Synthesis and reactivity of a cyclopentadienyl-indenyl ligand ring-coupled by a chiral bridge derived from ethyl (S)-(-) lactate

Article abstract of DOI:10.1039/c3dt33019b

In order to prepare a new unsymmetrical chiral ligand, C₉H ₇CH(CH₃)CH₂C₅H₅, with an indenyl moiety connected to a cyclopentadienyl unit by a chiral ethylene bridge, we reacted the optically active tosylate 4, derived from ethyl (S)-(-) lactate, with LiCp. The only product resulting from this reaction was an optically active spirocyclopropane 6 obtained with a high diastereoselectivity (81.8% de). We also observed that, when the reduction of the ethyl indene lactate 2 was realized with an excess of LiAlH₄ in Et₂O under reflux, spirocyclopropane 6 was obtained in high yield with the same diastereoselectivity. When tosylate 4 was reacted with MgCp₂, in place of LiCp, ligand 5 was obtained in good yield as a mixture of two double-bond isomers of the Cp unit. Ligand 5 was fully structurally characterized after conversion into transition monometallic complexes such as C₉H₇CH(CH₃)CH₂η⁵- C₅H₄Mo(CO)₃Me 7 and C₉H ₇CH(CH₃)CH₂η⁵-C ₅H₄Rh(COD) 9, in which the indene moiety was kept intact due to the difference in reactivity of the indenyl moiety with respect to the cyclopentadienyl unit. An attempt to prepare a heterobimetallic complex from the sodium indenide salt of 7 and [RhCl(COD)]₂, afforded a rhodium cyclopentadienyl complex 9, resulting from a metal exchange reaction with loss of the molybdenum part initially coordinated to the Cp unit, and conservation of the optical purity. An homobimetallic rhodium complex 10 could be prepared by deprotonation of ligand 5 with TlOEt, followed by quenching with [RhCl(COD)]₂. The bis-rhodium complex 10 is obtained as a mixture of two diastereoisomers 10_a and 10_b with respect to the planar chirality of the indenyl ring system, with a good diastereoisomeric excess de = 70%. The structures of both complexes 9 and major (pS)-diastereoisomer 10_a were determined by single crystal X-ray diffraction.

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Synthesis and reactivity of a cyclopentadienyl-indenyl
ligand ring-coupled by a chiral bridge derived from
ethyl (S)-(−) lactate†
Cite this: Dalton Trans., 2013, 42, 7980
Richard Laï,*a Jean-Claude Daran,b Didier Nuel,c Martial Sanz,a Nick Summerton,a
Nicolas Vanthuynea and Anaïs Zaragori-Benedettia
In order to prepare a new unsymmetrical chiral ligand, C9H7CH(CH3)CH2C5H5, with an indenyl moiety
connected to a cyclopentadienyl unit by a chiral ethylene bridge, we reacted the optically active tosylate
4, derived from ethyl (S)-(−) lactate, with LiCp. The only product resulting from this reaction was an opti-
cally active spirocyclopropane 6 obtained with a high diastereoselectivity (81.8% de). We also observed
that, when the reduction of the ethyl indene lactate 2 was realized with an excess of LiAlH4 in Et2O
under reflux, spirocyclopropane 6 was obtained in high yield with the same diastereoselectivity. When
tosylate 4 was reacted with MgCp2, in place of LiCp, ligand 5 was obtained in good yield as a mixture of
two double-bond isomers of the Cp unit. Ligand 5 was fully structurally characterized after conversion
into transition monometallic complexes such as C9H7CH(CH3)CH2η5-C5H4Mo(CO)3Me 7 and C9H7CH(CH3)-
CH2η5-C5H4Rh(COD) 9, in which the indene moiety was kept intact due to the difference in reactivity of
the indenyl moiety with respect to the cyclopentadienyl unit. An attempt to prepare a heterobimetallic
complex from the sodium indenide salt of 7 and [RhCl(COD)]2, afforded a rhodium cyclopentadienyl
complex 9, resulting from a metal exchange reaction with loss of the molybdenum part initially coordi-
nated to the Cp unit, and conservation of the optical purity. An homobimetallic rhodium complex 10
could be prepared by deprotonation of ligand 5 with TlOEt, followed by quenching with [RhCl(COD)]2.
The bis-rhodium complex 10 is obtained as a mixture of two diastereoisomers 10a and 10b with respect
to the planar chirality of the indenyl ring system, with a good diastereoisomeric excess de = 70%. The
structures of both complexes 9 and major (pS)-diastereoisomer 10a were determined by single crystal
X-ray diffraction.
Received 17th December 2012,
Accepted 12th February 2013
DOI: 10.1039/c3dt33019b
www.rsc.org/dalton
The name ansa-metallocene is now commonly used with
reference to bent metallocene complexes of the early transition
Introduction
Among the polydentate ligands connected by an interannular metals and lanthanides.2,3
bridge, those which belong to the cyclopentadienyl and
The construction of the ansa-bridge implies various syn-
indenyl family are very common and widely used in homo- thetic approaches with a variety of bridges. The nature of the
geneous catalysis.
bridge has a great influence on the structure and reactivity of
These types of ligands have been intensely studied after the ansa-complexes as compared with their unbridged counter-
Brintzinger and Kaminsky showed the usefulness of group IV parts.3,4 Depending on the nature of the bridge and of the
metallocenes as alkene polymerization catalysts and also as metal, mononuclear or dinuclear complexes can be
catalysts for asymmetric synthetic organic transformations.1
obtained.5,6
Disymmetric cyclopentadienyl–indenyl alkylidene bridged
dinuclear metallocene complexes have been reported.7–11
The synthesis of doubly linked bis-cyclopentadienyl ligands
has been mentioned by different groups.12,13
These homo or heterodinuclear compounds are of great
interest for many reasons and this is particularly true when
metal atoms are held in close proximity. Indeed, a polynuclear
transition metal center may provide a reaction pathway not
available to a single metal analog.14 The use of unsymmetrical
aAix Marseille Université, CNRS, iSm2 UMR 7313, 13397 Marseille, France.
E-mail: richard.lai@orange.fr
bLaboratoire de Chimie de Coordination, 205 route de Narbonne,
31077 Toulouse Cedex 04, France
cCentrale Marseille, Aix-Marseille Université, CNRS, iSm2 UMR 7313,
13397 Marseille, France
†CCDC 857069 and 857070. For crystallographic data in CIF or other electronic
format see DOI: 10.1039/c3dt33019b
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bis-cyclopentadienyl or cyclopentadienyl–indenyl may facilitate
the synthesis of heterodinuclear metal complexes since differ-
ences in the steric and electronic effects of either the cyclo-
pentadienyl or indenyl moieties might induce a different
reactivity in each metal center.14,15
Scheme 2
In spite of these different kinds of bridging structures,
there are few examples of ligands with a chiral interannular
bridge between the two sites of coordination, although this
feature seems to be very interesting as far as the reactivity of
the resulting complexes is concerned.16,17
For example, a C2-symmetric chiral bridge between the two
indene moieties could favor the formation of one of the two
possible bis(indenyl) metal diastereoisomers and suppress the
formation of the undesired meso complex of ansa-bis(indenyl)
compounds.3,18
Finally, such chiral complexes could be useful as chiral
auxiliaries for enantioselective organic transformations.19
During the course of our work on the synthesis and reacti-
vity of optically active cyclopentadienyl and indenyl complexes
derived from natural compounds, we planned to prepare an
asymmetric chiral cyclopentadiene–indene ligand derived
from ethyl (S)-(−) lactate, with a chiral ethylene bridge linking
the cyclopentadiene and indene moieties. Complexation with
transition metals of such a ligand should combine both
planar-indenyl-based chirality and central chirality on the
linking bridge.
[cyclopropane-1,1′-indene], instead of the expected ligand
cyclopentadiene–indene 5. Here, LiCp behaves, apparently, as
a base with 4 rather than a nucleophile (Scheme 2).
On the ground of 1H and 13C NMR, 6 was characterized as a
spirocyclopropane as a mixture of two diastereoisomers in the
1 : 0.1 ratio (de = 81.8%).
We easily deduced, from the initial ethyl (S)-lactate, an (R)
absolute configuration of the methyl cyclopropane. An NMR
NOESY sequence, which showed that the methyl and the
phenyl substituents of the cyclopropane are trans to each
other, allowed us to assign the relative (R) absolute configur-
ation of the spiro carbon of the major diastereoisomer.
Compound 6, described in the literature as two racemic syn
and anti isomers, has been obtained by the reaction of sodium
indenide with racemic 1,2-dibromopropane.21 To our knowledge,
no optically active version of compound 6 has been reported.
Other spiroindenes resulting from the action of bases on
mono or bis-sulfonates have been described but it is very rare
to observe diastereoselectivities as high as that of 6.17,22
Interestingly, during this work, we observed that when the
reduction of 2 was performed in Et2O at reflux for 14 h, with a
large excess of LiAlH4 (3.3 eq. LiAlH4/1 eq. 2), 3 was obtained
accompanied by 20% of the spirocyclopropane 6, isolated by
chromatography on silica, with the same diastereoisomeric
ratio (1 : 0.1) (Scheme 3).
Results and discussion
Synthesis of C9H7CH(CH3)CH2C5H5
The following reaction pathway was, at first, considered to
obtain the chiral bridged unsymmetrical cyclopentadiene–
indene ligand 5 (Scheme 1).
The rather surprising formation of 6 in these conditions
deserves a deeper insight and some comments.
The preparation of compound 2 has been described in a
previous paper from the reaction of LiInd on tosylate or triflate
of ethyl (S)-(−) lactate with modest to good yields and high
optical purity.20
Reduction of 2 with a slight excess of LiAlH4 gives the corres-
ponding alcohol 3, in good yield, with high optical purity.20
However, the reaction of LiCp with the corresponding tosylate
4 affords quantitatively a spirocyclopropane 6, 2-methylspiro-
In the literature, the formation of spiranic cyclopropanes
derived from indene derivatives by other methods has been
described.23,24
Some aryl-cyclopropanes have been obtained by the reduction
of cinnamic derivatives, either acids, esters or alcohols, with
LiAlH4, via a proposed organoaluminic intermediate.25,26
The reaction time and conversion into cyclopropane
depend on the nature of the solvent and of the excess of
LiAlH4.25,27,28
In our case, how can we explain the formation of 6? Is 6
formed from 3 or in a parallel reaction involving starting ester
2? Is it possible to obtain exclusively 6?
In order to understand the formation of 6 from the ester 2
we have run a series of experiments of which the most rep-
resentative results are summarized in Table 1.
Scheme 1
Scheme 3
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Table 1 Formation of 6 under different experimental conditions
Products (%)a
Entry
Substrate
LiAlH4 equiv.
LiOEt equiv.
Solvent
T
Time (h)
2
3
6
deb (R,R)/(R,S)
1
2
3
4
5
6
7
8
2
2
2
2
2
2
2
2
3
3
3
2
1.65
1.65
3.3
3.3
3.3
3.3
3.3
3.3
2
0
0
0
0
0
0
0
0
0
1
1
1
Et2O
Et2O
Et2O
Et2O
THF
THF
i-Pr2O
i-Pr2O
Et2O
Et2O
Et2O
Et2O
0 °C
0.25
48
14
65
0.5
2
0.3
25
19
13
28
0
0
0
0
0
0
0
0
0
0
0
0
100
100
80
0
100
0
100
100
100
0
0
100
0
0
20
100
0
100
0
0
0
100
100
0
—
—
Reflux
Reflux
Reflux
0 °C
Reflux
0 °C
Reflux
Reflux
Reflux
Reflux
Reflux
1/0.1
1/0.1
—
1/0.1
—
—
—
1/0.1
1/0.1
—
9
10
11
12
2
1
1.65
33
a Determined by GC analysis. b Determined by 1H NMR.
We have shown that when 2 is treated, at 0 °C in Et2O, with
1.65 equivalents of LiAlH4, 3 is obtained quantitatively within
15 min and, even after 48 h at reflux, no formation of 6 is
detected (entries 1 and 2). If the same reaction is run with 3.33
equivalents of LiAlH4 under reflux, 6 is obtained in 20% yield
in 14 h (entry 3) and quantitatively after 65 h (entry 4). We
observed that the diastereoselectivity is 1/0.1 in both cases. This
is indicative of the intermediacy of alcohol 3 in the formation
of spiroindene 6. The excess of LiAlH4 is crucial, since below
3.3 equivalents, no spirocyclopropane is formed (entry 2).
Scheme 4
The same result is obtained with only one equivalent of
LiAlH4 and one equivalent of LiOEt. This shows that there is
It seems that the thermic effect (boiling point of the solvent) no need of excess of LiAlH4 starting from 3, and that LiOEt
is an important factor to obtain 6, since in THF, at 0 °C, plays the role of a base (entry 11).
reduction of ester 2 into 3 is quantitative (entry 5) and, under
reflux, within 2 h, 3 is totally transformed into spirocyclo- and 1.65 equivalents of LiAlH4, addition of one equivalent of
propane 6 with the usual diastereoselectivity of 1/0.1 (entry 6).
LiOEt in Et2O, under reflux, does not produce 6 (entry 12).
Furthermore, we have observed that starting from ester 2
Nevertheless, the thermic effect (boiling point of the Accordingly, starting from 2, an excess of LiAlH4 (3.3 equi-
solvent) is not the only determining factor, as with 3.33 equiva- valents) is necessary to obtain 6.
lents of LiAlH4, in i-Pr2O either at 0 °C or at reflux, only the
As far as the mechanism and the stereochemistry of the for-
alcohol 3 is quantitatively obtained (entries 7 and 8).
mation of 6 are concerned, it seems that they involve a con-
The nature of the ether used in the reaction is very impor- certed intramolecular mechanism in which a leaving group
tant and in THF the reaction rate for the formation of 6 is sig- (tosyloxy or organoaluminic group) is stereospecifically
nificantly enhanced (entry 6). As suggested by Jorgenson,27 attacked by a carbanionic center. According to Jorgenson, this
and Chen,28 this is indicative of a complexation effect during kind of mechanism is under the control of steric and elec-
the intramolecular reaction leading to the ring closure step.
tronic effects.26
Since we have shown that 6 is formed via 3, by reduction of
The structure of the pseudo-benzylic indenide intermediate
2 by LiAlH4, we have tried to obtain 6 from 3 in Et2O and 2 seems to be responsible for the special reactivity of 2 and 4.
equivalents of LiAlH4. One equivalent is used to form the organo- Steric and electronic factors seem to exert strong control over
aluminic intermediate and a second one for the formation of the reaction.
the corresponding indenide species. After 19 h at reflux, no
In our view, the stereochemistry in 6 is primarily determined
spirocyclopropanic compound 6 is detected (entry 9). This can by a destabilizing methyl peri hydrogen interaction,21 which
be explained by the impossibility for LiAlH4 to play the role of induces a rotation about the bond linking the chiral bridge to
a base and to form the indenide anion susceptible to perform the indene unit so that the methyl falls in an anti-position with
the formation of the three membered ring. The base suitable respect to the peri hydrogen, as shown in Scheme 5.
to play this role could be the ethanolate anion formed in the
reduction steps of ester 2 (Scheme 4).
In the tosylate, as well as in the ester derivatives, deprotona-
tion can occur at position 3, however, due to the stabilization
Indeed, when the reaction is run from alcohol 3, in the same of the carbanionic C–Li bond with the oxygen atom of the tosyl-
conditions as those described above, but in the presence of one oxy group and the existence of a carbanionic C–Li⋯OAl bond
equivalent of LiOEt, 6 is obtained quantitatively after 13 h at in the reduced ester compound, it is the carbanion at position
reflux, with the same diastereoselectivity as usual (entry 10).
1 which prevails.
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Scheme 5
Scheme 6
Scheme 7
This stereorigid complexation could explain the observed
diastereoselectivity.
Indeed, the intramolecular substitution of the leaving
group (tosyloxy from 4, Scheme 6, or aluminate from 2,
Scheme 7) by the stabilized carbanion at position 1 can only
occur according to a stereo-electronic control mechanism so
that the HOMO of this carbanion and the LUMO of the carbon
atom bearing the leaving group can interact, which means that
they are coplanar and close to each other.
Scheme 8
The formation of spirocyclopropane 6, with a diastereo-
selectivity higher than 80%, leads one to envisage the possible
synthesis of optically active ligands, based on well-known reac-
tivity of such spirocyclopropanes. Indeed, thermolysis of 6
might lead to an optically active annulated ligand,29 and ring-
opening regiospecific reactions with different nucleophiles
should give new optically active chelating ligands.17,22,30
Since the ligand we are interested in is 5 and according to
the literature,31–33 we decided to use Cp2Mg as a nucleophile
to obtain 5. Indeed, with Cp2Mg, 4 affords exclusively 5 in
good yield, as a mixture of two double-bond isomers, with no
detectable spirocyclopropane (Scheme 8). The 1H NMR spec-
trum of 5 gives no reasonable structural information due to
the presence of the double-bond isomers of the Cp unit.
Ligand 5 was fully characterized by NMR after preparation of
different metal complexes.
Scheme 9
the 13C NMR spectrum and at 0.27 ppm, in the H NMR spec-
trum. The optical purity of 7, measured by chiral HPLC, was
ee = 74.6%.
From 7, we tried to prepare a heterobimetallic complex
according to the synthetic route described below (Scheme 10).
However, instead of the hoped-for compound 8, we obtained
the cyclopentadienyl rhodium complex 9 resulting from a
metal exchange reaction.
1
The yield of the reaction is rather high (60% yield) and it is
worth noting that the optical purity of complex 9 is main-
tained. The measured ee was 71.4% (14.3S/85.7R) on the crude
Syntheses of complexes
Attempts to obtain group IV transition metal complexes from product. However, after crystallization in hexane/Et2O at
5, either by salt elimination reaction or by the amine elimi- −20 °C, the crystals have lower ee (34.16%; 32.92S/67.08R) and
nation route, were unsuccessful, as we and others have the filtrate was enantio-enriched in the S enantiomer (99.47S/
observed.20,32,34–38
0.53R). This kind of enantiomeric enrichment by crystalliza-
A molybdenum methyltricarbonyl complex 7 was prepared tion is a well-documented common behavior.39 After succes-
according to the following reaction (Scheme 9).
sive crystallizations the R enantiomer is also obtained in high
Complex 7 was fully characterized by 1H and 13C NMR optical purity (ee = 95.2%; 2.4S/97.6R).
measurements. As usually found for this kind of molybdenum
cyclopentadienyl compounds, the characteristic CO resonances
This reaction, rather unexpected, deserves some comments.
At first glance, the scenario for the formation of 9 can be
can be detected, in the 13C NMR, at 240.3 and 227.0 ppm. The described as deprotonation of the indene moiety of complex 7,
methyl group attached to Mo is highly shifted at −19.4 ppm in followed by quenching with [RhCl(COD)]2 to give, apparently,
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Scheme 12
No mechanistic studies have yet been carried out on any of
the π-cyclopentadienyl transfer reactions. However, despite the
lack of experimental results in this area, a few attempts to
suggest a reasonable mechanism have been made.42
Scheme 10
Thus, some general deductions and inferences can be made
on the basis of our data and by analogy with the work of
others. Our results could be interpreted by a change in the hap-
ticity of the indenyl ligand from η5 to η3 and η1 as suggested
by Spradau43 and by Jaouen.44 This could be key to the
observed reaction, as shown in Scheme 11, although no low-
hapticity species could be detected for the assumed transient
molybdenum–rhodium complex, 9 being the only compound
observed and isolated in this reaction. During work-up, hydroly-
sis of the last bimetallic species could lead to complex 9.
However, at this stage, it is difficult to draw decisive con-
clusions about the reality of pathways leading to complex 9 in
the observed reaction, although this tentative explanation of
the experimental observations is consistent with the conserva-
tion of the optical purity of complex 9.
As expected, complex 9 can also be directly obtained in
good yield from ligand 5, as shown in Scheme 12, and can be
purified by chromatography on silica.
Suitable crystals for an X-ray structure determination were
obtained from a fraction containing almost the same pro-
portion of each enantiomer of the complex of rhodium 9.
The X-ray structure of 9 is represented in Fig. 1a. The com-
Scheme 11
an unstable η5-indenyl rhodium complex. The next step is ten- pound crystallizes in the noncentrosymmetric space group P21.
tatively described as a cyclopentadienyl transfer reaction where The asymmetric unit contains two molecules which have oppo-
a CpMo(CO)3Me moiety can act as a versatile source of the site absolute configuration S (atom C7) and R (atom C107).
cyclopentadienyl ligand via
(Scheme 11).
a
metal exchange reaction Although crystallizing in a noncentrosymmetric space group,
the compound is a racemic mixture. Fig. 1b displays the fitting
There are many examples in the literature concerning of the two molecules. In both molecules, the structural para-
π-ligand transfer reactions in which an organic π-ligand is meters around the metal are typical of CpRh(COD) moiety
transferred from one transition metal complex to another. (Table 2).37,38,45,46 The substituted C5 ring is uniformly η5 coor-
Among π-ligands susceptible to be used in this kind of dinated to the Rh with a Rh-centroid of 1.910(7) Å [1.912(7) Å].
process, π-cyclopentadienyl transfer represents the first known The bonds of the Rh atom to the centers of diene systems of
example of a π-ligand transfer reaction in which the formation the COD ligands are slightly longer with values ranging from
of ferrocene was obtained from chromocene and ferrous 1.985(7) to 2.005(4) Å. The coordination around the Rh is trigo-
chloride.40
Although π-cyclopentadienyl transfer reactions in organo- system and the diene systems of the COD ligands.
metallic chemistry are interesting, their practical applications Reaction of the bis lithium salt of 5 with two equivalents of
nal planar if considering the centroids of the cyclopentadienyl
are rather limited in scope and their synthetic feasibility was [RhCl(COD)]2 failed to produce a dinuclear rhodium complex
demonstrated only in a few cases.41 However, in certain cases, because of the difference in reactivity of the cyclopentadiene
π-cyclopentadienyl transfer reactions are the only known way and indene moieties. This kind of difference in reactivity
by which certain cyclopentadienyl metal complexes can be pre- between two differently substituted cyclopentadienes has been
pared. The reactions are run in a tetrahydrofuran solution used for the preparation of heterodinuclear metal
either at ambient temperature or under reflux conditions,42 complexes.14,48
but, most often, in high boiling aromatic solvents such as
xylene or mesitylene.
A homobimetallic complex of rhodium 10 could be pre-
pared when the deprotonation of 5 was run with thallium
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Fig. 1 (a) Molecular view of the molecule A (S absolute configuration) for compound 9 with the atom labeling scheme. Ellipsoids are drawn at the 30% probability
level. H atoms are represented as small spheres of arbitrary radii. (b) Molecular fitting of the two independent molecules within the asymmetric unit.47
Table 2 Selected bond distances and angles (Å) for compound 9. CT(1) and
CT(4) are the centroids of the cyclopentadienyl rings whereas CT(2), CT(3) and
CT(5), CT(6) are the centroids of the diene systems of the COD ligands
Molecule A
Molecule B
Rh(1)–CT(1)
Rh(1)–CT(3)
Rh(1)–CT(2)
C(1)–C(6)
C(6)–C(7)
C(7)–C(9)
C(7)–C(8)
CT(1)–Rh(1)–CT(3)
CT(1)–Rh(1)–CT(2)
CT(3)–Rh(1)–CT(2)
C(5)–C(1)–C(6)
C(2)–C(1)–C(6)
C(1)–C(6)–C(7)
C(9)–C(7)–C(8)
C(9)–C(7)–C(6)
C(8)–C(7)–C(6)
1.910(7)
1.985(7)
2.005(4)
1.488(5)
1.541(4)
1.496(5)
1.534(5)
136.28(4)
136.6(2)
87.1(3)
126.9(3)
125.7(3)
112.8(3)
113.1(3)
111.0(3)
111.2(3)
Rh(2)–CT(4)
Rh(2)–CT(5)
Rh(2)–CT(6)
C(101)–C(106)
C(106)–C(107)
C(107)–C(108)
C(107)–C(109)
CT(4)–Rh(2)–CT(5)
CT(4)–Rh(2)–CT(6)
CT(5)–Rh(2)–CT(6)
C(102)–C(101)–C(106)
C(105)–C(101)–C(106)
C(101)–C(106)–C(107)
C(108)–C(107)–C(109)
C(108)–C(107)–C(106)
C(109)–C(107)–C(106)
1.912(7)
1.987(7)
1.995(4)
1.502(5)
1.563(5)
1.503(6)
1.513(5)
136.03(5)
137.0(2)
86.9(3)
126.3(3)
126.1(3)
111.7(3)
113.6(3)
114.6(3)
107.4(3)
Scheme 13
ethoxide followed by the addition of a stoichiometric amount
of [RhCl(COD)]2 (Scheme 13).
The 1H NMR spectrum of the crude product showed the
presence of two diastereoisomers in an 85 : 15 ratio. Purifi-
cation by cooling this mixture in Et2O at −20 °C led to precipi-
tation of the major diasteroisomer 10a as a yellow solid.
Crystals of this compound allowed an X-ray structure
determination.
A view of compound 10a is shown in Fig. 2. The compound
crystallizes in the noncentrosymmetric space group P212121
and the absolute configuration at the stereogenic C1 carbon
atom is R. The Rh(COD) unit is attached to the prochiral (pS)
side of the indenyl moiety. The planar chirality in the indenyl-
rhodium complexes is assigned pR or pS according to
Halterman.49 The H atom attached to C1 is endo towards
the Rh atom with respect to the indene moiety. Both Rh atoms
Fig. 2 Molecular view of compound 10a with the atom labeling scheme. Ellip-
soids are drawn at the 30% probability level. H atoms are represented as small
are coordinated trigonal planar by the centroids of the spheres of arbitrary radii.
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Table 3 Selected bond lengths [Å] and angles [°] for 10a. CT(1) and CT(4) are
the centroids of the cyclopentadienyl rings whereas CT(2), CT(3) and CT(5),
CT(6) are the centroids of the diene systems of the COD ligands
Experimental
General
All the reactions were carried out under an atmosphere of
argon. The solvents were dried by the appropriate procedure54
and distilled under nitrogen before use. Standard Schlenk
Rh(1)–CT(1)
Rh(1)–CT(2)
Rh(1)–CT(3)
C(1)–C(31)
1.900(3)
Rh(2)–CT(4)
Rh(2)–CT(5)
Rh(2)–CT(6)
C(1)–C(2)
1.892(3)
1.9907(5)
1.9955(5)
1.504(10)
1.512(11)
139.39(3)
132.20(3)
87.947(19)
112.0(6)
1.9781(5)
1.9911(5)
1.531(9)
1.504(10)
136.09(3)
136.81(3)
87.082(19)
110.7(6)
1
techniques and conventional glass vessels were employed. H
C(1)–C(3)
C(2)–C(41)
and 13C NMR spectra were recorded on Bruker AM-200 and
Bruker Avance DRX-500 spectrometers, chemical shifts were
referenced to internal solvent resonances and reported relative
to TMS. Elemental analyses were carried out by the Spectro-
pole-Service d’Analyse Elémentaire-Faculté de St Jérôme. Mass
determination was obtained using ESI-MS HR in the Spectro-
pole department at Paul Cézanne Aix-Marseille III University.
Optical rotations were determined on a Perkin-Elmer Model
241 MC digital polarimeter operating at 20 °C using a 1 dm
cell length. Tosylate 1,55 triflate 156 of ethyl (S)-(−) lactate,
CT(1)–Rh(1)–CT(2)
CT(1)–Rh(1)–CT(3)
CT(2)–Rh(1)–CT(3)
C(31)–C(1)–C(3)
C(31)–C(1)–C(2)
CT(4)–Rh(2)–CT(5)
CT(4)–Rh(2)–CT(6)
CT(5)–Rh(2)–CT(6)
C(3)–C(1)–C(2)
C(41)–C(2)–C(1)
110.2(5)
113.9(6)
cyclopentadienyl rings and the diene systems of the COD
ligands (Table 3) as observed in related structures.49–52
The other minor diastereoisomer could be isolated pure
from the filtrate as an orange solid and its structure was tenta-
tively assigned as the other (pR)-diastereoisomer of the di-
rhodium complex 10b.
In the complexation of 5 to rhodium, the high induction of
planar chirality observed in the formation of 10a and 10b could
be explained by the presence of the stereogenic center in the
connecting bridge adjacent to the indenyl ring. This kind of
hypothesis has been proposed with related indenes and with
chiral linked indenyl-phosphine ligands.22,53
Zr(NMe2)4 and Cp2Mg58 were prepared according to litera-
57
ture methods. Ti(NMe2)4 was purchased from Strem Chemicals
and TlOEt from Aldrich [Caution: thallium ethoxide is highly
toxic and should be only handled with gloves and appropriate
clothing!].
Chiral HPLC: The chiral HPLC analyses were performed on
a
screening unit composed of a Merck D-7000 system
manager, a Merck-Lachrom L-7100 pump, a Merck-Lachrom
L-7360 oven that may accommodate 12 columns alimented by
a Valco 12 positions valve, a Merck-Lachrom L-7400 UV detec-
tor and an on-line chiroptical detector:Jasco OR-1590 polari-
meter. The sign given by the chiroptical detectors is the sign of
the enantiomer in the solvent used for the analysis.59 Reten-
tion times Rt in minutes, retention factors ki = (Rti − Rt0)/Rt0
and enantioselectivity factor α = k2/k1 are given. Rt0 was deter-
mined by injection of tri-tertio-butyl benzene. N-Hexane,
methanol and isopropanol are HPLC grade; the solvents for
It is probable that an optimization of the reaction con-
ditions, such as the influence of the reaction temperature
leading to 10, could influence the composition of the diastereo-
meric mixture in favor of complex 10a.
Conclusions
We have described the synthesis of a new dissymmetric ligand chromatography experiments are degassed and filtered on
where a chiral bridge, derived from ethyl (S)-(−) lactate, con- Millipore membrane 0.45 μm before use. The chiral stationary
nected a cyclopentadiene and an indene moieties. With this phases used are cellulose tris(3,5-dimethylphenylcarbamate)
ligand 5, because of the difference in reactivity between the Chiralcel OD-H (250 × 4.6 mm) and cellulose tris(4-methyl-
cycopentadiene and of the indene units, two new enantiomeri- benzoate) Chiralcel OJ-R (150 × 2.1 mm), all available from
cally pure cyclopentadienyl monometallic complexes of molyb- Chiral Technologies Europe (Illkirch, France).
denum 7 and of rhodium 9 have been prepared. An attempt to
Synthesis of tosylate 4: (S)-2-(1H-inden-3-yl)propyl 4-methyl-
prepare a heterobimetallic complex from the sodium anion of benzenesulfonate. Under argon, to a solution of tosyl chloride
7 and [RhCl(COD)]2 gave an unprecedented intramolecular (4.2 g, 22 mmol) in 40 mL CH2Cl2 cooled to −10 °C was slowly
cyclopentadienyl transfer with loss of the molybdenum, to added a solution of 3 (3.53 g, 20 mmol). Then, NEt3 (3.4 mL,
yield a rhodium complex 9, with conservation of the optical 24 mmol) purified by filtration on a column of basic alumina
purity of the original complex 7. Starting from the bis-thallium was added dropwise over 30 min. The mixture was stirred for
anion of ligand 5 and [RhCl(COD)]2, it was possible to obtain a 24 h at r.t. and poured on crushed ice containing 2 mL of HCl
homobimetallic rhodium complex 10. This complex was (10 N). The organic phase was separated and the aqueous
obtained with a good diastereoselectivity (70% de) with regard phase was extracted 2 times with CH2Cl2. The combined
to the chirality of the indenyl moiety.
organic layers were washed with water until neutrality and
These results, because of the difference in reactivity of dried on MgSO4. Evaporation of the solvent under vacuum
cyclopentadiene and indene moieties and of thallium and afforded 6.65 g (98.6% yield) of pure 4.
lithium anions of ligand 5, in metathetic reactions with metal
1H NMR (CDCl3, 200 MHz): δ 7.71 (d, 2H, 8.3, H arom
complexes, open up prospects of the preparation of a large ortho), 7.25 (d, 2H, 8.0, H arom meta), 7.45–7.10 (m, 4H, H
number of chiral mononuclear and hetero- and homo-dinuc- arom Ind), 6.20 (m, 1H, CH sp2 Ind), 4.26 (dd, 1H, 9.6, 5.0,
lear complexes of different transition metals.
part A of an ABX system), 3.98 (dd, 1H, 9.6, 7.8, part B of an
7986 | Dalton Trans., 2013, 42, 7980–7990
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ABX system), 3.26 (bs, 2H, CH2 Ind), 3.16 (h, 1H, CHCH3), 2.40
1H NMR (CDCl3, 200 MHz): δ 7.49–7.16 (m, 4H, CH arom),
(s, 3H, CH3 para), 1.31 (d, 3H, 6.8, CHCH3). 13C NMR (CDCl3, 6.48–6.06 (m, 3H, CH Cp), 6.22 (bs, 1H, CH sp2 Ind), 3.33 (bs,
50 MHz): δ 144.36, 144.0, 143.8, 143.5 (Cq Ind, Cq sp2 Ind, C 2H, CH2 Ind), 3.12–2.42 (m, 5H, CHCH3, CH2 Cp, CH2-Cq Cp),
ipso), 132.6 (Cq para), 129.4, 128.5, 127.4, 125.7, 124.5, 123.6 1.17 (d, 3H, 6.8, CHCH3). 13C NMR (CDCl3, 50 MHz): δ 149.6,
(CH arom), 118.5 (CH sp2 Ind), 73.1 (CH2 Ind), 37.5 (CH2CH), 148.0, 145.5, 144.9, 144.8 (Cq arom and Cq Cp), 134.9, 133.5,
31.9 (CHCH3), 21.2 (CH3 para), 15.9 (CH3CH). Analysis: Calc 132.4, 130.7, 128.0, 127.6, 126.3, 125.9, 124.4, 124.3, 123.8 (CH
for C19H20O3S; C, 69.48, H, 6.14. Found: C, 69.62, H, 6.34.
Chiral HPLC separation of enantiomers: Chiralcel OD-H, Ind), 37.6 (CH2 Cp), 37.1, 36.2 (CHCH3), 19.6, 19.3 (CHCH3).
hexane/isopropanol 9 : 1, 1 mL min−1, detection by UV 254 nm
Analysis: Calc. for C17H18: C 91.84; H 8.16. Found: C 92.00;
arom and CH Cp), 119.2, 119.1 (CH sp2 Ind), 43.5, 41.3 (CH2
and polarimeter, Rt(S,+) = 8.70, Rt(R,−) = 9.62, k(S) = 1.85, H 8.01.
k(R) = 2.15, α = 1.16. ee = 94.4% (97.22S/2.77R). [α2D5] = +24.3
(c 1.25, CHCl3).
(+)-(R)-[C9H7-CH(CH3)CH2-η5-C5H4] Mo(CO)3CH3 7. To
a
solution of 0.29 g (1.32 mmol) of 5 in 50 mL hexane, cooled at
0 °C, was added, dropwise via a syringe, 1.06 mL (2.65 mmol)
of n-BuLi (2.5 M in hexanes). After stirring for 3 h 30 min at
20 °C, a white precipitate was isolated by filtration and dried
under vacuum. 40 mL of THF was added and 0.34 g
(1.32 mmol) of Mo(CO)6 was dissolved. The solution was
refluxed overnight and, after cooling, 0.1 mL MeI was added.
After 1 h 30 min at reflux, the solution was cooled and THF
was removed under vacuum. The remaining dark-brown solid
was extracted with a mixture of hexane/Et2O to give 0.39 g of a
yellow-brown oil. Purification on a column of silica afforded
0.39 g (72.2% yield) of 7 as a yellow solid.
Preparations
Synthesis of spirocyclopropane 6: (−)-(1R,2R)-2-methylspiro-
[cyclopropane-1,1′-indene]. In a typical experiment, to 1.0 g of
LiAlH4 (26.35 mmol) in 90 mL of dry Et2O cooled at 0 °C was
added a solution of 1.71 g of 2 (7.91 mmol) in 40 mL of Et2O.
The mixture was then refluxed for 65 h, and then it was care-
fully hydrolyzed. After filtration the residue was extracted 3
times with 30 mL of Et2O. The organic extracts were combined
and the crude product was purified on a column of silica gel
to afford 0.98 g (6.27 mmol) of pure 6 (79.7% yield).
1H NMR (CDCl3, 200 MHz): δ 7.47–7.14 (m, 4H, CH arom),
6.15 (m, 1H, CH sp2 Ind), 5.07–5.00 (m, 4H, CH Cp), 3.30 (bs,
2H, CH2 Ind), 2.95 (m, 1H, CH-CH3), 2.62 (dd, 1H, part A of an
ABX system, JHAHB14, JHAHX 6), 2.38 (dd, 1H, part B of an ABX
system, JHBHA 14, JHBHX 7.2), 1.27 (d, 3H, 7, CHCH3), 0.27 (s,
3H, Mo-CH3). 13C NMR (CDCl3, 50 MHz): δ 240.3 (CO), 227.0 (2
CO), 148.3, 144.6, 144.4 (2Cq arom and Cq sp2 Ind), 127.3,
126.0, 124.7, 123.9 (CH arom), 119.1 (CH Ind), 113.3 (Cq Cp),
93.5, 93.3, 90.0, 89.7 (CH Cp), 37.6 (CH2 Ind), 34.9 (CH2-Cp),
34.7 (CHCH3), 19.4 (CHCH3), −19.4 (Mo-CH3). Analysis: Calc.
1H NMR (CDCl3, 400 MHz): δ 7.40 (dt, 1H, 7.4, 1.0, CH-9), 7.21 for C21H20MoO3: C 60.58; H 4.84. Found: C 60.62; H 4.91.
(td, 1H, 7.4, 1.1, CH-8), 7.14 (td, 1H, 7.5, 1.1, CH-7), 6.95 (dm,
Chiral HPLC separation of enantiomers: Chiralcel OJ-R,
1H, 8.0, CH-6), 6.93 (d, 1H, 7.0, CH-11), 6.39 (d, 1H, 5.5, methanol, 0.1 mL min−1, detection by UV 254 nm, Rt(S) =
CH-12), 2.02 (ddq, 1H, 7.1, 6.2, CH-2), 1.73 (dd, 1H, 8.6, 4.3, 9.35, Rt(R) = 10.38, k(S) = 1.92, k(R) = 2.24, α = 1.17. ee =
CH-4b), 1.55 (dd, 1H, 7.1, 4.3, CH-4a), 1.36 (d, 3H, 6.2, CH3-3), 74.6%. [α2D5] = +12.9 (c 0.16, CHCl3).
13C NMR (CDCl3, 100 MHz): δ 148.8 (C-10), 143.0 (C-5), 137.6
(+)-(R)-[C9H7-CH(CH3)CH2-η5-C5H4] Rh(COD) 9. To a solu-
(C-12), 129.6 (C-11), 125.4 (C-8), 124.2 (C-7), 121.4 (C-9), 117.3 tion of 1.01 g (4.55 mmol) of 5 in 100 mL hexane, cooled at
(C-6), 38.5 (C-1), 24.4 (C-2), 23.3 (C-4), 17.2 (C-3). Analysis: 0 °C, was added 3.6 mL of (9.1 mmol) of n-BuLi (2.5 M in
Calc. for C12H12: C 92.26; H 7.74. Found: C 92.30; H 7.71.
hexane). After stirring for 3 h 30 min at 20 °C, a white precipi-
Chiral HPLC separation of enantiomers: Chiralcel OD-H, tate of the lithium salt was isolated by filtration, dried under
hexane/isopropanol 99.5 : 0.5, 1 mL min−1, detection by UV vacuum (1.02 g, 4.14 mmol, 91.0%) and dissolved in 80 mL
254 nm and polarimeter, Rt(SS,+) = 5.37, Rt(RR,−) = 6.85, THF. A solution of 1.02 g (2.07 mmol) of [RhCl(COD)]2 in
k(SS) = 0.76, k(RR) = 1.25, α = 1.64. ee = 94.4%. [α2D5] = −162.9 40 mL of THF was slowly added and the orange-yellow solution
(c 4.38, CHCl3).
was stirred at 20 °C for 18 h. Afterwards, the solvent was
Synthesis of ligand C9H7CH(CH3)CH2C5H5 5: 3-((R)-1(cyclo- removed under vacuum and the crude complex 9 was purified
penta-1,3-dienyl)propan-2-yl)-1H-indene and 3-((R)-1(cyclo- by chromatography on silica to give 1.20 g of pure 9 (61.0%
penta-1,4-dienyl)propan-2-yl)-1H-indene. To 8.3 g (25.3 mmol) yield).
of tosylate 4 in 100 mL THF was slowly added over 1 h 30 min,
1H NMR (CDCl3, 200 MHz): δ 7.48–7.15 (m, 4H, CH arom),
under stirring at 0 °C, a solution of 5.2 g (33.6 mmol) of 6.17 (bs, 1H, CH sp2 Ind), 5.14, 5.11, 4.98, 4.90 (m, 4H, CH
Cp2Mg freshly sublimed. After evaporation of THF under Cp), 3.74 (m, 4H, CH sp2 COD), 3.32 (bs, 2H, CH2 Ind), 2.94
vacuum, the excess of Cp2Mg was carefully hydrolyzed and the (m, 1H, CHCH3), 2.6 (dd, 1H, part A of an ABX system,
organic product was extracted with Et2O. Purification on a JHAHB13.9, JHAHX 4.8), 2.25–2.14 (m, 5H, 1H, part B of an ABX
silica column afforded 4.32 g of pure 5 (77.0% yield).
system, and 4H, 2 CH2 COD), 1.95–1.82 (m, 4H, 2 CH2 COD),
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1.27 (d, 3H, 6.86, CHCH3). 13C NMR (CDCl3, 50 MHz): δ 149.5, 87.29 (d, 3.4, C-13), 85.37 (d, 3.7, C-14), 84.96 (d, 3.6, C-15),
144.8, 144.7 (2Cq arom and Cq sp2 Ind), 126.4, 125.9, 124.4, 72.86 (d, 4.6, C-3), 69.56 (d, 13.7, C-1′), 68.70 (d, 13.6, C-3′),
123.8 (CH arom), 119.2 (CH Ind), 104.3 (Cq Cp, JCRh = 3.7 Hz), 63.79 (d, 14.0, C-1′′), 63.73 (d, 14.0, C-3′′), 36.39 (C-11), 32.57
87.9 (CH Cp, JCRh = 3.5 Hz), 87.1 (CH Cp, JCRh = 3.6 Hz), 85.3 (C-10), 32.55 (C-4′′), 32.46 (C-2′′), 31.56 (C-2′), 31.15 (C-4′),
(CH Cp, JCRh = 4.3 Hz), 84.8 (CH Cp, JCRh = 3.6 Hz), 63.9 (CH 18.11 (C-17). [α2D5] = +50 (c 0.25, CHCl3). HRMS (ESI): for
+
sp2 COD, JCRh = 9.2 Hz), 63.6 (CH sp2 COD, JCRh = 9.4 Hz), 37.6 C33H41Rh2 (M + H)+ Calc. 643.1313, Found: 643.1312. Thus,
(CH2 Ind), 34.4 (CH2-Cp), 32.5 and 32.4 (CH2 COD), 34.3 M = 642.124 Da. Analysis: Calc. for C33H40Rh2: C 61.69; H 6.28.
(CHCH3), 19.3 (CHCH3). [α2D5] = +16.7 (c 0.9, CHCl3). Analysis: Found: C 61.56; H 6.38.
Calc. for C25H29Rh: C 69.44; H 6.76. Found: C 69.66; H 6.38.
(pR)-Minor diastereoisomer, (+)-(pR,RC)[η5-C9H6-CH(CH3)-
Chiral HPLC separation of enantiomers: Chiralcel OJ-R, CH2-η5-C5H4] [Rh(COD)]2 10b.
methanol, 0.1 mL min−1, detection by UV 254 nm, Rt(S) =
23.83, Rt(R) = 26.88, k(S) = 6.45, k(R) = 7.40, α = 1.15. ee =
95.2% (2.4S/97.6R). [α2D5] = +16.7 (c 0.9, CHCl3).
(+)-(pR/pS,R)-[η5-C9H6-CH(CH3)CH2-η5-C5H4] [Rh(COD)]2 10.
To 0.20 g of 5 (0.9 mmol) in 50 mL of dry hexane was added, at
0 °C, 0.13 mL TlOEt (1.83 mmol). After stirring overnight at
20 °C, hexane was evaporated and 70 mL THF was added to
give a red-brown solution. 0.5 g of [RhCl(COD)]2 (1.01 mmol)
dissolved in 20 mL THF was slowly added via canula and the
mixture was stirred for 24 h at 20 °C. After filtration of the TlCl
precipitate, the solution was passed over a short column of
neuter alumina to give 0.42 g of crude product (72.8%). Crys-
tallization from hexane/Et2O 10 : 15 gave a cream colored pre-
cipitate and
a red-orange filtrate. Crystallization of the
1H NMR (CDCl3, 500 MHz): δ 7.30 (d, 1H, 8.0, CH-4), 7.17 (d,
1H, 8.0, CH-7), 7.12 (t, 1H, 7.5, CH-6), 7.08 (t, 1H, 7.5, CH-5),
5.89 (brs, 1H, CH-2), 5.31 (brs, 1H, CH-16), 5.16 (brs, 1H,
CH-13), 4.95 (brs, 2H, CH-3 and CH-15), 3.82 (m, 2H, CH-3′′),
3.78 (m, 4H, CH-1′′ and CH-3′), 3.70 (m, 2H, CH-1′), 2.77 (dd,
1H,13.7, 11.1, part B of an ABMX3, CH-11), 2.57 (m, 1H,
CH-10), 2.29 (dd, 1H, 13.5, 2.5, part A of an ABMX3, CH-11),
1.98–2–26 (m, 8H, CH-2′′, 4′′), 1.88–1.93 (m, 4H, CH-2′),
1.68–1.83 (m, 4H, CH-4′), 1.26 (d, 3H, 6.8, CH-17). 13C NMR
(CDCl3, 125.76 MHz): δ 122.45 (C-6), 121.88 (C-5), 120.20 (C-4),
117.87 (C-7), 112.41 (C-9), 111.47 (C-8), 104.60 (d, 3.4, C-12),
101.33 (brs, C-1), 90.51 (d, 4.9, C-2), 88.30 (d, 3.4, C-16), 87.10
(d, 3.4, C-13), 86.12 (d, 4.0, C-14), 84.73 (d, 4.0, C-15), 72.95 (d,
4.9, C-3), 69.64 (d, 13.5, C-1′), 68.70 (d, 13.6, C-3′), 64.30 (d,
14.0, C-1′′), 63.76 (d, 14.1, C-3′′), 34.45 (C-11), 33.81 (C-10),
32.63 (C-4′′), 32.56 (C-2′′), 31.82 (C-2′), 30.98 (C-4′), 20.93
(C-17). [α2D5] = +236 (c 0.14, CHCl3). Anal. Calc. for C33H40Rh2:
C 61.69; H 6.28. Found: C 61.60; H 6.42.
precipitate from hexane/Et2O, afforded light yellow crystals
suitable for X-ray analysis 10a (0.29 g, 50.3%). Evaporation of
the filtrate afforded, after crystallization from hexane/Et2O,
red-orange crystals 10b (0.027 g, 4.8%).
(pS)-Major diastereoisomer, (+)-(pS,RC)[η5-C9H6-CH(CH3)-
CH2-η5-C5H4] [Rh(COD)]2 10a.
X-ray structure determination
1H NMR (CDCl3, 500 MHz) : δ 7.31 (d, 1H, 8.0, CH-4), 7.17 (d, Single crystals were mounted under inert perfluoropolyether at
1H, 8.0, CH-7), 7.14 (t, 1H, 7.5, CH-6), 7.09 (t, 1H, 7.5, CH-5), the tip of a glass fibre and cooled in the cryostream of either
5.87 (bs, 1H, CH-2), 5.19 (bs, 1H, CH-13), 5.00 (d, 1H, 1.3, the Stoe IPDS diffractometer for 9 or the Oxford-Diffraction
CH-14), 4.95 (d, 1H, 2.6, CH-3), 4.92 (d, 1H, 1.3, CH-15), 4.89 XCALIBUR CCD diffractometer for 10a. Data were collected
(bs, 1H, CH-16), 3.73 (m, 6H, CH-1′′, 3′, 3′′), 3.65 (m, 2H, using the monochromatic MoKα radiation (λ = 0.71073).
CH-1′), 2.71 (m, 1H, CH-10), 2.54 (dd, 1H, 13.9, 3.3, part B of
The structures were solved by direct methods (SIR9760) and
an ABMX3, CH-11), 2.13 (dd, 1H, 13.9, 9.9, part A of an ABMX3, refined by least-squares procedures on F2 using SHELXL-97.61
CH-11), 1.90–2.16 (m, 8H, CH-2′′, 4′′), 1.78–1.90 (m, 4H, CH-2′), All H atoms attached to carbon were introduced in calculation
1.69–1.83 (m, 4H, CH-4′), 1.37 (d, 3H, 6.8, CH3-17). δ 13C NMR in idealised positions and treated as riding models. For com-
(CDCl3, 125.76 MHz): 122.35 (C-6), 121.78 (C-5), 120.21 (C-4), pound 10a, the absolute configuration was deduced from the
117.73 (C-7), 112.41 (C-9), 111.23 (C-8), 103.74 (d, 3.5, C-12), refinement of Flack’s enantiopole parameter62,63 based on a
100.54 (d, 3.6, C-1), 90.75 (d, 4.8, C-2), 88.16 (d, 3.3, C-16), large number of Friedel pairs. The drawing of the molecules
7988 | Dalton Trans., 2013, 42, 7980–7990
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6 C. Bonifaci, A. Ceccon, A. Gambaro, F. Manoli,
L. Mantovani, P. Ganis, S. Santi and A. Venzo, J. Organomet.
Chem., 1998, 577, 97.
Table 4 Crystal data and structure refinement for 9 and 10a
Identification code
9
10a
7 M. Deppner, R. Burger and H. G. Alt, J. Organomet. Chem.,
2004, 689, 1194.
8 H. Ketzen, J. Hiermeir, B. Kanellakopulos, F. H. Köhler,
G. Müller and O. Steigelmann, J. Chem. Soc., Chem.
Commun., 1991, 997.
9 J. Y. Corey, J. L. Huhmann and N. P. Roth, Inorg. Chem.,
1991, 34, 3203.
10 J. Lin, S. Luo, B. Cheng, B. Wang, S. Xu and H. Song, Appl.
Organomet. Chem., 2006, 20, 375.
11 E. S. Cho, Y. C. Won, S. Y. Lee, B. Y. Lee, D. M. Shin and
Y. K. Chung, Inorg. Chim. Acta, 2004, 357, 2301.
12 P. S. Fier, R. R. Reinig, J. King, C. Dicherson, R. M. Chin,
M. Doucouré and W. Brennessel, Organometallics, 2012, 31,
261.
13 M. V. Ovchinnikov, D. P. Klein, I. A. Guzei, M.-G. Choi and
R. J. Angelici, Organometallics, 2002, 21, 617.
14 H. Komatsu and H. Yamazaki, J. Organomet. Chem., 2001,
634, 109.
15 R. Fierro, T. E. Bitterwolf, A. R. Rheingold, G. P. A. Yap and
L. M. Liable-Sands, J. Organomet. Chem., 1996, 524, 19.
16 G. Jany, R. Fawsi, M. Steimann and B. Rieger, Organo-
metallics, 1997, 16, 544.
17 B. Rieger, G. Jany, R. Fawzi and M. Steimann, Organo-
metallics, 1994, 13, 647.
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
a (Å)
b (Å)
c (Å)
α (°)
β (°)
C25H29Rh
432.39
200(2)
0.71070
Monoclinic
P21
7.6672(9)
23.6258(17)
10.9468(11)
90.0
96.389(12)
90.0
1970.6(3)
4
1.457
0.872
C33H40Rh2
642.48
180(2)
0.71073
Orthorhombic
P212121
8.2848(5)
23.8250(13)
13.0062(8)
90
90
90
2567.2(3)
4
1.641
1.306
1280
0.28 × 0.24 × 0.06
2.60 to 28.28°
23 053
6362 (0.0833)
99.9%
Multi-scan
1.0 and 0.592
6362/0/317
1.047
0.0559, 0.1068
0.0758, 0.1145
−0.01(6)
1.531 and −0.970
γ (°)
Volume (Å3)
Z
D (calcd) (Mg m−3
)
Abs. coeff. (mm−1
F(000)
)
896
Crystal size (mm3)
Theta range (°)
Reflts collected
Unique reflts [R(int)]
Completeness (%)
Abs. correction
Max./min. abs.
Data/restr./param.
GOF on F2
0.30 × 0.25 × 0.20
1.87 to 24.14
15 999
6192 (0.04)
98.9%
None
6192/1/471
1.020
R, wR2 [I > 2/s(I)]
R, wR2 (all data)
Flack’s parameter
0.0199, 0.0495
0.0210, 0.0506
−0.03(2)
Resid. density (e Å−3
)
0.510 and −0.246
18 M. J. Burk, S. L. Colletti and R. L. Halterman, Organo-
metallics, 1991, 10, 2998.
19 M. Ringwald, R. Stürmer and H. H. Brintzinger, J. Am.
Chem. Soc., 1999, 121, 1524.
20 R. Laï, F. Chanon, C. Roussel, M. Sanz, N. Vanthuyne and
J.-C. Daran, J. Organomet. Chem., 2008, 693, 23.
21 S. W. Staley, M. A. Fox and T. K. Hirzel, J. Am. Chem. Soc.,
1976, 98, 3910.
was realised with the help of ORTEP32.64 Crystal data and
refinement parameters are shown in Table 4. Bond distances
and angles are given in Table 2 for 9 and Table 3 for 10a.
Crystallographic data (excluding structure factors) have
been deposited with the Cambridge Crystallographic Data
Centre as supplementary publication no. CCDC 857069 and
857070.
22 D. C. Brookings, S. A. Harrison, R. J. Whitby, B. Crombie
and R. V. H. Jones, Organometallics, 2001, 20, 4574.
23 H. E. Zimmerman and T. P. Cutler, J. Org. Chem., 1978, 43,
3283.
24 C. R. Johnson, J. P. Lockard and E. R. Kennedy, J. Org.
Chem., 1980, 45, 264.
Acknowledgements
The authors are indebted to Prof. C. Roussel and Dr R. Faure
for valuable discussions.
25 M. J. Jorgenson and A. W. Friend, J. Am. Chem. Soc., 1965,
87, 1815.
26 M. J. Jorgenson and A. F. Thacher, J. Chem. Soc., Chem.
Commun., 1969, 1290.
References
1 W. Kaminsky, K. Külper, H. H. Brintzinger and 27 M. J. Jorgenson and A. F. Thacher, Org. Synth., 1968, 48, 75.
F. R. W. P. Wild, Angew. Chem., 1985, 24, 507. 28 S.-C. Chen, Synthesis, 1974, 691.
2 J. A. Smith, J. V. Seyerl, G. Huttner and H. H. Brintzinger, 29 R. L. Halterman, Chem. Rev., 1992, 92, 965.
J. Organomet. Chem., 1979, 173, 175.
30 S. Ciruelos, U. Englert, A. Salzer, C. Bolm and A. Maischak,
3 P. J. Shapiro, Coord. Chem. Rev., 2002, 231, 67 and refer-
ences therein.
4 U. Wieser, F. Shaper, H.-H. Brintzinger, N. I. Makela,
Organometallics, 2000, 19, 2240.
31 T. K. Hollis, A. L. Rheingold, N. P. Robinson, J. Whelan and
B. Bosnich, Organometallics, 1992, 11, 2812.
H. R. Knuuttila and M. Leskela, Organometallics, 2002, 21, 32 K.-L. Gibis, G. Helmchen, G. Huttner and L. Zsolnai,
541. J. Organomet. Chem., 1993, 445, 181.
5 D. Takeuchi, J. Kuwabara and K. Osakada, Organometallics, 33 R. L. Halterman, Z. Chen and M. A. Khan, Organometallics,
2003, 22, 2305.
1996, 15, 3957.
This journal is © The Royal Society of Chemistry 2013
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View Article Online
Paper
Dalton Transactions
34 R. L. Halterman, A. Tretyakov, D. Combs, J. Chang and 50 A. Bisello, A. Ceccon, A. Gambaro, P. Ganis, F. Manoli,
M. A. Khan, Organometallics, 1997, 16, 3333.
S. Santi and A. Venzo, J. Organomet. Chem., 2000, 593,
35 R. B. Grossman, J.-C. Tsai, W. M. Davis, A. Guttierrez and
S. R. Buchwald, Organometallics, 1994, 13, 3892.
315.
51 H. Komatsu, Y. Suzuki and H. Yamazaki, Chem. Lett., 2001,
36 K. C. Rupert, C. C. Liu, T. T. Nguyen, M. A. Whitener and
J. R. Sowa Jr, Organometallics, 2002, 27, 144.
37 F. Cicogna, B. Gaddi, G. Ingrosso, M. Marcaccio,
998.
52 P. E. Gaede and C. van Wullen, Z. Anorg. Allg. Chem., 2006,
632, 541.
F. Marchetti, D. Paolucci, F. Paolucci, C. Pinzino and 53 Y. Kataoka, Y. Iwato, T. Yamagata and K. Tani, Organo-
F. Viglione, Inorg. Chim. Acta, 2004, 357, 2915. metallics, 1999, 18, 5423.
38 P. Escarpa, P. E. Gaede, P. H. Moran and A.-N. Richarz, 54 D. D. Perrin and W. L. F. Armarego, Purification of Labora-
J. Organomet. Chem., 1998, 559, 107. tory Chemicals, Pergamon Press, Oxford, 3rd edn, 1988.
39 E. L. Eliel and S. H. Wilen, in Stereochemistry of Organic 55 J. Gabard and A. Collet, New J. Chem., 1986, 10, 685.
Compounds, Wiley, New York, 1st edn, 1994, p. 381.
40 G. Wilkinson, F. A. Cotton and J. M. Birmingham, J. Inorg.
Nucl. Chem., 1956, 2, 95.
41 A. C. Esqueda, S. Conejero, C. Maya and E. Carmona,
Organometallics, 2009, 28, 45.
56 F. Effenberger, U. Burkard and J. Willfahrt, Liebigs Ann.
Chem., 1986, 1986, 314.
57 G. M. Diamond, R. F. Jordan and J. L. Petersen, J. Am.
Chem. Soc., 1996, 118, 8024.
58 A. W. Duff, P. B. Hitchcock, M. F. Lappert, R. G. Taylor and
J. A. Segal, J. Organomet. Chem., 1985, 293, 271.
42 A. Efraty, J. Organomet. Chem., 1973, 57, 1.
43 T. W. Spradau and J. A. Katznellenbogen, Organometallics, 59 C. Roussel, N. Vanthuyne, M. Serradeil-Albalat and
1998, 17, 2009. J. C. Vallejos, J. Chromatogr., A, 2003, 995, 79.
44 S. Top, C. Lescop, J.-S. Lehn and G. Jaouen, J. Organomet. 60 A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano,
Chem., 2000, 593–594, 167.
45 C. Herrmann, G. Kehr, R. Frohlich and G. Erker, Organo-
metallics, 2008, 27, 2328.
46 X. You-Feng, S. Yan and P. Zhen, J. Organomet. Chem.,
2004, 689, 823.
47 A. L. Spek, J. Appl. Crystallogr., 2003, 36, 7.
C. Giacovazzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori
and R. Spagna, J. Appl.Crystallogr., 1999, 32, 115.
61 G. M. Sheldrick, Acta Crystallogr., Sect. A: Fundam. Crystal-
logr., 2008, 64, 112.
62 H. D. Flack, Acta Crystallogr., Sect A: Fundam. Crystallogr.,
1983, 39, 876.
48 D. Schneider and H. Werner, Organometallics, 1993, 12, 4420. 63 G. Bernardinelli and H. D. Flack, Acta Crystallogr., Sect A:
49 H. Schumann, O. Stenzel, S. Dechert, F. Girgsdies and
Fundam. Crystallogr., 1985, 41, 500.
R. L. Halterman, Organometallics, 2001, 20, 2215.
64 L. J. Farrugia, J. Appl. Crystallogr., 1997, 30, 565.
7990 | Dalton Trans., 2013, 42, 7980–7990
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