Induction of planar chirality in formation of (η5:η1-1-(1-cyclohexyl-2-(diphenylphosphino)ethyl) indenyl)-carbonylrhodium and (η5:η1-1-(2-phenyl-2-(diphenylphosphino)ethyl)inde nyl)carbonylrhodium

Article abstract of DOI:10.1021/om010367s

The enantiopure bidentate indenyl-phosphine ligands (1S)-[2-(3H-inden-1-yl)-1-phenyl-ethyl]diphenylphosphine (9) and [(2R)-2-cyclohexyl-2-(3H-inden-1-yl)ethyl]diphenylphosphine (18) were synthesized in 20% yield and three steps from (R)-styrene oxide and in 61% yield and four steps from vinylcyclohexane, respectively. In both cases ring opening of a spirocyclopropane-1,1′-indene with potassium diphenylphosphide was a key step. Addition of the lithium salts of 9 and 18 to [Rh(μ-Cl)(CO)₂]₂ gave (η⁵:η¹-indenyl-CH₂CH(Ph)PPh₂ )RhCO and (η⁵:η¹-indenyl-CH(Cy)CH₂PPh₂ )RhCO as 75:25 and 78:22 mixtures of diastereoisomers, from which the major complexes were readily obtained by crystallization. The chiral centers in the linking chain β and α to the indenyl ring had thus induced good planar chirality of the complexed indenyl moiety. Both complexes were characterized by X-ray crystallography.

Full text of DOI:10.1021/om010367s

4574
Organometallics 2001, 20, 4574-4583
In d u ction of P la n a r Ch ir a lity in F or m a tion of
(η5:η1-1-(1-Cycloh exyl-2-(d ip h en ylp h osp h in o)eth yl)in d en yl)-
ca r bon ylr h od iu m a n d (η5:η1-1-(2-P h en yl-2-
(d ip h en ylp h osp h in o)eth yl)in d en yl)ca r bon ylr h od iu m
Daniel C. Brookings, Stephen A. Harrison, and Richard J . Whitby*
Department of Chemistry, Southampton University, Highfield,
Southampton, HANTS SO17 1BJ , U.K.
Barry Crombie and Ray V. H. J ones
Syngenta, Earls Road, Grangemouth, Stirlingshire FK3 8XG, U.K.
Received May 7, 2001
The enantiopure bidentate indenyl-phosphine ligands (1S)-[2-(3H-inden-1-yl)-1-phenyl-
ethyl]diphenylphosphine (9) and [(2R)-2-cyclohexyl-2-(3H-inden-1-yl)ethyl]diphenylphosphine
(18) were synthesized in 20% yield and three steps from (R)-styrene oxide and in 61% yield
and four steps from vinylcyclohexane, respectively. In both cases ring opening of a spiro-
cyclopropane-1,1′-indene with potassium diphenylphosphide was a key step. Addition of the
lithium salts of 9 and 18 to [Rh(µ-Cl)(CO)2]2 gave (η5:η1-indenyl-CH2CH(Ph)PPh2)RhCO and
(η5:η1-indenyl-CH(Cy)CH2PPh2)RhCO as 75:25 and 78:22 mixtures of diastereoisomers, from
which the major complexes were readily obtained by crystallization. The chiral centers in
the linking chain â and R to the indenyl ring had thus induced good planar chirality of the
complexed indenyl moiety. Both complexes were characterized by X-ray crystallography.
In tr od u ction
cyclopentadienyl complexes to date, the ansa-metal-
locenes (e.g. 1), are illustrative.4
The development of chiral transition-metal catalysts
for asymmetric transformations has been one of the
most significant advances in synthetic organic chemistry
over the past decade.1 Most have been based on bis-
phosphine or bis-alkoxide ligands (usually C2 sym-
metric), with recent interest in less symmetric systems
such as aminophosphines.1 The most common ligand in
transition-metal chemistry is η5-cyclopentadienyl (and
related substituted and indenyl versions), and there
have been many attempts to develop effective chiral
versions, with limited success.2-9 For efficient transfer
of chirality from a metal complex to a substrate the
source of chirality needs to be close to the metal center.
The best prospect for this with η5-cyclopentadienyl
complexes is when the cyclopentadiene is nonsymmetri-
cally substituted, thus generating planar chirality on
coordination to the metal. The most successful chiral
A problem with 1 is that the ligand used in the
complexation, 1,2-bis(indenyl)ethane, is achiral; thus,
coordination of the metal to the enantiofaces of the
indenyl moieties is nonselective, resulting in a racemic
complex (as well as a meso form). A solution would be
(5) (a) Burk, M.; Colletti, S. L.; Halterman, R. L. Organometallics
1991, 10, 2998-3000. (b) Halterman, R. L.; Zhu, C.; Chen, Z.; Dunlap,
M. S.; Khan, M. A.; Nicholas, K. M. Organometallics 2000, 19, 3824-
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Organomet. Chem. 1996, 520, 163-170. (d) J any, G.; Fawzi, R.;
Steimann, M.; Rieger, B. Organometallics 1997, 16, 544-550. (e) J any,
G.; Repo, T.; Gustafsson, M.; Leskela, M.; Polamo, M.; Klinga, M.;
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Kru¨ger, C.; Nolte, M.; Werner, S. J . Am. Chem. Soc. 1993, 115, 4590.
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Tetrahedron Lett. 1996, 37, 7139-7142. (b) Bell, L.; Brookings, D. C.;
Dawson, G. J .; Whitby, R. J .; J ones, R. V. H.; Standen, M. C. H.
Tetrahedron 1998, 54, 14617-14634. (c) Dawson, G.; Durrant, C. A.;
Kirk, G. G.; Whitby, R. J .; J ones, R. V. H.; Standen, M. C. H.
Tetrahedron Lett. 1997, 38, 2335-2338.
* To whom correspondence should be addressed. E-mail: RJ W1@
soton.ac.uk.
(1) Catalytic Asymmetric Synthesis, 2nd ed.; Ojima, I., Ed.; Wiley:
New York, 2000. Comprehensive Asymmetric Catalysis; J acobsen, E.
N., Pfaltz, A., Yamamoto, H., Eds.; Springer-Verlag: Berlin, 1999.
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530, 225-234. (b) Halterman, R. L.; Chen, Z. L.; Khan, M. A.
Organometallics 1996, 15, 3957-3967. (c) Widauer, C.; Bernet, B.;
Vasella, A. Synth. Commun. 1998, 28, 593-602. (d) Salzer, A.; Hosang,
A.; Knuppertz, J .; Englert, U. Eur. J . Inorg. Chem. 1999, 1497-1505.
(e) Ringwald, M.; Sturmer, R.; Brintzinger, H. H. J . Am. Chem. Soc.
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(4) (a) Hoveyda, A. H.; Morken, J . P. Angew. Chem., Int. Ed. Engl.
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10.1021/om010367s CCC: $20.00 © 2001 American Chemical Society
Publication on Web 09/18/2001

Induction of Planar Chirality in Rhodium Complexes
Organometallics, Vol. 20, No. 22, 2001 4575
Sch em e 1
to use a chiral group in the ligand to direct selective
metalation of one enantioface of a nonsymmetrically
substituted cyclopentadiene. For ansa-metallocenes of
titanium and zirconium incorporation of a chiral center
in the connecting chain5 and replacement of the satu-
rated ring of the tetrahydroindenyl moiety with a chiral
bridged bicyclic system have been successful.6
For unlinked cyclopentadienes (and thus potentially
applicable to monocyclopentadienyl complexes) the 3-neo-
menthylindenyl ligand introduced by Erker7 and used
by us in the synthesis of complex 28 is particularly
significant. The neomenthyl group provides good “in-
duction of planar chirality” (6:1 dr) on complexation to
zirconium. The complex 2 gives good enantiomeric
inductions when used as a catalyst for ethylmagnesia-
tion and 2-aluminoethylalumination reactions.8 Fusion
of a chiral bridged bicyclic system to a cyclopentadiene
provides another method for enantiofacially directed
metalation.9
We wished to extend our studies on “planar chiral”
complexes to monocyclopentadienyl complexes of later
transition metals. A few chiral monocyclopentadienyl
complexes of rhodium, ruthenium, cobalt, and iron are
known but give low enantioinductions in catalyzed
reactions.10 Ferrocenes containing planar-chiral cyclo-
pentadienes are well-known and have generally been
produced by elaboration of the ligand after formation
of the complex.11 To provide orientation on the metal,
we chose to investigate complexes of bidentate linked
phosphine-indene ligands. Our aim was to direct the
metal to one enantioface of the indene using a chiral
center in the connecting chain (induction of planar
chirality).
We now report the synthesis of the novel bidentate
indenyl-phosphine ligands 9 and 18 and their rhodium-
(I) carbonyl complexes, in which a chiral center in the
linking chain induces selective complexation of the
metal to one enantioface of the indene.
Linked cyclopentadienyl-phosphine metal complexes
have been recently reviewed.12 The only use of linked
indenyl-phosphine ligands has been for some rhodium
complexes recently reported by Tani.13 Examples of
linked cyclopentadiene-phosphine ligands with chiral
centers in the connecting chain are known,14 but not
where induction of planar chirality on complexation of
the cyclopentadiene to the metal is a feature.15 Recently
Tani reported the 1-neomenthyl-3-(2-(diphenylphosphi-
no)ethyl)indenyl ligand, where (as with 2) the neomen-
thyl group directs enantiofacially selective metalation
to afford the complex 3.16
Resu lts a n d Discu ssion
Syn th esis a n d Com p lexa tion of a Liga n d w ith a
Ch ir a l Cen ter r to P h osp h or u s. Reaction of styrene
oxide (4) (commercially available as either enantiomer)
with indenyllithium according to the method of Reiger17
affords a 3:2 mixture of the readily separated alcohols
5 and 618 (Scheme 1). Tosylation of 5 followed by
reaction with potassium diphenylphosphide (14 h, 20
°C) gave the rearranged ligand 9. The regiochemistry
of ring opening was indicated by the chemical shifts and
couplings to phosphorus of the CHPh (δC 44.0 ppm,
J CP ) 14 Hz) and CH2Ind (δC 31.7 ppm, J CP ) 24 Hz)
2
carbons. It is usual for J CP > 1J CP in similar systems.19
(9) (a) Rousset, C. J .; Iyer, S.; Negishi, E. Tetrahedron: Asymmetry
1997, 8, 3921-3926. (b) Halterman, R. L.; Tretyakov, A. Tetrahedron
1995, 51, 4371-4382. (c) Liu, C.; Sowa, J . R. Tetrahedron Lett. 1996,
37, 7241-7244. (d) Pala, C.; Podewils, F.; Salzer, A.; Englert, U.;
Ganter, C. Tetrahedron 2000, 56, 17-20. (e) Pfister, B.; Stauber, R.;
Salzer, A. J . Organomet. Chem. 1997, 533, 131-141. (f) Ramsden, J .
A.; Milner, D. J .; Adams, H.; Bailey, N. A.; Hempstead, P. D.; White,
C. J . Organomet. Chem. 1998, 551, 355-366.
(10) (a) Ramsden, J . A.; Milner, D.; Adams, H.; Bailey, N. A.; White,
C. J . Organomet. Chem. 1995, 495, 215-220. (b) Ma, Y.; Bergman, R.
G. Organometallics 1994, 13, 2548-2550. (c) McArdle, P.; Ryder, A.
G.; Cunningham, D. Organometallics 1997, 16, 2638-2645. Also see
refs 3d and 9d-f.
(11) Richards, C. J .; Locke, A. J . Tetrahedron: Asymmetry 1998, 9,
2377-2407.
(12) Butenscho¨n, H. Chem. Rev. 2000, 100, 1527-1564.
(13) (a) Kataoka, Y.; Shibahara, A.; Saito, Y.; Yamagata, T.; Tani,
K. Organometallics 1998, 17, 4338-4340. (b) Kataoka, Y.; Saito, Y.;
Shibahara, A.; Tani, K. Chem. Lett. 1997, 621-622.
(14) (a) Kataoka, Y.; Saito, Y.; Nagata, K.; Kitamura, K.; Shibahara,
A.; Tani, K. Chem. Lett. 1995, 833-834. (b) Trost, B. M.; Vidal, B.;
Thommen, M. Chem. Eur. J . 1999, 5, 1055-1069. (c) van der Zeijden,
A. A. H.; J imenez, J .; Mattheis, C.; Wagner, C.; Merzweiler, K. Eur.
J . Inorg. Chem. 1999, 1919-1930. (d) Nishibayashi, Y.; Takei, I.; Hidai,
M. Organometallics 1997, 16, 3091-3093.
Further confirmation came from the observation of long-
range correlation between the alkyl chain CH2 protons
and the vinyl CH carbon on the indenyl ring. A reason-
(15) Tani reported complexation of [5-(3H-inden-1-ylmethyl)-2,2-
dimethyl[1,3]dioxolan-4-ylmethyl]diphenylphosphane to [Rh(µ-Cl)-
(CO)2]2 to give a 69:31 mixture of diastereoisomers.14a Trost reported14b
a variety of ruthenium complexes of 3-benzylcyclopentadienes attached
a four-carbon chain containing chiral substituents to a
diphenylphosphine group. The best mixture of diastereoisomers ob-
tained was 1.6:1.
through
(16) (a) Kataoka, Y.; Iwato, Y.; Shibahara, A.; Yamagata, T.; Tani,
K. Chem. Commun. 2000, 841-842. (b) Kataoka, Y.; Iwato, Y.;
Yamagata, T.; Tani, K. Organometallics 1999, 18, 5423-5425.
(17) Reiger, B.; J any, G.; Fawzi, R.; Steimann, M. Organometallics
1994, 13, 647-653.
(18) Reiger reports17 obtaining just the alcohol 5 in 67% yield,
although the proton NMR data he gives is only consistent with 6. Since
ring closure to the spiroindene 8 gives the same product from either
isomeric alcohol, the mixture could be used, although we found that
tosylation of 6 was slow and mesylation preferable.
(19) Krut’ko, D. P.; Borzov, M. V.; Veksler, E. N.; Kirsanov, R. S.;
Churakov, A. V. Eur. J . Inorg. Chem. 1999, 1973-1979.

4576 Organometallics, Vol. 20, No. 22, 2001
Brookings et al.
Ta ble 1. NMR Assign m en ts for 10 a n d 20
able explanation for the unexpected regiochemistry of
9 arises from the initial formation of the spirocycle 8
via deprotonation of the indenyl ligand by the diphen-
ylphosphide and ring closure. Attack on 8 by diphen-
ylphosphide at the activated benzylic position would
then afford 9.20 Support for this mechanism came from
treatment of a solution of 7 with n-butyllithium to afford
8 as a single diastereoisomer, confirmed to be as shown
by X-ray crystallography.21 Spiroindene 8 was then
opened efficiently by potassium diphenylphosphide to
afford 9. Selective attack at the benzylic position of 8
by cyclopentadienide has been previously noted.17 After
completion of this work Salzer reported the same
regiochemistry in opening 2-phenylspiro[2.4]hepta-4,6-
diene with diphenylphosphide.22 It is interesting that
we get complete conversion of 7 into 9 using 1.1 equiv
of Ph2PK, indicating a catalytic cycle in which the
indenyl anion formed by diphenylphosphide opening of
8 deprotonates the Ph2PH formed in the initial depro-
tonation of 7.
The (S)-indenyl phosphine 9 was treated with n-
butyllithium in THF and the deep red solution added
to a golden yellow solution of [Rh(µ-Cl)(CO)2]2 in THF
at -78 °C. The addition resulted in a dark brown
solution which was warmed to room temperature over-
10
20
δC
191.26 17.9 88.4
a
a
a
a
δC
190.29 17
137.53 13.5
135.3 39.5
131.95 10.5
J CP
J CRh
J CP
J CRh
CO
89
1
1
CO
o-Pha
i-Ph
o-Ph
i-Ph
o-Ph
p-Ph
134.48 13.8
134.42 38.4
131.72 11.6
1.0
1.0
1.2
1
night. H NMR analysis of the crude product revealed
o-Phb
the formation of a rhodium(I) indenyl complex as a 3:1
mixture of the diastereoisomers 10 and 11. The racemic
ligand gave a 5:2 mixture. Purification of the complex
was achieved by column chromatography on neutral
alumina to give a mixture of the complexes as a yellow
powder in an excellent 71% yield. The diastereoisomeri-
cally pure complex 10 was isolated by recrystallization
from diethyl ether/hexanes in 30% overall yield. IR and
13C NMR spectroscopy confirmed the presence of the
carbonyl group with νCO at 1946 cm-1 and a doublet of
doublets (J CRh ) 89 Hz, J CP ) 17 Hz) in the 13C NMR
spectrum at 191 ppm, characteristic of a carbonyl group
bound to rhodium.13 Analysis of the proton-decoupled
31P NMR spectrum showed a doublet at 86.2 ppm with
J PRh ) 214 Hz, indicative of a phosphorus attached to
a rhodium(I) center.23 The large downfield shift of the
phosphorus signal to 86.2 ppm is characteristic of the
formation of a five-membered chelate ring,23 lending
support to the proposed structure of 10. The increase
p-Pha 131.05
2.2
42.1
2.8
130.52
136.25 44.6
129.82 2.4
2.4
i-Ph
130.0
3.2 i-Ph
3.5
p-Phb 129.64
p-Ph
m-Ph
m-Ph
6
5
3a
4
7
m-Phb 128.48 10
128.50 10.4
128.44 10.6
m-Pha 127.61 11.5
6
5
3a
4
7
7a
2
1
3
9
124.31
121.91
120.95
118.46
117.13
116.1
98.4
92.1
72.4
67.77 18.4
30.46
137.8
124.37
121.09
116.41
117.92
117.42
116.08
91.36
103.23
76.09 10.6
52.60 29.7
0.7
1.0
1.6
2.3
1.2
1.4
2.1
5.6
4.8
1.6 7a
1.1
5.6
5.0
0.9
3.1
3.8
3.6
4.0
3.7
3.2
2
1
3
9
8
10
11/11′
11/11′
12/12′/13
12/12′/13
12/12′/13
10.8
8
9
39.37
4.8
10
12
11
13
9.5
3.0
2.2
2.2
1
42.95 22.4
33.56
31.17
26.58
26.42
128.36
128.20
127.37
26.25
1
in J PC to the attached phenyl rings from ∼16 Hz in the
10
20
free ligand to ∼40 Hz in the complex is also indicative
in an increase in coordination number around phospho-
rus from 3 to 4.24 The proton and carbon NMR of 10
was fully assigned using H-H COSY, long- and short-
range carbon-proton correlation (HMBC and HMQC),
δH
J HP
δH
J HP
J HRh
H-8a
2.636
2.813
5.552
14
62.3
14
H-8
2.63
2.93
3.30
9.0
7.0
13.3
H-8b
H-9
H-9a
H-9b
2.5
a
J CP and J CRh may be interchanged; the assignment is based
(20) (a) Berghus, K.; Hamsen, A.; Rensing, A.; Woltermann, A.;
Kauffmann, T. Angew. Chem., Int. Ed. Engl. 1981, 20, 117-118. (b)
Kauffmann, T.; Ennen, J .; Lhotak, H.; Rensing, A.; Steinseifer, F.;
Woltermann, A. Angew. Chem., Int. Ed. Engl. 1980, 19, 328-329.
(21) Crystal data: C17H14, Mr ) 218.28, monoclinic, space group P21/
c, a ) 6.9761(14) Å, b ) 12.498(3) Å, c ) 14.135(3) Å, â ) 93.36(3)°,
V ) 1230.3(4) Å3, Z ) 4, T ) 150 K, 9994 measured/2794 independent
reflections, R(int) ) 0.0458. The final R1 and wR2 values were 0.0516
and 0.1216 (0.0802, 0.1390, all data). This structure report will be
published elsewhere.
only on expected values.
and NOESY spectra in both CDCl3 and C6D6. Compari-
son of carbon-13 spectra at 100 and 75 MHz allowed
splittings due to chemical shift differences and coupling
to phosphorus or rhodium to be unambiguously distin-
guished. The results are shown in Table 1. The proton
NMR of 10 contained items of note relating to stereo-
chemistry. One is that one of the diastereotopic bridge
(22) Ciruelos, S.; Englert, U.; Salzer, A.; Bolm, C.; Maischak, A.
Organometallics 2000, 19, 2240-2242.
(23) (a) Lee, I.; Dahan, F.; Maisonnat, A.; Poilblanc, R. Organome-
tallics 1994, 13, 2743-2750. (b) Lefort, L.; Crane, T. W.; Farwell, M.
D.; Baruch, D. M.; Kaeuper, J . A.; Lachicotte, R. J .; J ones, W. D.
Organometallics 1998, 17, 3889-3899.
CH2- protons (H8b) shows J PH ) 63 Hz coupling to
phosphorus (confirmed in the proton-coupled phospho-
rus NMR). For comparison, the other CH2 proton (H8a)
and the CHPh proton show couplings of 14 Hz to the
4
(24) Dixon, K. R. Multinuclear NMR; Mason, J ., Ed.; Plenum
Press: New York, 1987; Chapter 13.

Induction of Planar Chirality in Rhodium Complexes
Organometallics, Vol. 20, No. 22, 2001 4577
Ta ble 2. Cr ysta llogr a p h ic Da ta for 10 a n d 20
10
20
empirical formula
fw
C
534.4
30H24OPRh
C30H30OPRh
540.4
cryst syst
space group
a (Å)
b (Å)
c (Å)
monoclinic
P21
orthorhombic
Pbca
17.055(3)
16.304(3)
17.645(4)
8.6414(2)
24.6807(5)
11.1050(3)
92.6787(1)
2365.84(10)
4
â (deg)
V (Å3)
Z
4906.5(17)
8
1.463
Dcalcd (g cm-3
)
1.500
0.810
µ(Mo KR) (mm-1
cryst size (mm)
F000
)
0.782
0.4 × 0.3 × 0.25
0.1 × 0.05 × 0.05
1088
2224
temp (K)
150(2)
150(2)
no. of measd rflns
no. of unique rflns
no. of observns
(I > 2σ(I))
31 633
31 323
10359 (Rint ) 0.055) 5617 (Rint ) 0.1083)
9443
3416
F igu r e 1. ORTEP view of the molecular structure of 10.
Thermal ellipsoids are drawn at 50% probability.
no. of variables
595
298
a
residuals: R; Rw
0.0444; 0.0995
0.0432; 0.0764
0.750/-0.620
0.945
F
max/Fmin (e Å-3
)
2.55b/-0.755
goodness of fit on F2 1.083
R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) [(∑w(|Fo| - |Fc|)2/∑wFo2)]1/2
.
A
a
b
ripple peak located 1.03 Å from Rh with no structural meaning.
phosphorus. The exceptionally high 63 Hz coupling
presumably reflects a close to 180° dihedral angle for
PCC(H8b). H8a also shows NOE correlations to the
indenyl proton on C2. For comparison, H8b shows an
NOE to H9 and that of H9 to H7 on the indenyl moiety.
Taken together, these observations confirm the relative
configurations of the side chain chiral center and the
planar chirality of the indenyl ring. NOE correlations
between both H2 and H8a and the ortho protons on one
of the phenyl rings attached to phosphorus allowed this
to be identified as Pha. A notable long-range coupling
F igu r e 2. Possible transition states for the formation of
10 and 11.
Ta ble 3. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 10 a n d 20
10
20
Rh-C(1)
Rh-C(2)
Rh-C(3)
Rh-C(3a)
Rh-C(7a)
Rh-P
2.171(5)
2.240(5)
2.267(5)
2.448(5)
2.381(5)
2.241(1)
1.843(6)
2.179(3)
2.227(3)
2.261(3)
2.433(3)
2.395(3)
2.2226(9)
1.836(4)
5
is J CP ) 2.2 Hz to C13, probably due to the close
alignment of the P-CHPh bond with the aromatic π
Rh-CO
1
system. Rhodium shows J CRh ) 1-6 Hz to the cyclo-
pentadienyl carbons,25 2J CRh ) 1 and 3.2 Hz to the ipso
Cpcentroid-Rh-P
118.0
116.9
3
P-Ph carbons, and a notable J CRh ) 1 Hz to C10,
Rh-P-C(9)-C(10)
Rh-P-C(9)-H(9a)
P-C(9)-C(8)-H(8a)
P-C(9)-C(8)-H(8b)
P-C(9)-C(8)-C(10)
P-C(9)-C(8)-H(8)
165.1(4)
presumably reflecting a close to 180° RhPC(C10) dihe-
dral angle.
162.9(2)
74.6(5)
167.6(4)
Slow crystallization of (S,S)-10 from pentane-ether
gave red cubic crystals suitable for X-ray crystal-
lography. Details of the crystal structure determination
are given in Table 2, an ORTEP picture is given in
Figure 1, and important geometric parameters are given
in Table 3. It was interesting to confirm the near 180°
dihedral angle PCC(H8b) and RhPC(C10) predicted by
the proton-phosphorus and carbon-rhodium coupling
constants described above. The indenyl ring shows a
166.9(2)
74.57(3)
C5H4(CH2)2PPh2Rh(CH2dCH2),23a (C5H4SiMe2CH2PPh2)-
Rh(CO),23b and (C5H4CH2CHPhPPh2)Rh(CH2dCH2).22
We were surprised to achieve such a high level of
induction of planar chirality with the inducing center
remote to the indenyl ring. The most likely explanation
is that complexation of phosphine to the rhodium
precedes chloride displacement by the metalated indene,
as suggested by Poilblanc for complexation of [Cp-
(CH2)2PPh2]- to [Rh(µ-Cl)CO2]2.23a Since chloride dis-
placement then takes place via a cyclic transition state,
perhaps resembling Figure 2 (A leads to 10), the
substantial effect of the phenyl substituent is reason-
able.28 Poilblanc further suggests that two ligands bind
to the rhodium dimer before chloride displacement,
which could explain the small but consistent difference
in facial selectivity observed with the chiral and racemic
ligands (3:1; cf. 5:2 for 10 and 11, respectively). The use
similar distortion toward η3 coordination as (Ind)Rh-
26a
(CO)2
and (Ind)Rh(PMe3)2,26b the bonds between
rhodium and the benzene-ring-fused cyclopentadienyl
carbons being around 0.2 Å longer than the others. The
chelate ring causes some tilting of the cyclopentadiene
(Rh-C(1) is 0.09 Å shorter than Rh-C(3)), and the Cp-
(centroid)-Rh-P angle (118.0°) is much smaller than
in CpRh(PPh3)(CO)27 (134.8°)seffects also observed in
(25) 13C NMR Data for Organometallic Compounds; Mann, B. E.,
Taylor, B. F., Eds.; Academic Press: New York, 1981.
(26) (a) Kakkar, A. K.; Taylor, N. J .; Calabrese, J . C.; Nugent, W.
A.; Roe, D. C.; Connaway, E. A.; Marder, T. B. J . Chem. Soc., Chem.
Commun. 1989, 990-992. (b) Marder, T. B.; Calabrese, J . C.; Roe, D.
C.; Tulip, T. H. Organometallics 1987, 6, 2012-2014.
(27) Choi, M.-G.; Brown, T. L. Inorg. Chem. 1993, 32, 5603-5610.

4578 Organometallics, Vol. 20, No. 22, 2001
Brookings et al.
Sch em e 2
F igu r e 3. “Favored rotamer” model for induction of planar
chirality.
of an initially formed zirconium-alkoxide bond has been
used by Baker to direct metalation to one enantioface
of an indene.29
Syn th esis a n d Com p lexa tion of a Liga n d w ith a
Ch ir a l Cen ter r to th e In d en e. In complexation of
3-neomenthylindene to zirconium7,8 and rhodium,30 and
in the formation of 3,16 high induction of planar chirality
is observed. Related indenes such as 3-(1-phenylethyl)-
indene, with a chiral center adjacent to the indenyl ring,
also give good diastereoinduction.30 The mechanism of
enantiofacial induction is thought to be that in the
favored rotamer of the indenyl-chiral substituent bond
the two faces of the indenyl ring are differentially
blocked by the large (RL) and small (RS) substituents
(Figure 3).7,8 This model predicts that a linked indenyl-
phosphine ligand with a substituent adjacent to the
indenyl ring should give good induction of planar
chirality on complexation. Intramolecular delivery of the
indene after prior coordination of the phosphine does
not change the prediction, although the transition states
are more complex. A suitable ligand should be available
by diphenylphosphide opening of an alkyl-substituted
1,1-spirocyclopropylindene at the less hindered ends
the expected regiochemistry when benzylic activation
is not a factor. Our synthesis of a suitable ligand 18 to
test the hypothesis started with vinylcyclohexane
(Scheme 2). Epoxidation with m-chloroperbenzoic acid
gave the racemic epoxide 13. The (R)-epoxide 13 was
synthesized31 from the (R)-diol 12, formed in 97%
enantiomeric excess by Sharpless asymmetric dihy-
droxylation of vinylcyclohexane.32 Ring opening of 13
with the indenyl anion gave the highly crystalline
alcohol 14, the optically active form of which was readily
recrystallized to >99% ee. Tosylation of 14 proved
difficult, but mesylation to afford 15 occurred readily.
Ring closure by addition of n-butyllithium at -78 °C
gave the spirocyclopropane as a 1:1 mixture of diaste-
reoisomers 16a and 16b. Although this route gave the
chiral spirocyclopropane 16 in excellent enantiomeric
excess, due to recrystallization of the alcohol 14 it took
five steps and gave only 30% overall yield from vinyl-
cyclohexane.
In the search for a more efficient method, we formed
the crystalline bis-mesylate 17 from 12 in 97% yield.
Unfortunately recrystallization of 17 did not enhance
the enantiomeric excess. Addition of indenyllithium to
a suspension of the bis-mesylate 17 in THF at 0 °C
followed by 1 equiv of n-butyllithium gave the spirocycle
16 in moderate yield, surprisingly as a 9:2 mixture of
isomers. A variety of other conditions and bases were
tried for the cyclization, and the highest yields were
obtained when the bis-mesylate 17 was added as a solid
to a solution of 2.4 equiv of indenyllithium (acting as
both the nucleophile and base) in THF at 0 °C. These
conditions gave the spirocycle 16 (9:2 ratio a :b ) as a
white crystalline solid in 84% yield after chromatogra-
phy, and removal of excess indene under vacuum.33 The
difference in ratios of 16a to 16b from the two synthetic
routes (9:2 from 17, 1:1 from 15) is surprising, since the
reaction of 17 presumably occurs via 15, although the
1H-indenyl tautomer will be first formed. The difference
in temperature used (0 °C; cf. -78 °C) is not responsible.
The major isomer could be obtained pure by recrystal-
(28) Assuming a chair-like transition state, that leading to 11 would
have either the phenyl group in an axial position and the aryl ring
part of the indenyl moiety eclipsing the CO ligand (as in A) or the
phenyl equatorial and the aryl ring part of the indenyl moiety eclipsing
the ClRh(9) fragment. The latter seems more likely and is shown as
B in Figure 2, but both should be less favorable than A. It is also
possible (on the basis of ref 23a) that delivery of the indenyl moiety
takes place at the rhodium opposite to that to which the phosphine is
bound. The transition states are then more complex, but the essential
point, that in a cyclic transition state substituents anywhere along
the connecting chain have a substantial effect on the conformation and
hence energies, remains.
(29) Baker, R. W.; Wallace, B. J . J . Chem. Soc., Chem. Commun.
1999, 1405-1406.
(30) Brookings, D. C. Ph.D. Thesis, University of Southampton,
1999.
(31) Klob, H. C.; Sharpless, K. B. Tetrahedron 1992, 48, 10515-
10530.
(32) Crispiro, G. A.; J eong, K.-S.; Klob, H. C.; Wang Z-M.; Xu, D.;
Sharpless, K. B. J . Org. Chem. 1993, 58, 3785-3786.
(33) After completion of this work Salzer reported a similar route
to 2-phenylspiro[2,4]hepta-4,6-diene.22

Induction of Planar Chirality in Rhodium Complexes
Organometallics, Vol. 20, No. 22, 2001 4579
lization from ethanol, but we have not yet proven its
structuresthat shown is by analogy to 8. Cyclopropane
16 of 97% ee was thus available in three steps and 69%
overall yield from vinylcyclohexane.
With large amounts of the cyclopropane 16 in hand,
we examined the ring opening with diphenylphosphide
anion. Under the conditions used to open 8 (Ph2PK,
THF, room temperature), little reaction occurred, but
raising the temperature to reflux gave 80% conversion
after 4 h. Most convenient, however, was to use Ph2PK
in THF with 2 mol % of 18-crown-6, under which
conditions the reaction reached completion after 38 h
at room temperature giving an excellent yield of the air-
sensitive phosphine 18 after chromatography on silica
under argon. For analysis, and convenience of storage
and weighing, the crystalline, air-stable borane adduct
19 could be formed by reaction of 18 with BH3‚SMe2 at
0 °C.34 It was important to control the temperature to
avoid hydroboration of the indene double bond. The
ligand 18 could be quantitatively liberated from the
borane adduct 19 by refluxing with diethylamine.34 To
avoid handling the air-sensitive phosphine 18, we found
that the spirocycle 16 could be opened directly to give
19 with the borane adduct of lithium diphenylphos-
phide35 in the presence of HMPA, although the yield
was lower than using uncomplexed diphenylphosphide.
Deprotonation of 18 with n-butyllithium followed by
addition to a solution of [Rh(µ-Cl)(CO)2]2 in THF at -78
°C, warming to room temperature overnight, and re-
moval of solvent gave the crude complex as a 78:22
mixture of 20 and 21. Racemic ligand gave a 72:28 ratio.
Purification by column chromatography (neutral alu-
mina, 50% petrol/toluene) gave a mixture of 20 and 21
as an orange powder (68%). Recrystallization from
diethyl ether/hexane at -30 °C afforded the major
diastereoisomer 20 as clear red crystals (36%).
F igu r e 4. ORTEP view of the molecular structure of 20.
Thermal ellipsoids are drawn at 50% probability.
carbonyl complexes. The ligands and complexes dem-
onstrate an important principle of chiral complex designs
that of induction of planar chirality on complexation of
a nonsymmetrically substituted cyclopentadiene in-
duced by a chiral center in a chain connecting to a
second coordinating group. These ligands should find
use with a variety of metals.
Exp er im en ta l Section
Gen er a l P r oced u r es. All experiments were carried out
under an argon atmosphere. Diisopropyl ether, diethyl ether,
and tetrahydrofuran were freshly distilled from dark purple
solutions of sodium/benzophenone ketyl under an argon at-
mosphere. Dichloromethane, pyridine, triethylamine, diethyl-
amine, and hexamethylphosphoramide (HMPA) were dried
over, and distilled from, calcium hydride. Petrol refers to the
fraction of petroleum ether which boils between 40 and 60 °C
and was redistilled before use. Potassium diphenylphosphide
(0.5 M solution in THF) was purchased from Aldrich. Tetra-
carbonylbis(µ-chloro)dirhodium(I) was prepared from rhodium
trichloride trihydrate.36 (R)-1-Cyclohexylethane-1,2-diol (12)
was prepared by Sharpless asymmetric dihydroxylation of
vinylcyclohexane using the (DHQD)2PYR ligand32 to give an
85% yield of material of 97% ee determined by HPLC resolu-
tion of its benzaldehyde acetal. (R)-2-Cyclohexyloxirane (13)
was prepared in 77% yield by the Sharpless method31 from
(R)-1-cyclohexylethane-1,2-diol (12) and had spectroscopic
properties and optical rotations in accord with those previously
reported. 1H and 13C NMR spectra were referenced to TMS or
residual protonated solvent (1H NMR) or to deuterated solvent
(13C NMR). The number of attached protons in 13C spectra was
determined by DEPT experiments. 31P NMR spectra were
recorded proton-decoupled and referenced to external 85% H3-
PO4. Electron impact (EI) mass spectra were recorded at 70
eV. Atmospheric pressure ionization (AP+) and Electrospray
(ES+) mass spectra were recorded on a VG Platform spectrom-
eter using acetonitrile as the solvent and a positively charged
cone.
As expected, the NMR of 20 closely resembled that
of 10 (Table 1), with similar C-Rh and C-P couplings
establishing the basic structure. Interesting features of
the NMR which relate to the stereostructure of 20
4
4
include J CP ) 22.4 Hz to C10 and J RhH ) 2.5 Hz to
H9b, both presumably reflecting close to 180° dihedral
angles. Crystals of rac-20 suitable for X-ray crystal-
lography resulted from the standard purification pro-
cedure. Details of the crystal structure determination
are given in Table 2, an ORTEP picture is given in
Figure 4, and important bond lengths and angles are
given in Table 3. The X-ray structure confirmed the
relative stereochemistry of 20 and the dihedral angles,
predicted from the NMR spectra. Otherwise, the struc-
ture is similar to that of 10 as discussed above. The
main difference is that the connecting chain twists in
opposite ways (relative to the indenyl ring) for the two
compounds 10 and 20.
Con clu sion
We have developed efficient synthetic routes to the
novel ligand types 9 and 18 and formed their rhodium
Syn th esis of (2R)-2-(3H-In d en -1-yl)-2-p h en yleth a n ol
(5) a n d (1S)-2-(3H-In d en -1-yl)-1-p h en yleth a n ol (6). A
solution of indene (5.8 g, 50 mmol) in diisopropyl ether (70
(34) (a) Langer, F.; Pu¨ntener, K.; Stu¨rmer, R.; Knochel, P. Tetra-
hedron: Asymmetry 1997, 8, 715-738. (b) Imamoto, T.; Oshiki, T.;
Onozawa, T.; Kusumoto, T.; Sato, K. J . Am. Chem. Soc. 1990, 112,
5244-5252.
(35) Brisset, H.; Gourdel, Y.; Pellon, P.; Le Corre, M. Tetrahedron
Lett. 1993, 34, 4523-4526.
(36) McCleverty, J . A.; Wilkinson, G. Inorg. Synth. 1966, 8, 210-
215.

4580 Organometallics, Vol. 20, No. 22, 2001
Brookings et al.
mL) was cooled to -78 °C and n-BuLi (20.0 mL, 2.5 M solution
in hexanes, 50 mmol) added dropwise. The resulting yellow
suspension was stirred at -78 °C for 15 min and then warmed
to room temperature and stirred for 2 h. The red suspension
was cooled to 0 °C and (R)-(+)-styrene oxide (5.0 g, 41.6 mmol)
added dropwise, maintaining the internal temperature at 0
°C. The mixture was stirred at 0 °C for 6 h and at room
temperature for a further 16 h. A saturated solution of
ammonium chloride (100 mL) was added and the product
extracted into diethyl ether (3 × 75 mL). The combined organic
layers were washed with brine (2 × 50 mL) and dried over
MgSO4 and the solvents removed in vacuo. Column chroma-
tography (SiO2, 5% Et2O/toluene) gave the title alcohol 6 (2.40
g, 24.4%) followed by 5 (3.696 g, 37.6%) as pale yellow viscous
oils. In the racemic series 5 was obtained as a white crystalline
solid from pentane at 0 °C (mp 61-63 °C). The proton NMR
of 6 is consistent with that reported for 5 by Rieger.17,18
Alcohol 5: [R]D ) -13.5 (c ) 0.96, CHCl3). H NMR (400
MHz, CDCl3): δ 7.46 (1H, m), 7.37-7.30 (4H, m), 7.24 (1H,
m), 7.20-7.15 (3H, m), 6.48 (1H, ddd, J ) 2.0, 2.0, 1.3 Hz),
4.24-4.21 (2H, m, CHPh and CHHOH), 4.11 (1H, ddd, J )
13.1, 9.6, 6.4 Hz, CHHOH), 3.46 (2H, br s, indenyl), 1.58 (1H,
t, J ) 6.4 Hz, OH) ppm. 13C NMR (75 MHz, CDCl3): δ 144.80
(C), 144.46 (C), 143.82 (C), 140.16 (C), 128.97 (CH), 128.91
(2 × CH) 128.64 (2 × CH), 127.23 (CH), 126.23 (CH), 125.02
(CH), 123.94 (CH), 119.99 (CH), 66.13 (CH2, CH2OH), 47.54
(CH), 38.25 (CH2, indenyl) ppm. IR (thin film): 3554 (s), 3399
(bs), 3060 (s), 2880 (s), 1602 (s), 1582 (m), 1493 (s), 1452 (s),
1393 (s), 1180 (bm), 1052 (bs) cm-1. LRMS (EI): m/z 236 (M+,
35%), 218 ((M - OH2)+, 24), 205 ((M - CH2OH)+, 100), 189
(9), 128 (24), 91 (21). Anal. Calcd for C17H16O: C, 86.40; H,
6.82. Found: C, 86.13; H, 6.71.
(CH2), 21.8 (CH3) ppm. IR (CHCl3 solution): 3066 (m), 3032
(bs), 2892 (w), 1770 (bw), 1730 (bw), 1599 (m), 1494 (m), 1455
(m), 1360 (s, SdO), 1189 (s, SdO), 1097 (s), 972 (s), 880 (m),
701 (m) cm-1. LRMS (EI): m/z 390 (M+, 3%), 218 ((M - TsOH)+,
100), 203 (25), 155 (10), 91 (20). Anal. Calcd for C24H22SO3:
C, 73.82; H, 5.68; Found: C, 73.78; H, 5.57.
Syn t h esis of (1S)-[2-(3H-In d en -1-yl)-1-p h en ylet h yl]-
d ip h en ylp h osp h in e (9). To a solution of tosylate 7 (1.56 g,
4 mmol), in THF (50 mL) at -78 °C was added dropwise via
syringe potassium diphenylphosphide (8.8 mL of a 0.5 M
solution in THF, 4.4 mmol). After addition was complete, the
reaction mixture was stirred at -78 °C for 30 min before being
warmed slowly to room temperature and stirred overnight, the
color changing from bright red to orange. Degassed ethanol
(5 mL) was added to quench the reaction; then approximately
half the volume of solvent was removed via vacuum transfer.
Toluene (50 mL) was added and the bright orange suspension
filtered through silica under argon on an in-line sinter (eluent
toluene) to give a pale green solution. The solvents were
removed to give the title phosphine as a white air-sensitive
20
1
18
solid (1.15 g, 70%). Mp: 98-99 °C. [R]D ) -114.9 (c ) 2.1,
1
CHCl3). H NMR (300 MHz, C6D6): δ 7.89 (2H, t + fs, J ) 7.5
Hz), 7.36 (2H, m), 7.05-7.30 (11H, m), 7.0 (4H, m), 5.85 (1H,
br s), 4.026 (1H, apparent dt, J ) 8.7, 6.2 Hz, CHPh; in CDCl3,
where the adjacent CH2 protons are not degenerate, it appears
as a ddd, J HH ) 11, 3.3 Hz, J PH ) 6.3 Hz), 3.26 (2H, app t + fs,
J HH ) 6.7 Hz, J PH ) 6.7 Hz, CH2Ind), 2.995 (1H, d, J ) 16 Hz,
indenyl), 2.910 (1H, d, J ) 16 Hz, indenyl) ppm. 13C NMR (100
MHz, C6D6; numbering as for ligand moiety of 10 in Table 1):
δ 145.65 (C, C7a), 144.50 (C, C3a), 142.20 (C, d, J CP ) 13.2
Hz, C1), 141.8 (C, d, J CP ) 8.3 Hz, C10), 138.0 (C, d, J CP
)
17.5 Hz, i-Ph), 137.65 (C, d, J CP ) 15.6 Hz, i-Ph), 134.6 (2 ×
CH, d, J CP ) 20.4 Hz, o-Ph), 133.75 (2 × CH, d, J CP ) 18.5 Hz,
o-Ph), 130.13 (CH, C2), 129.56 (2 × CH, d, J CP ) 7.6 Hz, m-Ph),
129.51 (CH, p-Ph), 128.86 (2 × CH, d, J CP ) 7.3 Hz. m-Ph),
128.49 (CH, p-Ph), 128.38 (2 × CH, C12), 128.12 (2 × CH, d,
J CP ) 6.3 Hz, C11), 126.38 (CH, d, J CP ) 2 Hz, C13), 126.26
(CH, C4/ 5/ 6/ 7), 124.80 (CH, C4/5/6/7), 123.93 (CH, C4/5/6/
7), 119.20 (CH, C4/5/6/7), 44.77 (CH, d, J CP ) 14.4 Hz, C9),
37.84 (CH2, C3), 32.34 (CH2, d, J CP ) 24.7 Hz, C8) ppm. 31P
NMR (120 MHz, CDCl3): δ 1.07 (s) ppm. IR (CH2Cl2 solution):
3040 (bs), 2900 (bm), 1600 (bm), 1492 (s), 1453 (s), 1436 (s),
Alcohol 6: [R]D25 ) -19.1 (c ) 2, CHCl3). 1H NMR (300 MHz,
CDCl3): δ 7.47 (1H, ddt, J ) 7.8, 0.9, 0.9 Hz), 7.44-7.41 (2H,
m), 7.40 (1H, dt, J ) 7.5, 0.9 Hz), 7.38-7.26 (4H, m), 7.22 (1H,
td, J ) 7.5, 1.3 Hz), 6.33 (1H, ddd, J ) 3.4, 2.1, 1.3 Hz), 5.03
(1H, ddd, J ) 7.9, 5.3, 2.5 Hz, CH(OH)Ph), 3.36 (2H, br s,
indenyl), 3.01-2.97 (2H, m, CH2 indenyl), 2.15 (1H, d, J ) 2.6
Hz, OH) ppm. 13C NMR (75 MHz, CDCl3): δ 144.84 (C), 144.39
(C), 144.07 (C), 140.72 (C), 131.03 (CH), 128.43 (2 × CH),
127.58 (CH), 126.11 (CH), 125.79 (2 × CH), 124.83 (CH),
123.87 (CH), 119.03 (CH), 72.49 (CH, CH(OH)Ph), 38.31 (CH2,
CH2 indenyl), 37.31 (CH2, indenyl) ppm. IR (thin film): 3400
(bs, OH), 3062 (m), 3028 (m), 2895 (m), 1606 (m), 1493 (m),
1455 (s), 1395 (s), 1201 (s), 1040 (bs), 970 (s), 913 (s), 873 (m)
cm-1. LRMS (EI): m/z 236 (M+, 5%),130 (M+ - PhCHO, 100),
107 (PhCHdO+H, 31), 79 (26), 77 (15).
1280 (s), 1117 (m), 1019 (m), 895 (s), 775 (s), 603 (s) cm-1
.
LRMS (EI): m/z 404 (M+, 100%), 275 (Ph2P+dCHPh, 70), 219
((M - PPh2)+, 53), 202 (87), 183 (35), 128 (70), 115 (50), 91
(84), 77 (61). Anal. Calcd (determined for BH3 adduct; prepared
as described for 19 below) for C29H28BP: C, 83.27; H, 6.75.
Found: C, 83.19; H, 6.76.
Syn th esis of Tolu en e-4-su lfon ic Acid (2R)-2-(3H-In d en -
1-yl)-2-p h en yleth yl Ester (7). To a solution of (2R)-2-(3H-
inden-1-yl)-2-phenylethanol (5; 3.55 g, 15 mmol) and dry
pyridine (2.4 mL, 30 mmol) in dichloromethane (20 mL) was
added p-toluenesulfonyl chloride (3.35 g, 16.6 mmol) portion-
wise at 0 °C. The reaction mixture was then stirred at 0 °C
for 3 h and at room temperature for 15 h before cooling to 0
°C and adding diethyl ether (50 mL) followed by hydrochloric
acid (50 mL, 2 M). The organic layer was separated and then
washed with 5% aqueous sodium bicarbonate (45 mL) and
water (45 mL) and dried over anhydrous magnesium sulfate.
Removal of solvent in vacuo gave crude tosylate as an off-white
solid. Recrystallization from hot ethanol afforded the title
compound 7 as a white crystalline solid (4.32 g, 74%). Mp: 90-
91 °C (sealed tube, under argon) (racemate mp 95-96 °C).
Syn th esis of r a c-(R,R)-Sp ir o[(2-p h en ylcyclop r op a n e)-
1,1′-in d en e] (8). A solution of the racemic tosylate r a c-7 (0.78
g, 2 mmol) in THF (25 mL) was cooled to -78 °C and n-BuLi
(0.96 mL of a 2.5 M solution in hexanes, 2.4 mmol, 1.2 equiv)
added dropwise. After it was stirred at -78 °C for 15 min and
room temperature for 2 h, the reaction mixture was quenched
with water (20 mL) and the product extracted into diethyl
ether (30 mL). The ether layer was washed with brine (20 mL)
and then dried over MgSO4. Concentration in vacuo, followed
by recrystallization from hot ethanol, provided the spirocycle
8 (0.30 g, 69%) as off-white crystals, mp 79-81 °C. The crystals
were suitable for X-ray crystallography, which confirmed the
relative stereochemistry of 8.21 1H NMR (300 MHz, CDCl3): δ
7.35 (1H, d, J ) 7.2 Hz), 7.02-7.29 (8H, m), 6.73 (1H, d, J )
5.7 Hz), 5.92 (1H, d, J ) 5.5 Hz), 3.15 (1H, dd, J ) 8.7, 7.2
Hz), 2.26 (1H, dd, J ) 7.2, 5.0 Hz), 1.94 (1H, dd, J ) 8.7, 5.0
Hz) ppm. 13C NMR (100 MHz, CDCl3): δ 147.9 (C), 143.4 (C),
139.3 (C), 137.6 (CH), 129.9 (CH), 128.5 (2 × CH), 128.4 (2 ×
CH), 126.9 (CH), 126.0 (CH), 124.6 (CH), 121.6 (CH), 117.7
(CH), 41.1 (C), 33.3 (CH), 19.5 (CH2) ppm. IR (thin film): 3044
(w), 1601 (m), 1497 (m), 1453 (s), 1200 (m), 1076 (m), 1048
18
1
[R]D ) -66.0 (c ) 0.56, CHCl3). H NMR (400 MHz, CDCl3):
δ 7.61 (2H, d, J ) 8.3 Hz), 7.40 (1H, m), 7.25-7.08 (9H, m),
6.99 (1H, m), 6.31 (1H, br d, J ) 1.4 Hz), 4.57 (1H, dd, J )
9.7, 7.0 Hz), 4.39 (1H, dd, J ) 9.7, 7.0 Hz), 4.29 (1H, td, J )
7.0, 1.1 Hz), 3.37 (2H, br s), 2.40 (3H, s, CH3) ppm. 13C NMR
(75 MHz, CDCl3): δ 144.8 (C), 144.2 (C), 142.0 (C), 144.0 (C),
138.3 (C), 132.9 (C), 129.9 (2 × CH), 129.7 (CH), 128.9 (2 ×
CH), 128.5 (2 × CH), 128.0 (2 × CH), 127.5 (CH), 126.2 (CH),
125.0 (CH), 123.9 (CH), 119.7 (CH), 72.1 (CH2), 44.1 (CH), 38.2
(m), 1018 (m), 983 (s), 905 (m), 882 (m), 756 (s), 728 (s) cm-1
.

Induction of Planar Chirality in Rhodium Complexes
Organometallics, Vol. 20, No. 22, 2001 4581
LRMS (AP+): m/z 218 (M+). Anal. Calcd for C17H14: C, 93.54;
H, 6.46. Found: C, 93.44; H, 6.48.
10% ethyl acetate/petrol) gave the title alcohol 14 as a white
crystalline solid (6.93 g, 71.5%). Recrystallization from ethanol
gave fine needles (mp 69-71 °C) of >99% ee by HPLC (250 ×
5 mm Chiracel OD-H column, eluting with 0.7% isopropyl
alcohol in hexane, 1 mL/min, Rt 17.5 min R enantiomer, Rt
21.0 min S enantiomer). The racemate had mp 60-62 °C.
[R]D ) -34.9 (c ) 0.75, CHCl3). H NMR (300 MHz, CDCl3):
δ 7.49 (1H, d + fs, J ) 7.3 Hz), 7.38 (1H, d + fs, J ) 7.2 Hz),
7.31 (1H, td, J ) 7.3, 1.1 Hz), 7.25 (1H, td, J ) 7.2, 1.5 Hz),
6.38 (1H, br s), 3.73 (1H, ddd, J ) 9.7, 5.6, 3.1 Hz, CHCyOH),
3.40 (2H, br s, indenyl), 2.88 (1H, dtd, J ) 14.4, 3.3, 1.8 Hz,
CH2ind), 2.61 (1H, ddd, J ) 14.4, 9.8, 1.1 Hz, CH2ind), 1.10-
1.90 (12H, m) ppm. 13C NMR (75 MHz, CDCl3): δ 145.2 (C),
144.7 (C), 141.8 (C), 130.7 (CH), 126.3 (CH), 125.0 (CH), 124.1
(CH), 119.3 (CH), 73.9 (CH), 43.6 (CH), 38.1 (CH2), 33.2 (CH2),
29.4 (CH2), 28.3 (CH2), 26.8 (CH2), 26.5 (CH2), 26.4 (CH2) ppm.
IR (Nujol mull): 3368 (bs), 2720 (m), 1580 (w), 1104 (m), 1026
(m), 991 (m), 966 (m), 914 (m), 891 (m) cm-1. LRMS (AP+):
m/z 225 ((M - OH)+, 19%), 224 ((M - H2O)+, 13), 131 ((M -
CyCH2OH)+, 100). Anal. Calcd for C17H22O: C, 84.25; H, 9.15.
Found: C, 84.54; H, 9.21.
Syn th esis of r a c-[2-(3H-In d en -1-yl)-1-p h en yleth yl]d i-
p h en ylp h osp h in e (9) fr om Sp ir ocycle 8. To a solution of
spirocycle 8 (0.218 g, 1 mmol) in THF (13 mL) at -78 °C was
added dropwise potassium diphenylphosphide (2.2 mL of a 0.5
M solution in THF, 1.1 mmol). The reaction mixture was
stirred at -78 °C for 30 min and room temperature for 2 h
and then quenched with degassed ethanol (1 mL). The solution
was concentrated to approximately half-volume, diluted with
toluene (30 mL), and filtered through a bed of silica gel, under
argon. Removal of solvent gave rac-9 as a white solid (0.286
26
1
1
g, 71%), >90% pure by H NMR.
Syn th esis of (η5:η1-in den yl-CH2CH(P h )P P h 2)Rh ICO (10).
To (1S)-[2-(3H-inden-1-yl)-1-phenylethyl]diphenylphosphine (9;
0.808 g, 2 mmol) in THF (20 mL) under argon at -78 °C was
added n-BuLi (0.8 mL, 2.5 M in hexanes, 2 mmol) dropwise to
give a deep red solution. The solution was stirred at -78 °C
for 30 min, warmed to room temperature, and stirred for a
further 2 h. Meanwhile a golden yellow solution of [RhI(µ-Cl)-
(CO)2]2 (0.389 g, 1 mmol), in THF (20 mL), was prepared under
argon and cooled to -78 °C. The red anion solution was cooled
to -78 °C and added via cannula dropwise over ca. 20 min to
the THF solution of [RhI(µ-Cl)(CO)2]2 at -78 °C, immediately
forming a dark orange-brown solution. The reaction mixture
was stirred at -78 °C for 40 min before being warmed to room
temperature and stirred overnight (ca. 16 h). The solvents were
removed in vacuo to give a brown solid, which was purified
by column chromatography (neutral grade III alumina, 20%
petroleum ether/toluene) to afford the title complex as a yellow
powder and a 3:1 mixture of diastereoisomers (0.764 g, 71%)
(complexation of the racemic ligand gave a 5:2 mixture of
diastereoisomers). There was no change in diastereoisomer
ratios from the crude material on chromatography. Recrys-
tallization from diethyl ether/pentane at -20 °C gave the
diastereoisomerically pure complex 10 (0.324 g, 30%). Mp:
Syn th esis of (S)-Meth a n esu lfon ic Acid 1-Cycloh exyl-
2-(3H-in d en -1-yl)eth yl Ester (15). To a stirred solution of
alcohol 14 (5.94 g, 24.5 mmol) and triethylamine (8.5 mL, 6.2
g, 61.2 mmol) in dichloromethane (130 mL) at -30 °C was
added dropwise methanesulfonyl chloride (2.5 mL, 3.7 g, 31.9
mmol). After it was stirred at -20 °C for 2 h, the solution was
filtered and the organic phase washed with water (90 mL) and
brine (90 mL) and then dried over MgSO4 and concentrated
in vacuo, yielding the crude product as a brown solid (6.63 g,
∼77%), which was used immediately in the formation of the
1
spirocycle 16. H NMR (300 MHz, CDCl3): δ 7.48 (1H, d, J )
7.2 Hz), 7.43 (1H, d, J ) 7.5 Hz), 7.34 (1H, t, J ) 7.2 Hz), 7.24
(1H, t, J ) 7.5 Hz), 6.39 (1H, br s), 5.85 (1H, ddd, J ) 6.7, 6.7,
4.2 Hz), 3.37 (2H, br s), 2.99 (2H, d, J ) 6.7 Hz), 2.62 (3H, s),
1.60-1.95 (7H, m), 1.20-1.40 (4H, m) ppm.
18
197-198 °C (racemate mp 195-197 °C). [R]D ) -105 (c )
Syn th esis of Meth a n esu lfon ic Acid (R)-1-Cycloh exyl-
2-((m eth a n esu lfon yl)oxy)eth yl Ester (17). A stirred solu-
tion of (1R)-1-cyclohexyl-1,2-ethanediol (12; 6.49 g, 45 mmol)
in dichloromethane (340 mL) was cooled to -30 °C, under
argon. Triethylamine (22 mL, 158 mmol) was then added,
followed by dropwise addition of methanesulfonyl chloride (8.7
mL, 113 mmol), causing the precipitation of a white solid. A
further portion of dichloromethane (245 mL) was added to
enable efficient stirring. The reaction mixture was stirred at
-30 to -20 °C for 2 h and then filtered cold (-20 °C) and the
residue washed with cold dichloromethane (120 mL, -20 °C).
Water (300 mL) was then added to the collected filtrate, and
the aqueous layer was separated and extracted with dichlo-
romethane (3 × 180 mL). The combined organic layers were
dried over MgSO4 and concentrated in vacuo to yield the crude
dimesylate as an off-white solid (14.82 g, ∼109%). Recrystal-
lization from dichloromethane/hexane at 5 °C gave three crops
of the title compound as white crystals (13.1 g, 97%). All three
crops retained the 97% ee of the diol starting material, as
judged from their independent conversion into spirocyclopro-
0.42, CHCl3). 1H NMR (400 MHz, C6D6; numbering as in Table
1): δ 7.66 (2H, m, o-Pha), 7.57 (2H, m, o-Phb), 7.49 (1H, m, H7),
7.41 (1H, m, H4), 7.22 (2H, m, H5 + H6), 7.16 (1H, m, p-Pha),
7.06 (3H, m, m-Pha + H13), 6.99 (2H, t, J ) 7.8 Hz, 2 H12),
6.96 (3H, m, p-Phb + m-Phb), 6.73 (2H, d + fs, 2 H11), 6.206
(1H, dd, J HP* ) 2.2 Hz, J HH ) 3.0 Hz, H2), 6.001 (1H, dd,
J
HP* ) 4.5 Hz, J HH ) 3.0 Hz, H3), 5.552 (1H, ddd, J HP ) 14
Hz, J HH ) 8.0, 6.0 Hz, H9), 2.813 (1H, dd, J HP ) 62.3 Hz,
J HH ) 14.0, 5.8 Hz, H8a), 2.636 (1H, ddd, J HP ) 14 Hz, J HH
)
14.0, 8.0 Hz, H8b) ppm. The asterisk indicates that the
couplings could be to Rh rather than P. 13C NMR: see Table
1. 31P NMR (120 MHz, C6D6): δ 86.2 (d, J PRh ) 214 Hz) ppm;
minor isomer, in crude product, δ 84.1 (d, J PRh ) 214 Hz) ppm.
IR (CHCl3 solution): 3060 (bm), 2904 (w), 2337 (w), 1946 (s,
CO), 1600 (m), 1479 (m), 1436 (s), 1320 (m), 1095 (s), 1010
(w), 864 (w), 698 (s), 540 (s), 504 (s) cm-1. UV/vis (c ) 3 mg/
125 mL, CH2Cl2): λmax 328 (ꢀ 6898), 288 (ꢀ 13 795), 204 (ꢀ
24 920) nm. LRMS (EI): m/z 534 (M+, 30%), 506 ((M - CO)+,
100), 320 (50), 298 (14), 253 (7), 210 (12). Anal. Calcd for
C30H24RhPO: C, 67.43; H, 4.53. Found: C, 67.40; H, 4.63.
Syn th esis of (S)-1-Cycloh exyl-2-(3H-in d en -1-yl)eth a n ol
(14). A solution of indene (5.6 mL, 48 mmol) in THF (70 mL)
was cooled to -78 °C, and n-BuLi (19.2 mL of a 2.5 M solution
in hexanes, 48 mmol) was added dropwise. The resulting
yellow suspension was stirred for 20 min at -78 °C, before
being warmed to room temperature and stirred for 2 h. The
anion solution was then cooled to -5 °C, and (R)-cyclohexyl-
oxirane (5.05 g, 40 mmol) in THF (20 mL) was added dropwise
and the mixture stirred at room temperature for 16 h.
Saturated ammonium chloride solution (100 mL) was added
and the product extracted into diethyl ether (3 × 100 mL).
The combined organic layers were then washed with brine (100
mL) and dried over MgSO4, and the solvents were removed in
vacuo to yield a yellow solid. Column chromatography (SiO2,
25
pane 16 of 97% ee. Mp: 114-116 °C. [R]D ) -17.2 (c ) 1,
CHCl3). 1H NMR (400 MHz, CDCl3): δ 4.68 (1H, ddd, J ) 6.6,
6.6, 2.6 Hz), 4.47 (1H, dd, J ) 11.4, 2.6 Hz), 4.36 (1H, dd, J )
11.7, 6.6 Hz), 3.12 (3H, s), 3.10 (3H, s), 1.67-1.91 (6H, m),
1.03-1.37 (5H, m) ppm. 13C NMR (100 MHz, CDCl3): δ 82.8
(CH), 67.3 (CH2), 37.9 (CH3), 37.8 (CH3), 36.7 (CH), 27.5 (CH2),
27.2 (CH2), 24.8 (CH2), 24.6 (CH2), 24.5 (CH2) ppm. IR (thin
film): 3029 (w), 2958 (m), 2929 (m), 2857 (w), 1452 (w), 1355
(s), 1344 (s), 1332 (s), 1175 (s), 1034 (m), 979 (s), 904 (s), 844
(s), 792 (s) cm-1. LRMS (AP+): m/z 300.3 (M)+. Anal. Calcd
for C10H20O6S2: C, 39.99; H, 6.71. Found: C, 39.99; H, 6.74.
Syn th esis of Sp ir o[(2-cycloh exylcyclop r op a n e)-1,1′-
in d en e] (16). F r om Mesyla te 15. To a solution of the crude
mesylate 15 (6.63 g, ∼21 mmol) in THF (130 mL) at -78 °C
under argon was added n-BuLi (11.9 mL, 2.5 M solution in

4582 Organometallics, Vol. 20, No. 22, 2001
Brookings et al.
hexanes, 29.7 mmol). The reaction mixture was stirred at -78
°C for 15 min and then at room temperature for 2 h before
quenching with water (40 mL). Diethyl ether (45 mL) was
added, and the organic layer was separated, washed with brine
(40 mL), and then dried over MgSO4. Concentration in vacuo,
followed by chromatography (SiO2, petrol), provided the title
product as a clear oil (3.45 g, 63% from 14) and a 1:1 mixture
of diastereoisomers.
Hz, J HP ) 3.0 Hz, H9), 2.40 (1H, ddd, J HH ) 13.6, 10.2 Hz,
J HP ) 2.0 Hz, H9), 1.53-1.89 (6H, m, cyclohexyl ring), 0.85-
1.23 (5H, m, cyclohexyl ring) ppm. 13C NMR (100 MHz,
CDCl3): δ 146.46 (C, d, J CP ) 3.9 Hz, C1), 145.65 (C, C3a/7a),
144.94 (C, C3a/7a), 139.99 (C, d, J CP ) 13.5 Hz, i-Ph), 139.15
(C, d, J CP ) 15.0 Hz, i-Ph), 133.49 (2 × CH, d, J CP ) 19.3 Hz,
o-Ph), 132.69 (2 × CH, d, J CP ) 18.3 Hz, o-Ph), 129.89 (CH, d,
J CP ) 1.5 Hz, C2), 128.84 (CH, p-Ph), 128.54 (2 × CH, d,
J CP ) 6.8 Hz, m-Ph), 128.32 (2 × CH, d, J CP ) 6.3 Hz, m-Ph),
128.27 (CH, p-Ph), 125.91 (CH, C4/5/6/7), 124.52 (CH, C4/5/
6/7), 123.98 (CH, C4/5/ 6/7), 119.96 (CH, C4/5/6/7), 42.47 (CH,
d, J CP ) 8.2 Hz, CH of cyclohexane), 41.68 (CH, d, J CP ) 14.0
Hz, C8), 37.91 (CH2, C3), 31.05 (2 × CH2, d, J CP ) 6.3 Hz,
CHCH2 of cyclohexane), 30.76 (CH2, d, J CP ) 12.1 Hz, C9),
26.78 (2 × CH2, cyclohexane), 26.75 (CH2, cyclohexane) ppm.
31P NMR (120 MHz, CDCl3): δ -17.9 (s) ppm. IR (thin film):
3068 (w), 2923 (bs), 2850 (bm), 1585 (w), 1480 (w), 1448 (m),
1433 (m), 1393 (w), 1263 (w), 1095 (m), 1026 (m), 969 (m), 915
(w), 845 (w), 769 (s), 738 (s), 696 (s) cm-1. LRMS (ES+): m/z
411.4 (M + H)+ (fully oxidized by air when in solution: m/z
427.3, (M + O + H)+). Anal.: determined for BH3 derivative
19 (see below).
F r om Bis-m esyla te 17. A solution of indene (5.3 mL, 45
mmol) in THF (50 mL) was cooled to -78 °C and n-BuLi (18
mL of a 2.5 M solution in hexanes, 45 mmol) added dropwise,
in the dark. The resulting yellow suspension was stirred at
-78 °C for 15 min and then warmed to room temperature and
stirred for 1.5 h. The anion mixture was cooled to 0 °C and
diluted with THF (90 mL) and dimesylate 17 (5.6 g, 18.8 mmol)
added portionwise over 2 min. The mixture was stirred at 0
°C for 15 min and then warmed to room temperature overnight
(ca. 17 h). The reaction mixture was quenched with water (150
mL) and extracted with diethyl ether (4 × 75 mL). The
combined organic layers were washed with saturated sodium
bicarbonate solution (150 mL) and then dried over MgSO4 and
concentrated in vacuo. Chromatography (SiO2, petrol) gave the
desired product contaminated with a small amount of indene,
which was removed by evaporation under vacuum (0.3 mmHg)
for 24 h at room temperature, to yield the clean spirocycle 16
as a white solid (3.56 g, 84%) and a 9:2 mixture of diastereo-
isomers. Chiral HPLC (250 × 5 mm Chiracel OD-H column,
eluting with 1% isopropyl alcohol in hexane, 1 mL/min, Rt )
4.7 min (minor isomer, + enantiomer), Rt ) 4.9 min (major
isomer, + enantiomer), Rt ) 5.4 min (major isomer, -
enantiomer), Rt ) 7.3 min (minor isomer, - enantiomer))
showed the product has retained chirality (97% ee) from the
Syn th esis of 2-Cycloh exyl-2-(3H-in d en -1-yl)eth yl]d i-
p h en ylp h osp h in e-Bor a n e Com p lex (19). i. F r om Ad d i-
tion of Bor a n e to Liga n d 18. A solution of cyclohexyl-
substituted ligand 18 (180 mg, 0.44 mmol) was prepared in
THF (10 mL) under argon and cooled to 0 °C. A solution of
borane-dimethyl sulfide complex (0.05 mL, 0.53 mmol) in THF
(1 mL) was then added dropwise. The clear reaction mixture
was stirred at 0 °C for 30 min before quenching by addition of
ice-water (10 mL) at 0 °C and extraction of the product into
ethyl acetate (4 × 20 mL). The combined organic layers were
washed with brine (20 mL), dried over MgSO4, then concen-
trated in vacuo. Recrystallization of the crude product from
hexane at -30 °C gave the title compound as a white air-stable
solid (125 mg, 68%).
diol 12. Recrystallization from hot ethanol afforded the enan-
25
tiopure major isomer as clear crystals, mp 79-80 °C. [R]D
)
1
+216.0 (c ) 0.5, CHCl3) (major isomer). H NMR (400 MHz,
major diastereoisomer, CDCl3): δ 7.44 (1H, dt, J ) 7.4, 0.9
Hz), 7.25 (1H, td, J ) 7.4, 1.1 Hz), 7.18 (1H, td, J ) 7.4, 0.9
Hz), 6.97 (1H, dt, J ) 7.4, 0.9 Hz), 6.97 (1H, d, J ) 5.7 Hz),
6.41 (1H, d, J ) 5.7 Hz), 2.00 (1H, m), 2.00-1.50 (5H, m), 1.72
(1H, dd, J ) 8.5, 4.3 Hz), 1.61 (1H, dd, J ) 7.2, 4.3 Hz), 1.37-
1.12 (4H, m), 1.24 (1H, dd, J ) 11.1, 8.6 Hz), 0.94 (1H, m)
ppm. 13C NMR (100 MHz, major diastereoisomer, CDCl3): δ
148.94 (C), 143.09 (C), 138.01 (CH), 129.38 (CH), 125.40 (CH),
124.34 (CH), 121.42 (CH), 117.56 (CH), 42.15 (CH), 38.08 (C),
37.04 (CH), 33.56 (CH2), 33.28 (CH2), 26.65 (CH2), 26.56 (CH2),
26.31 (CH2), 21.60 (CH2) ppm. IR (thin film): 3029 (w), 2958
(m), 2929 (m), 2857 (w), 1452 (m), 1355 (s), 1344 (s), 1332 (s),
1175 (s), 1034 (m), 979 (s), 904 (bs), 844 (s), 793 (s), 762 (m),
739 (m) cm-1. LRMS (AP+): m/z 225 ((M + H)+, 42%), 224 (M+,
100), 181 (9), 168 (11). Anal. Calcd for C17H20: C, 91.01; H,
8.99. Found: C, 91.16; H, 9.02.
ii. By R in g Op en in g of Sp ir ocycle 16 w it h [P h 2-
P BH3]-Li+. A solution of lithium diphenylphosphide-borane
complex35 (4 mL of a 0.25 M solution in THF, 1.0 mmol) and
HMPA (0.14 mL, 0.83 mmol) was prepared and cooled to 0
°C, under argon. A solution of spiro[(2-cyclohexylcyclopropane)-
1,1′-indene] (16; 186 mg, 0.83 mmol) in THF (1 mL) was then
added dropwise. The reaction mixture was stirred for 15 min
at 0 °C, then warmed to room temperature, and stirred for 24
h. The reaction was quenched with water (2 mL), and the
product was extracted with ethyl acetate (3 × 10 mL). The
combined organic layers were washed with brine (10 mL),
dried over MgSO4, and then concentrated in vacuo. The
product was purified by column chromatography (SiO2, 10%
ethyl acetate in petrol) and isolated as a white solid (212 mg,
61%). Mp: 124-126 °C (enantiopure). [R]D25 ) -14.0 (c ) 0.5,
CHCl3). Numbering of 1H and 13C NMR as in the ligand moiety
of 20 in Table 1. 1H NMR (400 MHz, CDCl3): δ 7.607 (2H, t +
fs, J ) 8.3 Hz), 7.35-7.41 (6H, m), 7.325 (1H, d, J ) 7.4 Hz),
7.240 (2H, br t, J ) 8.8 Hz), 7.19 (1H, tq, J ) 7.4, 1.4 Hz),
7.126 (1H, td, J ) 7.4, 1.0 Hz), 7.050 (2H, tq, J ) 7.7, 2 Hz),
5.942 (1H, t, J ) 2 Hz, H2), 3.187 (1H, dddd, J ) 12.7, 10.3,
7.5, 2.6 Hz, H8), 2.7-2.9 (3H, m, 2 H3 + H9), 2.575 (1H, ddd,
J ) 14.2, 9.4, 2.8 Hz, H9), 1.931 (1H, br d, J ) 12.5 Hz), 1.5-
1.8 (5H, m), 0.85-1.25 (8H, m) ppm. 13C NMR (100 MHz,
CDCl3): δ 144.83 (C, s, C1/7a/3a), 144.71 (C, s, C1/7a/3a),
144.62 (C, s, C1/7a/3a), 132.74 (2 × CH, d, J CP ) 9.2 Hz, o-Ph),
132.00 (2 × CH, d, J CP ) 8.7 Hz, o-Ph), 131.67 (CH, br d,
Syn th esis of [(2R)-2-Cycloh exyl-2-(3H-in d en -1-yl)eth -
yl]d ip h en ylp h osp h in e (18). To a solution of spiro-[(2-cyclo-
hexylcyclopropane)-1,1′-indene] (16; 2.02 g, 9.0 mmol) and 18-
crown-6 (48 mg, 2 mol %) in THF (45 mL) at 0 °C was added
dropwise a deep red solution of potassium diphenylphosphide
(21.6 mL of a 0.5 M solution in THF, 10.8 mmol). The reaction
mixture was stirred at room temperature for 48 h before
quenching with degassed ethanol (10 mL). Approximately half
the THF was removed by vacuum transfer, the residue diluted
with toluene (30 mL), and the mixture filtered through a 3
cm bed of silica under argon, washing through with more
toluene (60 mL). Removal of solvent and chromatography of
the crude product (SiO2, 0-3% ethyl acetate in hexane) under
argon gave the title compound as a white, cloudy, air-sensitive
oil (3.26 g, 88%), with no oxidized product present in the mass
J
CP* ) 11.4 Hz, C2), 131.06 (CH, br d, J CP* ) 21.8 Hz, i-Ph),
130.96 (CH, d, J CP ) 2.2 Hz, p-Ph), 130.72 (CH, d, J CP ) 2.4
Hz, p-Ph), 128.85 (2 × CH, d, J CP ) 9.7 Hz, m-Ph), 128.83 (C,
d, J CP* ) 33.8 Hz, i-Ph), 127.96 (2 × CH, d, J CP ) 9.9 Hz,
m-Ph), 125.82 (CH, s, C7/4/6/5), 124.49 (CH, s, C7/4/6/5), 123.85
(CH, s, C7/4/6/5), 120.23 (CH, s, C7/4/6/5), 42.39 (CH, br d,
1
spectrum. [R]D26 +23.0 (c ) 1.0, CHCl3). Numbering in H and
1
13C NMR as for ligand moiety of 20 in Table 1. H NMR (400
MHz, CDCl3): δ 7.12-7.41 (14H, m), 6.12 (1H, t, J ) 1.8 Hz,
H2), 3.24 (2H, d, J ) 1.8 Hz, H3), 2.64 (1H, dddd, J HH ) 10.2,
6.2, 4.2 Hz, J HP ) 10.2 Hz, H8), 2.55 (1H, ddd, J HH ) 13.6, 4.2
J
CP* ) 9.2 Hz, C10), 39.87 (CH, br s,* C8), 37.64 (CH2, s, C3),
31.27 (CH2, s, C11), 30.74 (CH, s, C11′), 27.35 (CH2, br d,

Induction of Planar Chirality in Rhodium Complexes
Organometallics, Vol. 20, No. 22, 2001 4583
J CP* ) 36.0 Hz, C9), 26.66 (CH2, s, C12/12′/13), 26.59 (CH2, s,
C12/12′/13), 26.58 (CH2, s, C12/12′/13) ppm. The asterisks
indicate that these signals and coupling constants were
difficult to distinguish, owing to borane-broadening of the 13C
resonances. LRMS (AP+): m/z 464.5 ((M - H + CH3CN)+,
72%), 423.3 ((M - H)+, 100), 411.2 ((M - BH3 + H)+, 67). IR
(thin film): 2933 (bm), 2914 (bm), 2848 (m), 1458 (m), 1436
(s), 1107 (m), 1064 (s), 965 (m), 870 (m), 791 (m), 767 (s), 747
(m), 727 (s) cm-1. Anal. Calcd for C29H34BP: C, 82.08; H, 8.08;
P, 7.30. Found: C, 82.22; H, 8.18; P, 7.37.
p-Ph), 7.07 (1H, ddd, J HH ) 8.0, 7.0, 1.0 Hz, H5), 6.98 (1H,
d + fs, J HH ) 8.0 Hz, H7), 6.20 (1H, dd, J HH ) 2.8 Hz, J HP* )
2.7 Hz, H3), 6.14 (1H, dd, J HH ) 2.8 Hz, J HP* ) 2.5 Hz, H2),
3.30 (1H, dddd, J HP ) 13.3 Hz, J HH ) 13.3, 4.6 Hz, J HRh ) 2.5
Hz, H9), 2.93 (1H, ddd, J HH ) 13.6, 13.3 Hz, J HP ) 7.0 Hz,
H9), 2.63 (1H, dddd, J HH ) 13.6, 4.6, 4.6 Hz, J HP ) 9.0 Hz,
H8), 1.80-0.72 (11H, m, cyclohexyl ring) ppm. Asterisks denote
where the coupling could be to Rh rather than P. 13C NMR
(100 MHz, C6D6): see Table 1. IR (CH2Cl2 solution): 2929 (m),
2853 (m), 1939 (s, CO), 1479 (w), 1436 (w), 1095 (w) cm-1
.
Dep r otection of th e Bor a n e Com p lex 19. The borane-
protected phosphine ligand (50 mg, 0.12 mmol) was treated
with neat diethylamine (1 mL), under argon and warmed to
50 °C. The reaction mixture was stirred with monitoring by
TLC (10% ethyl acetate in petrol) for 3 h. After this time TLC
showed the deprotected phosphine ligand present at Rf 0.6,
along with remaining borane-protected phosphine at Rf 0.4.
The reaction mixture was cooled and then evacuated to
dryness, to remove remaining diethylamine and the diethyl-
amine-borane complex. Fresh diethylamine (1 mL) was then
added to the mixture of starting material and product, and
the reaction mixture was heated again to 50 °C overnight.
After this time, TLC showed only the free phosphine present.
The reaction mixture was then cooled and evacuated to
dryness, leaving the ligand 18 as an air-sensitive oil (48 mg,
LRMS (AP+) m/z 554 ((M + CH3CN + H - CO)+, 100%), 553
((M + CH3CN - CO)+, 46), 541 ((M + H)+, 33), 513 ((M +
H - CO)+, 10), 512 ((M - CO)+, 4). Anal. Calcd for C30H30
-
OPRh: C, 66.67; H, 5.60; P, 5.73. Found: C, 66.71; H, 5.67;
P, 5.67.
X-r a y Cr ysta llogr a p h y of Com p lexes 10 a n d 20. A
summary of crystal data, intensity collection details, and
refinement parameters is reported in Table 2. A single crystal
of 10 or 20 was mounted on a glass fiber, and data collections
were performed at 150 K using an Enraf-Nonius Kappa CCD
area detector (λ(Mo KR) ) 0.710 73 Å).37 In each case the data
were corrected for absorption effects using SORTAV38 and the
structures solved by direct methods using SHELXS97.39
Hydrogen atoms were included in calculated positions, and all
atoms were refined anisotropically using full-matrix least-
squares refinement on F2 (SHELXL9740) to give R1 ) 0.0444
and wR2 ) 0.0995 for 10 and R1 ) 0.0432 and wR2 ) 0.0764
for 20. For 10 the absolute stereochemistry was confirmed by
determination of the Flack absolute structure parameter x as
-0.0349 (esd 0.0271).
1
99%). H NMR was identical with that of 18 prepared above.
Syn th esis of (η5:η1-in den yl-CH(Cy)CH2P P h 2)Rh ICO (20).
To a solution of chiral ligand 18 (0.41 g, 1 mmol) in THF (20
mL) under argon at -78 °C was added slowly n-BuLi (0.4 mL
of a 2.5 M solution in hexanes, 1.0 mmol), and the reaction
mixture was stirred at -78 °C for 30 min and then warmed
to room temperature and stirred for a further 2 h. The dark
red ligand anion solution was then cooled to -78 °C and added
via cannula dropwise over ca. 20 min to a solution of [RhI(µ-
Cl)(CO)2]2 (194 mg, 0.5 mmol) in THF (20 mL) at -78 °C,
immediately forming a dark brown solution. This solution was
stirred at -78 °C for 2 h before being warmed slowly to room
temperature, overnight (16 h). The solvents were then removed
Ack n ow led gm en t. We are grateful to the EPSRC,
Zeneca Agrochemicals (now Syngenta), and Avecia Life
Sciences for support of this work through the CASE
scheme. We thank the EPSRC national X-ray service
at Southampton, U.K., for X-ray data and Dr. Simon
Coles for help in structure solution.
1
in vacuo, to give a brown foamy solid. H NMR spectroscopy
Su p p or tin g In for m a tion Ava ila ble: Listings of all frac-
tional atomic coordinates and equivalent isotropic displace-
ment parameters, bond lengths and angles, and anisotropic
displacement parameters for 10 and 20. This material is
available free of charge via the Internet at http://pubs.acs.org.
showed the desired complex formed as a 78:22 mixture of 20
and 21 (using the racemic ligand, the ratio was typically 72:
28). The crude material was purified by column chromatog-
raphy (neutral alumina, 30-50% toluene in petrol) to afford
the product as an orange powder (367 mg, 68%). There was
no change in isomer ratios from the crude product on chro-
matography. Recrystallization from diethyl ether/hexane at
-30 °C afforded the major diastereoisomer 20 as clear red
crystals (195 mg, 36%). Mp (chiral): 168 °C dec (sealed tube).
[R]D21 ) -75.6 (c ) 1, CHCl3). Mp (racemic): 170 °C dec (sealed
OM010367S
(37) Otwinowski, Z.; Minor, W. In Methods in Enzymology; Carter,
C. W., Sweet, R. M., Eds.; Academic Press: New York, 1997; Vol. 276
(Macromolecular Crystallography), Part A, pp 307-326.
(38) Blessing, R. H. Acta Crystallogr. 1995, A51, 33-37. Blessing,
R. H. J . Appl. Crystallogr. 1997, 30, 421-426.
(39) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467-473.
(40) Sheldrick, G. M. University of Go¨ttingen, Go¨ttingen, Germany,
1997.
1
tube). H NMR (400 MHz, C6D6; numbering as in Table 1): δ
7.75-7.68 (2H, m, o-Ph), 7.59 (2H, ddd, J HP ) 11.7 Hz, J HH
)
7.8, 1.7 Hz, o-Ph), 7.38 (1H, d + fs, J HH ) 8.0 Hz, H4), 7.21-
7.17 (4H, m, m-Ph + p-Ph + H6), 7.12-7.08 (3H, m, m-Ph +