Functionalized-arene ruthenium half-sandwich compounds as enantioselective hydrogen transfer catalysts. Crystal structures of [RuCl{TsNCH(R)CH(R)NH2}(η6-C6H 5OCH2CH2OH)] (R = H or Ph)

Article abstract of DOI:10.1016/S0020-1693(03)00151-8

In an azetropic mixture of formic acid-triethylamine (5:2) the complexes [RuCl(TsDPEN)(η⁶-C₆H₅OCH₂CH ₂OH)] (where TsDPEN=(1R,2R))- or (1S,2S)-N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine) effectively catalyse the asymmetric transfer hydrogenation of ketones with complete conversion and good to excellent enantioselectivities, usually 87-95% ee. In contrast, in basic propan-2-ol this catalyst shows a similar stereoselectivity but a reduced activity. It is proposed that this arises because the functionalized side arm competes effectively with propan-2-ol for the free co-ordination site. The crystal structures of [RuCl{(R,R)-TsDPEN)(η⁶-C₆H₅OCH ₂CH₂OH)] and [RuCl(NH₂CH₂CH₂NTs)(η⁶-C ₆H₅OCH₂CH₂OH)] are reported.

Full text of DOI:10.1016/S0020-1693(03)00151-8

Inorganica Chimica Acta 352 (2003) 121Á128
/
www.elsevier.com/locate/ica
Functionalized-arene ruthenium half-sandwich compounds
as enantioselective hydrogen transfer catalysts.
Crystal structures of [RuCl{TsNCH(R)CH(R)NH2}-
(h6-C6H5OCH2CH2OH)] (Rꢀ
/
H or Ph)
Janet Soleimannejad, Adam Sisson, Colin White *
Department of Chemistry, The University, Sheffield S3 7HF, UK
Received 25 July 2002; accepted 23 August 2002
Dedicated to Professor Martin Bennett on his retirement
Abstract
In an azetropic mixture of formic acidÁ
TsDPENꢀ(1R,2R))- or (1S,2S)-N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine) effectively catalyse the asymmetric transfer
hydrogenation of ketones with complete conversion and good to excellent enantioselectivities, usually 87Á95% ee. In contrast, in
/
triethylamine (5:2) the complexes [RuCl(TsDPEN)(h6-C6H5OCH2CH2OH)] (where
/
/
basic propan-2-ol this catalyst shows a similar stereoselectivity but a reduced activity. It is proposed that this arises because the
functionalized side arm competes effectively with propan-2-ol for the free co-ordination site. The crystal structures of [RuCl{(R,R)-
TsDPEN)(h6-C6H5OCH2CH2OH)] and [RuCl(NH2CH2CH2NTs)(h6-C6H5OCH2CH2OH)] are reported.
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Asymmetric reduction; Ketones; Catalysis; Crystal structures
1. Introduction
enantioselectivity.Werecentlydevelopedasimplemethod
of synthesising functionalized-arene ruthenium com-
plexes such as [RuCl2(h6-C6H5OCH2CH2OH)]2 (1) [10]
andwewishtoexploitthisbyusingthefunctionalitytolink
the arene to polymer supports in order to prepare easily
recyclable‘Noyoritype’catalysts.Beforeembarkingupon
this programme, however, we thought it prudent to check
that the functionality on the arene would not impair either
the activity or enantioselectivity of the ‘Noyori catalysts’.
The results of this preliminary investigation are reported
herein.
Arene ruthenium half-sandwich complexes were first
prepared by Wilkhaus and Singer [1], and their chemistry
was investigated briefly by Zelonka and Baird [2].
However, it was the seminal work of Bennett and co-
workers who developed the chemistry of this class of
compounds and first demonstrated their catalytic proper-
ties [3]. This, in turn, stimulated an enormous body of
research, and arene ruthenium half-sandwich compounds
are today used to catalyse a wide range of reactions
including alkene- [4] and aromatic-hydrogenation [5],
DielsÁAlder reactions [6] and alkene metathesis [7].
/
2. Results and discussion
Undoubtedly, one of their most successful applications
has been by Noyori who has adapted these compounds to
efficiently catalyse the asymmetric hydrogen transfer
reduction of ketones [8] and imines [9], with very high
The modified ‘Noyori catalysts’ containing a functio-
nalized arene were synthesised as shown in Scheme 1. In
addition to the chiral complexes (R,R)-2 and (S,S)-2,
containing the expensive chiral ligands (1R,2R)- and
(1S,2S)-N-(p-toluenesulfonyl)-1,2-diphenylethylenedia-
mine, i.e. (1R,2R)-TsDPEN and (1S,2S)-TsDPEN,
* Corresponding author. Tel.: ꢁ
273-8673.
E-mail address: colin.white@sheffield.ac.uk (C. White).
/
44-114-222-9310; fax: ꢁ44-114-
/
0020-1693/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0020-1693(03)00151-8

122
J. Soleimannejad et al. / Inorganica Chimica Acta 352 (2003) 121Á
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Scheme 1.
respectively, we also synthesised the achiral analogue 3,
containing N-tolylsulfonylethylenediamine, TsEN, in
order to have a cheap catalyst for preliminary studies.
All complexes have been characterised by elemental
analysis and NMR spectroscopy; in addition, the
structures of (R,R)-2 and 3 have been determined by
X-ray crystallography.
2.2. Catalytic asymmetric hydrogen transfer reactions
using HCOOHÁ/Et3N (5:2) as the hydrogen donor
An azetropic mixture of formic acidÁ/triethylamine
(5:2) is known to be a powerful hydrogen donor [12].
Noyori has shown that in this medium the complex
Table 1
Crystallographic data for (R,R)-2 and 3
2.1. The molecular structures of (R,R)-2 and 3
(R,R)-2×
/
CH2Cl2
3×
/
H2O
Experimental data on the crystal structure determina-
tions are summarized in Table 1 and the molecular
structures of (R,R)-2 and 3 are shown in Figs. 1 and 2,
respectively. Selected bond lengths and angles are
compared in Table 2. The crystal lattice of (R,R)-2
contains one dichloromethane molecule for each mole-
cule of the complex and in this solvent molecule atom
Cl(3) and C(1S) were found to be disordered over two
positions and refined to an occupancy of 41 and 59%.
Similarly, in this structure, C(27) was disordered and
refined to an occupancy of 33 and 67%. The crystal
lattice of 3 contains one water molecule per ruthenium
atom. Interestingly, the structure contains large chan-
nels running perpendicularly through the centre of the C
face of the unit cell, from which solvent molecules have
apparently been lost without significantly undermining
the integrity of the crystal. As expected, both complexes
contain ruthenium in a distorted octahedral environ-
ment with similar bond angles and lengths. The main
difference between the two structures is that in 3 the
OCH2CH2OH side chain sits above the chloride ligand
whereas in (R,R)-2 it is directed away from the chloride
on the opposite side of the molecule. The reason for this
difference is not obvious. In both structures there is
evidence of intramolecular hydrogen bonding between
Empirical formula
Formula weight
Temperature (K)
C
30H33Cl3N2O4RuS C17H25ClN2O5RuS
725.06
150(2)
0.71073
505.97
150(2)
˚
Wavelength (A)
0.71073
monoclinic
C2/c
Crystal system
Space group
Unit cell dimensions
monoclinic
P21
˚
a (A)
10.357(2)
12.652(3)
11.910(3)
94.471(5)
1555.9(6)
2
33.915(7)
9.8624(19)
14.010(3)
94.544(6)
4588.4(16)
8
˚
b (A)
˚
c (A)
b (8)
3
˚
V (A )
Z
rcalc (Mg mꢂ3
)
1.548
0.867
740
1.465
0.918
2064
m (Mo Ka) (mmꢂ1
F(000)
)
Crystal size (mm3)
2u Range (8)
Index ranges
0.26ꢃ
3.4Á56.3
135h 5
95k 516,
155l 515
/
0.07ꢃ
/
0.07
0.32ꢃ
4.3Á56.6
445h 5
125k 5
185l 518
/
0.21ꢃ
/
0.08
/
/
ꢂ
/
/
/12,
ꢂ
/
/
/30,
ꢂ
/
/
/
ꢂ
/
/
/
12,
ꢂ
/
/
/
ꢂ/
/
/
Reflections collected
Independent reflections
9380
5636
[Rint
13830
5513
ꢀ/0.1127]
[Rint
96.5
ꢀ/0.0947]
Completeness to uꢀ
(%)
/
28.168 95.7
Absorption correction
Max. and min.
transmission
empirical
0.9418 and 0.8061
empirical
0.9302 and 0.7578
Refinement method
full-matrix
least-squares on F2 least-squares on F2
full-matrix
the Cl and a hydrogen on the NH2 group, i.e. in (R,R)-2
˚
NH1AÁ Á ÁCl distanceꢀ
/
2.680 A and in 3 NH(2B)Á Á ÁCl
Data/restraints/parameters 5636/41/392
Goodness-of-fit on F2
5513/6/256
1.019
0.0528
˚
distanceꢀ2.78 A, both much shorter than the van der
0.930
/
˚
R1 [I ꢀ2s(I)]
/
0.0755
0.1966
0.47(9)
Waals separation of 3.0 A. Similar hydrogen bonding
has been proposed in related ‘Noyori type catalysts’ [9b].
In (R,R)-2 the TsDPEN forms a d-configurated five-
membered ring and the absolute configuration of the
wR2 (all data)
Absolute structure
parameter
0.1678
Largest difference peak
ꢂ3
0.716 and ꢂ
/0.863
1.139 and ꢂ1.587
/
˚
and hole (e A
)
ruthenium centre is S according to the StanleyÁ
/Baird
convention [11].

J. Soleimannejad et al. / Inorganica Chimica Acta 352 (2003) 121Á
/128
123
Fig. 1. Molecular structure of [Ru(h6-C6H5OCH2CH2OH)Cl{(R,R)-TsDPEN}], (R,R)-2 (thermal ellipsoids at 50% probability). Solvate CH2Cl2
and hydrogen atoms have been omitted for clarity.
[RuCl(S,S-TsDPEN)(p-cymene)], formed in situ, is an
efficient hydrogen transfer catalyst which reduces ke-
tones to the corresponding alcohol with high enantios-
electivity [8b]. We therefore compared the activity and
enantioselectivity of 2 with Noyori’s catalyst. Acetophe-
none was chosen as the test substrate and reactions were
carried out under an inert atmosphere at 30 8C with a
substrate/catalyst ratio 200/1 and a diamine ligand/Ru
atom ratio of 1.1/1; the results are shown in Table 3. It
can be seen that Noyori’s system (entry 1) gave 98% e.e.,
marginally higher than the 95% ee obtained using in situ
formed 2 (entry 3); thus, it is clear that the presence of
the functionalized-arene ligand in 2 does not have any
serious consequences on the enantioselectivity of the
reduction process. The pre-formed catalyst 2 (entry 2)
gave 93% ee which, within experimental error, is the
same as that obtained with the in situ catalyst. All three
catalytic systems showed comparable activity.
Fig. 2. Molecular structure of [Ru(h6-C6H5OCH2CH2OH)Cl(TsEN] (3) (thermal ellipsoids at 50% probability). Solvate H2O and hydrogen atoms
have been omitted for clarity.

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J. Soleimannejad et al. / Inorganica Chimica Acta 352 (2003) 121Á128
/
Table 2
Table 3
˚
Comparison of important bond lengths (A) and bond angles (8) in
(R,R)-2 and 3
Asymmetric transfer hydrogenation of ketones in formic acidÁ
/
triethylamine azeotrope at 30 8C using [RuCl{(S,S)-TsDPEN)(h6-
C6H5OCH2CH2OH)] (S,S)-2
(R,R)-2×/CH2Cl2
3×H2O
/
Bond lengths
Ru(1)Á
Ru(1)Á
Ru(1)Á
/
NH2
NTs
Cl(1)
2.145(10)
2.151(9)
2.430(4)
1.40(2)
2.128(4)
2.121(4)
2.4118(13)
1.409(8)
2.181(5)
1.666
/
/
Average CÁ
RuÁCaverage
Ru(1)Áarene centre
/
Carene
/
2.196(4)
1.679
/
Bond angles
N(1)ÁRu(1)Á
N(1)ÁRu(1)Á
N(2)ÁRu(1)Á
/
/
N(2)
Cl(1)
Cl(1)
78.7(4)
84.0(3)
87.1(3)
78.88(17)
86.24(13)
85.65(12)
/
/
/
/
The effect of changing the solvent was briefly
investigated. Using a mixture of dichloromethane/for-
mic acidÁtriethylamine azeotrope (2:1) gave 97% con-
/
version after 20 h (entry 4), marginally lower than when
the corresponding reduction was carried out in neat
formic acidÁtriethylamine azeotrope (entry 3). In con-
/
trast, changing from dichloromethane to the more co-
ordinating acetonitrile reduced the conversion signifi-
cantly; thus, using a mixture of acetonitrile/formic acid-
triethylamine azeotrope (2:1) gave only 72% conversion
after 20 h (entry 5). Within experimental error, these
changes of solvent did not affect the enantioselectivity.
The ability of the in situ catalyst 2 to catalyse the
reduction of a range of ketones was then investigated
and the results are also shown in Table 3. Each reaction
with a different substrate was run in parallel with
acetophenone as a standard under identical conditions
and the results for acetophenone in each case fluctuated
very little, so it can be assumed that the entire set of
results was obtained under the same reaction conditions.
Using S,S-2 all the substrates investigated were quanti-
tatively reduced to the corresponding S-alcohols; thus,
the configuration of the product alcohol is the same as
that obtained with Noyori’s catalyst [RuCl{(1S,2S)-
TsDPEN}(p-cymene)]. Those substrates containing
electron-donating substituents (entries 6 and 7) took
40 h or more to go to completion whereas those
containing electron-withdrawing substituents (entries
8Á
10) took 30 h or less.1 This may be expected as
/
reduction involves the substrate gaining electrons and
this would be more facile at an electron deficient centre.
This does not reflect the whole story, however, as the
acetonaphthone derivatives (entries 13 and 14) are also
a Determined by chiral GC (see Section 3), all alcohol products have
S-configuration. b Catalystꢀ
tylene)] (4). c Catalystꢀ
CH2CH2OH)] S,S-2. d Catalystꢀ
TsDPEN)(h6-C6H5OCH2CH2OH)] S,S-2. e Solventꢀ
COOHÁ MeCN/HCOOHÁ
Et3N azeotrope (2:1). f Solventꢀ
azeotrope (2:1).
/
Noyori’s [RuCl(S,S-TsDPEN)(h6-mesi-
/
pre-formed [RuCl(S,S-TsDPEN)(h6-C6H5O-
in situ formed [RuCl(S,S-
CH2Cl2/H-
Et3N
1
The conversion times stated in Table 3 for the trifluoro substituted
/
derivatives (entries 11 and 12) are misleading and are a result of not
being able to quench the reactions before that time. Analysis during
the first. few hours of reaction with these substrates indicated a rate
roughly equal to that of the acetophenone reduction.
/
/
/
/

J. Soleimannejad et al. / Inorganica Chimica Acta 352 (2003) 121Á
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125
Table 4
Asymmetric transfer hydrogenation of acetophenone in 2-propanol using [RuCl(TsDPEN)(h6-C6H5OCH2CH2OH)] (2)
Catalyst
Temp (8C)
Time (h)
Conversion (%)
Alcohol
ee (%) a
Configuration
b
(R,R)-4
(R,R)-2
(S,S)-2
(R,R)-2
20
20
20
50
44
20
20
20
94
28
24
48
88
89
86
88
R
R
S
R
All reactions carried out using an acetophenone:catalyst of 200:1 and a Ru:diamine of 1:1.
a
Measured by chiral GC.
Catalystꢀ
Noyori’s [RuCl(R,R-TsDPEN)(h6-mesitylene)] (4).
b
/
electron-withdrawing but showed slower rates, suggest-
ing that steric factors are also involved. The enantios-
electivities of the reductions shown in Table 3, whilst
generally very high, do show some significant differ-
ences. In particular, steric crowding around the keto
group appears detrimental to the enantioselectivity
(entries 9 and 14). Also trifluoroacetophenone (entry
12), which is sterically very similar to acetophenone, was
only reduced with 28% ee; electron-withdrawing groups
and formic acid-triethylamine azeotrope since, in the
latter acidic medium, alkoxide co-ordination is unlikely.
Thus, in propan-2-ol the functionalized side-chain acts
as a catalyst poison blocking a co-ordination site and
preventing formation of the necessary rutheniumÁhy-
/
dride intermediate. Such an intramolecular coordination
is extremely favoured entropically and may well be
dominant over propan-2-ol even though propan-2-ol is
present in excess. Support for this proposal comes from
the work of Kurosawa and co-workers who have shown
similar side-chain co-ordination in the related
[RuCl(PCy3)(h6,h1-C6H5CH2CH2CH2OH)][BF4] and
[Ru(bipy)(h6,h1-C6H5CH2CH2CH2O)][BF4] complexes.
Significantly, these alcohol and alkoxy complexes do not
undergo b-hydrogen elimination, possibly because of
their geometry [13]; hence they cannot generate a
ruthenium-hydride intermediate required for hydrogen
transfer catalysis.
in the aryl ring (entries 8Á11) have a less dramatic effect
/
but also tend to lower the enantioselectivity.
2.3. Cataltytic asymmetric hydrogen transfer reactions
using propan-2-ol as the hydrogen donor
Attempts to effect the efficient asymmetric hydro-
genation of acetophenone in propan-2-ol using
[RuCl(TsDPEN)(h6-C6H5OCH2CH2OH)] (2) proved
unsuccessful. The substrate to catalyst ratio, KOH
concentration, chiral ligand to Ru atom ratio and
temperature were altered without achieving results any-
where near as impressive as those reported by Noyori
[8a]. Some typical results are shown in Table 4 and it can
be seen that, although the % ee’s were comparable to
Noyori’s catalyst, the conversions were significantly less,
with the reaction appearing to stop after a certain time.
Speculating on the reason for this difference we believe
that the hydroxyl group in [RuCl(TsDPEN)(h6-
C6H5OCH2CH2OH)] (2) may well compete with pro-
pan-2-ol for co-ordination to ruthenium, especially in
the presence of base when it can co-ordinate more
strongly as an alkoxide (Fig. 3). This would explain the
contrasting behaviour observed in basic propan-2-ol
2.4. Conclusion
It has been shown that the complex [RuCl(TsDPEN)-
(h6-C6H5OCH2CH2OH)] in formic acidÁ
/triethylamine
azeotrope catalyses the transfer hydrogenation of ke-
tones to the corresponding alcohols with complete
conversion and good to excellent enantioselectivities,
usually 87Á95% ee. This is comparable to the perfor-
/
mance of the catalyst [RuCl(TsDPEN)(h6-mesitylene)]
(4), demonstrating that in this medium our modification
of adding a functionalized side arm to the Noyori’s
ruthenium catalyst did not affect the reactivity or the
stereoselectivity of the catalyst. In contrast, the same
modified catalyst in propan-2-ol showed a similar
Fig. 3. Proposed poisoning mechanism that operates in basic propan-2-ol.

126
J. Soleimannejad et al. / Inorganica Chimica Acta 352 (2003) 121Á128
/
stereoselectivity to Noyori’s catalyst but a reduced
activity. It is proposed that this arises because the
functionalized side arm competes effectively with pro-
pan-2-ol for the free co-ordination site. Actually, for our
purposes, this is not a serious set back since, if the
catalyst is attached to a support through the functiona-
lized side chain, then this poisoning mechanism cannot
operate.
(1S,2S)-N-p-Toluenesulfonyl-1,2-diphenylethylene-
diamine, (1S,2S)-TsDPEN) was prepared as above but
using (S,S)-DPEN (41% yield).
3.2. Preparation of [RuCl{(R,R)-TsDPEN}(h6-
C6H5OCH2CH2OH)] ((R,R)-2)
A mixture of [RuCl2(h6-C6H5OCH2CH2OH)]2 (0.12
g, 0.20 mmol), (1R,2R)-N-(p-toluenesulfonyl)-1,2-di-
phenylethylenediamine [(1R,2R)-TsDPEN] (0.15 g,
0.40 mmol), and triethylamine (0.12 ml, 0.80 mmol) in
2-propanol (5 ml) was heated at 80 8C for 1 h under
nitrogen. The red solution was concentrated and the
resulting solid was collected by filtration. The crude
compound was washed with a small amount of water
and dried under reduced pressure to give the product.
Recrystallization from a mixture of dichloromethane
and methanol (5:1) layered with diethyl ether furnished
orange crystals, one of which was selected for the
structure determination (0.16 g, 63% yield). Anal.
Calc. for C29H31O4ClN2RuS C, 54.4; H, 4.9; Cl, 5.5;
N, 4.4; S, 5.0; Found: C, 53.6; H, 5.1; Cl, 5.2; N, 4.3; S,
5.5%. 1H NMR (CD2Cl2:CD3OD, 5:1, 250 MHz): d
3. Experimental
N-Tolylsulfonylethylenediamine [14], [RuCl2(h6-
C6H5OCH2CH2OH]2 [10] and formic acidÁtriethyla-
/
mine (5;2) azeotrope [12] were prepared by published
procedures. All solvents were dried by standard techni-
ques and distilled under nitrogen prior to use. Data for
both crystal structures were collected using a Bruker
SMART1000 CCD area detector fitted with an Oxford
Cryosystems low temperature system and graphite
monochromator. The structures were solved by direct
methods and complex scattering factors were taken from
the program package SHELXTL [15] as implemented on
the Viglen Pentium computer.
2.91 (s, 3H, CH3 in p-Ts), 4.57 (t, Jꢀ
4.36Á4.74 (bm, 3H, CHNH2, CHNTs, NHH), 5.00 (m,
2H, CH2), 5.94 (t, Jꢀ6.3 Hz, 2H, C6H5OCH2CH2OH),
6.17 (br, 1H, C6H5OCH2CH2OH), 6.74 (m, 2H,
/4.3 Hz, 2H, CH2),
/
/
3.1. (1R,2R)-N-p-Toluenesulfonyl-1,2-
diphenylethylenediamine ((1R,2R)-TsDPEN)
C6H5OCH2CH2OH), 7.22Á7.92 (m, 15H, p-CH3
/
C6H4SO2NCH(C6H5)CH(C6H5)NHH). 13C NMR
(CD2Cl2:CD3OD, 5:1, 62.90 MHz): d 21.2 (CH3 in p-
Ts), 60.6 (1C, CH2), 66.0 (1C, OPh), 68.7 (2C, OPh),
(1R,2R)-(ꢁ)-1,2-Diphenylethylenediamine (0.53 g,
/
2.5 mmol) was dissolved in dichloromethane (33 ml),
triethylamine (0.53 ml, 3.75 mmol) was added and the
mixture cooled in ice. A solution of p-toluenesulfonyl
chloride (0.45 g, 2.36 mmol) in dichloromethane (14 ml)
was added in three portions over 10 min. The reaction
mixture was stirred for 30 min then warmed to room
temperature, stirred a further hour and stored in a fridge
at 4 8C. The reaction progress was followed by TLC
71.5 (1C, CH2), 72.4 (1C, OPh), 84.2 (1C, OPh), 126.6Á
129.5 (15C, Caromatic), 134.5, 138.9, 139.8, 143.0 (4C,
Caromatic). FAB MS: m/z 641 ([Mꢁ
1ꢁ], 8%), 605
/
/
([Mꢁ]ꢂ
The
C6H5OCH2CH2OH)] was prepared by an identical
/
Cl, 100%)
corresponding
[RuCl{(S,S)-TsDPEN}(h6-
procedure but using (S,S)-TsDPEN.
(silica gel, EtOAc, Rf: productꢀ
/
0.7, starting materialꢀ
/
3.3. Preparation of [RuCl(TsEN)(h-
C6H5OCH2CH2OH)] (3)
0 and ditosylatedꢀ1) and it was complete after 16 h at
/
4 8C. The resulting mixture was washed successively
with water (20 ml), saturated NaHCO3 (20 ml), water
(20 ml), brine (20 ml) and then dried over MgSO4.
This was prepared in 58% yield as orange crystals
using the above procedure and TsEN in place of
TsDPEN. Anal. Calc. for C17H23ClN2O4RuS C, 41.8;
H, 4.7; N, 5.7; Cl, 7.3; S, 6.6; Found: C, 41.7; H, 4.6; N,
5.4; Cl, 7.3; S, 6.7%. 1H NMR (acetone-d6, 250 MHz): d
2.20 (s, 3H, CH3 in p-Ts), 2.85 (br, 5H, CH2NTs,
Recrystallisation from ethyl acetateÁpentane afforded
/
N-tosyl-1,2-diphenylethylenediamine as white crystals
(0.48 g, 56% yield).
1H NMR (CDCl3, 250 MHz): d 2.30 (s, 3H, CH3 in
p-Ts), 2.50 (br, s, 2H, NH2), 4.12, 4.39 (d, Jꢀ
each 1H, CHN), 6.95 (d, Jꢀ8.2 Hz, 2H, p-CH3C6H4),
7.10 (m, 11H, CH(C6H5)CH(C6H5)NHTs), 7.31 (d, 2H,
p-CH3C6H4Á
). 13C NMR (CDCl3, 62.90 MHz): d 21.4
(1C, CH3 in p-Ts), 60.6 (1C, CNH2), 63.4 (1C, CNH-p-
Ts), 126.6Á129.1 (14C, Caromatic), 137.2, 139.3, 141.5,
142.5 (4C, Caromatic); m/z (ESꢁ 1, 75%),
) 367 ([Mꢁ]ꢁ
350 ([Mꢁ]ꢂ
NH2, 100%).
/
5.4 Hz,
CH2NHH), 3.75 (m, 2H, CH2), 4.15 (t, Jꢀ
CH2), 5.05 (t, Jꢀ5.2 Hz, 2H, C6H5O), 5.25 (d, Jꢀ
Hz, 1H, C6H5O), 5.80 (t, Jꢀ5.5 Hz, 2H, C6H5O), 7.02
(d, Jꢀ8.0 Hz, 2H, p-CH3C6H4SO2) 7.62 (d, 2H, d, p-
/
4.4 Hz, 2H,
/
/
/5.5
/
/
/
CH3C6H4SO2). 13C NMR (acetone-d6, 62.90 MHz): d
21.1 (1C, CH3 in p-Ts), 60.2 (1C, CH2), 71.2 (1C, CH2),
63.8, 65.0, 71.9, 87.5, 90.7 (each 1C, PhO), 127.5, 129.1
(each 2C, p-CH3C6H4SO2), 133.5, 140.7 (each 1C, p-
/
/
/
/

J. Soleimannejad et al. / Inorganica Chimica Acta 352 (2003) 121Á
/128
127
CH3C6H4SO2), 141.4 (1C, PhO). FAB MS: m/z 488
([M]ꢁꢁHꢁ, 48%), 453 [([Mꢁꢂ Hꢁ, 100%).
Cl]ꢁ
4. Supplementary material
/
/
/
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 189816 and 189817 for
compounds 2 and 3, respectively. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge, CB2
3.4. General procedure for catalytic reactions using
formic acid
All reactions were carried out in three- or five-
chambered flasks to allow comparison of results under
identical conditions. A typical procedure is given below.
Acetophenone (73 ml, 0.72 mmol) followed by formic
1EZ, UK (fax: ꢁ44-1223-336-033; e-mail: deposit@
/
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
acidÁ
stirred catalyst precursor ruthenium dimer complex (1)
(1 mg, 1.8ꢃ
10ꢂ3 mmol) and (S,S)-TsDPEN (1.5 mg,
4.0ꢃ
10ꢂ3 mmol) under nitrogen. The stirred reaction
/triethylamine azeotrope (0.31 ml) was added to the
Acknowledgements
/
We wish to express our sincere thanks to the Iranian
government for the award of a scholarship (to J.S.) and
to Johnson Matthey for the generous loan of ruthenium
trichloride (to C.W.).
/
mixture was heated using an oil bath, the continuous
evolution of gas was observed almost instantaneously.
The reaction was followed by GC and GC analysis
samples were prepared via the following method. A few
drops of reaction mixture were shaken in a biphasic
mixture of EtOAc (1 ml) and sat. NaHCO3 (1 ml). The
organic phase was then separated, dried over MgSO4
and filtered through a plug of cotton wool to give a GC
sample of required dilution. The enantiomeric excess of
the product was also analysed by chiral gas chromato-
graphy using a Perkin Elmer 8700 gas chromatograph
fitted with a 30-m b-Chiradex capilliary column as
described previously [16]. At the end of the reactions
NMR samples of the product alcohols were prepared by
the following method. The remaining reaction mixture
was shaken in a biphasic mixture of EtOAc (2 ml) and
sat. NaHCO3 (2 ml). The organic phase was then
separated, dried over MgSO4 and filtered through a
plug of cotton wool. Removal of the solvent under
reduced pressure gave the product as a slightly brown oil
which was analysed by NMR.
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