Construction of metal-centered chirality: Diastereoselective addition of the meerwein reagent (Me3OBF4) to Rhodium Carbonyl complexes having the Cp′-P ligand

Article abstract of DOI:10.1021/om030688z

Reaction of the rhodium(I) carbonyl complexes [η⁵: η¹-{3-(R)Ind-P}_n=2]Rh(CO) (1; R = H (a), Et (b), Cy (c), (1′S,2′S,5′R)-neomenthyl (NM) (d), (1′R,2′R, 5′R)-neoisomenthyl (NIM) (e)) with the Meerwein reagent (Me ₃OBF₄) afforded the cationic rhodium(III) complexes [[η⁵: η¹-{3-(R)Ind-P}_n=2]RhMe(CO)] BF₄, having metal-centered chirality, in good to excellent yields. When a bulkier substituent (R) was used, the corresponding cationic complex was obtained with higher diastereoselectivity. In the case of using an optically active substituent such as NM or NIM, complete stereodiscrimination around the rhodium center by the Meerwein reagent occurred to give the cationic complexes with 100% de.

Full text of DOI:10.1021/om030688z

Organometallics 2004, 23, 2095-2099
2095
Con str u ction of Meta l-Cen ter ed Ch ir a lity:
Dia ster eoselective Ad d ition of th e Meer w ein Rea gen t
(Me3OBF 4) to Rh od iu m Ca r bon yl Com p lexes Ha vin g th e
Cp ′-P Liga n d
Yasutaka Kataoka,*,† Yousuke Nakagawa,† Atsushi Shibahara,†
Tsuneaki Yamagata,† Kazushi Mashima,† and Kazuhide Tani‡
Department of Chemistry, Graduate School of Engineering Science, Osaka University,
Toyonaka, Osaka 560-8531, J apan, and Higashiosaka University,
Higashiosaka, Osaka 577-8567, J apan
Received December 15, 2003
Reaction of the rhodium(I) carbonyl complexes [η5:η1-{3-(R)Ind-P}n)2]Rh(CO) (1; R ) H
(a ), Et (b), Cy (c), (1′S,2′S,5′R)-neomenthyl (NM) (d ), (1′R,2′R,5′R)-neoisomenthyl (NIM)
(e)) with the Meerwein reagent (Me3OBF4) afforded the cationic rhodium(III) complexes [[η5:
η1-{3-(R)Ind-P}n)2]RhMe(CO)]BF4, having metal-centered chirality, in good to excellent yields.
When a bulkier substituent (R) was used, the corresponding cationic complex was obtained
with higher diastereoselectivity. In the case of using an optically active substituent such as
NM or NIM, complete stereodiscrimination around the rhodium center by the Meerwein
reagent occurred to give the cationic complexes with 100% de.
In tr od u ction
nation to the metal. We demonstrated that the planar
chirality was very effective for controlling the central
chirality arising at the metal in the oxidative addition
of alkyl halide to the Rh(I) carbonyl complex.16c,d Later,
we also reported that the stereogenic center at the metal
controlled by the Ind-P ligand was very stable through
the stereospecific addition of alkynes to Rh(III) methyl
complexes and the stereospecific migration of a methyl
group between cationic Rh(III) methyl complexes and
Rh(III) acyl complexes.16e,f These observations suggest
A three-legged piano-stool complex, Cp′ML1L2L3 (Cp′
) cyclopentadienyl derivatives, M ) metal, Ln ) ligand),
has a stereogenic center on the central metal, if all
ligands are different. So far, several examples of asym-
metric reactions catalyzed by such optically active
Cp′ML1L2L3-type complexes have been reported,1 but
it is too much to declare that their progress reaches the
level of asymmetric reactions accomplished by organo-
metallic catalysts having chiral ligands.2 One reason is
that easy and convenient methods for the preparation
of the optically active complexes that are configuration-
ally stable at the chiral center on the metal have not
been established.3
Cp′-P denotes a “linked cyclopentadienyl and phos-
phine ligand“ in which a cyclopentadienyl derivative and
a tertiary phosphine group are connected by an ap-
propriate spacer. The syntheses, reactivities, and cata-
lytic activities of transition-metal complexes bearing the
Cp′-P ligand recently have received much attention.4-15
We also have been interested in such ligands and
designed several types of Cp′-P ligands.16 A Cp′-P ligand
having an indenyl group as the cyclopentadienyl deriva-
tive part, which is called the Ind-P ligand here, gener-
ates planar chirality on the indenyl ring upon coordi-
(4) For a recent review on cyclopentadienylmetal complexes bearing
tethered P-donor ligands, see: Butenscho¨n, H. Chem. Rev. 2000, 100,
1527.
(5) (a) Foerstner, J . Kakoschke, A.; Wartchow, R.; Butenscho¨n, H.
Organometallics 2000, 19, 2108. (b) Foerstner, J . Kakoschke, A.;
Goddard, R.; Rust, J .; Wartchow, R.; Butenscho¨n, H. J . Organomet.
Chem. 2001, 617, 412. (c) Yong, L.; Butenscho¨n, H. Chem. Commun,
2002, 2852. (d) Kakoschke, A.; Yong, L.; Wartchow, R.; Butenscho¨n,
H. J . Organomet. Chem. 2003, 674, 86.
(6) (a) Matsushima, Y.; Onitsuka, K.; Takahashi, S. Chem. Lett.
2000, 760. (b) Dodo, N.; Matsushima, Y.; Yno, M.; Onitsuka, K.;
Takahashi, S. J . Chem. Soc., Dalton Trans. 2000, 35. (c) Matsushima,
Y.; Onitsuka, K.; Kondo, T.; Mitsudo, T.; Takahashi, S. J . Am. Chem.
Soc. 2001, 123, 10405. (d) Matsushima, Y.; Komatsuzaki, N.; Ajioka,
Y.; Yamamoto, M.; Kikuchi, H.; Takata, Y.; Dodo, N.; Onitsuka, K.;
Uno, M.; Takahashi, S. Bull. Chem. Soc. J pn. 2001, 74, 527. (e)
Onitsuka, K. Dodo, N.; Matsushima, Y.; Takahashi, S. Chem. Commun.
2001, 521. (f) Onitsuka, K.; Ajioka, Y,; Matsushima, Y.; Takahashi, S.
Organometallics 2001, 20, 3274. (g) Onitsuka, K.; Matsushima, Y.;
Takahashi, S. J . Synth. Org. Chem. J pn. 2002, 60, 752.
(7) (a) Klei, S. R.; Tilley, T. D.; Bergman, R. G. Organometallics
2002, 21, 4905. (b) Paisner, S. N.; Lavoie, G. G.; Bergman, R. G. Inorg.
Chim. Acta 2002, 334, 253.
(8) (a) Ciruelos, S.; Englert, U.; Salzer, A.; Bolm, C.; Maischak, A.
Organometallics 2000, 19, 2240. (b) Ciruelos, S.; Doppio, A.; Englert,
U.; Salzer, A. J . Organomet. Chem. 2002, 663, 183. (c) Doppiu, A.;
Englert, U.; Salzer, A. Inorg. Chim. Acta 2003, 350, 435.
(9) Kaulen, C.; Pala, C.; Hu, C.; Ganter, C. Organometallics 2001,
20, 1614.
† Osaka University.
‡ Higashiosaka University.
(1) For a recent review, see: Brunner, H. Angew. Chem., Int. Ed.
1999, 38, 1195.
(2) Asymmetric Catalysis in Organic Synthesis; Noyori, R., Ed.;
Wiley: New York, 1994. Chiral Auxiliaries and Ligands in Asymmetric
Synthesis; J acqueline, S.-P., Ed.; Wiley: New York, 1995. Comprehen-
sive Asymmetric Catalysis; J acobsen, E. N., Pfalts, A., Yamamoto, H.,
Eds.; Springer-Verlag: Berlin, 1999. Catalytic Asymmetric Synthesis,
2nd ed.; Ojima, I., Ed.; Wiley: New York, 2000.
(3) (a) Brunner, H.; Zwack, T. Organometallics 2000, 19, 2423. (b)
Pfeffer, M. Organometallics 2000, 19, 2427. (c) Brunner, H. Eur. J .
Inorg. Chem. 2001, 905.
(10) Brookings, D. C.; Harrison, S. A.; Whitby, R. J .; Crombie, B.;
J ones, R. V. H. Organometallics 2001, 20. 4574.
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2002, 648, 231.
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202.
10.1021/om030688z CCC: $27.50 © 2004 American Chemical Society
Publication on Web 03/26/2004

2096 Organometallics, Vol. 23, No. 9, 2004
Kataoka et al.
that optically active complexes having the Cp′-P ligand,
in which configurational instability at the metal-
centered chirality is prevented, might be useful for
catalytic asymmetric reactions. Therefore, new conven-
ient methodology for the preparation of complexes
having metal-centered chirality is required.17 Herein,
we report another method for the generation of metal-
centered chirality, in which diastereoselective addition
of the Meerwein reagent (Me3OBF4) to rhodium carbo-
nyl complexes having the Ind-P ligand provides cationic
Rh(III) methyl complexes having a stereogenic center
on the metal.
configuration of the cationic complex 2a was easily
determined by the chemical shift of the methyl group
attached directly to the rhodium.16f The methyl group
located under the indene ring was shielded by the ring
current of the benzene ring of the indenyl group, and
the protons of the methyl group were shifted to upper
field compared to that of the isomer. For example, the
methyl signal of 2a -major in the 1H NMR spectrum
appeared at δ -0.47 and that of 2a -minor at δ 1.20,
indicating that the relative configurations of 2a -major
and 2a -minor were R*pl,S*Rh and R*pl,R*Rh, respectively.
Several substituents were easily introduced at the
3-position of the indenyl group of the Ind-P ligand. We
named the ligand “the third generation of the Cp′-P
ligand”.16d We have prepared four kinds of the third
generation of the Cp′-P ligand, [{3-(R)Ind-P}n)2]H, with
R ) Et, Cy, 1′S,2′S,5′R-neomenthyl (NM), 1′R,2′R,5′R-
neoisomenthyl (NIM).19 Some representative results of
the reaction of rhodium carbonyl complexes having the
third generation of the Cp′-P ligand, [η5:η1-{3-(R)Ind-
P}n)2]Rh(CO), with the Meerwein reagent are shown
in Table 1. When [η5:η1-{3-(Et)Ind-P}n)2]Rh(CO) (1b),
in which an ethyl group was attached to the indenyl
ring, was used, the corresponding cationic complex 2b
was obtained quantitatively with 88% de (major:minor
) 94:6) (entry 2).18
Resu lts a n d Discu ssion
When the rhodium(I) carbonyl complex having the
Ind-P ligand {η5:η1-(Ind-P)n)2}Rh(CO) (1a ) was treated
with 1 equiv of the Meerwein reagent in CH2Cl2 at room
temperature for 2 h, oxidative attack of the methyl
group of the Meerwein reagent occurred to give the
cationic rhodium(III) complex [{η5:η1-(Ind-P)n)2}RhMe-
(CO)]BF4 (2a ) in 86% isolated yield (eq 1). We have
Recrystallization of a mixture of 2b-major and 2b-
minor from ether and THF gave reddish orange single
crystals of 2b-major suitable for X-ray analysis. An
ORTEP drawing and selected bond distances and angles
are given in Figure 1, and relevant crystal and data
parameters are presented in Table 2. The ORTEP
drawing of 2b-major showed that the relative configu-
ration was R*pl,S*Rh with the methyl group located
under the indenyl ring, which was the same relative
configuration as that of 2a -major. The short length of
the spacer (the ethylene group) causes distortion around
the rhodium center. For example, the Cp-Rh-P angle
(114.45°) was smaller than that (123.6°) in [{η5:η1-(Ind-
P)n)3}RhMe(CO)]BF4 having a propylene group as a
spacer.16f,20 Similar distortion was also observed in other
rhodium(I) and -(III) complexes having the Cp′-P
ligand.8a,10,21 Although the bond length of Rh-C(4) or
Rh-C(5) was slightly longer than those of other bonds,
the distortion of the indenyl ring toward η3-coordination
was not observed clearly, compared to that in rhodium
already prepared the same complex 2a by the “AgBF4
method”, involving oxidative addition of MeI to 1a ,
affording the acetyl rhodium(III) complex, {η5:η1-(Ind-
P)n)2}Rh(COMe)(I), followed by stereospecific migration
of the methyl group by AgBF4.16c,f The spectral and
physical data of the complex obtained here were com-
pletely the same as those of 2a prepared by the AgBF4
method. The 31P and 1H NMR spectra of the reaction
mixture before purification showed that 2a was a
mixture of two diastereomers (36% de, major:minor )
68:32), based on the difference in planar chirality on
the indenyl ring and a stereogenic center on the metal.
Each diastereomer of 2a was configurationally very
stable and did not epimerize at all after heating at 60
°C for 24 h in CDCl3.18 We reported that the relative
1
complexes having the indenyl ligand.10,22 The H NMR
data are consistent with the X-ray analysis. The 1H
NMR signal of the methyl group of 2b-major appeared
at δ -0.51, while that of 2b-minor appeared at δ 1.11.
From the fact that the methyl protons of 2b-major were
shifted to upper field compared to that of 2b-minor, the
major isomer was also assigned to R*pl,S*Rh as the same
(13) McConnell, A. E. C.; Foster, D. F.; Pogorzelec, P.; Slawin, A.
M. Z.; Law, D. J .; Cole-Hamilton, D. J . Dalton 2003, 510.
(17) For recent examples on the preparation of complexes having
metal-centered chirality by using arene ligands bearing side chains,
see: (a) Therrien, B.; Ward, T. R. Angew. Chem., Int. Ed. 1999, 38,
405. (b) Therrien, B.; Ko¨nig, A.; Ward, T. R. Organometallics 1999,
18, 1565. (c) Faller, J . W.; D’Alliessi, D. G. Organometallics 2003, 22,
2749. (d) Marconi, G.; Baier, H.; Heinemann, F. W.; Pinto, P.; Pritzkow,
H.; Zenneck, U. Inorg. Chim. Acta 2003, 352, 188. (e) Pinto, P.;
Marconi, G.; Heinemann, F. W.; Zenneck, U. Organometallics 2004,
23, 374.
(18) The cationic complexes described in this paper are all configu-
rationally rigid in solution. We did not observe any epimerization of
the metal-centered chirality below 60 °C in CDCl3.
(19) The third generation of the Cp′-P ligand could be prepared by
a method similar to that described in our previous paper.16d A detailed
procedure for the preparation of the ligand will be reported separately.
(14) (a) Bellabarba, R. M.; Nieuwenhuyzen, M.; Saunders, G. C.
Dalton 2001, 512. (b) Bellabarba, R. M.; Nieuwenhuyzen, M.; Saunders,
G. C. Inorg. Chim. Acta 2001, 323, 78. (c) Bellabarba, R. M.; Nieu-
wenhuyzen, M.; Saunders, G. C. Organometallics 2002, 21, 5726.
(15) Vogelgesang, J .; Frick, A.; Huttner, G.; Kircher, P. Eur. J . Inorg.
Chem. 2001, 949.
(16) (a) Kataoka, Y.; Saito, Y.; Nagata, K.; Kitamura, K.; Shibahara,
A.; Tani, K. Chem. Lett. 1995, 833. (b) Kataoka, Y.; Saito, Y.;
Shibahara, A.; Tani, K. Chem. Lett. 1997, 621. (c) Kataoka, Y.;
Shibahara, A.; Saito, Y.; Yamagata, T.; Tani, K. Organometallics 1998,
17, 4338. (d) Kataoka, Y.; Iwato, Y.; Yamagata, T.; Tani, K. Organo-
metallics 1999, 18, 5423. (e) Kataoka, Y.; Iwato, Y.; Shibahara, A.;
Yamagata, T.; Tani, K. Chem. Commun. 2000, 841. (f) Kataoka, Y.;
Shibahara, A.; Yamagata, T.; Tani, K. Organometallics 2001, 20, 2431.

Construction of Metal-Centered Chirality
Ta ble 1. Rea ction of [η5:η1-{3-(R)In d -P }n )2]Rh (CO) (1) w ith Meer w ein Rea gen ta
cationic complex (2)
chemical shift of the
Organometallics, Vol. 23, No. 9, 2004 2097
Me group (δH, ppm)e
carbonyl
complex (1)
yield
(%)b
selectivity
(% de)c
stereochemistry of
the major isomerd
selectivity by the “AgBF4
method”f (% de)
entry
major
minor
1
2
3
4
1a
86
100
100
83h
36
88
R*pl,S*Rh
R*pl,S*Rh
R*pl,S*Rh
-0.47
-0.51
-0.51
-0.63
-0.56
-0.48
-0.68
1.20
1.11
1.14
36
66
76
96
92
92
74
1b
1c
90
g
1d -major (Spl
)
100
100
100
100
Spl,RRh
1d -minor (Rpl)g
Rpl,SRh
Rpl,SRh
Spl,RRh
5
1e-major (Rpl)i
87j
i
1e-minor (Spl
)
a
b
[η5:η1-{3-(R)Ind-P}n)2]Rh(CO) (1) was treated with Meerwein reagent in CH2Cl2 at room temperature. Isolated yield. c The ratio
was determined by 31P NMR of the reaction mixture. The stereochemistry was determined by 1H NMR and/or X-ray analyses. e Measured
d
in CDCl3 at 30 °C. f See the text; further details of this method will be reported separately. A mixuure of (Spl)-1d and (Rpl)-1d (66:34)
g
h
i
was used. Combined yield of the isolated acyl complex derived from 1d -major and 1d -minor. A mixuure of (Rpl)-1e and (Spl)-1e (85:15)
was used. Combined yield of the isolated acyl complex derived from 1e-major and 1e-minor.
j
Ta ble 2. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
Deta ils for (R*p l,S*Rh )-2b (2b-m a jor )
empirical formula
formula wt
temp, K
C27H27OBF4PRh
588.18
100(1)
wavelength, Å
cryst syst
space group
unit cell dimens
a, Å
0.710 69
monoclinic
P21/c
15.14844(10)
b, Å
14.31749(13)
c, Å
15.22641(9)
â, deg
133.4424(2)
2397.78(3); 4
1.629
0.830
V, Å3; Z
F igu r e 1. ORTEP drawing of the cationic part of
(R*pl,S*Rh)-2b (2b-major). Selected bond lengths (Å): Rh-
C1 ) 2.2623(15), Rh-C2 ) 2.2405(15), Rh-C3 ) 2.1961-
(15), Rh-C4 ) 2.3041(15), Rh-C5 ) 2.3145(15), Rh-P )
2.2712(4), Rh-C26 ) 2.1118(16), Rh-C27 ) 1.8844(17).
Selected bond angles (deg): C27-Rh-C26 ) 86.14(7),
C27-Rh-P ) 101.31(5), C26-Rh-P ) 86.44(5), Cp-Rh-P
) 114.45, Cp-Rh-C26 ) 121.80, Cp-Rh-C27 ) 134.50.
Cp is the gravimetric center of the cyclopentadienyl part
of the indenyl group.
calcd density, Mg/m3
abs coeff, mm-1
F(000)
cryst size, mm
θ range for data collecn, deg
limiting indices
1192
0.23 × 0.13 × 0.11
2.76-31.50
-22 e h e 22, -21 k e 21,
-22 e l e 22
no. of rflns collected/unique
completeness to θ ) 31.50°, %
abs cor
71 981/7988 (Rint ) 0.0471)
99.9
numerical
max and min transmissn
refinement method
0.9897 and 0.9672
full-matrix least squares on F2
7988/0/424
result as the X-ray analysis. Reaction of [η5:η1-{3-(Cy)-
Ind-P}n)2]Rh(CO) (1c) with the Meerwein reagent under
the same conditions afforded [[η5:η1-{3-(Cy)Ind-P}n)2]-
RhMe(CO)]BF4 (2c) quantitatively with 90% de (major:
minor ) 95:5) (entry 3).18 Although we have not been
able to succeed in obtaining an X-ray analysis of 2c so
no. of data/restraints/params
GOF on F2
1.107
final R indices (I > 2σ(I))
R indices (all data)
R1 ) 0.0307, wR2 ) 0.0550
R1 ) 0.0404, wR2 ) 0.0573
largest diff peak and hole, e Å-3 0.478 and -0.695
1
far, the H NMR spectrum, in which the chemical shift
signals at δ 71.9 (d, J ) 148 Hz) and 72.1 (d, J ) 147
Hz) in a 70:30 ratio,18 indicating that 2d consists of only
two diastereomers though formation of four isomers (two
isomers from each diastereomer of 1d ) is possible (eq
2). In the case of using 1d with 90% de ((Spl)-1d :(Rpl)-
of the methyl group of the major isomer (δ -0.51)
appeared at upper field compared to that of the minor
isomer (δ 1.14), indicated that the relative configuration
of the major isomer of 2c was also R*pl,S*Rh
.
When an optically active substituent such as NM or
NIM was introduced to the indenyl ring, the corre-
sponding carbonyl complexes [η5:η1-{3-(NM)Ind-P}n)2]-
Rh(CO) (1d ) and [η5:η1-{3-(NIM)Ind-P}n)2]Rh(CO) (1e)
formed as a mixture of two diastereomers due to a
combination of the arising planar chirality and the
stereogenic centers of the substituent. The absolute
configuration of the major isomer of 1d was determined
to be Spl by X-ray analysis.16d The absolute configuration
of 1e-major was determined to be Rpl by an X-ray
analysis of the derivative complex of 1e obtained by the
stereospecific addition of 1-phenylpropyne to 2e.16e In
an analogous way, reaction of 1d ((Spl)-1d :(Rpl)-1d ) 66:
34) at room temperature afforded the cationic complex
[[η5:η1-{3-(NM)Ind-P}n)2]RhMe(CO)]BF4 (2d ) in 83%
isolated yield. The 31P NMR spectrum of the reaction
mixture before purification showed only two doublet

2098 Organometallics, Vol. 23, No. 9, 2004
Kataoka et al.
which is consistent with the relative configuration of
all major isomers obtained in this procedure. In the case
of using an optically active substituent such as NM and
NIM, double stereodifferentiation occurs, due to induc-
tion by both the planar chirality and the stereogenic
centers in the substituent.23 By the AgBF4 method,
carbonyl complexes such as (Spl)-1d and (Rpl)-1e were
converted to the cationic complex with selectivities
obviously higher than those from the complexes having
opposite planar chirality, (Rpl)-1d and (Spl)-1e (see Table
1). In particular, (Spl)-1e afforded the corresponding
cationic complex with lower selectivity, indicating that
two inductions by the planar chirality of S configuration
and the stereogenic centers in NIM (1′R,2′R,5′R) coun-
teract each other. On the other hand, the Meerwein
method described here afforded the cationic complex
under complete stereocontrol (entries 4 and 5 in Table
1). Steric hindrance arising from the bulkiness of the
substituent in the Ind-P ligand would be effective to a
great extent for stereodiscrimination of the Meerwein
reagent around the rhodium center to prevent decrease
of the selectivity by the competition between the two
inductions.
F igu r e 2.
1d ) 5:95), 2d was obtained as a mixture of two
diastereomers in a 5:95 ratio. The diastereomer ratios
of the carbonyl complex 1d were almost the same as
those of the cationic complex 2d , indicating that both
1d -major and 1d -minor afford only a single isomer of
the corresponding cationic complex. Although we have
not determined the absolute configuration at the rhod-
ium center in 2d due to the lack of single crystals
suitable for X-ray analysis, we can assume the absolute
configuration from the chemical shift of the methyl
In summary, we have developed a new method for the
preparation of cationic rhodium(III) complexes having
a stereogenic center on the metal by diastereoselective
addition of the methyl group of the Meerwein reagent
to rhodium(I) carbonyl complexes bearing the Ind-P
ligand. Introduction of a bulkier substituent at the
3-position of the indenyl group in the Ind-P ligand was
found to be crucial for the formation of cationic com-
plexes with higher stereoselectivities.
1
group in the H NMR spectrum. The methyl signal of
the cationic complex in the H NMR derived from (Spl)-
1
1d appeared at δ -0.63 and that from (Rpl)-1d at δ
-0.56. The chemical shift of the methyl group which
appeared around -0.5 ppm is characteristic of the
methyl group affected by the phenyl ring current (see
Table 1). Therefore, it is likely that the absolute con-
figuration of the cationic complex derived from (Spl)-1d
was Spl,RRh and that from (Rpl)-1d was Rpl,SRh, respec-
tively (eq 2). A similar result was obtained in the case
of using 1e as the starting carbonyl complex. Reaction
of 1e with 70% de ((Rpl)-1e:(Spl)-1e ) 85:15) and 1e with
92% de ((Rpl)-1e:(Spl)-1e ) 96:4) with the Meerwein
reagent at room temperature in CH2Cl2 afforded the
cationic complex 2e in 72% de ((Rpl,SRh):(Spl,RRh) ) 86:
14) and 92% de ((Rpl,SRh):(Spl,RRh) ) 96:4), respec-
tively,18 indicating that the methyl group added to the
rhodium center in a completely stereodiscriminative
manner. The relative relation between planar chirality
and arising metal-centered chirality in 2d ,e was the
same as that observed in 2a -c.
Higher diastereoselectivity of the major isomer was
obtained when bulkier substituents were introduced at
the indenyl group in the Ind-P ligand, indicating that
the methyl group of the Meerwein reagent approaches
the rhodium center from a direction that avoids steric
interaction between the substituent and the Meerwein
reagent; that is, it adopts route A in Figure 2. Approach
of the methyl group via route A results in the formation
of the cationic complex with a R*pl,S*Rh configuration,
Exp er im en ta l Section
Gen er a l In for m a tion . All reactions and manipulations
were performed under argon by use of standard vacuum line
and Schlenk tube techniques. All melting points were recorded
on a Yanaco MP-52982 instrument and are uncorrected.
Infrared spectra were recorded on a J ASCO FT/IR-230 instru-
ment. Mass spectra were obtained on a J EOL J MS DX-303HF
spectrometer. 1H NMR spectra were recorded at either 270
MHz on a J EOL J NM-GSX270 or at 300 MHz on a Varian
MERCURY 300 spectrometer. Chemical shifts are reported in
ppm (δ) relative to tetramethylsilane and referenced to the
chemical shift of the residual CHCl3 resonance (δ 7.26). 31P-
{1H} NMR spectra were recorded at either 109.25 MHz on a
J EOL J NM-GSX270 or at 121.49 MHz on a Varian MERCURY
300 spectrometer, and the chemical shifts were referenced to
external 85% H3PO4. Elemental analyses were recorded on a
Perkin-Elmer 2400 instrument.
Dichloromethane was distilled from calcium hydride under
argon prior to use, and other solvents for recrystallization were
dried using standard procedures. The Ind-P ligands [{3-(R)-
Ind-P}n)2]H and their rhodium carbonyl complexes [η5:η1-{3-
(R)Ind-P}n)2]Rh(CO) (1) were prepared according to the pub-
lished procedures.16,19 The Meerwein reagent (Me3OBF4) was
purchased from Tokyo Kasei Kogyo and used without further
purification.
[{η5:η1-(In d -P )n )2}Rh Me(CO)]BF 4 (2a ).16f To a solution of
{η5:η1-(Ind-P)n)2Rh(CO) (1a ; 42 mg, 0.092 mmol) in CH2Cl2 (5
mL) was added Me3OBF4 (14 mg, 0.095 mmol) in CH2Cl2 (5
mL) at room temperature. The reaction mixture was stirred
for 2 h, and then the solvent was removed in vacuo to afford
2a (36% de, (R*pl,S*Rh)-2a :(R*pl,R*Rh)-2a ) ) 68:32; the ratio
(20) Cp is the gravimetric center of the cyclopentadienyl part of the
indenyl group in the Cp′-P ligand.
(21) (a) Lee, I.; Dahan, F.; Maisonnat, A.; Poilblanc, R. Organome-
tallics 1994, 13, 2743. (b) Lee, I.; Dahan, F.; Maisonnat, A.; Poilblanc,
R. J . Organomet. Chem. 1997, 532, 159. (c) 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.
(22) (a) Marder, T. B.; Calabrese, J . C.; Roe, D. C.; Tulip, T. H.
Organometallics 1987, 6, 2012. (b) 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.
(23) Masamune, S.; Choy, W.; Petersen, J . S.; Sita, L. R. Angew.
Chem., Int. Ed. Engl. 1985, 24, 1.

Construction of Metal-Centered Chirality
Organometallics, Vol. 23, No. 9, 2004 2099
was determined by 31P NMR) as yellow powders. The residue
was crystallized from THF and hexane to give 2a as a yellow
microcrystalline material (46 mg, 0.082 mmol, 86%, (R*pl,S*Rh)-
2a :(R*pl,R*Rh)-2a ) 68:32; the ratio was determined by 31P
NMR).
((Spl,RRh)-2d :(Rpl,SRh)-2d ) 8:92): 115-122 °C dec. 1H NMR
(CDCl3): (Spl,RRh)-2d , δ -0.63 (dd, J ) 1.4, 4.1 Hz, 3H, RhCH3),
0.48 (d, J ) 6.6 Hz, 3H, CH3), 0.68 (d, J ) 6.6 Hz, 3H, CH3),
0.74-1.32 (m, 2H), 1.09 (d, J ) 5.8 Hz, 3H, CH3), 1.38-2.16
(m, 2H), 1.62-1.82 (m, 4H), 2.34-2.58 (m, 2H), 2.94-3.26 (m,
1H), 3.38-3.46 (m, 1H), 3.68-3.86 (m, 1H), 4.10-4.28 (m, 1H),
5.74 (s, 1H), 7.18-7.30 (m, 4H), 7.32-7.46 (m, 2H), 7.46-7.64
(m, 5H), 7.62-7.84 (m, 3H); (Rpl,SRh)-2d , δ -0.56 (dd, J ) 1.7,
4.1 Hz, 3H, RhCH3), 0.67 (d, J ) 6.3 Hz, 3H, CH3), 0.84-1.04
(m, 1H), 1.08 (d, J ) 6.5 Hz, 3H, CH3), 1.12 (d, J ) 6.3 Hz,
3H, CH3), 1.34-1.50 (m, 3H), 1.68-2.00 (m, 4H), 2.20-2.34
(m, 1H), 2.34-2.58 (m, 1H), 2.94-3.24 (m, 1H), 3.70-3.84 (m,
1H), 3.68-3.86 (m, 1H), 4.10-4.28 (m, 1H), 5.59 (s, 1H), 7.18-
7.26 (m, 4H), 7.24-7.46 (m, 2H), 7.40-7.66 (m, 5H), 7.64-
7.82 (m, 3H). 31P{1H} NMR (CDCl3): δ 71.9 (d, J P-Rh ) 148
Hz, (Spl,RRh)-2d ), 72.1 (d, J P-Rh ) 149 Hz, (Rpl,SRh)-2d ). IR (KBr,
Nujol, cm-1): 3050, 2038 (νCdO), 1308, 1187, 1058, 755, 694,
523. MS (FAB): m/z 611 (M+, cationic part), 596 (M+ - CH3).
Anal. Calcd for C35H41OPBF4Rh: C, 60.19; H, 5.92. Found: C,
59.88; H, 5.82.
[{η5:η1-{3-(NIM)In d -P }n )2Rh Me(CO)}]BF 4 (2e). To a solu-
tion of [η5:η1-{3-(NIM)Ind-P}n)2]Rh(CO) (1e; 49 mg, 0.082
mmol, (Rpl)-1e:(Spl)-1e ) 85:15) in CH2Cl2 (5 mL) was added
Me3OBF4 (13 mg, 0.088 mmol) in CH2Cl2 (5 mL) at room
temperature. The reaction mixture was stirred for 2 h and then
the solvent was removed in vacuo to afford 2e as a brown
powder. The 31P NMR spectrum of the reaction mixture showed
two peaks at δ 70.4 (d, J ) 148 Hz, (Spl,RRh)-2e) and 71.0 (d,
[{η5:η1-{3-(Et)In d -P }n )2Rh Me(CO)}]BF 4 (2b). To a solu-
tion of [η5:η1-{3-(Et)Ind-P}n)2]Rh(CO) (1b; 35 mg, 0.072 mmol)
in CH2Cl2 (5 mL) was added Me3OBF4 (11 mg, 0.074 mmol) in
CH2Cl2 (5 mL) at room temperature. The reaction mixture was
stirred for 2 h, and then the solvent was removed in vacuo to
afford 2b (88% de, (R*pl,S*Rh)-2b:(R*pl,R*Rh)-2b ) 89:11; the
ratio was determined by 31P NMR) as a brown powder. The
residue was crystallized from THF and hexane to give 2b as
a yellow microcrystalline material (42 mg, 0.072 mmol, 100%,
(R*pl,S*Rh)-2b:(R*pl,R*Rh)-2b ) 94:6; the ratio was determined
by 31P NMR). Mp: 108-115 °C. 1H NMR (CDCl3): δ -0.51
(dd, J ) 4.4, 1.6 Hz, 3H, RhCH3, (R*pl,S*Rh)-2b), 1.11 (dd, J )
5.2, 2.2 Hz, 3H, RhCH3, (R*pl,R*Rh)-2b), 1.42 (t, J ) 7.4 Hz,
3H, -CH2CH3, (R*pl,R*Rh)-2b), 1.51 (t, J ) 7.4 Hz, 3H,
-CH2CH3, (R*pl,S*Rh)-2b), 2.42-2.62 (m, 1H, -CH2-), 2.74-
3.04 (m, 3H, -CH2-), 3.66-3.82 (m, 1H, -CH2-), 4.02-4.18
(m, 1H, -CH2-), 5.96-6.00 (m, 1H, Cp, (R*pl,S*Rh)-2b), 6.18-
6.20 (m, 1H, Cp, (R*pl,R*Rh)-2b), 7.20-7.40 (m, 3H), 7.36-7.54
(m, 5H), 7.52-7.68 (m, 4H), 7.69-7.83 (m, 2H). 31P{1H} NMR
(CDCl3): δ 71.2 (d, J ) 149 Hz, major), 68.8 (d, J ) 141 Hz,
minor). 13C{1H} NMR (CDCl3, major): δ 184.4 (dd, J C-Rh ) 78
Hz, J C-P ) 12 Hz, CO), 1.70 (dd, J C-Rh ) 17 Hz, J C-P ) 4 Hz,
RhCH3). IR (KBr, tablet, cm-1): 2967, 2929, 2042 (νCdO), 1675,
1646, 1436, 1084, 748, 694, 523. Anal. Calcd for C27H27OPBF4-
Rh: C, 55.13; H, 4.63. Found: C, 54.58; H, 4.29.
J
) 147 Hz, (Rpl,SRh)-2e) along with small amounts of
[{η5:η1-{3-(Cy)In d -P }n )2Rh Me(CO)}]BF 4 (2c). To a solu-
tion of [η5:η1-{3-(Cy)Ind-P}n)2]Rh(CO) (1c; 53 mg, 0.098 mmol)
in CH2Cl2 (5 mL) was added Me3OBF4 (16 mg, 0.11 mmol) in
CH2Cl2 (5 mL) at room temperature. The reaction mixture was
stirred for 2 h, and then the solvent was removed in vacuo to
afford 2c (90% de, (R*pl,S*Rh)-2c:(R*pl,R*Rh)-2c ) 95:5; the ratio
was determined by 31P NMR) as an orange powder. The
residue was crystallized from THF and hexane to give 2c as
an orange powder (63 mg, 0.098 mmol, 100%, (R*pl,S*Rh)-2c:
(R*pl,R*Rh)-2c ) 95:5; the ratio was determined by 31P NMR).
undefined peaks (less than 5%). The ratio of the two peaks
was 14:86. The residue was crystallized from THF and hexane
to give 2e as a yellow powder (50 mg, 0.071 mmol, 87%,
(Rpl,SRh)-2e:(Spl,RRh)-2e ) 86:14; the ratio was determined by
31P NMR). When the carbonyl complex 1e in 92% de ((Rpl)-1e:
(Spl)-1e ) 96:4) was used, the corresponding cationic complex
2e was obtained in 92% de ((Rpl,SRh)-2e:(Spl,RRh)-2e ) 96:4).
Mp: 110-112 °C dec. 1H NMR (CDCl3): δ -0.68 (m, 3H,
RhCH3, (Spl,RRh)-2e), -0.48 (dd, J ) 1.6, 4.7 Hz, 3H, RhCH3,
(Rpl,SRh)-2e), 0.36 (d, J ) 6.6 Hz, 3H, CH3), 0.87 (d, J ) 5.8
Hz, 3H, CH3), 1.14 (d, J ) 6.0 Hz, 3H, CH3), 1.22-1.34 (m,
2H), 1.46-1.97 (m, 5H), 1.92-2.14 (m, 2H), 2.41-2.63 (m, 1H),
2.99-3.30 (m, 1H), 3.31-3.44 (m, 1H), 3.70-3.92 (m, 1H),
4.10-4.32 (m, 1H), 5.73 (s, 1H, (Rpl,SRh)-2e), 6.12 (s, 1H,
(Spl,RRh)-2e), 7.24-7.51 (m, 7H), 7.54-7.70 (m, 5H), 7.76-7.88
(m, 2H). 31P{1H} NMR (CDCl3): δ 70.4 (d, J P-Rh ) 148 Hz,
(Spl,RRh)-2e), 71.0 (d, J P-Rh ) 148 Hz, (Rpl,SRh)-2e). 13C{1H}
NMR (CDCl3, (Rpl,SRh)-2e): δ 189.2 (dd, J C-Rh ) 79 Hz, J C-P
) 12 Hz, RhCO). IR (KBr, Nujol, cm-1): 3050, 2038, 1308,
1187, 1058, 755, 715, 694, 523. MS (FAB): m/z 611 (M+,
cationic part), 596 (M+ - CH3). Anal. Calcd for C35H41OPBF4-
Rh: C, 60.19; H, 5.92. Found: C, 59.52; H, 5.88.
1
Mp: 132-138 °C. H NMR (CDCl3): δ -0.51 (dd, J ) 4.4, 1.6
Hz, 3H, RhCH3, (R*pl,S*Rh)-2c), 1.14 (dd, J ) 5.8, 2.5 Hz, 3H,
RhCH3, (R*pl,R*Rh)-2c), 1.26-1.66 (m, 5H), 1.72-1.94 (m, 4H),
1.98-2.20 (m, 3H), 2.42-2.62 (m, 1H, -CH2-), 2.78-2.90 (m,
1H), 2.92-3.22 (m, 1H, -CH2-), 3.68-3.84 (m, 1H, -CH2-),
4.08-4.24 (m, 1H, -CH2-), 5.84-5.86 (m, 1H, Cp, (R*pl,S*Rh)-
2c), 6.26-6.28 (m, 1H, Cp, (R*pl,R*Rh)-2c), 7.26-7.42 (m, 4H),
7.41-7.55 (m, 4H), 7.53-7.68 (m, 4H), 7.69-7.80 (m, 2H). 31P-
{1H} NMR (CDCl3): δ 71.1 (d, J ) 149 Hz, (R*pl,S*Rh)-2c), 68.0
(d, J ) 141 Hz, (R*pl,R*Rh)-2c). 13C{1H} NMR (CDCl3, major):
δ 184.8 (dd, J C-Rh ) 78 Hz, J C-P ) 12 Hz, RhCO), 1.88 (dd,
J C-Rh ) 17 Hz, J C-P ) 4 Hz, RhCH3). IR (KBr, tablet, cm-1):
2927, 2852, 2038 (νCdO), 1674, 1651, 1436, 1084, 753, 694, 523.
MS (FAB): m/z 555 (M+, cationic part) 527 (M+ - CO), 512
(M+ - CO - CH3). Anal. Calcd for C31H33OPBF4Rh: C, 57.97;
H, 5.18. Found: C, 57.55; H, 5.08.
[{η5:η1-{3-(NM)In d -P }n )2Rh Me(CO)}]BF 4 (2d ). To a solu-
tion of [η5:η1-{3-(NM)Ind-P}n)2]Rh(CO) (1d ; 42 mg, 0.070
mmol, (Spl)-1d :(Rpl)-1d ) 66:34) in CH2Cl2 (5 mL) was added
Me3OBF4 (12 mg, 0.081 mmol) in CH2Cl2 (5 mL) at room
temperature. The reaction mixture was stirred for 2 h, and
then the solvent was removed in vacuo to afford 2d as a brown
powder. The 31P NMR spectrum of the reaction mixture showed
two peaks at δ 71.9 (d, J ) 148 Hz, Spl,RRh) and 72.1 (d, J )
147 Hz, Rpl,SRh). The ratio of the two peaks was 70:30. The
residue was crystallized from THF and hexane to give 2d as
X-r a y Str u ctu r e Deter m in a tion . Single crystals of 2b-
major, suitable for X-ray analysis, were obtained by recrys-
tallization from ether and THF. Crystallographic data are
collected in Table 2, and an ORTEP drawing is presented in
Figure 1. Additional crystallographic data are available in the
Supporting Information.
Ack n ow led gm en t. This work was supported in part
by Grants-in-Aid for Scientific Research from the Min-
istry of Education, Science, Sports and Culture of J apan.
Su p p or tin g In for m a tion Ava ila ble: Detailed crystal-
lographic data, atomic positional parameters, and bond lengths
and angles for 2b-major. This material is available free of
charge via the Internet at http://pubs.acs.org.
a
yellow powder (41 mg, 0.059 mmol, 83%, (Spl,RRh)-1d :
(Rpl,SRh)-1d ) 79:21; the ratio was determined by 31P NMR).
When the carbonyl complex 1d in 90% de ((Spl)-1d :(Rpl)-1d )
5:95) was used, the corresponding cationic complex 2d was
obtained in 86% de ((Spl,RRh)-2d :(Rpl,SRh)-2d ) 8:92). Mp
OM030688Z