Hemilabile amidomonophosphine ligand-rhodium(I) complex-catalyzed asymmetric 1,4-addition of arylboronic acids to cycloalkenones

Article abstract of DOI:10.1021/ja0261933

The asymmetric 1,4-addition reaction of arylboronic acids with cycloalkenonas was catalyzed by 1 mol % of an amidomonophosphine-rhodium(I) catalyst in a 10: 1 mixture of 1,4-dioxane and water at 100 °C, affording 3-arylcycloalkanones in reasonably high enantioselectivity and high yields. It was revealed by NMR, IR, and X-ray spectroscopies that this bidentate amidomonophosphine behaves as a hemilabile ligand that contains a hard donor site in addition to the soft donor in a molecule. Phosphorus atom strongly bonds to rhodium(l), and the amide carbonyl oxygen is coordinatively labile. The reaction efficacy of phenylboronic acid with cyclopent-2-en-l-one was significantly dependent on the possibility of coordination of the amide carbonyl oxygen to rhodium(l).

Full text of DOI:10.1021/ja0261933

Published on Web 07/09/2002
Hemilabile Amidomonophosphine Ligand-Rhodium(I)
Complex-Catalyzed Asymmetric 1,4-Addition of Arylboronic
Acids to Cycloalkenones
Masami Kuriyama, Kazushige Nagai, Ken-ichi Yamada, Yoshinao Miwa,
Tooru Taga, and Kiyoshi Tomioka*
Contribution from the Graduate School of Pharmaceutical Sciences, Kyoto UniVersity, Yoshida,
Sakyo-ku, Kyoto 606-8501, Japan
Received March 14, 2002
Abstract: The asymmetric 1,4-addition reaction of arylboronic acids with cycloalkenones was catalyzed
by 1 mol % of an amidomonophosphine-rhodium(I) catalyst in a 10:1 mixture of 1,4-dioxane and water at
100 °C, affording 3-arylcycloalkanones in reasonably high enantioselectivity and high yields. It was revealed
by NMR, IR, and X-ray spectroscopies that this bidentate amidomonophosphine behaves as a hemilabile
ligand that contains a hard donor site in addition to the soft donor in a molecule. Phosphorus atom strongly
bonds to rhodium(I), and the amide carbonyl oxygen is coordinatively labile. The reaction efficacy of
phenylboronic acid with cyclopent-2-en-1-one was significantly dependent on the possibility of coordination
of the amide carbonyl oxygen to rhodium(I).
Introduction
rhodium(I) complex catalyst for 1,4-addition of aryl- and
alkenylboronic acids to R,â-unsaturated ketones, giving the
The discovery and development of new and efficient chiral
catalysts are of fundamental importance for efficient and clean
organic synthesis.1,2 In particular, asymmetric carbon-carbon
bond-forming processes have become a focus for advanced
materials and pharmaceuticals. Of interest is that a chiral
amidomonophosphine 13-copper(I) catalyzes conjugate addition
of alkylzinc and alkyl Grignard reagents to enones, resulting in
production of the corresponding adducts in reasonably high
enantioselectivity.4,5 However, the addition reaction suffers from
unsatisfactory poor efficacy with the addition of aryl groups.6,7
In 1997, Miyaura and co-workers discovered a phosphine-
corresponding â-substituted ketones in high yield.8 In 1998, on
the basis of this finding, Hayashi and Miyaura developed a
rhodium(I)-catalyzed asymmetric 1,4-addition reaction of or-
ganoboron reagents with enones, enoates, alkenylphosphonates,
nitroalkenes, and alkenamides.9,10,11 High enantioselectivity and
high yields were achieved only when (S)-binap12 was used as a
chiral bisphosphine ligand for rhodium(I). The catalysis per-
formance was critically dependent on the structural features of
the phosphine ligands. Some other bisphosphines, (S,S)-diop,13
(S,S)-chiraphos,14 (S)-(R)-bppfa,15 and (S,S)-me-duphos,16 and
monodentate phosphines, (R)-meo-mop17 and (S)-ip-phox,18
* Corresponding author. E-mail: tomioka@pharm.kyoto-u.ac.jp.
(1) (a) Tomioka, K. Synthesis 1990, 541-549. (b) Noyori, R. Asymmetric
Catalysis in Organic Synthesis; John Wiley and Sons: New York, 1994.
(c) Tomioka, K.; Nagaoka, Y. In ComprehensiVe Asymmetric Catalysis;
Jacobsen, E. N., Pfaltz, A., Yamamoto, H., Eds; Springer: New York, 1999;
Vol. III, Chapter 31. (d) Lagasse, F.; Kagan, H. B. Chem. Pharm. Bull.
2000, 48, 315-324. (e) Bolm, C.; Hildebrand, J. P.; Mun˜iz, K.; Hermanns,
N. Angew. Chem., Int. Ed. 2001, 40, 3284-3308. (f) Trost, B. M. Chem.
Pharm. Bull. 2002, 50, 1-14.
(8) Sakai, M.; Hayashi, H.; Miyaura, N. Organometallics 1997, 16, 4429-
4231.
(9) (a) Takaya, Y.; Ogasawara, M.; Hayashi, T.; Sakai, M.; Miyaura, N. J.
Am. Chem. Soc. 1998, 120, 5579-5580. (b) Takaya, Y.; Ogasawara, M.;
Hayashi, T. Tetrahedron Lett. 1998, 39, 8479-8482. (c) Takaya, Y.;
Ogasawara, M.; Hayashi, T. Tetrahedron Lett. 1999, 40, 6957-6961. (d)
Takaya, Y.; Senda, T.; Kurushima, H.; Ogasawara, M.; Hayashi, T.
Tetrahedron: Asymmetry 1999, 10, 4047-4056. (e). Hayashi, T.; Senda,
T.; Takaya, Y.; Ogasawara, M. J. Am. Chem. Soc. 1999, 121, 11591-
11592. (f) Hayashi, T.; Senda, T.; Ogasawara, M. J. Am. Chem. Soc. 2000,
122, 10716-10717. (g) Senda, T.; Ogasawara, M.; Hayashi, T. J. Org.
Chem. 2001, 66, 6852-6856. (h) Hayashi, T. Synlett. 2001, 879-887.
(10) (a) Sakuma, S.; Sakai, M.; Itooka, R.; Miyaura, N. J. Org. Chem. 2000,
65, 5951-5955. (b) Sakuma, S.; Miyaura, N. J. Org. Chem. 2001, 66,
8944-8946.
(2) Anastas, P. T.; Warner, J. C. Green Chemistry: Theory and Practice;
Oxford University Press: Oxford, 1998.
(3) (a) Nakagawa, Y.; Kanai, M.; Nagaoka, Y.; Tomioka, K. Tetrahedron 1998,
54, 10295-10307. (b) Kanai, M.; Nakagawa, Y.; Tomioka, K. Tetrahedron
1999, 55, 3843-3854.
(4) (a) Nakagawa, Y.; Matsumoto, K.; Tomioka, K. Tetrahedron 2000, 56,
2857-2863, and references therein. (b) Mori, T.; Kosaka, K.; Nakagawa,
Y.; Nagaoka, Y.; Tomioka, K. Tetrahedron: Asymmetry 1998, 9, 3175-
3178.
(5) The amidophosphine and its derivatives were useful in copper-catalyzed
asymmetric ethylation of imines. (a) Fujihara, H.; Nagai, K.; Tomioka, K.
J. Am. Chem. Soc. 2000, 122, 12055-12056. (b) Nagai, K.; Fujihara, H.;
Kuriyama, M.; Yamada, K.; Tomioka, K. Chem. Lett. 2002, 8-9.
(6) Tomioka, K. in Modern Carbonyl Chemistry; Otera, J., Ed.; Wiley-VCH,
Germany, 2000; Chapter 12.
(7) For recent examples of asymmetric arylation, see: (a) Asano, Y.; Iida, A.;
Tomioka, K. Tetrahedron Lett. 1997, 38, 8973-8976. (b) Xu, F.; Tillyer,
R. D.; Tschaen, D. M.; Grabowski, E. J. J.; Reider, P. J. Tetrahedron:
Asymmetry 1998, 9, 1651-1654. (c) Chung, K.-G.; Miyake, Y.; Uemura,
S. J. Chem. Soc., Perkin Trans. 1 2000, 15-18.
(11) Reetz and co-workers have recently discovered that BINOL-based diphos-
phonites were also useful in rhodium-catalyzed asymmetric 1,4-addition
of arylboronic acids. Reetz, M. T.; Moulin, D.; Gosberg, A. Org. Lett.
2001, 3, 4083-4085.
(12) Takaya, H.; Akutagawa, S.; Noyori, R. Org. Synth. 1989, 67, 20-32.
(13) Kagan, H. B.; Dang, T.-P. J. Am. Chem. Soc. 1972, 94, 6429-6433.
(14) Fryzuk, M. D.; Bosnich, B. J. Am. Chem. Soc. 1977, 99, 6262-6267.
(15) Hayashi, T.; Mise, T.; Fukushima, M.; Kagotani, M.; Nagashima, N.;
Hamada, Y.; Matsumoto, A.; Kawakami, S.; Konishi, M.; Yamamoto, K.;
Kumada, M. Bull. Chem. Soc. Jpn. 1980, 53, 1138-1151.
(16) Burk, M. J.; Feaster, J. E.; Nugent, W. A.; Harlow, R. L. J. Am. Chem.
Soc. 1993, 115, 10125-10138.
(17) Uozumi, Y.; Tanahashi, A.; Lee, S.-Y.; Hayashi, T. J. Org. Chem. 1993,
58, 1945-1948.
9
8932
J. AM. CHEM. SOC. 2002, 124, 8932-8939
10.1021/ja0261933 CCC: $22.00 © 2002 American Chemical Society

1,4-Addition of Arylboronic Acids to Cycloalkenones
A R T I C L E S
Scheme 1. Amidomonophosphine-Rhodium(I)-Catalyzed
Asymmetric 1,4-Addition of Arylboronic Acids to Cycloalkenones
conveyed poor enantioselectivity and poor yields.10,19 We were
very pleased to find that a high level of catalysis performance
in enantioselectivity and yield was attainable in the asymmetric
1,4-addition of a variety of arylboronic acids to cycloalkenones
using amidomonophosphine 1 as a monophosphine ligand for
rhodium(I) (Scheme 1).20
Amidomonophosphine 1, which we designed, contains a
carbonyl oxygen atom as the hard donor site in addition to the
soft phosphorus atom donor. It is interesting that 1 may behave
as a bidentate hemilabile ligand. The concept of hemilability
in coordination chemistry was introduced at the end of 1970s,21
and the chemistry of hemilabile ligands, which contain both
subsitutionally inert and labile groups, has received considerable
attention in recent years.22 Late-transition-metal complex cata-
lysts often employ phosphines as stabilizing and selectivity-
controlling ligands. In catalytic and stoichometric reactions, the
phosphorus atoms in hemilabile ligands keep them anchored to
transition-metal centers. The hard donor sites are capable of
temporarily holding coordination sites at reactive transition metal
centers in the absence of small molecule substrates and can be
easily displaced by small molecule substrates to form a metal-
small molecule complex.23 Here, we describe that amidomono-
phosphine 1 behaves as a hemilabile ligand in which the
phosphorus atom strongly bonds to rhodium(I) and the amide
carbonyl oxygen is weakly bonding, and the reaction efficacy
of phenylboronic acid with cyclopent-2-en-1-one significantly
depends on the possibility of coordination of the amide carbonyl
oxygen to rhodium(I).
Figure 1. 31P NMR spectrum (202 MHz, C6D6) of Rh-1 complex with
the following molar ratio of Rh(acac)(C2H4)2/1: (a) 1:1; (b) 1:1.5; (c) 1:2;
(d) 1:3.
Results and Discussion
Scheme 2
NMR of the Rhodium-Amidomonophosphine Complex
Prepared from Rh(acac)(C2H4)2 and Amidomonophosphine
1. The benzene-d6 solutions of Rh(I)-1 complex were prepared
in various molar ratios from 1:1 to 1:3 of Rh(acac)(C2H4)224/1.
A representative procedure is given for the preparation of a 1:1
Rh-1 complex. In an NMR sample tube were placed 1 (0.048
mmol) and Rh(acac)(C2H4)2 (0.048 mmol). The tube was filled
with argon, and C6D6 (0.6 mL) was added to form a yellow
solution. The 31P NMR spectrum of a 1:1 Rh-1 complex
showed only one doublet signal of 186 Hz coupling constant
due to large heteronuclear Rh-P coupling at 42.7 ppm (Figure
1a). When the molar ratio of Rh(acac)(C2H4)2/1 was raised to
1:1.5, a new doublet signal appeared at 39.9 ppm (J ) 194 Hz)
(Figure 1b), and the signal of 42.7 ppm disappeared when the
molar ratio of Rh(acac)(C2H4)2/1 was 1:2 (Figure 1c). This
revealed that only one Rh-1 complex, in which one molecule
of 1 coordinated to one molecule of Rh, was generated when
the molar ratio of Rh/1 was 1:1 (Scheme 2). When the molar
ratio of Rh(acac)(C2H4)2/1 was 1:3, the singlet signal of free
amidomonophosphine 1 was observed at -21.7 ppm in addition
to the doublet signal at 39.9 ppm (Figure 1d). The signal at
39.9 ppm corresponds to the Rh-1 complex in which two
molecules of 1 coordinate to one molecule of Rh. This result
meant that the composition of the Rh-1 complex changed as
shown in Scheme 2 when the Rh(I)-1 complex was prepared
in molar ratios from 1:1 to 1:3 of Rh(acac)(C2H4)2/1.
(18) (a) Dawson, G. J.; Frost, C. G.; Williams, J. M. J.; Coote, S. J. Tetrahedron
Lett. 1993, 34, 3149-3150. (b) Matt, P. von; Pfaltz, A. Angew. Chem.,
Int. Ed. Engl. 1993, 32, 566-568.
(19) Takaya, Y.; Ogasawara, M.; Hayashi, T. Chirality 2000, 12, 469-471.
(20) Kuriyama, M.; Tomioka, K. Tetrahedron Lett. 2001, 42, 921-923.
(21) Jeffrey, J. C.; Rauchfuss, T. B. Inorg. Chem. 1979, 18, 2658-2666.
(22) Slone, C. S.; Weinberger, D. A.; Mirkin, C. A. Prog. Inorg. Chem. 1999,
48, 233-350, and references therein.
(23) For recent examples of asymmetric C-C bond-forming reactions with use
of hemilabile ligands, see: (a) Gladiali, S.; Alberico, E.; Pulacchini, S.;
Kolla`r, L. J. Mol. Catal. A 1999, 143, 155-162. (b) Nandi, M.; Jin, J.;
RajanBabu, T. V. J. Am. Chem. Soc. 1999, 121, 9899-9900. (c) Verdaguer,
X.; Moyano, A.; Perica`s, M. A.; Riera, A.; Maestro, M. A.; Mah´ıa, J. J.
Am. Chem. Soc. 2000, 122, 10242-10243.
Then, we analyzed the solution behavior of the amide
carbonyl group of the 1:1 molar ratio complex of Rh(acac)-
(24) Cramer, R. Inorg. Synth. 1974, 15, 16-17.
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J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002 8933

A R T I C L E S
Kuriyama et al.
amide carbonyl group to rhodium(I) was observed at 1562 cm-1
as a strong band (Figure 2). The wavenumber of the coordinated
carbonyl band in 2 was lowered by ca. 50 cm-1 compared to
the free amidomonophosphine 1. The 13C NMR signal of the
carbonyl carbon atom was shifted downfield by 6.9 ppm. This
result revealed that most of the amide carbonyl oxygen of 1
coordinated to rhodium(I) in the cationic complex in solution.
Addition of 2 equiv of n-BuNC to the solution of 2 resulted in
complete displacement of the carbonyl group of 1 by n-BuNC
to give the complex 3; only the IR bands of the uncoordinated
amide carbonyl group and coordinated isonitrile were observed
at 1620 and 2179 cm-1, respectively (free n-BuNC was observed
at 2145 cm-1), and the 13C NMR signal of the carbonyl carbon
atom was shifted back upfield (Scheme 3). The 31P NMR
spectrum of cationic rhodium-amidomonophosphine complex
3 showed two signals at 20.2 ppm (d, J ) 123 Hz) and 20.8
ppm (d, J ) 125 Hz) (Figure 2). This result meant that the
amide carbonyl group, which temporarily held coordination sites
of rhodium(I), was easily displaced by n-BuNC to form a
rhodium(I)-n-BuNC complex, and amidomonophosphine 1
behaved as a hemilabile ligand in the cationic rhodium-
amidomonophosphine complex in solution.
Figure 2. 31P NMR spectrum (202 MHz, CD2Cl2) and IR spectrum (CH2-
Cl2) of the complex of the cationic Rh-1 complex 2 and 3.
Scheme 3. Hemilability of Amidomonophosphine in the Cationic
Rhodium-Amidomonophosphine Complex
X-ray Structure of the Cationic Rhodium-Amidomono-
phosphine Complex Prepared from [RhCl(cod)]2, Ami-
domonophosphine 1, and AgSbF6. The structure of the 1:1
molar ratio complex of Rh(I)/1 was unequivocally determined
by the X-ray crystallographical analysis of the cationic rhodium-
amidomonophosphine complex. The cationic rhodium-ami-
domonophosphine complex 2 was prepared as yellow cubes in
high yield and was subjected to estimation of the coordination
behavior of the carbonyl group of 1. Under argon atmosphere,
a reaction tube was charged with [RhCl(cod)]2(0.08 mmol),
amidomonophosphine 1 (0.16 mmol), and AgSbF6 (0.16 mmol).
To the mixture was added 2 mL of CH2Cl2 at room temperature,
and the whole was ultrasonicated for 5 min. After centrifugal
sedimentation, the supernatant was separated and concentrated
to remove CH2Cl2 under vacuum. The residue was washed with
hexane and filtered to give a yellow solid. This yellow solid
was recrystallized from a mixture of hexane and CH2Cl2, giving
yellow cubes of mp 236-8 °C (dec). FAB-MS m/z: 564 ([Rh-
(cod)(1)]+). Anal. Calcd for C30H40F6NOPRhSb: C, 45.02; H,
5.04; N, 1.75. Found: C, 44.74; H, 4.95; N, 1.73. The structural
information on rhodium species coordinated with 1 was collected
from the X-ray crystal structure of 2. As can be seen in Figure
3a, the conformation of the seven-membered heterometallacyclic
ring, which is formed by the chelate coordination of the
phosphorus and the amide carbonyl oxygen of 1, is boat like.
This means that the amide carbonyl oxygen of 1 coordinates to
rhodium(I) in the crystalline state and 1 is a bidentate ligand.
One of the phenyls of diphenylphosphiono group, Ph(A), is
oriented axially and Ph(B) is oriented equatorially (Figure 3b).
The axial Ph(A) group extrudes toward the same direction as
the tert-butyl group and the equatorial Ph(B) group extrudes
toward the coordination site of the 1,5-cyclooctadiene. The bite
angle of 1 is 86.2°, and the Rh-P and the Rh-O distances are
2.277 and 2.106 Å, respectively. The dihedral angle of Rh-
O-C-N is 4.0°. It is important to note that at the coordination
site B of the cationic complex 2, as shown in Figure 3c, the
upper part is blocked by the two phenyl rings of 1 and the
coordination site A is unblocked.
(C2H4)2/1. To our sorrow, we were not able to confirm by IR
and NMR spectra that the amide carbonyl oxygen of 1
coordinated to rhodium(I), because the IR bands of the carbonyl
groups of 1 and acetylacetonato were observed at almost the
same area. The 13C NMR signal of the carbonyl carbon atom
was observed at 175.5 ppm and shifted downfield by only 0.1
ppm (the carbonyl carbon atom of free amidemonophosphine
1 was observed at 175.4 ppm in C6D6). Attempted isolation of
crystals of the 1:1 molar ratio complex of Rh(acac)(C2H4)2/1
for X-ray crystallographical analysis was unsuccessful because
of its air sensitivity.
NMR and IR of the Cationic Rhodium-Aamidomono-
phosphine Complex Prepared from [RhCl(cod)]2, Ami-
domonophosphine 1, and AgSbF6. We have employed both
NMR and IR to analyze the solution behavior of the amide
carbonyl group in the cationic rhodium-amidomonophosphine
complex 2 (Scheme 3). The complex was obtained by the
following procedure. Under argon atmosphere, a test tube was
charged with [RhCl(cod)]2 (0.072 mmol), 1 (0.144 mmol), and
AgSbF6 (0.144 mmol). To the test tube was added 1.8 mL of
CD2Cl2 at room temperature, and the whole was ultrasonicated
for 5 min. After centrifugal sedimentation, the supernatant was
transferred to an NMR tube via cannula. The 31P NMR spectrum
of the cationic complex 2 showed only one doublet signal due
to large Rh-P coupling (148 Hz) at 25.8 ppm (Figure 2). The
coordination of the carbonyl oxygen atom to rhodium(I) caused
characteristic changes in the IR and 13C NMR spectra. The IR
band of the uncoordinated amide carbonyl group was observed
at 1605 cm-1 as a weak band and the IR band of the coordinated
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8934 J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002

1,4-Addition of Arylboronic Acids to Cycloalkenones
A R T I C L E S
Figure 4. 31P NMR spectrum (202 MHz, CD2Cl2) and IR spectrum (CH2-
Cl2) of the neutral complex 4.
Scheme 4. Hemilability of Amidomonophosphine in the Neutral
Rhodium-Amidomonophosphine Complex
Scheme 5
complex whose amide carbonyl group has a fluxional process
that involves dissociation and recoordination (Scheme 4).
NMR and IR of the Rhodium-Amidomonophosphine
Complex Prepared from [RhCl(C2H4)2]2, Amidomonophos-
phine 1, and KOH. We examined the hemilability of ami-
domonophosphine 1 in another neutral complex prepared from
[RhCl(C2H4)2]2, 1, and KOH. This complex was obtained by
the following procedure (Scheme 5). Under argon atmosphere,
a test tube was charged with [RhCl(C2H4)2]2 (0.04 mmol) and
1 (0.08 mmol). To the test tube were added successively 1,4-
dioxane-d8 (1.0 mL) and 6 M aq KOH (0.67 mL) at 0 °C. The
mixture was stirred at room temperature for 0.5 h. The organic
layer of this mixture was transferred to an NMR sample tube
via cannula. The 31P NMR spectrum of the complex showed
two doublet signals at 43.9 ppm (J ) 182 Hz) and 44.1 ppm (J
) 184 Hz) (Figure 5). The smaller signal at 43.9 ppm
corresponded to the phosphorus atom of the complex whose
amide carbonyl oxygen coordinates to rhodium(I), and the larger
signal at 44.1 ppm was assignable to the phosphorus atom of
the complex whose amide carbonyl oxygen uncoordinated to
rhodium(I) based on the relative magnitude of IR absorption
(vide infra). The IR band of the uncoordinated amide carbonyl
group was observed at 1609 cm-1 as a strong band, and the IR
band of the coordinated amide carbonyl group to rhodium(I)
was observed at 1574 cm-1 as a weak band (Figure 5). This
Figure 3. Chem3D presentation of X-ray crystal structure of the cationic
rhodium-amidomonophosphine complex 2 (SbF6- is omitted for simplic-
ity): (a) the view of the whole 2, (b) the viewpoint of Ph(B) side, (c) the
viewpoint of Ph(B) side (1,5-cyclooctadiene is omitted for simplicity).
NMR and IR of the Rhodium-Amidomonophosphine
Complex Prepared from [RhCl(cod)]2 and Amidomono-
phosphine 1. The neutral rhodium-amidomonophosphine com-
plex 4 was obtained by the following procedure. Under argon
atmosphere, a test tube was charged with [RhCl(cod)]2 (0.024
mmol) and 1 (0.048 mmol). To the test tube was added 0.6 mL
of CD2Cl2 to form a yellow solution. The 31P NMR spectrum
of the neutral complex showed only one doublet signal due to
large Rh-P coupling (150 Hz) at 21.5 ppm (Figure 4). The 13
C
NMR signal of the carbonyl carbon atom was observed at 175.8
ppm downfield shifted by 0.3 ppm from the peak of 1. The IR
band of the uncoordinated amide carbonyl group was observed
at 1609 cm-1 as a strong band and the IR band of the coordin-
ated amide carbonyl group to rhodium(I) was observed at 1558
cm-1 as a weak band (Figure 4). This result revealed that amido-
monophosphine 1 behaves as a hemilabile ligand in the neutral
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J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002 8935

A R T I C L E S
Kuriyama et al.
Figure 6.
conditions. For example, while the 1:1 molar ratio Rh(I)/1
catalyst gave (S)-3-phenylcyclohexanone 1325,26 in 99% yield
and 97% ee (Table 1, entry 1), the 1:3 molar ratio Rh(I)/1
catalyst gave the adduct in 80% yield and 94% ee (Table 1,
entry 2). The enantioselectivity in the asymmetric 1,4-addition
of 11 with 10 using the cationic complex 2 was very poor,
affording the racemic adduct in 99% yield (Table 1, entry 3),
and the catalyst prepared from [RhCl(cod)]2 and 1 gave the
racemic adduct in 98% yield (Table 1, entry 4). The reason
enantioselectivity was extremely poor was that [RhCl(cod)]2
catalyzed the reaction without 1 (Table 1, entries 5 and 6). The
asymmetric 1,4-addition reaction of 11 with 10 was catalyzed
by the catalyst prepared from [RhCl(C2H4)2]2, 1, and KOH,
giving the adduct in 99% yield and 94% ee (Table 1, entry 7).
On the other hand, the catalyst generated from [RhCl(C2H4)2]2
and amidomonophosphine 1 did not catalyze the reaction (Table
1, entry 8). These results indicated that (hydroxo)rhodium(I)
species,27 which was generated from [RhCl(C2H4)2]2, 1, and
KOH, was an active species for transmetalation, in which the
basicity of transition-metal hydroxides and the high oxophilicity
of the boron center induced transmetalation.9h,10,28
Figure 5. 31P NMR spectrum (202 MHz, 1,4-dioxane-d8) and IR spectrum
(CH2Cl2) of the complex generated from 1, [RhCl(C2H4)2]2, and KOH.
Table 1. Amidomonophosphine-Rhodium-Catalyzed Asymmetric
1,4-Addition of Phenylboronic Acid to Cycloalkenones
phosphine
(mol %)
time,
h
yield,
%
ee,
%
entry
n
Rh(I) (mol %)
1
2
6
6
6
6
6
6
6
6
5
5
5
5
5
1 (1)
Rh(acac)(C2H4)2 (1)
Rh(acac)(C2H4)2 (1)
[RhCl(cod)]2 (0.5)/AgSbF6
[RhCl(cod)]2 (0.5)
[RhCl(cod)]2 (0.5)/AgSbF6
[RhCl(cod)]2 (0.5)
[RhCl(C2H4)2]2 (1.5)/KOH
[RhCl(C2H4)2]2 (0.5)
Rh(acac)(C2H4)2 (1)
Rh(acac)(C2H4)2 (1)
Rh(acac)(C2H4)2 (1)
Rh(acac)(C2H4)2 (1)
Rh(acac)(C2H4)2 (1)
1
1
1
1
1
1
1
1
6
6
6
6
6
99
80
99
98
65
61
99
0
97
94
0
1 (3)
3
1 (1.3)
1 (1.3)
4
0
5
6
7
1 (3.9)
1 (1.3)
1 (1.3)
5 (1.3)
6 (1.3)
7 (1.3)
8 (1.3)
94
8
9
90
21
27
2
83
12
4
0
1
10
11
12
13
Amidomonophosphine 1 promoted the reaction with cyclo-
pentenone 9, giving (S)-3-phenylcyclopentanone 1225,29 in 90%
yield and 83% ee (Table 1, entry 9). However, with use of an
amidephosphine 5 bearing two methyl groups on the pyrrolidine
ring, the reaction was not completed, and afforded the adduct
in 21% yield and 12% ee (Table 1, entry 10). The catalytic
performance of 6 bearing two bulkier benzyl groups was poorer,
giving the product in 27% yield and 4% ee (Table 1, entry 11).
Comparison of three amidomonophosphines 1, 5, and 6, bearing
no substitution, two methyl, and two benzyl groups on the
pyrrolidine ring, indicated that smaller substitution gave better
catalytic performance in yield and enantioselectivity (Table 1,
entries 9-11). Furthermore, the catalytic performance of 7 and
8, whose carbonyl groups and phosphorus atoms point toward
the opposite directions, was very poor, affording the almost
racemic adduct in miserable yield (Table 1, entries 12 and 13).
Coordination of both phosphorus and amide carbonyl oxygen
atoms to rhodium(I) forms a chelate, which is available only
when the carbonyl group and phophorous atom point to the same
direction as shown in structure 1 not 7 or 8. The possibility of
coordination of the amide carbonyl oxygen atom to rhodium(I)
in forming a chelate is one of the critical factors affecting the
reaction efficacy of 11 with 9.
16
result revealed that amidomonophosphine 1 behaves as a
hemilabile ligand in the neutral complex prepared from [RhCl-
(C2H4)2]2, 1, and KOH.
Discussion on the Coordination Manner of the Amide
Carbonyl Group to Rhodium(I). It is revealed that the amide
carbonyl group of amidophosphine 1 coordinates to rhodium-
(I) and 1 behaves as a hemilabile ligand both in the neutral
complex and in the cationic complex in which the seven-
membered heterometallacyclic ring is formed. The coordination
of the amide carbonyl group to rhodium(I) in the neutral
complex is weaker than in the cationic complex because a
counteranion directly coordinates to rhodium(I) in the neutral
complex. When the coordination of the amide carbonyl group
to rhodium(I) is weak, the 13C NMR signal of the amide
carbonyl carbon atom is shifted downfield only a little, but the
coordination of the amide carbonyl group to rhodium(I) is clearly
confirmed as a weak band by the IR spectrum. Consequently,
there is the high probability that the amide carbonyl group
coordinates to rhodium(I) in the complex prepared from Rh-
(acac)(C2H4)2 and 1, even if the 13C NMR signal of the amide
carbonyl carbon atom is shifted downfield only a little.
Asymmetric 1,4-Addition of Phenylboronic Acid to Cy-
cloalkenones. We examined the reaction of phenylboronic acid
11 with cyclohex-2-en-1-one 10 using amidomonophosphine 1
as a chiral ligand for Rh(I) (Table 1). It is important to note
that the phosphine-rhodium(I) molar ratio influenced enanti-
oselectivity and yield, and the performance of the 1:1 molar
ratio Rh(I)/1 catalyst was better than those of other molar ratio
(25) Larock, R. C.; Yum, E. K.; Yang, H. Tetrahedron 1994, 50, 305-321.
(26) Schults, A. G.; Harrington, R. E. J. Am. Chem. Soc. 1991, 113, 4926-
4931.
(27) (a) Brune, H.-A.; Unsin, J.; Hemmer, R.; Reichhardt, M. J. Organomet.
Chem. 1989, 369, 335-342. (b) Uson, R.; Oro, L. A.; Cabeza, J. A. Inorg.
Synth. 1985, 23, 126-130. (c) Grushin, V. V.; Kuznetsov, V. F.; Bensimon,
C.; Alper, H. Organometallics 1995, 14, 3927-3932.
(28) Itooka, R.; Iguchi, Y.; Miyaura, N. Chem. Lett. 2001, 722-723.
(29) Barnhart, R. W.; Wang, X.; Noheda, P.; Bergens, S. H.; Whelan, J.; Bosnich,
B. J. Am. Chem. Soc. 1994, 116, 1821-1830.
9
8936 J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002

1,4-Addition of Arylboronic Acids to Cycloalkenones
A R T I C L E S
Figure 8.
coordination site and influenced by the trans effect of phosphine
(a shown in Scheme 6). Amidomonophosphine-rhodium
intermediate a should have an open space in the bottom part of
the vacant coordination site, the upper part being blocked by
the two phenyl rings of 1. The olefinic double bond of cyclohex-
2-en-1-one coordinates to rhodium(I) with its 2-si face forming
b rather than its 2-re face, which undergoes migratory insertion
to form a stereogenic carbon center in c, whose absolute
configuration is S. In this time, cyclohex-2-en-1-one would
coordinate to rhodium(I) smoothly, because the amide carbonyl
oxygen atom, which is capable of temporarily holding coordina-
tion site at rhodium(I), can be readily displaced by cyclohex-
2-en-1-one (Figure 8). Then, the amide carbonyl oxygen atom
recoodinates to the other coordination site at rhodium(I) (Figure
8), and migratory insertion would be induced.
Figure 7. IR spectrum of the cationic rhodium-amidomonophosphine
complexes 14 in CH2Cl2.
Scheme 6. A Plausible Model of Enantioselectiona
In previous reports, binap, amidomonophosphine 1, and
diphosphonites progressed the rhodium(I)-catalyzed asymmetric
1,4-addition of arylboronic acids to R,â-unsaturated compounds
in high efficacy, but monodentate phosphines and most bis-
phosphines conveyed poor yields.10,11,19,20 The electron-donating
ability of monodentate phosphines to rhodium(I) would be too
poor, such as meo-mop and ip-phox, and the reaction hardly
takes place. On the other hand, the high electron-donating ability
of electron-rich bisphosphines, such as diop, whose phosphorus
is substituted by alkyl groups, would prevent the reaction and
give 10-45% yields, with the exception of me-duphos and
chiraphos. The steric hindrance of the coordination site sur-
mounts the electron-donating ability of me-duphos and chiraphos
to prevent the efficient coordination of phosphorus atom to
rhodium(I). Binaps, whose phosphorus is substituted only by
aryl groups, diphosphonites, whose phosphorus is substituted
by binaphthols, and amidomonophosphine 1 exert the moderate
electron-donating abilitiy by the coordination of phosphorus to
catalyze the reaction in the high efficiency. The reason the
catalytic performance was very poor in case of amidomono-
phosphine 5 and 6 is that the amide carbonyl group would not
be able to donate an electron to rhodium(I) because the P-CH2
bond rotates away by the steric repulsion of substituents on the
pyrrolidine ring and phenyl groups on the phosphorus atom
(Figure 9).
a The pyrrolidine ring in 1 is omitted for simplicity. (a) Ph-Rh(I)-1
species, (b) Ph-Rh(I)-1 species coordinated by cyclohex-2-en-1-one, (c)
Rh(I)-1 species after migratory insertion, (d) (hydroxo)rhodium(I) species.
Substituent Influence of the Pyrrolidine Ring on Coor-
dination of the Amide Carbonyl Group to Rhodium(I). The
cationic rhodium-amidomonophosphine complex 14 was pre-
pared by following the synthetic procedure of 2 and estimated
the influence of substitution of the pyrrolidine ring on coordina-
tion behavior of the carbonyl group (Figure 7). In the cationic
rhodium-amidomonophosphine complex 2, the IR band of the
uncoordinated amide carbonyl group was observed at 1605 cm-1
as a weak band and the IR band of the coordinated amide
carbonyl group to rhodium(I) was observed at 1562 cm-1 as a
strong band (Figure 2). This means that the greater part of the
amide carbonyl group coordinates to rhodium(I) in the cationic
complex 2. On the contrary, compared to Figure 2, the cationic
rhodium-amidomonophosphine complex 14 showed a band at
1605 cm-1 corresponding to the uncoordinated carbonyl group
larger than the 1605 cm-1 band of 2. This clearly demonstrated
that the influence of the substituent on the pyrrolidine ring
prevented coordination of the carbonyl group to rhodium(I).
Because the strength of the amide carbonyl oxygen-rhodium-
(I) bond, even in the cationic complex 14, is weak, the amide
carbonyl oxygen of 6 hardly coordinates to rhodium(I) in the
neutral complex that is generated in the actual asymmetric
reaction.
Conclusion
We found that a high level of catalysis performance for
enantioselectivity and yield is attainable in the asymmetric 1,4-
addition of arylboronic acids to cycloalkenones using an
amidomonophosphine 1 as a hemilabile phosphine ligand for
rhodium(I). The structural features of the Rh(I)-1 complex were
Mechanism and Plausible Stereochemical Pathway. Scheme
6 shows the stereochemical pathway in forming the (S)-products
in the reaction of cyclohex-2-en-1-one. According to the X-ray
structure shown in Figure 3, the Ph-Rh(I) species10,30 is formed
by transmetalation between rhodium(I) and phenylboronic acid
at the trans side to phosphorus, which is the most vacant
(30) The arylrhodium(I) complexes are key intermediates for carrying out various
coupling reactions with organic halides and additions to alkenes and alkynes.
(a) Michman, M.; Balog, M. J. Organomet. Chem. 1971, 31, 395-402.
(b) Semmelhack, M. F.; Ryono, L. Tetrahedron Lett. 1973, 14, 2967-
2970. (c) Hegedus, L. S.; Kendall, P. MLo, S. M.; Sheats, J. R. J. Am.
Chem. Soc. 1975, 97, 5448-5452.
9
J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002 8937

A R T I C L E S
Kuriyama et al.
NMR of the 1:2 Molar Ratio Complex of Rh(acac)(C2H4)2/1
(Figure 1c). In an NMR sample tube were placed 1 (33.9 mg, 0.096
mmol) and Rh(acac)(C2H4)2 (12.4 mg, 0.048 mmol). The tube was filled
with argon, and C6D6 (0.6 mL) was added. 1H NMR (C6D6): 1.19 (18H,
s), 1.32-1.35 (2H, m), 1.66 (6H, s), 1.69-1.77 (4H, m), 2.13-2.18
(2H, m), 2.76-2.82 (2H, m), 3.15-3.27 (6H, m), 5.05-5.13 (2H, m),
5.45 (1H, s), 6.91-7.05 (12H, m), 8.00-8.06 (8H, m). 13C NMR
(C6D6): 25.4, 27.4, 27.9, 29.7-29.9 (m), 30.1, 39.3, 47.7, 58.3, 99.8,
127.35-127.42 (m), 127.6-127.7 (m), 128.3, 128.5, 133.2-133.3 (m),
133.9-134.0 (m), 138.3-138.7 (m), 138.9-139.2 (m), 175.0, 184.0.
31P NMR (C6D6): 39.9 (d, J ) 194).
NMR of the 1:3 Molar Ratio Complex of Rh(acac)(C2H4)2/1
(Figure 1d). In an NMR sample tube were placed 1 (50.8 mg, 0.144
mmol) and Rh(acac)(C2H4)2 (12.4 mg, 0.048 mmol). The tube was filled
with argon, and C6D6 (0.6 mL) was added. 31P NMR (C6D6): -21.7
(1P, s), 39.9 (2P, d, J ) 194).
Figure 9.
clarified by NMR, IR, and X-ray analyses. And it was revealed
that amidomonophosphine 1 behaves as a hemilabile ligand
whose phosphorus atom strongly bonds to rhodium(I), the amide
carbonyl oxygen atom has a fluxional process involving
dissociation and recoordination, and the reaction efficacy of
phenylboronic acid with cyclopent-2-en-1-one was significantly
dependent on the capability of coordination of the amide
carbonyl oxygen atom to rhodium(I), giving a chelate.
NMR and IR of [Rh(cod)(1)]+SbF6- (2). Under argon atmosphere,
a test tube was charged with [RhCl(cod)]2 (35.5 mg, 0.072 mmol), 1
(50.8 mg, 0.144 mmol), and AgSbF6 (49.5 mg, 0.144 mmol). To the
test tube was added 1.8 mL of methylene chloride-d2 at room
temperature, and the whole was ultrasonicated for 5 min. After
centrifugal sedimentation, the supernatant was transferred to an NMR
Experimental Section
General. All melting points are uncorrected. IR spectra were
expressed in cm-1. H, 13C, and 31P NMR spectra were taken at 500,
1
125, and 202 MHz, respectively. Chemical shift values are expressed
in ppm relative to internal or external TMS or to external 85% H3PO4.
Abbreviations are as follows: s, singlet; d, doublet; t, triplet; q, quartet;
m, multiplet; br, broad.
1
tube via cannula. H NMR (CD2Cl2): 0.79 (9H, s), 1.86-1.90 (1H,
m), 2.01-2.27 (7H, m), 2.38-2.45 (2H, m), 2.62-2.73 (2H, m), 2.77-
2.81 (2H, m), 3.07 (1H, m), 3.23-3.28 (2H, m), 3.66-3.71 (1H, m),
5.29-5.35 (1H, m), 5.39-5.44 (2H, m), 6.99-7.03 (2H, m), 7.33-
7.40 (3H, m), 7.60-7.66 (3H, m), 8.03-8.07 (2H, m). 13C NMR (CD2-
Cl2): 23.3, 26.3, 26.7, 28.3, 31.2, 31.4, 34.3 (d, J ) 3.1), 34.8 (d, J )
22.7), 39.9, 47.9, 58.9 (d, J ) 5.2), 68.0 (d, J ) 15.5), 68.4 (d, J )
15.5), 108.8 (dd, J ) 3.0, 10.3), 109.5 (dd, J ) 3.0, 10.3), 127.2 (d, J
) 45.5), 128.5 (d, J ) 9.3), 129.3 (d, J ) 13.4), 129.5 (d, J ) 45.5)
130.2 (d, J ) 2.0), 130.7 (d, J ) 9.3), 132.1 (d, J ) 2.0), 134.2 (d, J
) 13.4), 182.4. 31P NMR (CD2Cl2): 25.8 (d, J ) 148).
Preparation Procedure of [Rh(cod)(1)]+SbF6 (2). Under argon
-
atmosphere, a test tube was charged with [RhCl(cod)]2 (39.4 mg, 0.08
mmol), 1 (56.5 mg, 0.16 mmol), and AgSbF6 (55.0 mg, 0.16 mmol).
To the mixture was added 2.0 mL of methylene chloride at room
temperature, and the whole was ultrasonicated for 5 min. After
centrifugal sedimentation, the supernatant was separated and concen-
trated to remove methylene chloride under vacuum. The residue was
washed with hexane and filtered to give a yellow solid (127 mg, 99%
yield). The yellow solid (30 mg) was recrystallized from a mixture of
hexane and methylene chloride (Hex/CH2Cl2 ) 8:5), giving yellow
cubes of mp 236-8 °C (dec) (23 mg). [R]24D: -22.1 (c 0.96, CH2-
Cl2). 1H NMR (CD2Cl2): 0.79 (9H, s), 1.86-1.90 (1H, m), 2.01-2.27
(7H, m), 2.38-2.45 (2H, m), 2.62-2.73 (2H, m), 2.77-2.81 (2H, m),
3.07 (1H, m), 3.23-3.28 (2H, m), 3.66-3.71 (1H, m), 5.29-5.35 (1H,
m), 5.39-5.44 (2H, m), 6.99-7.03 (2H, m), 7.33-7.40 (3H, m), 7.60-
7.66 (3H, m), 8.03-8.07 (2H, m). 13C NMR (CD2Cl2): 23.3, 26.3,
26.7, 28.3, 31.2, 31.4, 34.3 (d, J ) 3.1), 34.8 (d, J ) 22.7), 39.9, 47.9,
58.9 (d, J ) 5.2), 68.0 (d, J ) 15.5), 68.4 (d, J ) 15.5), 108.8 (dd, J
) 3.0, 10.3), 109.5 (dd, J, 3.0, 10.3), 127.2 (d, J ) 45.5), 128.5 (d, J
) 9.3), 129.3 (d, J ) 13.4), 129.5 (d, J ) 45.5) 130.2 (d, J ) 2.0),
130.7 (d, J ) 9.3), 132.1 (d, J ) 2.0), 134.2 (d, J ) 13.4), 182.4. 31P
NMR (CD2Cl2): 25.8 (d, J ) 148). IR (CH2Cl2): 1605 (shoulder),
1562 cm-1. FAB-MS m/z: 564 ([Rh(cod)(1)]+). Anal. Calcd for
C30H40F6NOPRhSb: C, 45.02; H, 5.04; N, 1.75. Found: C, 44.74; H,
4.95; N, 1.73.
NMR of the 1:1 Molar Ratio Complex of Rh(acac)(C2H4)2/1
(Figure 1a). In an NMR sample tube were placed 1 (16.9 mg, 0.048
mmol) and Rh(acac)(C2H4)2 (12.4 mg, 0.048 mmol). The tube was filled
with argon, and C6D6 (0.6 mL) was added. 1H NMR (C6D6): 1.19 (9H,
s), 1.27-1.34 (1H, m), 1.54-1.59 (1H, m), 1.80 (6H, s), 1.93-2.03
(1H, m), 2.20-2.26 (1H, m), 2.82-3.00 (1H, m), 3.10 (2H, m), 3.41
(1H, m), 4.91 (1H, m), 5.30 (1H, s), 6.98-7.11 (6H, m), 7.77-8.05
(4H, m). 13C NMR (C6D6): 25.4, 27.2, 27.8, 27.99, 28.03, 31.1, 31.6
(d, J ) 23.7), 39.3, 47.7, 57.7, 99.4, 128.09, 128.14, 128.3, 128.5, 129.7,
133.5 (d, J ) 43.3), 133.9, 135.5 (d, J ) 43.3), 175.5, 184.0, 187.4.
31P NMR (C6D6): 42.7 (d, J ) 186).
Under argon atmosphere, a test tube was charged with [RhCl(cod)]2
(11.8 mg, 0.024 mmol), 1 (16.9 mg, 0.048 mmol), and AgSbF6 (16.5
mg, 0.048 mmol). To the test tube was added 2.4 mL of methylene
chloride at room temperature, and the whole was ultrasonicated for 5
min. After the centrifugal sedimentation, the supernatant was transferred
to an IR cell via cannula. IR (CH2Cl2): 1605 (shoulder), 1562 cm-1
.
-
NMR and IR of the Complex Prepared from [Rh(cod)(1)]+SbF6
and n-BuNC (3). Under argon atmosphere, a test tube was charged
with [RhCl(cod)]2 (23.7 mg, 0.048 mmol), 1 (33.9 mg, 0.096 mmol),
and AgSbF6 (33.0 mg, 0.096 mmol). To the test tube was added 1.2
mL of methylene chloride-d2 at room temperature, and the whole was
ultrasonicated for 5 min. After centrifugal sedimentation, the supernatant
was transferred to a flask via cannula. n-BuNC (15.9 mg, 0.192 mmol)
was added at room temperature, and the whole was stirred for 10 min.
The reaction mixture was transferred to an NMR tube via cannula. 31
P
NMR (CD2Cl2): 20.2 (d, J ) 123), 20.8 (d, J ) 125).
Under argon atmosphere, a test tube was charged with [RhCl(cod)]2
(11.8 mg, 0.024 mmol), 1 (16.9 mg, 0.048 mmol), and AgSbF6 (16.5
mg, 0.048 mmol). To the test tube was added 2.4 mL of methylene
chloride at room temperature, and the whole was ultrasonicated for 5
min. After centrifugal sedimentation, the supernatant was transferred
to a flask via cannula. n-BuNC (8.0 mg, 0.096 mmol) was added at
room temperature, and the whole was stirred for 10 min. The reaction
mixture was transferred to an IR cell via cannula. IR (CH2Cl2): 2179,
1620 cm-1
.
NMR and IR of [RhCl(cod)(1)] (4). In an NMR sample tube were
placed 1 (16.9 mg, 0.048 mmol) and [RhCl(cod)]2 (11.8 mg, 0.024
mmol). The tube was filled with argon, and methylene chloride-d2 (0.6
mL) was added. 1H NMR (CD2Cl2): 1.26 (9H, s), 1.88-2.14 (7H, m),
2.33-2.57 (5H, m), 3.04-3.18 (4H, m), 3.65-3.68 (2H, m), 4.75 (1H,
m), 5.42 (2H, m), 7.32-7.44 (6H, m), 7.60-7.68 (2H, m), 7.90-7.94
(2H, m). 13C NMR (CD2Cl2): 24.7, 27.1, 28.2, 28.6, 29.9, 30.0 (d, J )
20.6), 32.2, 32.9, 38.8, 47.3, 56.7, 69.5 (d, J ) 14.4), 70.4 (d, J )
NMR of the 1:1.5 Molar Ratio Complex of Rh(acac)(C2H4)2/1
(Figure 1b). In an NMR sample tube were placed 1 (25.4 mg, 0.072
mmol) and Rh(acac)(C2H4)2 (12.4 mg, 0.048 mmol). The tube was filled
with argon, and C6D6 (0.6 mL) was added. 31P NMR (C6D6): 39.9
(1P, d, J ) 194), 42.7 (2P, d, J ) 186).
9
8938 J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002

1,4-Addition of Arylboronic Acids to Cycloalkenones
A R T I C L E S
14.4), 103.4, 104.0, 127.56 (d, J ) 9.3), 127.62 (d, J ) 9.3), 129.3 (d,
J ) 2.0), 129.8, 131.9 (d, J ) 44.4), 132.7 (d, J ) 11.3), 133.2 (d, J
) 44.4), 134.4 (d, J ) 11.3), 175.8. 31P NMR (CD2Cl2): 21.5 (d, J )
150).
(S)-3-Phenylcyclohexanone25 (Table 1, entry 1). [R]20 -21.4 (c
D
1.22, CHCl3). 97% ee (HPLC, Daicel Chiralpak AD, hexane/i-PrOH
) 50/1, 0.5 mL/min, 254 nm, major 20.0 min and minor 23.6 min). 1H
NMR (CDCl3): 1.75-1.90 (2H, m), 2.07-2.11 (1H, m), 2.13-2.18
(1H, m), 2.35-2.42 (1H, m), 2.44-2.49 (1H, m), 2.50-2.56 (1H, m),
2.58-2.63 (1H, m), 3.01 (1H, tt, J ) 4.0, 11.9) 7.22-7.35 (5H, m).
13C NMR (CDCl3): 25.5, 32.7, 41.1, 44.7, 48.9, 126.5, 126.6, 128.6,
144.3, 211.0. IR (neat): 1710 cm-1. EIMS m/z: 174 (M+). The absolute
configuration was determined to be S by comparison of the specific
Under argon atmosphere, a test tube was charged with [RhCl(cod)]2
(11.8 mg, 0.024 mmol), 1 (16.9 mg, 0.048 mmol), and AgSbF6 (16.5
mg, 0.048 mmol). To the test tube was added 2.4 mL of methylene
chloride. The reaction mixture was transferred to an IR cell via cannula.
IR (CH2Cl2): 1609, 1558 (shoulder) cm-1
.
NMR and IR of the Complex Prepared from [RhCl(C2H4)2]2, 1,
and KOH (Scheme 5). Under argon atmosphere, a test tube was
charged with [RhCl(C2H4)2]2 (15.6 mg, 0.04 mmol) and 1 (28.2 mg,
0.08 mmol). To the test tube were added successively 1,4-dioxane-d8
(1.0 mL) and 6 M aq KOH (0.67 mL) at 0 °C. The mixture was stirred
at room temperature for 0.5 h. The organic layer of this mixture was
transferred to an NMR sample tube via cannula. 31P NMR (dioxane-
d8): 43.9 (d, J ) 182), 44.1 (d, J ) 184).
rotation with reported [R]20 +20.5 (c 0.58, CHCl3) for (R)-3-
D
phenylcyclohexanone (98.7% ee).26
(S)-3-Phenylcyclopentanone25 (Table 1, entry 9). [R]20D -80.7 (c
1.23, CHCl3). 83% ee (HPLC, Shiseido RU-1, MeOH only, 0.5 mL/
min, 250 nm, major 12.5 min and minor 15.9 min). 1H NMR (CDCl3):
1.95-2.04 (1H, m), 2.27-2.38 (2H, m), 2.42-2.58 (2H, m), 2.67 (1H,
dd, J ) 7.3, 18.0), 3.39-3.46 (1H, m), 7.23-7.37 (5H, m). 13C NMR
(CDCl3): 31.2, 38.8, 42.2, 45.8, 126.7, 128.6, 143.0, 218.4. IR (neat):
1735 cm-1. EIMS m/z: 160 (M+). The absolute configuration was
determined to be S by comparison of the specific rotation with reported
[R]RTD -67.7 (c 1.0, CHCl3) for (S)-3-phenylcyclopentanone (70% ee).29
Procedure for the Amidomonophosphine-Rhodium(I)-Catalyzed
Asymmetric 1,4-Addition of Phenylboronic Acid to Cyclohex-2-en-
1-one Using the Complex Prepared from [RhCl(C2H4)2]2, 1, and
KOH (Table 1, entry 7). Under argon atmosphere, a test tube was
charged with [RhCl(C2H4)2]2 (5.8 mg, 0.015 mmol) and 1 (13.8 mg,
0.039 mmol). To the test tube were added successively 1,4-dioxane
(0.5 mL) and 6 M aq KOH (0.25 mL) at 0 °C. The mixture was stirred
at room temperature for 0.5 h. This mixture was transferred to the
reaction flask (washed with 2 mL of 1,4-dioxane), which was charged
with PhB(OH)2 (610 mg, 5.0 mmol) under argon atmosphere. After
addition of cyclohex-2-en-1-one (96 mg, 1.0 mmol), the mixture was
heated to 100 °C and then stirred at 100 °C for 1 h. After dilution with
AcOEt, the mixture was washed with 10% NaOH and brine and then
dried over Na2SO4. Concentration and purification through silica gel
column chromatography gave (S)-3-phenylcyclohexane.
Under argon atmosphere, a test tube was charged with [RhCl(C2H4)2]2
(18.7 mg, 0.048 mmol) and 1 (33.9 mg, 0.096 mmol). To the test tube
were added successively 1,4-dioxane (4.8 mL) and 6 M aq KOH (1.5
mL) at 0 °C. The mixture was stirred at room temperature for 0.5 h.
The organic layer of this mixture was transferred to the flask via
cannula, and the whole was concentrated under vacuum. The residue
was dissolved with 12 mL of methylene chloride, and this sample was
transferred to an IR cell via cannula. IR (CH2Cl2): 1609, 1574
(shoulder) cm-1
.
NMR and IR of [Rh(cod)(6)]+SbF6- (14). Under argon atmosphere,
a test tube was charged with [RhCl(cod)]2 (15.8 mg, 0.032 mmol), 6
(34.2 mg, 0.064 mmol), and AgSbF6 (22.0 mg, 0.064 mmol). To the
test tube was added 0.8 mL of methylene chloride-d2 at room
temperature, and the whole was ultrasonicated for 5 min. After
centrifugal sedimentation, the supernatant was transferred to an NMR
sample tube via cannula. 1H NMR (CD2Cl2): 0.84 (9H, s), 1.63-1.68
(1H, m), 1.88-1.93 (1H, m), 1.98-2.05 (1H, m), 2.22-2.33 (3H, m),
2.38-2.44 (2H, m), 2.53-2.58 (1H, m), 2.54 (1H, d, J ) 13.4), 2.64-
2.73 (3H, m), 2.77 (1H, d, J ) 13.4), 2.82 (1H, d, J ) 13.8), 2.88 (1H,
d, J ) 13.8), 3.14-3.16 (1H, m), 3.21-3.23 (1H, m), 3.36 (1H, d, J
) 11.3), 3.70 (1H, d, J ) 11.3), 5.18-5.21 (1H, m), 5.37-5.40 (1H,
m), 5.44-5.50 (1H, m), 6.97-7.01 (2H, m), 7.14-7.15 (2H, m), 7.25-
7.45 (11H, m), 7.55-7.63 (3H, m), 7.87-7.91 (2H, m). 13C NMR (CD2-
Cl2): 26.7, 28.7, 31.2, 34.32, 34.34, 37.7 (d, J ) 22.6), 38.7 (d, J )
13.4), 39.9, 41.1, 42.8, 46.2, 57.3, 57.8 (d, J ) 6.2), 68.4 (d, J ) 16.5),
68.9 (d, J ) 16.5), 108.0 (dd, J ) 6.2, 10.3), 109.4 (dd, J ) 6.2, 10.3),
126.6, 126.8, 127.6 (d, J ) 44.4), 128.2, 128.3, 128.6 (d, J ) 9.3),
129.1 (d, J ) 12.4), 129.3 (d, J ) 44.4), 130.2, 130.3 (d, J ) 2.0),
130.4, 130.6 (d, J ) 9.3), 132.0 (d, J ) 2.0), 134.4 (d, J ) 12.4),
136.4, 136.5, 182.5. 31P NMR (CD2Cl2): 27.5 (d, J ) 150).
Procedure for the Amidomonophosphine-Rhodium(I)-Catalyzed
Asymmetric 1,4-Addition of Phenylboronic Acid to Cyclohex-2-en-
1-one Using the Complex Prepared from [RhCl(cod)]2, 1, and
AgSbF6 (Table 1, entry 3). Under argon atmosphere, a test tube was
charged with [RhCl(cod)]2 (2.5 mg, 0.005 mmol), 1 (4.6 mg, 0.013
mmol), and AgSbF6 (3.4 mg, 0.01 mmol). To the test tube was added
0.5 mL of 1,4-dioxane at room temperature, and the whole was
ultrasonicated for 5 min. After centrifugal sedimentation, the supernatant
was was transferred to the flask. This mixture was transferred to the
reaction flask (washed with 2 mL of 1,4-dioxane), which was charged
with PhB(OH)2 (610 mg, 5.0 mmol) under argon atmosphere. After
addition of cyclohex-2-en-1-one (96 mg, 1.0 mmol) and water (0.25
mL), the mixture was heated to 100 °C and then stirred at 100 °C for
1 h. After dilution with AcOEt, the mixture was washed with 10%
NaOH and brine and then dried over Na2SO4. Concentration and
purification through silica gel column chromatography gave 3-phenyl-
cyclohexane.
Under argon atmosphere, a test tube was charged with [RhCl(cod)]2
(7.4 mg, 0.015 mmol), 6 (16.0 mg, 0.03 mmol), and AgSbF6 (10.3
mg, 0.03 mmol). To the test tube was added 1.5 mL of methylene
chloride at room temperature, and the whole was ultrasonicated for 5
min. After centrifugal sedimentation, the supernatant was transferred
to an IR cell via cannula. IR (CH2Cl2): 1605, 1566 cm-1
.
Acknowledgment. We gratefully acknowledge financial
support from a Grant-in-Aid for Scientific Research on Priority
Areas (A) “Exploitation of Multi-Element Cyclic Molecules”
from the Ministry of Education, Culture, Sports, Science and
Technology, Japan.
General Procedure for the Amidomonophosphine-Rhodium(I)-
Catalyzed Asymmetric 1,4-Addition of Phenylboronic Acid to
Cycloalkenones Using the Complex Prepared from Rh(acac)(C2H4)2
and 1 (Table 1, entries 1, 2, and 9-13). Under argon atmosphere, a
reaction flask was charged with Rh(acac)(C2H4)2 (2.6 mg, 0.01 mmol),
amiodomonophosphine (0.01-0.03 mmol), and PhB(OH)2 (610 mg,
5.0 mmol). To the flask were added successively 1,4-dioxane (2.5 mL),
water (0.25 mL), and cycloalkenone (1.0 mmol). The mixture was
heated to 100 °C and then stirred at 100 °C for 1 or 6 h. After dilution
with AcOEt, the mixture was washed with 10% NaOH and brine and
then dried over Na2SO4. Concentration and purification through silica
gel column chromatography gave the desired product.
Supporting Information Available: Chart listing 1H and 13
C
NMR data of the some complexes and the crystal data of 2
(PDF). This material is available free of charge via the Internet
at http://pubs.acs.org.
JA0261933
9
J. AM. CHEM. SOC. VOL. 124, NO. 30, 2002 8939