Asymmetric synthesis of chiral amine derivatives through enantioselective hydrogenation with a highly effective rhodium catalyst containing a chiral bisaminophosphine ligand [2]

Full text of DOI:10.1021/ja974045k

5808
J. Am. Chem. Soc. 1998, 120, 5808-5809
Asymmetric Synthesis of Chiral Amine Derivatives
through Enantioselective Hydrogenation with a
Highly Effective Rhodium Catalyst Containing a
Chiral Bisaminophosphine Ligand
hydrogenation of arylenamides with Rh catalysts containing
Duphos and BPE ligands (ee ) 74.8-98.5%).16 From a practical
point of view, it is important to develop effective chiral ligands
which are easy to prepare so that the related chemistry can be
widely used. Herein we wish to report a highly effective Rh
catalyst containing an easily prepared chiral bisaminophosphine
ligand for the synthesis of a variety of valuable R-arylethylamine
derivatives with excellent enantioselectivities (up to 99.0% ee)
and high reactivities.
Fu-Yao Zhang, Cheng-Chao Pai, and Albert S. C. Chan*
Union Laboratory of Asymmetric Synthesis and
Department of Applied Biology and Chemical Technology,
The Hong Kong Polytechnic UniVersity, Hong Kong
ReceiVed December 1, 1997
Homogeneous asymmetric hydrogenation by transition-metal
complexes is one of the most powerful methods for the synthesis
of optically active organic compounds.1 High enantioselectivities
were obtained in the synthesis of chiral amino acids and their
derivatives through the asymmetric hydrogenation catalyzed by
rhodium complexes containing chiral diphosphine ligands such
2
3
4
5
6
7
as DIPAMP, DIOP, Chiraphos, Norphos, BPPM, BDPP,
8
9
10
11
BINAP, Duphos, BICP, and others. The easily prepared
bisaminophosphines12 were also found to be effective ligands for
the catalytic hydrogenation reactions leading to chiral amino acids.
Recently, a diphosphinite ligand bearing a spirocyclic backbone
has been found to be very efficient and highly enantioselective
in the hydrogenation of dehydroamino acid derivatives and other
In our initial study we focused our attention on the development
of chiral catalysts containing 2,2′-bis(diphenylphosphinoamino)-
2e
1
5
,1′-binaphthyl (BDPAB)1 and 2,2′-bis(diphenylphosphinoamino)-
1
7
8
,5′,6,6′,7,7′,8,8′-octahydro-1,1′-binaphthyl (H -BDPAB). An
13
substrates in our laboratory. Phosphinite ligands derived from
D-glucose were also found to be highly effective.14 In striking
contrast to the broad success in the synthesis of optically active
amino acids and other chiral compounds, only limited success
has been achieved on the asymmetric synthesis of chiral amines
and their derivatives through enantioselective hydrogenation of
enamides. The well-known chiral diphosphine ligands such as
DIOP, Phellanphos, and Nopaphos were used as chiral ligands
in the asymmetric catalytic hydrogenation of R-phenylenamide
important advantage of the use of this class of catalysts is that
the ligands can be easily prepared from the corresponding
diamines.
(
1a).15 However, the enantiomeric excess (ee) values of the
product 2a were quite low (25-68%). Recently, Burk et al.
reported an important breakthrough on the enantioselective
(1) (a) Asymmetric Synthesis; Morrison, J. D., Ed.; Academic Press: New
York, 1985; Vol. 5. (b) Noyori, R. Asymmetric Catalysis in Organic Synthesis;
Wiley & Sons: New York, 1994. (c) Catalytic Asymmetric Synthesis; Ojima,
I., Ed.; VCH: New York, 1993.
(2) (a) Knowles, W. S.; Sabacky, M. J.; Vineyard, B. D.; Weinkauff, D. J.
J. Am. Chem. Soc. 1975, 97, 2567. (b) Vineyard, B. D.; Knowles, W. S.;
Sabacky, M. J.; Bachman, G. L.; Weinkauff, D. J. J. Am. Chem. Soc. 1977,
9
9, 5946. (c) Schmidt, U.; Riedl, B.; Griesser, H.; Fitz, C. Synthesis 1991,
6
55.
(3) (a) Kagan H. B.; Dang, T. P. J. Am. Chem. Soc. 1972, 94, 6429. (b)
Murrer, B. A.; Brown, J. M.; Chalonner, P. A.; Nicholson, P. N.; Parker, D.
Synthesis 1979, 350.
(15) (a) Kagan, H. B.; Langlois, N.; Dang, T. P. J. Organomet. Chem.
1975, 90, 353. (b) Sinou, D.; Kagan, H. B. J. Organomet. Chem. 1976, 114,
325. (c) Samuel, O.; Couffignal, R.; Lauer, M.; Zhang, S. Y.; Kagan, H. B.
NouV. J. Chim. 1981, 5, 15.
(16) Burk, M. J.; Wang, Y. M.; Lee, J. R. J. Am. Chem. Soc. 1996, 118,
5142.
(
4) Fryzuk, M. D.; Bonisch, B. J. Am. Chem. Soc. 1977, 99, 6262.
(
5) Brunner, H.; Pieronczyk, W.; Sch o¨ nhammer, B.; Streng, K.; Bernal,
I.; Korp, J. Chem. Ber. 1981, 114, 1137.
(
6) Achiwa, K. J. Am. Chem. Soc. 1976, 98, 8265.
(
7) McNeil, P. A.; Roberts, N. K.; Bonisch, B. J. Am. Chem. Soc. 1981,
1
03, 2280.
(
(17) The procedure for the preparation of (R)-4: (R)-5,5′6 6′,7,7′,8,8′-
Octahydro-1,1′-binaphthyl-2,2′-diamine (200 mg, 0.7 mmol) in THF (20 mL)
was charged to a 50 mL flask under a nitrogen atmosphere. This flask was
cooled to -30 °C, and into the solution was added a solution of n-butyllithium
in hexane (0.88 mL of a 1.6 M solution, 1.4 mmol) in a dropwise manner.
The mixture was stirred for 2 h at -30 °C with a magnetic stirrer. Then a
solution of chlorodiphenylphosphine (0.32 mL, 1.8 mmol) in THF (5 mL)
was added dropwise. The system was allowed to stir for 5 h, and the
temperature was raised to about 25 °C. The mixture was filtered to remove
the solid. The THF solvent was removed in Vacuo to give 420 mg of (R)-4.
The crude product was purified by recrystallization in diethyl ether solvent at
-30 °C for 24 h to afford 390 mg of white, needlelike crystals of (R)-4 (84.0%
8) Miyashita, A.; Yasuda, A.; Takaya, H.; Toriumi, K.; Ito, T.; Souchi.
T.; Noyori, R. J. Am. Chem. Soc. 1980, 102, 7932.
9) (a) Burk, M. J. J. Am. Chem. Soc. 1991, 113, 8158. (b) Burk, M. J.;
(
Feaster, J. E.; Nugent, W. A.; Harlow, R. L. J. Am. Chem. Soc. 1993, 115,
10125. (c) Burk, M. J.; Gross, M. F.; Martinez, J. P. J. Am. Chem. Soc. 1995,
117, 9375.
(10) Zhu, G.; Cao, P.; Jiang, Q.; Zhang, X. J. Am. Chem. Soc. 1997, 119,
1
799.
11) (a) Riley, D. P.; Shumate, R. E. J. Org. Chem. 1980, 45, 5187. (b)
(
Bergstein, W.; Kleemann, A.; Martens, J. Synthesis 1981, 76.
12) (a) Fiorini, M.; Giongo, G. J. Mol. Catal. 1979, 5, 303. (b) Fiorini,
(
M.; Giongo, G. J. Mol. Catal. 1980, 7, 411. (c) Onuma, K.; Ito, T.; Nakamura,
A. Bull. Chem. Soc. Jpn. 1980, 53, 2016. (d) Miyano, S.; Nawa, M.;
Hashimoto, H. Chem. Lett. 1980, 729. (e) Miyano, S.; Nawa, M.; Mori, A.;
Hashimoto, H. Bull. Chem. Soc. Jpn. 1984, 2171.
of theoretical yield). The analytical data of (R)-4 were as follows: mp: 137-
1
139 °C. [R]
D
) - 47° (c ) 1.0, CH
2
Cl
2
). H NMR (400 MHz, CDCl
3
) δ:
7.24 (m, 22H); 6.98 (d, JH-H ) 8.34 Hz, 2H); 4.27 (d, JP-H ) 7.0 Hz, 2H);
1
3
3
2.67 (m, 4H); 2.10 (m, 4H); 1.58 (m, 8H). C NMR (101 MHz, CDCl ) δ:
(
13) Chan, A. S. C.; Hu, W.; Pai, C.; Lau, C.; Jiang, Y.; Mi, A.; Yan, M.;
Sun, J.; Lou, R.; Deng, J. J. Am. Chem. Soc. 1997, 119, 9570.
14) Rajanbabu, T. V.; Ayers, T. A.; Casaluovo, A. L. J. Am. Chem. Soc.
994, 116, 4101.
141.9, 141.7, 141.2, 141.0, 140.6, 140.5, 136.1, 131.0, 130.8, 130.4, 130.2,
129.6, 128.9, 128.7, 128.4, 128.3, 128.2, 123.2, 112.7, 112.5, 29.3, 27.3, 23.1,
3
1
(
23.0. P NMR (162 MHz, CDCl
3
) δ: 27.25 ppm. Anal. Calcd for
1
44 42 2 2
C H N P
: C 79.97, H 6.41, N 4.24. Found: C 79.78, H 6.40, N 4.24.
S0002-7863(97)04045-6 CCC: $15.00 © 1998 American Chemical Society
Published on Web 05/30/1998

Communications to the Editor
J. Am. Chem. Soc., Vol. 120, No. 23, 1998 5809
Table 1. Asymmetric Hydrogenation of 1a Using Rh-(R)-4
Catalyst
Table 2. Asymmetric Hydrogenation of 1 Catalyzed by Rh-(R)-4
or Rh-(R)-3 Complexesa
a
entry
solvent
THF
methanol
benzene
diethyl ether
THF
ee value (%)
config
1
2
3
4
5
6
92.1
91.0
80.5
73.2
91.0
89.5
96.8
R
R
R
R
R
R
R
convb
(%)
b
entry
Ar
product
cat.
ee (%) config
b
c
1
2
3
C6H5
C6H5
2a [Rh(R)-4(COD)]BF4 100 96.8 (13.7)
2a [Rh(R)-3(COD)]BF4 100 92.9
2b [Rh(R)-4(COD)]BF4 100 99.0 (4.6)
2b [Rh(R)-4(COD)]BF4 100 98.7
2b [Rh(R)-3(COD)]BF4 100 95.1
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
THF
THF
d
7
p-CF3C6H4
p-CF3C6H4
p-CF3C6H4
p-CH3C6H4
p-CH3C6H4
p-ClC6H4
p-ClC6H4
p-FC6H4
p-FC6H4
m-CH3C6H4 2f
m-CH3C6H4 2f
2-furanyl
2-furanyl
a
c
Unless otherwise noted, the reaction conditions were S/C ) 100,
4
b
P
1
H2 ) 14.5 psi, reaction time ) 10 min, room temperature. S/C )
000.
min.
5
6
7
8
9
0
1
2
3
4
5
c
d
P
H2 ) 1000 psi. Hydrogenation was performed at 5 °C for 30
2c
2c
[Rh(R)-4(COD)]BF4 100 97.0 (4.6)
[Rh(R)-3(COD)]BF4 97.6 95.1
2d [Rh(R)-4(COD)]BF4 100 97.0 (1.9)
2d [Rh(R)-3(COD)]BF4 100 94.9
H
8
-BINAM18 (H
8
-BINAM ) 5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-
1
1
1
1
1
1
2e
2e
[Rh(R)-4(COD)]BF4 100 96.0
[Rh(R)-3(COD)]BF4 85.5 90.1
[Rh(R)-4(COD)]BF4 100 97.7
[Rh(R)-3(COD)]BF4 93.4 94.8
binaphthyl-2,2′-diamine) was easily obtained via the partial hydro-
genation of BINAM (BINAM ) 1,1′-binaphthyl-2,2′-diamine)
using a similar method as in the preparation of H
8
-BINOL.19
The hydrogenation of 1a with a Rh catalyst containing (R)-4
gave excellent ee value (96.8% ee) for the product 2a, and the
rate of reaction was very fast. (Reaction conditions: S/C ) 200,
atm H , 5 °C, THF as solvent. Complete conversion was
2
achieved within 30 min.) In comparison, the same reaction under
otherwise identical conditions except with a Rh catalyst containing
2g [Rh(R)-4(COD)]BF4 100 98.4
2g [Rh(R)-3(COD)]BF4 100 96.1
a
sub/cat. ) 200; PH2 ) 1 atm; reaction temperature ) 5 °C; reaction
1
time ) 30 min, THF as solvent. The conversion and ee values were
determined by GLC with a CHIRASIL-L-VAL column. The configura-
tions were determined by comparing optical rotations with the reported
(
R)-3 gave only 92.9% ee for the product. The results of the
16
b
values.
Data in brackets were obtained using [Rh(S-BINAP)-
asymmetric hydrogenation of 1a catalyzed by Rh-(R)-4 complex
under a variety of conditions are summarized in Table 1. It was
noted that the enantioselectivity of the catalyst was sensitive to
the solvent used. Higher ee values of 2a were achieved in protic
and/or polar solvents. In contrast, the hydrogen pressure had very
little effect on the enantioselectivity. For example, in the
hydrogenation of 1a using Rh-(R)-4 catalyst in THF, the following
(COD)]BF as catalyst (sub/cat. ) 20; P ) 100 psi; 25 °C; 83 h;
4
H2
c
THF as solvent). sub/cat. ) 1000, reaction time ) 1.0 h.
2
-naphthol) and Ti-BINOL (BINOL )1,1′-bi-2-naphthol) cata-
20
lysts. It is quite possible that the improved enantioselectivity
of the catalysts is due to the increased steric effect caused by the
partial hydrogenation of the binaphthyl backbone. A similar effect
was also observed by Takaya et al. in the asymmetric hydrogena-
tion of some unsaturated carboxylic acids and other substrates
results were obtained: P 2 ) 14.5 psi, ee ) 92.1%; PH2 ) 100
H
psi, ee ) 90.7%; PH2 ) 1000 psi, ee ) 89.5%. The substrate/
catalyst ratio had a small influence on the enantioselectivity in
the Rh-(R)-4 catalyzed hydrogenation of 1a (entry 5 vs 1). Lower
reaction temperature led to higher ee values of 2a (entry 7 vs 1).
The rates of the hydrogenation of 1a catalyzed by Rh-(R)-4 or
Rh-(R)-3 complex were substantially higher than those using other
catalyst systems. Complete conversion for the hydrogenation of
catalyzed by Ru catalysts containing H
8 8
-BINAP [H -BINAP )
2,2′-bis(diphenylphosphino)-5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-bi-
naphthyl] and BINAP [BINAP ) 2,2′-bis(diphenylphosphino)-
1
,1′-binaphthyl].21
The high catalytic activity and enantioselectivity of Rh-(R)-4
are relatively independent of the electronic features of the
substrates. Substitution at meta- or para-position of the phenyl
ring of the parent enamide 1a did not give much influence on
the enantioselectivity for the products. However, no reaction was
observed in the hydrogenation of the ortho-substituted 1a under
the standard conditions. This might have been due to the strong
steric hindrance effect of the ortho-substituent which significantly
weakened the coordination of the substrate to the catalyst.
In conclusion, we have developed an easily prepared chiral
bisaminophosphine ligand which has been found to be extremely
effective in the Rh-catalyzed asymmetric hydrogenation of
enamides leading to chiral arylamine derivatives with excellent
ee. The simplicity and high efficiency clearly make it an excellent
choice of catalyst for the practical preparation of highly valued
chiral amine derivatives via the catalytic asymmetric hydrogena-
tion of enamides.
1a using Rh-(R)-4 or Rh-(R)-3 catalyst was achieved within 10
min at ambient temperature and within half an hour at 5 °C.
A variety of valuable chiral amine derivatives with high ee
values can be synthesized through the asymmetric hydrogenation
of enamides 1 with Rh-(R)-4 or Rh-(R)-3 catalyst, as shown in
Table 2.
It was clearly observed that the enantioselectivities of the
hydrogenation of 1 catalyzed by Rh-(R)-4 were consistently higher
than those from the same reaction with Rh-(R)-3 catalyst. These
results are consistent with our previous studies on the alkylation
of aldehydes with trialkylaluminum and with diethylzinc using
8 8
Ti-H -BINOL (H -BINOL ) 5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-bi-
(
18) The procedure for the preparation of (R)-6: A 50 mL autoclave
equipped with a magnetic stirring bar was charged with 200 mg (R)-1, 1′-
binaphthyl-2,2′-diamine (purchased from Aldrich Chemical Co.), 20 mg of
PtO
closed, and 3 atm of H
C. After releasing the hydrogen gas and removing the solid catalyst by
filtration, the mixture was neutralized with aqueous NaHCO solution followed
2
, 20 mL of glacial acetic acid, and 2 mL of water. The autoclave was
Acknowledgment. We thank the Hong Kong Research Grant Council
for financial support of this study.
2
was charged. The solution was stirred for 24 h at 50
°
3
JA974045K
by extraction with 20 mL of ethyl acetate three times. The combined extracts
were dried with sodium sulfate, and the solvent was removed with a rotary
evaporator to give 200 mg of crude product. The crude product was purified
by crystallization with 5 mL of ethyl acetate and 15 mL of hexane to give
(20) (a) Chan, A. S. C.; Zhang, F.-Y.; Yip, C.-W. J. Am. Chem. Soc. 1997,
119, 4080. (b) Zhang, F.-Y.; Yip, C. W.; Cao, R.; Chan, A. S. C.
Tetrahedron: Asymmetry 1997, 8, 585. (c) Zhang, F.-Y.; Chan, A. S. C.
Tetrahedron: Asymmetry 1997, 8, 3651.
(21) (a) Zhang, X.; Mashima, K.; Koyano, K.; Sayo, N.; Kumobayashi,
H.; Akutagawa, S.; Takaya, H. Tetrahedron Lett. 1991, 32, 7283. (b) Zhang,
X.; Mashima, K.; Koyano, K.; Sayo, N.; Kumobayashi, H.; Akutagawa, S.;
Takaya, H. J. Chem. Soc., Perkin Trans. 1 1994, 2309. (c) Zhang, X.; Uemura,
T.; Matsumura, K.; Sayo, N.; Kumobayashi, H.; Takaya, H. Synlett. 1994,
501. (d) Xiao, J.; Nefkens, S. C. A.; Jessop, P. G.; Ikariya, T.; Noyori, R.
Tetrahedron Lett. 1996, 37, 2813. (e) Uemura, T.; Zhang, X.; Matsumura,
K.; Sayo, N.; Kumobayashi, H.; Ohta, T.; Nozaki, K.; Takaya, H. J. Org.
Chem. 1996, 61, 5510.
1
80 mg of crystals of (R)-6 (88% of theoretical yield). The analytical data for
1
(
R)-6 were as follows: mp: 210 °C dec; [R]
D
) 133° (c ) 1.0, pyridine); H
NMR (400 MHz, CDCl
3
) δ: 6.90 (d, JH-H ) 8.0 Hz, 2H); 6.60 (d, JH-H
)
13
8
.2 Hz, 2H); 3.07 (s, 4H); 2.70 (m, 4H); 2.22 (m, 4H); 1.67 (m, 8H).
C
NMR (101 MHz, CDCl
3
) δ: 141.9, 136.6, 129.6, 128.0, 122.4, 113.5, 29.7,
7.4, 23.6 ppm. Anal. Calcd for C20H N : C 82.15, H 8.27, N 9.58. Found:
2
24 2
C 82.34, H 8.06, N 9.61.
(
19) Cram, D. J.; Helgeson, R. C.; Peacock, S. C.; Kaplan, L. J.; Domeier,
L. A.; Moreau, P.; Koga, K.; Mayer, J. M.; Chao, Y.; Siegel, M. G.; Hoffman,
D. H.; Sogah, G. D. Y. J. Org. Chem. 1978, 43, 1930.