was heat-
dried in vacuum. Chemicals and solvents were purchased from
SigmaeAldrich (Gillingham,UK). Benzimidazolium salts as NHC
precursors were synthesized according to our previous literature
4.2.2. Dichloro [1-(n-butyl)-3-(4-methylbenzyl)benzimidazol-2-
ylidene] (p-cymene) ruthenium(II), B
Silver oxide (1.0 mmol) was added to a solution of benzimida-
zolium salt (2.0 mmol), in dichloromethane (30 mL), solution was
stirred for 12 h under dark condition. The resulting solution was
[41]. Solvents were dried with standard methods and freshly
distilled prior to use. Elemental analyses were carried out by
TUBI_TAK analytical services with a Carlo Erba (Milan, Italy) Stru-
mentaziona model 1106 apparatus, and the results agreed favorably
with the calculated values. Melting points were measured in open
capillary tubes with a Thermo Scientific (Waltham, MA, USA)
Electrothermal 9200 melting point apparatus. FT-IR spectra were
filtered, then RuCl
solution. The solution was stirred for 12 h. The resulting solution
was filtered and concentrated to 10 mL, and Et O (20 mL) was
added and product was obtained as a crystallize solid.
2 2
(p-cymene)] (0.5 mmol) was added to above
2
1
H NMR (300 MHz, CDCl
NCH CH CH CH
); 1.25 (h, J ¼ 7.0 Hz, 2H NCH
J ¼ 6.9 Hz, 6H, p-(CH )C (CH(CH ); 2.01 (s, 3H, p-(CH
(CH(CH ); 2.34 (s, 3H, NCH (CH )-4); 2.89 (m, 1H, p-
)C (CH(CH CH CH CH );
); 2.98 (p, J ¼ 7.0 Hz, 2H, NCH
4.39 (t, J ¼ 7.3 Hz, 2H, NCH CH CH CH ); 5.36 (d, J ¼ 7.5 Hz, 2H, p-
(CH )C (CH(CH ); 5.45 (s, 2H, NCH (CH )-4); 5.32e5.70
(m, 2H, p-(CH )C (CH(CH ); 6.95e7.50 (m, 8H, NC
NCH (CH )-4). NMR (75 MHz, CDCl ):
(NCH CH CH ); 18.6 (NCH CH CH CH
); 21.1 (p-(CH )C (CH(CH
); 32.3 (NCH (CH )-4); 32.4 (NCH
CH CH ); 52.3 (NCH (CH )-4); 83.6, 87.2, 98.9,
and 108.5 (p-(CH )C (CH(CH ); 110.8, 111.6, 122.8, 122.9, 125.8,
129.5, 134.6, 135.1, 135.8, 137.1, (NC
3
):
d
1.04 (t, J ¼ 7.0 Hz, 3H,
2
2
2
3
2
CH CH CH ); 1.30 (d,
2
2
3
ꢁ1
recorded as KBr pellets in the range 400e4000 cm on an ATI
Unicam (Cambridge, UK) 1000 spectrometer. MS analyses were
performed on an Agilent Technologies (Santa Clara, CA, USA) 1100
3
6
H
4
3
)
2
3
)
C
6
H
4
3
)
2
2
C
6
H
4
3
(CH
3
6
H
4
3
)
2
2
2
2
3
1
13
series LC/MSD SL mass spectrometer. H NMR and C NMR spectra
were recorded using a Varian (Palo Alto, CA, USA) As 400 Merkur
2
2
2
3
3
6
H
4
3
)
2
2
C
6
H
4
3
1
13
spectrometer operating at 400 MHz ( H) and 100 MHz ( C) in
CDCl with tetramethylsilane used as an internal reference. The
3
6
H
4
3
)
2
6
H
4
N and
13
3
2
C
6
H
4
3
C
3
d 13.9
NMR studies were carried out in high-quality 5 mm NMR tubes.
Signals are quoted in parts per million as d downfield from tetra-
methylsilane (d ¼ 0.00), used as an internal standard. Coupling
constants (J values) are given in hertz. NMR multiplicities are
abbreviated as follows: s ¼ singlet, d ¼ doublet, t ¼ triplet,
m ¼ multiplet signal. All catalytic reactions were monitored on a
Agilent 6890N GC system by GC-FID with a HP-5 column of 30 m
2
CH
(CH(CH
(CH(CH
2
2
3
2
2
2
3
); 20.4 (p-(CH
); 30.6 (p-(CH
CH CH CH
3
)
)
);
C
C
6
H
H
4
3
)
2
3
6
H
4
3 2
)
3
6
4
3
)
2
2
C
6
H
4
3
2
2
2
3
2
50.2 (NCH CH
2
2
3
2
C
6
H
4
3
3
6
H
4
3 2
)
6
H
4
N and NCH
2
C
6
H
4
(CH
3
)-4);
ꢀ
ꢁ1
189.6 (Ru-carbene); m.p.¼ 213e214 C,
n(CN) ¼ 1438 cm , yield
length, 0.32 mm diameter and 0.25
mm film thickness. Column
85%. Anal. Calcd for C29
36 2 2
H N RuCl : C: 59.58; H: 6.21; N: 4.79.
chromatography was performed using silica gel 60 (70e230 mesh).
The structure was solved by direct methods using the SIR97 pro-
gram [42], and then refined with full-matrix least-square methods
Found C: 59.52; H: 6.25; N: 4.73%.
4.2.3. Dichloro[1-(2,4,6-trimethylbenzyl)-3-(3,5-di-ter-
2
based on F (SHELXL-97) [43] with the aid of the WINGX [44] pro-
butylbenzyl)benzimidazol-2-ylidene] (p-cymene) ruthenium(II), C
Silver oxide (1.0 mmol) was added to a solution of benzimida-
zolium salt (2.0 mmol), in dichloromethane (30 mL), solution was
stirred for 12 h under dark condition. The resulting solution was
gram. All non-hydrogen atoms were refined with anisotropic
atomic displacement parameters. H atoms were finally included in
2
their calculated positions. A final refinement on F with 4158
unique intensities and 205 parameters converged at
filtered, then RuCl
solution. The solution was stirred for 12 h. The resulting solution
was filtered and concentrated to 10 mL, and Et O (20 mL) was
added and product was obtained as a crystallize solid.
2 2
(p-cymene)] (0.5 mmol) was added to above
2
u
R(F ) ¼ 0.1527 (R(F) ¼ 0.0511) for 3525 observed reflections with
I > 2
diffractometer, Mo-K
monoclinic P 2
c ¼ 16.2288(8) Å,
s
(I). (C19
H20 Br
2
N
2
Ru); M ¼ 537.26. APEXII, Bruker-AXS
2
a
radiation (
l
¼ 0.71073 Å), T ¼ 150(2) K;
1
1
/n(I.T.#14), a ¼ 10.5527(6), b ¼ 10.9516(5),
H NMR (300 MHz, CDCl
3,5); 1.32 (d, J ¼ 6.9 Hz, 6H, p-(CH
(s, 9H, NCH (CH -2,4,6); 2.07 (s, 3H, p-(CH
.82 (hept. J ¼ 6.9 Hz, 1H, p-(CH )C (CH(CH
NCH (CH -2,4,6); 5.32 (s, 2H, NCH
5.39e5.55 (m, 2H, p-(CH )C (CH(CH ); 5.62e5.72 (m, 2H, p-
CH )C (CH(CH ); 6.86 (s, 2H, NCH (CH -2,4,6); 6.18 (d,
J ¼ 8.4 Hz, 1H, NC N); 6.94e7.04 (m, 2H, NC N); 7.30 (d,
J ¼ 8.4 Hz, 1H, NC N); 6.76e6.81 (m, 3H, NCH (C(CH )-
3,5). C NMR (75 MHz, CDCl ): 16.7 and 17.2 (NCH (CH
2,4,6); 18.5 (p-(CH )C (CH(CH ); 22.5 (p-(CH )C (CH(CH
30.9 (p-(CH )C (CH(CH ); 31.4 (NCH (C(CH
(C(CH )-3,5); 52.6 (NCH (CH
(C(CH )-3,5); 84.5, 85.4, 96.1, and 106.9 (p-(CH
3
):
d
1.27 (s, 18H, NCH
2
C
6
H
3
(C(CH
); 2.19 and 2.31
)C (CH(CH );
); 5.30 (s, 2H,
(C(CH )-3,5);
3 3
) )-
ꢀ
3
b
¼ 104.520(2) , V ¼ 1815.64(16) Å .Z ¼ 4,
3
)C (CH(CH
6
H
4
3 2
)
ꢁ
3
ꢁ1
d ¼ 1.965 g cm
,
m
¼ 5.268 mm
.
2
C
6
H
2
3
)
3
3
6
H
4
3 2
)
2
3
H
6 4
3 2
)
4.2. Synthesis and characterization of ruthenium N-heterocyclic
2
C
6
H
2
3
)
3
2
C
6
H
3
3 3
)
carbene complexes
3
6
H
4
3 2
)
(
3
6
H
4
3
)
2
2
C
6
H
2
3 3
)
4
2
.2.1. Dibromo-[1-( 6
-ylidene]ruthenium(II), A
h
ebenzyl)-3-cyclobutylmethyl]benzimidazol-
6
H
4
6 4
H
6
H
4
2
C
6
H
3
3 3
)
13
A suspension of benzimidazolium salt (2.10 mmol), Cs
2
CO
3
3
d
2
C
6
H
2
3
)
3
-
(
2.14 mmol) and [RuCl
2
(p-cymene)]
2
(0.82 mmol) was heated un-
3
6
H
4
3
)
2
3
6
H
4
3
)
2
);
der reflux in degassed toluene (20 mL) for 6 h. The reaction mixture
was then filtered while hot, and the volume was reduced to about
3
6
H
4
3
)
2
2
C
6
H
3
3
)
3
)-3,5); 34.9
(NCH
2
C
C
6
H
H
3
3
)
)
3
2
C
6
H
2
3 3
) -2,4,6); 53.5
10 mL before addition of n-hexane (15 mL). The precipitate formed
(NCH
2
6
3
3
3
3
)
was crystallized from CH
2
Cl
2
/hexane (5:15 mL) to give of orange-
C
6
H
4
(CH(CH
3
)
2
); 111.2, 111.8, 119.7, 120.7, 122.3, 122.6, 129.4, 132.7,
N,
brown crystals.
133.7, 135.0, 135.5, 135.6, 136.9, and 151.4 (NC H
NCH
6 4
1
H NMR (300 MHz, CDCl
3
)
d
(ppm) ¼ 1.78e1.67 (m, 2H, CH
, CH -cyclobutane); 3.42
-cyclobutane); 4.82 (d, 2H, J ¼ 7.8 Hz,
2
,
2
C
H
6 3
(C(CH
3
)
3
)-3,5 and NCH
2
C
6
H
2
(CH
3
)
3
-2,4,6); 189.8 (Ru-
ꢀ
ꢁ1
CH
2
-cyclobutane); 2.23e2.01 (m, 4H, CH
2
2
carbene); m.p. ¼ 202e203 C,
n
(CN) ¼ 1436 cm , yield 72%. Anal.
(
hept., 1H, J ¼ 8.1 Hz, CH, CH
2
54 2 2
Calcd for C42H N RuCl : C: 66.47; H: 7.17; N: 3.69. Found C: 66.45;

_
€
I. Ozdemir et al. / Journal of Organometallic Chemistry 799-800 (2015) 311e315
315
H: 7.21; N: 3.70%.
.3. General procedure for ruthenium NHC catalyzed alkylation of
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[
4
5
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cyclic amines
2
To a stirred solution of cyclic amine (2.0 eq.) in 1 mL of toluene
was added D-(þ)-Comphor sulfonic acid (10 mol %). Subsequently
aldehyde 1.0 (eq.) and ruthenium catalyst (2.5 mol%) were added
(
[
[
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ꢀ
and then reaction mixture was stirred at 150 C for 16 h. After that
the schlenk tube was cooled down and then HCOOH (1.5 eq.) was
added and stirring continued at 150 C for 1 h. The crude mixture
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(2003) 1215e1221.
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was directly taken for GC analysis folloed by evaporation of the
solvent and the crude mixture was purified by column chroma-
tography(EtOAc/PE; Acetone/Hexane; EtOAc/Hexane) to afford the
tallics 28 (2009) 819e823.
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2
1
5 (1999)
alkylated cyclic amine as oil. Product was determined by H NMR
1
spectroscopy and GC and GCeMS.
[
24] F.E. Hahn, L. Wittenbecher, D.L. Van, R. Fr o€ hlich, Angew. Chem. Int. Ed. 39
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(
Acknowledgments
[
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25] A. Zanardi, J.A. Mata, E. Peris, Eur. J. Inorg. Chem. (2011) 416e421.
26] Y. Han, L.J. Lee, H.V. Huynh, Chem. Eur. J. 16 (2010) 771e773.
_
€
This work was financially supported by the Inonü University
[27] Y. Unger, D. Meyer, T. Strassner, Dalton Trans. 39 (2010) 4295e4301.
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Research Fund. We thank Thierry Roisnel for X-ray analyses.
[
Appendix A. Supplementary data
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4
[
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2015.10.011.
6
2
[
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