Versatile synthesis of chiral aminophosphine phosphinites (AMPPs) as ligands for enantioselective hydrogenation

Article abstract of DOI:10.1055/s-2004-829183

New chiral aminophosphine phosphinite (AMPP) ligands with different P-aryl substituents were prepared from (1R,3S,4S)-2-azabicyclo[2.2.1]hept-3-ylmethanol by a new and chemoselective synthetic approach. The ligands showed good enantioselectivity (up to 91

Full text of DOI:10.1055/s-2004-829183

PAPER
2047
Versatile Synthesis of Chiral Aminophosphine Phosphinites (AMPPs) as
Ligands for Enantioselective Hydrogenation
Versatile
S
ynthesis
a
of Chira
l
A
minop
a
hosphine
P
l
hosphi
i
nites a V. Dubrovina,a Vitali I. Tararov,a Zenfira Kadyrova,a Axel Monsees,b Armin Börner*a,c
a
b
c
Leibniz-Institut für Organische Katalyse an der Universität Rostock e.V., Buchbinderstr. 5/6, 18055 Rostock, Germany
Degussa AG, Projekthaus Katalyse, Industriepark Hoechst, Gebäude G 830, 65926 Frankfurt/Main, Germany
Fachbereich Chemie der Universität Rostock, A.-Einstein-Str. 3a, 18059 Rostock, Germany
Fax +49(381)4669324; E-mail: armin.boerner@ifok.uni-rostock.de
Received 3 May 2004
no and hydroxyl group. As an alternative the ‘borane
methodology’ was suggested, which allows even the prep-
aration of P-stereogenic AMPPs.5 However, this method
requires several additional steps. A protocol for a conve-
Abstract: New chiral aminophosphine phosphinite (AMPP)
ligands with different P-aryl substituents were prepared from
(1R,3S,4S)-2-azabicyclo[2.2.1]hept-3-ylmethanol by a new and
chemoselective synthetic approach. The ligands showed good enan-
tioselectivity (up to 91%) in the Rh-catalyzed enantioselective hy- nient one-pot procedure could be the transphosphinyla-
tion reaction of phosphinous amides (aminophosphines).6
drogenation of benchmark substrates.
To the best of our knowledge this methodology has never
been used for the synthesis of ‘mixed’ P-ligands.
Key words: hydrogenation, transition metals, asymmetric cataly-
sis, amino alcohols, phosphorus
In order to show the high potential of this methodology,
herein we report our results in the preparation of AMPP-
ligands of type 1 (Figure 1) starting from the amino alco-
hol (1R,3S,4S)-2-azabicyclo[2.2.1]hept-3-ylmethanol (3)
(Scheme 1).7 The amino alcohol 3 represents a prolinol
analogue bearing a rigid backbone.8 In particular the
group of Andersson investigated the potential of this un-
natural enantiopure material as a chiral auxiliary and
ligand.9 It is available in a multi-gram scale now.10 Since
a related aminophosphine phosphinite ligand ProloPHOS
2 derived from prolinol is known from the work of Cesa-
rotti and Chiesa,11 a comparison of the hydrogenation
properties seemed to be simultaneously of considerable
interest. Thus the role of the rigid backbone in the ligand
for the enantioselection would become clear.
Among enantioselective catalytic reactions in an industri-
al scale, the hydrogenation with rhodium complexes bear-
ing chiral P-ligands is of pivotal importance.1 Since the
design of more efficient and selective catalysts is far from
being understood, the synthesis and test of new ligands is
still one of the most promising method for the optimiza-
tion of enantioselective hydrogenations. This situation is
forced by the increasing level of modern high-throughput
methods, which allow the fast testing of series of catalysts
and reaction conditions. For this approach the availability
of broad arrays of related ligands is indispensable.
For the establishment of comprehensive ligand libraries,
aminophosphine phosphinites (AMPPs)2 are of particular
value.3 They can be synthesized from chiral amino alco-
hols in one step. An overwhelming part of the latter can be
easily derived from chiral amino acids, which are avail-
able in a large variety, sufficient quantity and high optical
purity from nature or industrial processes. In the past sev-
eral research groups have shown the versatility of this ap-
proach.4 In due course several aminophosphine
phosphinites as efficient ligands for enantioselective hy-
drogenations were disclosed.
Figure 1 AMPP ligand 1 and ProloPHOS 2
The new ligands were prepared as shown in Scheme 1
using (dimethylamino)(diphenyl)phosphine and (diethyl-
amino)[bis(4-methylphenyl)]phosphine,12 respectively,
as reagent.
Generally, the synthesis of aminophosphine phosphinites
is carried out by condensation reaction of the amino alco-
hol with dialkyl- or diarylchlorophosphines in the pres-
ence of a tertiary amine as a base. Hydroxyl and amino
group can be esterified simultaneously. However, on the
other hand under these conditions the selective synthesis
of ‘mixed’ ligands with different substituents on both
phosphorous atoms, which opens up another level of vari-
ation, frequently fails due to the similar reactivity of ami-
In a first approach applying two equivalents of dialkyl-
aminophosphines, AMPPs 1a,b bearing the same substit-
uents on both phosphorous atoms were obtained in nearly
quantitative yield. The synthesis of ‘mixed’ ligands 1c,d
was performed in two consecutive steps involving differ-
ent dialkylaminophosphines as reagent. As clearly indi-
cated by 31P NMR spectroscopy, the hydroxyl group
reacted in the first step selectively when only one equiva-
lent of (dimethylamino)(diphenyl)phosphine and (dieth-
SYNTHESIS 2004, No. 12, pp 2047–2051
x
x.
x
x
.
2
0
0
4
Advanced online publication: 27.07.2004
DOI: 10.1055/s-2004-829183; Art ID: Z08704SS
© Georg Thieme Verlag Stuttgart · New York

2048
N. V. Dubrovina et al.
PAPER
benchmark substrates (Z)-N-acetylaminocinnamic acid,
its methyl ester and methyl N-acetylaminoacrylate. The
cationic Rh(I)-precatalysts were prepared by reaction of
ligands 1a–d with [Rh(COD)acac] and subsequent addi-
tion of HBF4.
As clearly seen from Table 1, complexes based on the new
ligands 1a–d provide highly active catalysts for the hydro-
genation of functionalized olefins. In general new cata-
lysts afforded superior enantioselectivities compared to
the ProloPHOS-catalyst. This feature gives evidence for
the benefit of the additional carbocyclic ring in the back-
bone of the prolinol derivative. Highest enantioselectivi-
ties for all substrates tried were noted by application of
ligand 1a in methanol as solvent. Substitution of one or
both P-phenyl groups by p-tolyl groups decreased slightly
the enantioselectivity independent on the heteroatom link-
er (O or N).
Scheme 1
In conclusion, a series of new aminophosphine phosphin-
ites (AMPPs) have been synthesized by a simple and fast
one-pot procedure. Due to its versatility and high yields
this method can be used for the synthesis of broad arrays
of ligands in combinatorial approaches. The new ligands
were used in Rh-catalyzed hydrogenations where up to
91% ees were achieved in the benchmark test.
ylamino)[bis(4-methylphenyl)]phosphine, respectively,
was employed. The amino group was esterified only after
addition of a second equivalent of the same or another di-
alkylaminophosphine. Based on this method, AMPPs
1c,d could be obtained in more than 90% overall yield.
The new bidentate chiral phosphorous ligands were tested
in the Rh-catalyzed asymmetric hydrogenation of the
a
Table 1 Enantioselective Hydrogenations with [Rh(COD)(Ligand)]BF4
Run
Ligand
Substrate
R1
Solvent
ee (%)b
TOF (h–1)
Ar1
Ar2
R2
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
1
2
1a
1a
1a
1a
1b
1b
1b
1b
1c
1c
1c
1d
1d
2
Ph
Ph
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
MeOH
CH2Cl2
EtOAc
THF
91 (S)c
88 (S)c
83 (S)c
84 (S)c
85 (S)c
82 (S)c
78 (S)c
78 (S)c
71 (S)c
78 (S)c
76 (S)c
74 (S)c
78 (S)c
80 (S)c
3500
1600
2000
1700
2700
1300
2400
1500
2700
1200
2000
3000
1500
1100
Ph
Ph
3
Ph
Ph
4
Ph
Ph
5
p-Tol
p-Tol
p-Tol
p-Tol
Ph
p-Tol
p-Tol
p-Tol
p-Tol
p-Tol
p-Tol
p-Tol
Ph
MeOH
CH2Cl2
EtOAc
THF
6
7
8
9
MeOH
CH2Cl2
EtOAc
MeOH
CH2Cl2
MeOH
10
11
12
13
14
Ph
Ph
p-Tol
p-Tol
Ph
Synthesis 2004, No. 12, 2047–2051 © Thieme Stuttgart · New York

PAPER
Versatile Synthesis of Chiral Aminophosphine Phosphinites
2049
Table 1 Enantioselective Hydrogenations with [Rh(COD)(Ligand)]BF4a (continued)
Run
Ligand
Substrate
R1
Solvent
ee (%)b
TOF (h–1)
Ar1
Ar2
R2
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
H
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
2
CO2Me
CO2Me
CO2H
CH2Cl2
EtOAc
MeOH
CH2Cl2
MeOH
CH2Cl2
MeOH
CH2Cl2
MeOH
CH2Cl2
CH2Cl2
MeOH
MeOH
CH2Cl2
MeOH
CH2Cl2
MeOH
CH2Cl2
MeOH
CH2Cl2
CH2Cl2
MeOH
79 (S)c
74 (S)c
90 (S)d
83 (S)d
86 (S)d
66 (S)d
82 (S)d
67 (S)d
80 (S)d
65 (S)d
65 (S)d
80 (S)d
85 (S)e
70 (S)e
80 (S)e
61 (S)e
80 (S)e
63 (S)e
77 (S)e
59 (S)e
69 (S)e
79 (S)e
2000
500
2
1a
1a
1b
1b
1c
1c
1d
1d
2
Ph
Ph
3100
600
Ph
Ph
CO2H
p-Tol
p-Tol
Ph
p-Tol
p-Tol
p-Tol
p-Tol
Ph
CO2H
2400
300
CO2H
CO2H
2000
300
Ph
CO2H
p-Tol
p-Tol
CO2H
2400
300
Ph
CO2H
CO2H
2000
250
2
CO2H
1a
1a
1b
1b
1c
1c
1d
1d
2
Ph
Ph
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
3500
1500
4000
2000
3600
1200
4500
2500
1500
2500
Ph
Ph
H
p-Tol
p-Tol
Ph
p-Tol
p-Tol
p-Tol
p-Tol
Ph
H
H
H
Ph
H
p-Tol
p-Tol
H
Ph
H
H
2
H
a Conditions: 0.01 mmol of precatalyst, 1.0 mmol of prochiral olefin in 15.0 mL solvent at 25.0 °C, 1.0 atm overall pressure over the solution.
b Measured after consumption of the calculated amount of H2.
c Determined by GC, 25 m Chirasil-val (Alltech), 150 °C.
d After esterification with diazomethane.
e Determined by GC, 25 m Chirasil-val (Alltech), 120 °C.
All reagents were purchased from commercial sources and used
without additional purification unless otherwise mentioned. Sol-
vents were dried and freshly distilled under argon before use. All re-
actions were performed under argon by using standard Schlenk
techniques. Optical rotations were measured on a ‘gyromat-HP’ in-
strument (Fa. Dr. Kernchen). NMR spectra were recorded at the fol-
lowing frequencies: 400.13 MHz (1H), 100.63 MHz (13C), 161.98
MHz (31P). Chemical shifts of 1H and 13C NMR spectra are reported
in ppm downfield from TMS as an internal standard. Chemical
shifts of 31P NMR spectra are referred to H3PO4 as an external stan-
dard. Elemental analyses were performed with a LEGO CHNS-932.
Aminophosphine Phosphinites 1a,b
A mixture of the amino alcohol 3 (0.455 g, 3.59 mmol) and (di-
methylamino)(diphenyl)phosphine (1.65 g, 7.23 mmol) and (dieth-
ylamino)[bis(4-methylphenyl)]phosphine (2.07 g, 7.23 mmol),
respectively, in xylene (5 mL) was refluxed for 12 h. The solvent
was removed under vacuum to give the product as a colorless oil.
This product was used without purification for precatalyst forma-
tion.
(1R,3S,4S)-2-Diphenylphosphinyl-3-diphenylphosphinyloxy-
methyl-2-azabicyclo[2.2.1]heptane (1a)
Yield: 1.74 g (98%); [a]D25 –52 (c = 0.8, CHCl3).
Synthesis 2004, No. 12, 2047–2051 © Thieme Stuttgart · New York

2050
N. V. Dubrovina et al.
PAPER
1H NMR (CDCl3): d = 0.92–1.44 (6 H, m), 1.75–1.84 (1 H, m), 2.63
(1 H, s), 3.30–3.38 (1 H, m), 3.90 (1 H, m), 4.15–4.24 (1 H, m),
7.03–7.74 (20 Harom, m).
13C NMR (CDCl3): d = 28.7 (CH2), 31.2 (CH2), 36.6 (CH2), 41.3
(CH), 59.6 (CH), 67.6 (CH), 72.6 (OCH2), 128.2–134.3 (Carom),
141.2 (Carom), 143.3 (Carom).
was used without purification for complexation to rhodium; yield:
1.73 g (92%); [a]D25 –38 (c = 0.8, CHCl3).
1H NMR (C6D6): d = 0.62–1.11 (6 H, m), 1.45–1.55 (1 H, m), 1.77
(3 H, s, CH3), 1.86 (3 H, s, CH3), 2.96–3.08 (1 H, m), 3.27 (1 H, s),
3.58–3.64 (1 H, m), 3.82–3.97 (1 H, m), 6.71–7.78 (18 Harom, m).
13C NMR (C6D6): d = 21.5 (CH3), 28.6 (CH2), 31.2 (CH2), 36.6
(CH2), 41.3 (CH), 59.6 (CH), 67.5 (CH), 72.5 (OCH2), 128.5–134.2
(Carom), 139.0–139.5 (Carom), 141.4 (Carom).
31P NMR (CDCl3): d = 38.3 (s, NP), 114.9 (s, OP).
MS (70 eV): m/z (%) = 495 ([M]+, 19), 310 ([M – PPh2]+, 27), 293
([M – HOPPh2]+, 89), 183 ([PPh2]+, 100).
31P NMR (C6D6): d = 38.3 (s, NP), 115.7 (s, OP).
Anal. Calcd for C31H31NOP2 (495.54): C, 75.13; H, 6.30; N, 2.82;
P, 12.50. Found: C, 74.22; H, 5.72; N, 2.83; P, 12.72.
MS (70 eV): m/z (%) = 523 ([M]+, 20), 310 ([M – P(p-Tol)2]+, 18),
293 ([M – HOP(p-Tol)2], 100), 213 ([P(p-Tol)2]+, 36), 183 ([PPh2]+,
65).
(1R,3S,4S)-2-Bis(4-methylphenyl)phosphinyl-3-bis(4-methyl-
phenyl)phosphinyloxymethyl-2-azabicyclo[2.2.1]heptane (1b)
Yield: 1.92 g (97%); [a]D25 –40 (c = 0.8, CHCl3).
1H NMR (C6D6): d = 1.00–1.58 (6 H, m), 1.92–1.97 (1 H, m), 2.20
(6 H, s, CH3), 2.32 (6 H, s, CH3), 2.79 (1 H, s), 3.43–3.51 (1 H, m),
3.98–4.08 (1 H, m), 4.28–4.38 (1 H, m), 7.00–7.81 (16 Harom, m).
13C NMR (C6D6): d = 21.6 (CH3), 28.7 (CH2), 31.5 (CH2), 36.6
(CH2), 41.3 (CH), 59.8 (CH), 67.5 (CH), 72.6 (CH2O), 127.7–132.5
(Carom), 134.1 (Carom), 136.2 (Carom), 137.7–139.5 (Carom), 142.1
(Carom).
31P NMR (C6D6): d = 37.8 (s, NP), 115.4 (s, OP).
MS (70 eV): m/z (%) = 551 ([M]+, 15), 338 ([M – P(p-Tol)2]+, 22),
321 ([M – HOP(p-Tol)2]+, 69), 229 ([OP(p-Tol)2]+, 63), 213 ([P(p-
Tol)2]+, 100).
The compound was characterized as its BH3-complex
C33H41B2NOP2 (551.25) by MS and elemental analysis.
MS (70 eV): m/z (%) = 537 ([M – BH3]+, 26), 536 ([M – BH4]+, 78),
213 ([P(p-Tol)2]+, 39), 183 ([PPh2]+, 100).
Anal. Calcd for C33H41B2NOP2 (551.25): C, 71.90; H, 7.50; N, 2.54;
P, 11.24: Found: C, 70.55; H, 7.59; N, 2.40; P, 10.98.
[Rh(COD)1a–d]BF4
Aminophosphine phosphinite 1a–d (3.0 mmol) was dissolved in
THF (10 mL) and slowly added to a solution of [Rh(COD)acac]
(0.93 g, 3.0 mmol) in THF (20 mL). The solution was stirred for 15
min. Then a stoichiometric amount of aq 8 M HBF4 was added and
the stirring was continued for another 15 min. The complex was pre-
cipitated by Et2O and crystallized from THF–Et2O.
[Rh(COD)(1a)]BF4
Yield: 1.98 g (83%).
(1R,3S,4S)-2-Diphenylphosphinyl-3-bis(4-methylphenyl)phos-
phinyloxymethyl-2-azabicyclo[2.2.1]heptane (1c)
A mixture of the amino alcohol 3 (0.455 g, 3.59 mmol) and (di-
methylamino)(diphenyl)phosphine (0.83 g, 3.61 mmol) in xylene (5
mL) was refluxed for 12 h. To this solution (diethylamino)[bis(4-
methylphenyl)]phosphine (1.03 g, 3.61 mmol) was added at r.t. and
the mixture was refluxed for another 12 h. The solvent was removed
under vacuum to give the product as a colorless oil. This product
was used without purification for complexation to rhodium; yield:
1.73 g (92%); [a]D25 –45 (c = 0.8, CHCl3).
13C NMR (CDCl3): d = 26.8 (CH2), 28.4 (CH2), 29.7, 30.3, 31.1,
32.5 (CH2, COD), 37.8 (CH2), 41.9 (CH), 62.8 (CH), 63.8 (CH),
70.8 (OCH2), 94.8, 103.2, 104.6, 108.2 (=CH, COD), 128.7–136.3
(Carom).
31P NMR (CDCl3): d = 66.9 [dd, J(P,Rh) = 162 Hz, J(P,P) = 36 Hz,
NP], 127.3 [dd, J(P,Rh) = 173 Hz, J(P,P) = 36 Hz, OP].
FAB-MS: m/z (%) = 706 ([M – BF4]+, 60), 598 ([M – BF4 – COD]+,
100).
1H NMR (C6D6): d =1.10–1.58 (6 H, m), 1.91–2.22 (1 H, m), 2.29
(3 H, s, CH3), 2.36 (3 H, s, CH3), 2.74–2.84 (1 H, m), 3.42–3.52 (1
Anal. Calcd for C39H43BF4NOP2Rh (794.43): C, 58.96; H, 5.45; N,
1.76; P, 7.79; Rh, 12.95. Found: C, 58.67; H, 5.64; N, 1.71; P, 7.71;
Rh, 11.54.
H, m), 4.00–4.12 (1 H, m), 4.27–4.39 (1 H, m), 7.13–7.86 (18 Harom
m).
,
13C NMR (C6D6): d = 21.5 (CH3), 28.7 (CH2), 31.5 (CH2), 36.6
(CH2), 41.4 (CH), 59.8 (CH), 67.5 (CH), 72.4 (OCH2), 129.4–134.2
(Carom), 138.0–140.3 (Carom), 143.4 (Carom).
31P NMR (C6D6): d = 37.9 (s, NP), 114.8 (s, OP).
[Rh(COD)(1b)]BF4
Yield: 1.81 g (71%).
13C NMR (CDCl3): d = 22.1 (CH3), 27.1 (CH2), 28.4 (CH2), 29.8,
30.2, 31.0, 32.6 (CH2, COD), 37.7 (CH2), 41.9 (CH), 62.5 (CH),
64.1 (CH), 70.7 (m, OCH2), 94.7, 102.3, 104.7, 106.5 (=CH, COD),
129.3–135.8 (Carom), 141.6 (Carom).
MS (70 eV): m/z (%) = 523 ([M]+, 29), 338 ([M – PPh2]+, 28), 321
([M – HOPPh2 ]+, 92), 213 ([P(p-Tol)2]+, 100), 183 ([PPh2]+, 40).
The compound was characterized analytically as its BH3-complex.
31P NMR (CDCl3): d = 66.5 8dd, J(P,Rh) = 161 Hz, J(P,P) = 35 Hz,
NP], 126.3 [dd, J(P,Rh) = 175 Hz, J(P,P) = 35 Hz, OP].
MS (70 eV): m/z (%) = 537 ([M – BH3]+, 43), 536 ([M – BH4]+, 82),
213 ([P(p-Tol)2]+, 100), 183 ([PPh2]+, 60).
FAB-MS: m/z (%) = 762 ([M – BF4]+, 100), 654 ([M – BF4 –
COD]+, 95).
Anal. Calcd for C33H41B2NOP2 (551.25): C ,71.90; H, 7.50; N, 2.54;
P, 11.24. Found: C, 71.81; H, 7.37; N, 2.44; P, 11.50.
Anal. Calcd for C43H51BF4NOP2Rh (849.54): C, 60.79; H, 6.05; N,
1.64; P, 7.29; Rh, 12.11. Found: C, 58.66; H, 6.02; N, 2.03; P, 7.24;
Rh, 11.99.
(1R,3S,4S)-2-Bis(4-methylphenyl)phosphinyl-3-diphenylphos-
phinyloxymethyl-2-azabicyclo[2.2.1]heptane (1d)
A mixture of the amino alcohol 3 (0.455 g, 3.59 mmol) and (dieth-
ylamino)[bis(4-methylphenyl)]phosphine (1.03 g, 3.61 mmol) in
xylene (5 mL) was refluxed for 12 h. To this solution (dimethylami-
no)(diphenyl)phosphine (0.83 g, 3.61 mmol) was added at r.t. and
the mixture was refluxed for another 12 h. The solvent was removed
under vacuum to give the product as a colorless oil. This product
[Rh(COD)(1c)]BF4
Yield: 1.63 g (66%).
13C NMR (CDCl3): d = 22.0 (CH3), 26.9 (CH2), 28.4 (CH2), 29.9,
30.1, 31.3, 32.5 (CH2, COD), 37.7 (CH2), 41.9 (CH), 62.5 (CH),
63.7 (CH), 70.7 (OCH2), 95.0, 102.3, 104.4, 106.5 (=CH, COD),
129.3–135.8 (Carom), 140.8 (Carom).
Synthesis 2004, No. 12, 2047–2051 © Thieme Stuttgart · New York

PAPER
Versatile Synthesis of Chiral Aminophosphine Phosphinites
2051
31P NMR (CDCl3): d = 67.0 [dd, J(P,Rh) = 161 Hz, J(P,P) = 35 Hz,
NP], 127.1 [dd, J(P,Rh) = 173 Hz, J(P,P) = 35 Hz, OP].
(2) Petit, M.; Mortreux, A.; Petit, F.; Buono, G.; Pfeiffer, G.
New. J. Chem. 1983, 7, 593.
(3) (a) Brunner, H.; Zettlmeier, W. Handbook of
Enantioselective Catalysis with Transition Metal
Compounds, Ligands, Vol. 2; VCH: Weinheim, 1993.
(b) Seyden-Penne, J. Chiral Auxiliaries and Ligands in
Asymmetric Synthesis; Wiley: New York, 1995.
(4) For a recent review, see: Agbossou-Niedercorn, F.; Suisse, I.
Coord. Chem. Rev. 2003, 242, 145; and references cited
therein.
(5) Jugé, S.; Stephan, M.; Merdés, R.; Genêt, J.-P.; Halut-
Desportes, S. J. Chem. Soc., Chem. Commun. 1993, 531.
(6) Kosolapoff, G. M.; Maier, L. Organic Phosphorus
Compounds, Vol. 4; Wiley: New York, 1972, 504.
(7) This work is part of the Ph.D. thesis of Dubrovina, N. V.;
Rostock, 2003.
(8) Coppola, G. M.; Schuster, H. F. Asymmmetric Synthesis:
Construction of Chiral Molecules using Amino Acids; Wiley
Interscience: New York, 1987.
(9) (a) Brandt, P.; Andersson, P. G. Synlett 2000, 1092; and
references cited therein. (b) Genov, M.; Scherer, G.; Studer,
M.; Pfalz, A. Synthesis 2002, 2037.
FAB-MS: m/z (%) = 734 ([M – BF4]+, 70), 626 [M – BF4 – COD]+,
100).
[Rh(COD)(1d)]BF4
Yield: 1.61 g (65%).
13C NMR (CDCl3): d = 22.0 (CH3), 27.0 (CH2), 28.4 (CH2), 29.8,
30.2, 31.1, 32.3 (CH2, COD), 37.7 (CH2), 41.9 (CH), 62.6 (CH),
64.0 (CH), 70.6 (OCH2), 95.0, 103.1, 104.6, 106.5 (=CH, COD),
129.1–135.8 (Carom), 141.6 (Carom).
31P NMR (CDCl3): d = 67.2 [dd, J(P,Rh) = 162 Hz, J(P,P) = 36 Hz,
NP], 126.5 [dd, J(P,Rh) = 173 Hz, J(P,P) = 36 Hz, OP].
FAB-MS: m/z (%) = 734 ([M – BF4]+, 75), 626 ([M – BF4 – COD]+,
100).
Acknowledgment
Authors from academia are grateful for the financial support provi-
ded by the Degussa AG, Projekthaus Katalyse (Frankfurt/Main,
Germany) and the European Commission (Descartes Prize 2001).
We thank Dr. C. Fischer for GC measurements, Mrs. H. Borgwaldt
and Mrs. S. Buchholz for skilled technical assistance.
(10) (a) Tararov, V. I.; Kadyrov, R.; Kadyrova, Z.; Dubrovina,
N.; Börner, A. Tetrahedron: Asymmetry 2002, 13, 25.
(b) Ekegren, J. K.; Modin, S. A.; Alonso, D. A.; Andersson,
P. G. Tetrahedron: Asymmetry 2002, 13, 447.
(11) Cesarotti, E.; Chiesa, A.; Ciani, G.; Sironi, A. J. Organomet.
Chem. 1983, 251, 79.
References
(12) McEwen, W. E.; Janes, A. B.; Knapczyk, J. W.; Kyllingstad,
V. L.; Shiau, W.-I.; Shore, S.; Smith, J. H. J. Am. Chem. Soc.
1978, 100, 7304.
(1) (a) Ohkuma, T.; Kitamura, M.; Noyori, R. Asymmetric
Hydrogenation, In Catalytic Asymmetric Synthesis; Ojima,
I., Ed.; Wiley-VCH: New York, 2000, 1. (b) Asymmetric
Catalysis on Industrial Scale; Blaser, H. U.; Schmidt, E.,
Eds.; Wiley-VCH: Weinheim, 2003.
Synthesis 2004, No. 12, 2047–2051 © Thieme Stuttgart · New York