Asymmetric transfer hydrogenation of aromatic ketones with the ruthenium(II) catalyst derived from C2 symmetric N,N′-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl]ethanediamide

Article abstract of DOI:10.1016/j.jorganchem.2010.02.003

Asymmetric transfer hydrogenation of ketones with chiral molecular catalysts is realized to be one of the most magnificent tools to access chiral alcohols in organic synthesis. A new chiral phosphinite compound N,N′-bis[(1S)-1-benzyl-2-O-(diphenylphosphin

Full text of DOI:10.1016/j.jorganchem.2010.02.003

Journal of Organometallic Chemistry 695 (2010) 1392–1398
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Asymmetric transfer hydrogenation of aromatic ketones with the
ruthenium(II) catalyst derived from C2 symmetric
N,N0-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl]ethanediamide
*
Murat Aydemir, Nermin Meriç, Feyyaz Durap , Akın Baysal, Mahmut Tog˘rul
Department of Chemistry, Dicle University, 21280 Diyarbakir, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
Asymmetric transfer hydrogenation of ketones with chiral molecular catalysts is realized to be one of the
most magnificent tools to access chiral alcohols in organic synthesis. A new chiral phosphinite compound
N,N0-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl]ethanediamide (1), has been synthesized by the
reaction of chlorodiphenylphosphine with N,N0-bis[(1S)-1-benzyl-2-hydroxyethyl]ethanediamide under
argon atmosphere. The oxidation of 1 with aqueous hydrogen peroxide, elemental sulfur or grey selenium
in toluene gave the corresponding oxide 1a, sulfide 1b and selenide 1c, respectively. Pd, Pt and Ru com-
plexes were obtained by the reaction of 1 with [MCl2(cod)] (M: Pd 1d, Pt 1e) and [Ru(p-cymene)Cl2]2 1f,
respectively. All these new complexes were characterized by using NMR, FT-IR spectroscopies and micro-
analysis. Additionally, as a demonstration of their catalytic reactivity, the ruthenium complex 1f was
tested as catalyst in the asymmetric transfer hydrogenation reactions of acetophenone derivatives with
iPrOH was also investigated.
Received 22 December 2009
Received in revised form 1 February 2010
Accepted 3 February 2010
Available online 10 February 2010
Dedicated to Prof. Dr. Bahattin Gümgüm on
the occasion of 60th birthday
Keywords:
Chiral phosphinite
Ruthenium
Asymmetric transfer hydrogenation
Catalysis
Ó 2010 Elsevier B.V. All rights reserved.
Complexes
1. Introduction
electronic properties. Phosphinites provide different chemical,
electronic and structural properties compared to phosphines. The
The use of chiral transition metal complex catalysis is a power-
ful and economically feasible tool for the preparation of optically
active compounds on both laboratory and industrial scales [1–3].
Nowadays, there is an immense interest in obtaining enantiomeri-
cally pure compounds as building blocks for pharmaceuticals and
bioactive agents. The preparation of optically active hydroxy com-
pounds by the catalytic asymmetric hydrogenation of prochiral ke-
tones is a well-known method that possesses a great significance
for the research in enantioselective organometallic catalysis [4].
Noyori and co-workers devoted much effort for the asymmetric
catalytic hydrogenation [5–7] and asymmetric transfer hydrogena-
tion of simple ketones [8,9] which are the most common unsatu-
rated substrates used in organic synthesis. This extensive effort
has been receiving increased attention as well and has led to ex-
tend the concept of molecular catalysts and to new catalysts sys-
tem both in academia and industry. In particular, the metals
coordinated by one or more chiral phosphorus ligands exhibit
exciting enantioselectivity and reactivity. Among the phosphorus
based ligands, phosphines and phosphinites are the most
commonly used ligands because of their wide range of steric and
metal–phosphorus bonds are often stronger for phosphinites than
that of phosphines due to the presence of the electron withdrawing
P–OR group [10]. Already more than a thousand of chiral nonrace-
mic bis(phosphines), striking examples include L-DOPA [11],
L-menthol [12,13], and dissymmetric phosphine ligand BINAP
[14], have been synthesized. Recently, phosphine [15–17],
phosphite [18], bis(phosphinites) [19–21], and aminophosphine-
phosphinite [22–24] (abbreviated as AMPP) compounds have been
of great interest and widely used in asymmetric transfer hydroge-
nation reactions.
In general, the most successful chiral ligands used in the asym-
metric hydrogenation reactions are rigid chelating diphosphines
possessing a C2 symmetry axis thus reducing the number of diaste-
reomeric transition states [25–28]. In addition, most of them bear
at least two aryl substituents on their phosphorus atoms. If one
analyzed the structures of these ligands [29], several design princi-
ples can be identified which might lead to good enantiocontrol.
Generally speaking, these measures create the necessary flexibility
of the ligand to give high turnover rates and impart sufficient rigid-
ity to control stereoselectivity. It has to be stressed though that
there are always examples where just the opposite is true. A ligand
is more likely to induce high enantioselectivity if it has a C2
symmetry [30,31] (first example: diop) or is very strongly
* Corresponding author.
E-mail address: fdurap@dicle.edu.tr (F. Durap).
0022-328X/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.02.003

M. Aydemir et al. / Journal of Organometallic Chemistry 695 (2010) 1392–1398
1393
unsymmetrical [32] (e.g. josiphos) in order to reduce the number
of possible isomeric catalyst-substrate complexes.
As part of our research program on this subject, herein, we re-
port the synthesis of a new C2 symmetric chiral phosphinite ligand
N,N0-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl] ethane-
diamide (1), and corresponding oxide, sulfide and selenide as well
spectrum of 1 gives characteristic bands at 3310, 1658, and
951 cmꢀ1 due to
(N–H), (C@O) and (P–O) stretching, respec-
tively and (O–H) stretching band was not observed. The com-
pound 1 could be isolated as analytically pure solid material and
fully characterized microanalysis as well, and found to be in good
agreement with the theoretical values.
m
m
m
m
as its complexes with selected transition metal ions (Pd2+, Pt2+
,
Ru2+). The compounds were fully characterized using elemental
analysis, FT-IR and multi-nuclear NMR spectroscopies. We also re-
port the catalytic activity of ruthenium(II) complex as a pre-cata-
lyst in asymmetric transfer hydrogenation reactions of
acetophenone derivatives with iPrOH.
2.2. Synthesis of chalcogenides
The corresponding oxidized derivatives of 1, with aqueous
hydrogen peroxide, elemental sulfur or grey selenium gave the cor-
responding oxide 1a, sulfide 1b or selenide 1c derivatives, respec-
tively (Scheme 2). The 31P–{H} NMR spectra of 1a, 1b and 1c
display one singlet at 33.8, 84.9 and 88.7 ppm (1J(PSe) = 805 Hz for
1c) [34,37,38], respectively. The oxidation reaction using aqueous
hydrogen peroxide was very rapid and takes place spontaneously
under ambient conditions. A small amount of hydrolysis product
Ph2P(O)H was also formed as evidenced by the signal at about
20.0 ppm in the 31P–{1H} NMR spectra [39]. In contrast, the oxida-
tions with elemental sulfur and selenium were slow compared
with 1a and had to be carried out under reflux conditions. This is
not surprising since elemental sulfur and selenium are weaker oxi-
dizing agents than hydrogen peroxide. In the 13C–{1H} NMR spec-
2. Results and discussion
2.1. Synthesis of chiral ligand
N,N0-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl]ethane-
diamide (1) with a high yield (94%), was prepared from the reac-
tion of N,N0-bis[(1S)-1-benzyl-2-hydroxyethyl]ethanediamide [33]
with 2 equiv of chlorodiphenylphosphine in the presence of Et3N
at room temperature under argon atmosphere (Scheme 1). The
31P–{1H} NMR spectrum of compound 1 shows a single resonance
due to phosphinite at 121.1 ppm, indicating that two phosphorus
atoms in the molecule are equivalent [34]. The 31P–{H} NMR spec-
trum also displays formation of PPh2PPh2 and P(O)Ph2PPh2 which
give signals at d ꢀ14.3 ppm as singlet and d 37.4 ppm and d
tra of oxide, sulfide and selenide, J31
coupling constants of the
P—13C
carbons of the phenyls rings were observed, which are in agree-
ment with the literature values [36]. Furthermore, the coupling be-
tween the i-carbon and phosphorus in the oxidized P(V)
1
compounds is quite large JPC = 136.0, 110.0 and 95.5 Hz, respec-
1
tively, corresponding to O, S and Se oxidized species [40]. The FT-
ꢀ22.5 ppm as doublets with J(PP) 220 Hz, respectively [35]. These
IR spectra of 1a–c consist of characteristic bands at 1192, 650,
by products were easily eliminated by washing the solid residue
with copious amounts of dried diethyl ether. Solution of 1 in CDCl3,
prepared under anaerobic conditions, is unstable and decomposes
gradually to give oxide and bis(diphenylphosphino)monoxide
[P(O)Ph2PPh2] derivatives. Compound 1 is also not stable in the so-
lid state and decomposes rapidly when it exposes to air or mois-
and 579 cmꢀ1 due to
m(P@O), m(P@S) and m(P@Se) stretching,
respectively [37]. The structures of the oxidized derivative 1a, sul-
fide 1b and selenide 1c were further confirmed by microanalysis
and found to be in good agreement with the theoretical values.
ture. In the 13C NMR spectra characteristic Jð31
coupling
2.3. Synthesis of metal complexes
P—13C
Þ
constants of the carbons of the phenyl rings were observed (includ-
ing i-, o-, m-, p-carbons of phenyl rings, for details see Section 4),
which are consistent with the literature values [36]. The FT-IR
In the reaction of [M(cod)Cl2] (M = Pd, Pt; cod = 1,5-cyclooctadi-
ene) with 1 equiv of
1 in toluene, cod is replaced by the
Scheme 1. Synthesis of N,N0-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)-ethyl]ethanediamide (1).
Scheme 2. Oxidation of N,N0-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl]ethanediamide (1) with aqueous H2O2 (1a), elemental sulfur (1b) and grey selenium (1c).

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M. Aydemir et al. / Journal of Organometallic Chemistry 695 (2010) 1392–1398
Scheme 3. Reactions of N,N0-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl]ethanediamide (1) with M(cod)Cl2 (M: Pd (1d), Pt (1e)) and [Ru(p-cymene)Cl2]2 in toluene.
[Ru(p-cymene)Cl2]2in which the coordination to ruthenium being
N,N0-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl]ethanedia-
carried out at room temperature. The 31P–{1H} NMR chemical shift
mide (1) as bidentate ligand yielding the respective [M(N,N0-
bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl]ethanediamide)-
Cl2] complexes 1d, 1e, (M: Pd, Pt, respectively). The reaction of
of 1f is also within the expected range, 115.3 ppm for structurally
similar complexes [45–47]. 1H NMR analysis reveals that this com-
pound to be diamagnetic, exhibiting signals apart from phosphi-
nite ligand consisting of two doublets centered at 5.40 and
5.35 ppm are due to the presence of the aromatic protons in the
[Ru(p-cymene) Cl2]2 with 2 equiv of 1 gives the expected complex
[Ru(chloro(p-cymene)(N,N0-bis[(1S)-1-benzyl-2-O-(diphenylphos-
phinite)ethyl]ethanediamide)] chloride 1f, these reactions are
p-cymene group and at 2.27 and 0.92 ppm due to the CH and
summarized in Scheme 3. The synthesis of compounds 1d and 1e
CH3 of the iso-propyl group of the p-cymene moiety and a signal
were followed by 31P–{1H} NMR spectroscopy. The 31P–{1H}
due to the methyl group in the p-cymene group is observed at
NMR spectra of 1d and 1e show single resonances at d 112.9 and
1.60 ppm. Characteristic J31
coupling constants of the carbons
1
P—13C
85.6 ppm, respectively [10,41]. The complex 1e shows large JPtP
of the phenyls rings were observed in the 13C NMR spectra. Fur-
thermore 1H, 13C NMR, IR spectra and microanalysis values of 1f
confirmed the proposed structure (for details see Section 4). 31P–
{1H} NMR spectra show that all complexes, 1d–f, are quite stable
in the solid state, when they expose to air or moisture for several
months.
coupling (1J31
= 4189 Hz) which is characteristics for phos-
P—195Pt
phines having mutually cis-disposition [42,43]. In the 13C NMR
spectra a long range P–C coupling was observed [44]. Furthermore,
1H NMR spectral data of 1d and 1e are in agreement with the struc-
tures proposed which were also confirmed by elemental analysis.
We also examined simple coordination chemistry of 1 with
Scheme 4. Hydrogen transfer from iPrOH to acetophenone derivatives.

M. Aydemir et al. / Journal of Organometallic Chemistry 695 (2010) 1392–1398
1395
2.4. Asymmetric transfer hydrogenation of prochiral ketones
was tested in transfer hydrogenation of acetophenone derivatives
in which iPrOH/NaOH used as the reducing system as described
in Scheme 4.
2-Propanol was selected as the conventional hydrogen source
because of its well-know advantages: (i) having stable, (ii) easy
to handle, (iii) nontoxic, (iv) environmentally benign, (v) inexpen-
sive, (vi) dissolves in many organic solvents [47]. The catalytic
activity of 1f was tested under different reaction conditions in
transfer hydrogenation of acetophenone and the results are col-
lected in Table 1.
The outstanding catalytic performance of phosphinite based
transition metal complexes in the asymmetric hydrogenation [22
and references there in] prompted us to develop new chiral phos-
phinite based ruthenium(II) complex. The catalytic activity of 1f
Table 1
Transfer hydrogenation of acetophenone catalyzed by 1f.
Entry Catalyst S/C/NaOH Time (h) Temperature Conversion TOF
The formation of 1-phenylethanol was found to be negligible at
room temperature and proceeds slowly even at 50 °C. However,
reduction of acetophenone into 1-phenylethanol could be achieved
in high yield by increasing the temperature up to 82 °C. The negli-
gible catalytic activity of [Ru(p-cymene)Cl2]2 was observed under
the applied experimental conditions at room temperature. It
should be also pointed out that complex 1f is more active catalyst
b,c
(°C)
(%)a
(hꢀ1
)
1
2
3
1f
1f
1f
100:1:5
100:1:5
100:1:5
1
25
50
82
82
82
82
82
82
82
3<
32
81
97
24
0.5
(1)
1
162
97
4
5
6
7
8
1f
1f
100:1
500:1:5
1000:1:5 2 (7)
100:1:5
100:1:5
4
96
120
than the corresponding precursor: [Ru(g l-Cl)Cl]2
6-p-cymene)(
1f
30 (100)
64 (100)
95
150 (143)
64 (25)
16
1fd
1fe
1 (4)
6
(41% maximum yield in 24 h) with a 1/14 complex/NaOH ratio
[48]. The results obtained from the optimization of reaction condi-
tions indicate that the high conversion and high TOF value can be
achieved in the reduction of acetophenone into 1-phenylethanol
by using 1f as a pre-catalyst (1 equiv.) in a system that contains
100 equiv. of acetophenone in iPrOH containing 0.025 mmol of
NaOH at 82 °C (see Table 2). Catalyst prepared from ruthenium
a
Determined by GC (three independent catalytic experiments).
Referred at the reaction time indicated in column; TOF: (mol product/mol
b
1f) ꢁ hꢀ1
.
c
No significant ee was observed.
Added 0.1 mL H2O.
Carried out (refluxing) the reaction in air.
d
e
Table 2
Catalytic transfer hydrogenation of acetophenone derivatives with iPrOH catalyzed by 1f.
c
Entry
1
Substrate
Product
Time (h)
1
Conversion (%)a,b
97
TOF (hꢀ1
97
)
2
3
4
5
6
1
1
1
1
1
92
91
98
95
92
92
91
98
95
92
a
b
c
Catalyst (0.005 mmol), substrate (0.5 mmol), iPrOH (5 mL), NaOH (0.025), 82 °C.
Purity of compounds is checked by NMR and GC, yields are based on methyl aryl ketone.
TOF: (mol product/mol 1f) ꢁ hꢀ1, No significant ee was observed.

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M. Aydemir et al. / Journal of Organometallic Chemistry 695 (2010) 1392–1398
precursor and xanthene derived diphosphonite ligand which is re-
ported by Reetz and Li shows remarkable catalytic activity (with
88% conversion) and high stereoselectivity (97% ee) for the reduc-
tion of acetophenone by iPrOH at 40 °C within 20 h in the presence
of NaOH as base [48]. However, we obtained the highest ee value
(16%) in the reduction of acetophenone to (S), (R)-1-phenylethanol
catalyzed by 1f. As seen from Table 1 (entry 4) NaOH is necessary
to observe appreciable conversions and a lower concentration of
substrate gives a higher conversion of the alcohol. Furthermore,
for the asymmetric transfer hydrogenation of acetophenone, the
catalyst showed high activity in the presence of small amount
(0.1 mL) of water and under ambient conditions. Under the
optimized conditions, reaction of acetophenone, p-fluoroacetophe-
none, p-chloroacetophenone, p-bromoacetophenone, p-methoxy-
acetophenone, o-methoxyacetophenone with iPrOH gave high
yields within 1 h in the absence of induction time period by using
1f (Table 2). In order to investigate the evolution of the catalyst, 1f,
31P–{1H} NMR spectrum was recorded immediately after the cat-
alytic reaction.
4.2. Synthesis of N,N0-bis[(1S)-1-benzyl-2-O-
(diphenylphosphinite)ethyl]ethanediamide (1)
Chlorodiphenylphosphine (0.26 g, 1.12 mmol) was added drop-
wise over a period of 20 min to a solution of N,N0-bis[(1S)-1-ben-
zyl-2-hydroxyethyl]ethanediamide (0.20 g, 0.56 mmol) and
triethylamine (1.16 g, 1.12 mmol) in toluene (40 mL) at room tem-
perature with vigorous stirring. The mixture was stirred for 8 h,
and then the white precipitate (triethylamine hydrogen chloride)
was filtered off under argon and the solvent removed in vacuum.
The remaining solid was washed with cold diethyl ether
(3 ꢁ 10 mL) and dried in vacuum to produce a white solid com-
pound 1 (Yield: 0.38 g, 94 %); mp: 71–73 °C. ½a D27
= ꢀ43 (c 0.025,
ꢂ
CH2Cl2). 1H NMR (DMSO) d(ppm): 2.84 (dd, 2H, J = 7.2 and
10.4 Hz, CH2Ar (a)), 2.81 (dd, 2H, J = 7.2 and 10.4 Hz, CH2Ar (b)),
3.72 (m, 4H, CH2O), 4.21 (m, 2H, CH–N), 7.03–7.23 (m, 10H, CH2Ar),
7.30 (m, 8H, m-protons of phenyls), 7.42 (m, 4H, p-protons of phen-
yls), 7.70 (dd, 8H, J = 5.1 and 10.8 Hz, o-protons of phenyls), 8.46
(br, 2H, NH). 13C–{1H} NMR (DMSO) d(ppm): 36.09 (CH2Ar),
The observed singlet at 21.6 ppm in the spectrum is corre-
sponding to hydrolysis product diphenylphosphinous acid,
Ph2P(O)H [39].
51.96 (CH–N), 68.97 (CH2O), 126.74, 128.60, 129.3, 134.29
3
(CH2C6H5), 129.70 (d, J31
= 7.0 Hz, m-carbons of phenyls),
P—13C
2
130.75 (d, J31
= 11.1 Hz, o-carbons of phenyls), 132.61 (d,
P—13C
4J31
= 2.0 Hz, p-carbons of phenyls), 140.13 (d, J31
=
1
P—13C
P—13C
20.1 Hz, i-carbons of phenyls), 157.95 (s, C@O), assignment was
based on the 1H–13C HETCOR and 1H–1H COSY spectra. 31P–{1H}
3. Conclusions
NMR (DMSO) d(ppm): 121.1 (s). Selected IR,
m
(cmꢀ1): 3310 (N–
In conclusion, we have synthesized a new chiral phosphinite
H), 3013, 3049 (Ar–H), 1658 (C@O), 1099 (C–O), 951 (P–O). Anal.
Calc. for C44H42N2O4P2: C, 72.92; H, 5.84; N, 3.87. Found: C,
72.75; H, 5.68; N, 3.77%.
ligand
N,N0-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl]-
ethanediamide (1). Additionally, its corresponding oxidized deriv-
atives and Pd(II), Pt(II) and Ru(II) complexes were also synthesized
and characterized successfully. It was found that the use of [Ru(-
chloro(p-cymene)((S,S)-1)] chloride, 1f as a catalyst in the transfer
hydrogenation of aromatic ketones provides secondary alcohols
with high conversion and notable TOF values.
4.3. Synthesis of N,N0-bis[(1S)-1-benzyl-2-O-
(diphenyloxophosphinite) ethyl]ethanediamide (1a)
Aqueous hydrogen peroxide (30%, w/w, 0.06 mL, 0.56 mmol)
was added dropwise to a suspension of N,N0-bis[(1S)-1-benzyl-2-
O-(diphenylphosphinite)ethyl]ethanediamide
(1),
(0.20 g,
4. Experimental
0.28 mmol) in toluene and the mixture was stirred for 1 h at room
temperature. The volume was concentrated in vacuum to ca. 1–
2 mL and addition of n-hexane (20 mL) gave 1a as a white solid
which was collected by filtration (yield: 0.18 g, 88%); mp: 83–
All reactions and manipulations were performed under argon
atmosphere unless otherwise stated. Ph2PCl and [Ru(p-cyme-
ne)Cl2]2 were purchased from Fluka and used directly. Analytical
grade and deuterated solvents were purchased from Merck. The
starting materials [MCl2(cod)] (M = Pd [49], Pt [50], cod = 1,5-
85 °C. ½a 2D7
ꢂ
= ꢀ40 (c 0.025, CH2Cl2). 1H NMR (DMSO) d(ppm):
2.87 (m, 4H, CH2Ar (a)), 3.92 (m, 4H, CH2Ar (b)), 3.92 (br, 4H,
CH2O), 4.30 (m, 2H, CH–N), 7.13–7.22 (m 10H, CH2Ar), 7.43–7.52
(m, 12 H, m-, p-protons of phenyls), 7.73 (dd, 8H, J = 6.4 Hz and
11.4 Hz o-protons of phenyls) 8.88 (d, 2H, J = 9.2 Hz, NH). 13C–
{1H} NMR (DMSO) d(ppm): 35.53 (CH2Ar), 45.58 (CH–N), 65.10
cyclooctadiene)
and
N,N0-bis[(1S)-1-benzyl-2-hydroxyethyl]-
ethanediamide [33] were prepared according to literature proce-
dures. Solvents were dried using the appropriate reagents and
distilled prior to use. Infrared spectra were recorded as KBr pellet
in the range 4000–400 cmꢀ1 on a Mattson 1000 ATI UNICAM FT-
IR spectrometer. 1H (400.1 MHz), 13C NMR (100.6 MHz) and 31P–
{1H} NMR spectra (162.0 MHz) were recorded on a Bruker Avance
400 spectrometer, with d referenced to external TMS and 85%
H3PO4, respectively. Optical rotations were taken on a Perkin Elmer
341 model polarimeter. Elemental analysis was carried out on a Fi-
sons EA 1108 CHNS-O instrument. Melting points were determined
by Gallenkamp Model apparatus with open capillaries.
(CH2O), 126.18, 128.17, 128.85, 137.89 (CH2C6H5), 128.71 (d,
3J31
= 13.1 Hz, m-carbons of phenyls), 131.21 (d, J31
=
2
P—13C
P—13C
4
10.0 Hz, o-carbons of phenyls), 132.28 (d, J31
= 2.3 Hz, p-car-
P—13C
bons of phenyls), 131.25 (d, 1J31
= 136.0 Hz, i-carbons of phen-
P—13C
yls), 159.90 (s, C@O), assignment was based on the 1H–13C
HETCOR and 1H–1H COSY spectra. 31P–{1H} NMR (DMSO)
d(ppm): 33.9 (s). Selected IR,
m
(cmꢀ1): 3294 (N–H), 3034, 3063
(Ar–H), 1664 (C@O), 1118 (C–O), 1192 (P@O), 998 (P–O). Anal.
Calc. for C44H42N2O6P2: C, 69.83; H, 5.59; N, 3.70. Found: C,
69.75; H 5.48; N 3.57%.
4.1. GC analysis
4.4. Synthesis of N,N0-bis[(1S)-1-benzyl-2-O-
GC analyses were performed on a HP 6890N Gas Chromato-
(diphenylthiophosphinite) ethyl]ethanediamide (1b)
graph equipped with cyclodex
B (Agilent) capillary column
(30 m ꢁ 0.32 mm I.D. ꢁ 0.25 m film thickness). The GC parame-
l
N,N0-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl]ethane-
diamide (1), (0.20 g, 0.28 mmol) and elemental sulfur (0.018 g,
0.56 mmol) were heated to reflux in toluene (20 mL) for 1 h. After
allowing the mixture to cool room temperature, the white solid 1b
was collected by filtration and dried in vacuum (yield: 0.20 g, 91%);
ters for asymmetric transfer hydrogenation of ketones were as fol-
lows; initial temperature, 110 °C; initial time, 1 min; solvent delay,
4.48 min; temperature ramp 80 °C/min; final temperature, 200 °C;
final time, 21.13 min; injector port temperature, 200 °C; detector
temperature, 200 °C; injection volume, 2.0
l
L.
mp: 120–122 °C. ½a D27
ꢂ
= ꢀ32 (c 0.025, CH2Cl2). 1H NMR (DMSO)

M. Aydemir et al. / Journal of Organometallic Chemistry 695 (2010) 1392–1398
1397
d(ppm): 2.90 (m, 4H, CH2Ar), 3.93 (m, 4H, CH2O), 4.33 (m, 2H, CH–
4.7. Synthesis of N,N0-bis[(1S)-1-benzyl-2-O-
N), 7.14–7.43 (m, 10H, CH2Ar), 7.43–7.53 (m, 12H, m-, p-protons of
phenyls), 7.81 (dd, 8H, J = 6.9 and 13.2 Hz, o-protons of phenyls),
8.90 (d, 2H, J = 9.2 Hz, NH). 13C–{1H} NMR (DMSO) d(ppm): 35.39
(diphenylphosphinite)ethyl]-ethanediamideplatinum(II)chloride (1e)
[Pt(cod)Cl2] (0.10 g, 0.28 mmol) and N,N0-bis[(1S)-1-benzyl-2-
(CH2Ar), 50.89 (CH–N), 65.32 (CH2O), 126.19, 128.16, 128.88,
O-(diphenylphosphinite)ethyl]-ethanediamide
(1)
(0.20 g,
3
137.92 (CH2C6H5), 128.64 (d, J31
= 12.1 Hz, m-carbons of
0.28 mmol) were dissolved in dry toluene (30 mL) and stirred for
2 h. The volume was concentrated to ca. 1–2 mL by evaporation
under reduced pressure and addition of diethyl ether (25 mL) affor-
ded 1e as a white solid. The product was collected by filtration and
P—13C
2
phenyls), 130.68 (d, J31
= 11.5 Hz, o-carbons of phenyls),
P—13C
1
132.11 (d, p-carbons of phenyls), 133.70 (d, J31
= 110.0 Hz, i-
P—13C
carbons of phenyls), 159.56 (s, C@O), assignment was based on
the 1H–13C HETCOR and 1H–1H COSY spectra. 31P–{1H} NMR
dried in vacuum (yield: 0.24 g, 87%; mp: 205–207 °C. ½a D27
= ꢀ35 (c
ꢂ
(DMSO) d(ppm): 84.9 (s). Selected IR,
m
(cmꢀ1): 3286 (N–H),
0.025, CH2Cl2). 1H NMR (DMSO) d(ppm): 2.78–2.85 (m, 4H, CH2Ar),
4.17 (m, 6H, CH2O and CH–N), 7.01–7.28 (m, 10H, CH2Ar), 7.46–
7.52 (m, 12H, m- and p-protons of phenyls), 7.74 (dd, 8H, J = 6.1
and 10.8 Hz, o-protons of phenyls), 8.78 (d, 2H, J = 8.4 Hz, NH).
13C–{1H} NMR (DMSO) d(ppm): 36.51 (CH2Ar), 51.01 (CH–N),
70.61 (CH2O), 126.34, 128.15, 128.85, 137.09 (CH2C6H5), 128.30
3030, 3057 (Ar–H), 1658 (C@O), 1113 (C–O), 650 (P@S), 911 (P–
O). Anal. Calc. for C44H42N2O4S2P2: C, 66.99; H, 5.37; N, 3.57; S,
8.13. Found: C, 66.83; H, 5.48; N, 3.48; S, 8.01%.
4.5. Synthesis of N,N0-bis[(1S)-1-benzyl-2-O-
(diphenylselenophosphinite) ethyl]ethanediamide (1c)
(br, m-carbons of phenyls), 131.72 (s, p-carbons of phenyls),
2
132.11 (d, J31
= 39.0 Hz, o-carbons of phenyls), 131.09 (br, i-
P—13C
carbons of phenyls), 158.80 (s, C@O), assignment was based on
N,N0-Bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl]ethane-
diamide (1) (0.20 g, 0.28 mmol) and grey selenium (0.044 g,
0.56 mmol) were heated to reflux in toluene (20 mL) for 1 h. After
allowing the mixture to cool room temperature the dirty white so-
lid 1c was collected by filtration and dried in vacuum (yield: 0.21 g,
the 1H–13C HETCOR and 1H–1H COSY spectrum. 31P–{1H} NMR
1
(DMSO) d(ppm): 85.6 [s, JPPt: 4189 Hz]. Selected IR,
m
(cmꢀ1):
3306 (N–H), 3057, 3043 (Ar–H), 1675 (C@O), 1115 (C–O), 885
(P–O). Anal. Calc. for C44H42N2O4P2PtCl2: C, 53.54; H, 4.27; N,
2.83. Found: C, 53.63; H, 4.16; N, 2.64%.
85%); mp: 145–147 °C. ½a D27
ꢂ
= ꢀ41 (c 0.025, CH2Cl2). 1H NMR
(DMSO) d(ppm): 2.92 (dd, 2H, J = 10.6 and 22.8 Hz, CH2Ar (a)),
2.86 (dd, 2H, J = 12.6 and 20.8 Hz, CH2Ar (b)), 3.93 (m, 4H, CH2O),
4.34 (m, 2H, CH–N), 7.14–7.23 (m 10H, CH2Ar), 7.40–7.52 (m,
12H, m-, p-protons of phenyls), 7.79 (dd, 8H, J = 6.40 and 12.8 Hz,
o-protons of phenyls), 8.92 (d, 2H, J = 9.2 Hz, NH). 13C–{1H} NMR
4.8. Synthesis of [Ru(chloro(p-cymene)(N,N0-bis[(1S)-1-benzyl-2-O-
(diphenylphosphinite)ethyl]ethanediamide)] chloride (1f)
[Ru(p-cymene)Cl2]2 (0.08 g, 0.14 mmol) and N,N0-bis[(1S)-1-
benzyl-2-O-(diphenylphosphinite)ethyl]ethanediamide
(1),
(DMSO) d(ppm): 36.09 (CH2Ar), 51.21 (CH–N), 66.82 (CH2O),
(0.20 g, 0.28 mmol) were dissolved in toluene (30 mL) and stirred
for 2 h at room temperature. The volume was then concentrated
to ca. 1–2 mL under reduced pressure and addition of diethyl ether
(25 mL) gave 1f as a clear red solid. The product was collected by
filtration and dried in vacuum (yield: 0.22 g, 78%); mp: 140–
3
126.70, 128.66, 129.39, 138.40 (CH2C6H5), 129.10 (d, J31
=
P—13C
2
13.1 Hz, m-carbons of phenyls), 131.22 (d, J31
= 11.9 Hz, o-
P—13C
carbons of phenyls), 132.71 (d, p-carbons of phenyls), 134.83 (d,
1J1
= 95.5 Hz, i-carbons of phenyls), 160.06 (s, C@O), assign-
P—13C
ment was based on the 1H–13C HETCOR and 1H–1H COSY spectra.
141 °C. ½a 2D7
ꢂ
= ꢀ41 (c 0.025, CH2Cl2). 1H NMR (DMSO) d(ppm):
31P–{1H} NMR (DMSO) d(ppm): 88.7 [(s), J31
lected IR,
= 805.1 Hz] Se-
1
P—13Se
0.92 (d, 6H, J = 6.8 Hz, CH3C6H4CH(CH3)2), 1.60 (s, 3H,
CH3C6H4CH(CH3)2), 2.27 (m, 1H, CH3C6H4CH(CH3)2), 2.91–2.95
(m, 4H, CH2Ar), 3.70 (m, 4H, CH2O), 4.32 (m, 2H, CH–N), 5.34 (d,
2H, J = 6.4 Hz, aromatic hydrogen of p-cymene), 5.38 (d, 2H,
J = 7.6 Hz, aromatic hydrogen of p-cymene), 7.18–7.26 (m, 10H,
m
(cmꢀ1): 3286 (N–H), 3024, 3049 (Ar–H), 1664 (C@O),
1105 (C–O), 579 (P@Se), 888 (P–O). Anal. Calc. for C44H42N2O4-
Se2P2: C, 59.87; H, 4.80; N, 3.18. Found: C, 59.96; H, 4.68; N, 3.02%.
*
C HCH2Ar), 7.32–7.40 (m, 12H, m- and p-protons of phenyls),
4.6. Synthesis of N,N0-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)-
ethyl]ethanediamidepalladium(II)chloride (1d)
7.82 (dd, 8H, J = 8.1 and 14.4 Hz, o-protons of phenyls), 8.93 (d,
2H, J = 8.8 Hz, NH). 13C–{1H} NMR (DMSO) d(ppm): 17.02, 21.43,
29.58 (aliphatic protons of p-cymene) 35.84 (CH2Ar), 51.20 (CH–
N), 67.47 (CH2O), 87.98, 89.16, 98.32, 109.18, (aromatic carbons
[Pd(cod)Cl2] (0.08 g, 0.28 mmol) and N,N0-bis[(1S)-1-benzyl-
2-O-(diphenylphosphinite)ethyl]ethanediamide
(1),
(0.20 g,
*
of p-cymene); 121.17, 127.54, 127.63, 138.11 (C HCH2C6H5),
0.28 mmol) were dissolved in toluene (30 mL) and stirred for 2 h
at room temperature. The volume was concentrated to ca. 1–
2 mL under reduced pressure and addition of diethyl ether
(25 mL) gave 1d as a yellow solid. The product was collected by fil-
tration and dried in vacuum (yield: 0.23 g, 92%); mp: 157–159 °C.
3
127.64 (d, J31
= 9.1 Hz, m-carbons of phenyls), 130.57 (d, p-
P—13C
2
carbons of phenyls), 132.07 (d, J31
= 11.1 Hz, o-carbons of
= 11.1 Hz, i-carbons of phenyls),
P—13C
1
phenyls), 131.85 (d, J31
P—13C
159.65 (s, C@O), assignment was based on the 1H–13C HETCOR
and 1H–1H COSY spectra. 31P–{1H} NMR (DMSO) d(ppm): 115.3
½
a 2D7
ꢂ
= ꢀ37 (c 0.025, CH2Cl2). 1H NMR (DMSO) d(ppm): 2.77–2.81
(s). Selected IR,
m
(cmꢀ1): 3391 (N–H), 3063, 3052 (Ar–H), 1677
(m, 4H, CH2Ar), 4.16 (m, 6H, CH2O and CH–N), 7.18–7.26 (m 10H,
CH2Ar), 7.46–7.52 (m, 12H, m-, p-protons of phenyls), 7.74 (dd,
8H, J = 6.8 and 12.60 Hz, o-protons of phenyls), 8.78 (d, 2H,
J = 8.4 Hz, NH). 13C–{1H} NMR (DMSO) d(ppm): 36.48 (CH2Ar),
51.12 (CH–N), 72.04 (CH2O), 126.36, 128.18, 128.87, 137.32
(C@O), 1099 (C–O), 883 (P–O). Anal. Calc. for (C44H42N2O4P2)-
RuCl2(CH3C6H4CH(CH3)2: C, 51.26; H, 4.11; N, 2.72. Found: C,
51.11; H, 4.08; N, 2.67%.
(CH2C6H5), 128.41 (br, m-carbons of phenyls), 131.16 (s, p-carbons
4.9. General procedure for the transfer hydrogenation of ketones
2
of phenyls), 132.16 (d, J31
= 22.5 Hz, o-carbons of phenyls),
P—13C
136.98 (br, i-carbons of phenyls), 158.74 (s, C@O), assignment
Typical procedure for the catalytic hydrogen-transfer reaction:
a solution of the ruthenium complex [Ru(chloro(p-cymene)
was based on the 1H–13C HETCOR and 1H–1H COSY spectrum.
31P–{1H} NMR (DMSO) d(ppm): 112.9 (s). Selected IR,
m
(cmꢀ1):
(N,N0-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl]ethanedia-
mide))] chloride 1f (0.005 mmol), NaOH (0.025 mmol) and the
corresponding ketone (0.5 mmol) in degassed iPrOH (5 mL) was re-
fluxed for 1 h. After this time a sample of the reaction mixture is
3300 (N–H), 3063, 3040 (Ar–H), 1670 (C@O), 1113 (C–O), 886
(P–O). Anal. Calc. for C44H42N2O4P2PdCl2: C, 58.58; H, 4.69; N,
3.11. Found: C, 58.65; H, 4.56; N, 3.05%.

1398
M. Aydemir et al. / Journal of Organometallic Chemistry 695 (2010) 1392–1398
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Acknowledgment
Partial support by Dicle University (DUBAP-07-01-22) is grate-
fully acknowledged.
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