Modular chiral bidentate phosphonites: Design, synthesis, and application in catalytic asymmetric hydroformylation reactions

Article abstract of DOI:10.1002/chem.200800388

A new class of C₂-symmetric chiral bidentate phosphonite ligands has been synthesized in moderate to good yields from readily available starting materials. Application of these air-stable chiral phosphonites in the Rh ^I-catalyzed asymmetric hydroformylation of styrene derivatives, vinyl acetate, and allyl cyanide afforded the corresponding chiral aldehydes with high regio- and enantioselectivities under mild reaction conditions. The modular nature of the ligands allows fine-tuning of the selectivities through judicious modifications of the substituents on the ligand backbone. X-ray structural analysis of the catalyst precursor suggested that the steric hindrance caused by the protruding remote substituents of the ligands into the vicinity of the metal center might be an important factor for the enantio-control of the reaction, whereas the sense of asymmetric induction can be rationalized on the basis of a trigonal-bipyramidal transition state diagram.

Full text of DOI:10.1002/chem.200800388

FULL PAPER
DOI: 10.1002/chem.200800388
Modular Chiral Bidentate Phosphonites: Design,Synthesis,and Application
in Catalytic Asymmetric Hydroformylation Reactions
Baoguo Zhao,[a] Xingao Peng,[a,b] Zheng Wang,[a] Chungu Xia,*[b] and Kuiling Ding*[a]
Dedicated to Professor Xiyan Lu on the occasion of his 80th birthday
Abstract: A new class of C2-symmetric
chiral bidentate phosphonite ligands
has been synthesized in moderate to
good yields from readily available
starting materials. Application of these
air-stable chiral phosphonites in the
RhI-catalyzed asymmetric hydroformy-
lation of styrene derivatives, vinyl ace-
tate, and allyl cyanide afforded the cor-
responding chiral aldehydes with high
regio- and enantioselectivities under
mild reaction conditions. The modular
nature of the ligands allows fine-tuning
of the selectivities through judicious
modifications of the substituents on the
ligand backbone. X-ray structural anal-
ysis of the catalyst precursor suggested
that the steric hindrance caused by the
protruding remote substituents of the
ligands into the vicinity of the metal
center might be an important factor for
the enantio-control of the reaction,
whereas the sense of asymmetric induc-
tion can be rationalized on the basis of
a trigonal-bipyramidal transition state
diagram.
Keywords: asymmetric catalysis
bidentate ligands hydro-
formylation · phosphonite ligands ·
rhodium
·
·
AHCTREUNG
Introduction
and academia, however, the catalytic AHF is still a challeng-
ing area in comparison with the rapid development of other
catalytic asymmetric reactions.[4] One of the major problems
involved in the reaction is how to control both the regio-
and enantioselectivities while maintaining reasonable reac-
tion rates at moderately high temperatures (60–1008C). This
is usually a difficult goal since reduced regio- and enantiose-
lectivities are often obtained at higher temperatures. Al-
though these selectivities can be modulated to some extent
by altering reaction parameters, such as gas pressure and re-
action temperature, the employed chiral ligand is the most
important factor in selectivity control.[2] Therefore, in the
area of RhI-catalyzed AHF, significant improvements with
regard to catalytic activity and/or selectivity have always
been closely associated with the successful discovery/devel-
opment of new ligands. Over the past three decades, al-
though a large variety of chiral ligands has been examined
in RhI-catalyzed AHF, excellent results have only been re-
ported for a limited number of ligands so far.[2e] Some of the
representative ligands are shown in Scheme 1. The catalysis
involving chiral bisphosphites 1 and 2 demonstrated some
degree of substrate specificity. Whereas the former exhibited
good enantioselectivity in the reaction of styrene,[5] the
latter was found quite efficient in the stereocontrol of the
hydroformylation of allyl cyanide and vinyl acetate.[6] Wills
et al. reported the first phospholane-type ligand (3) was ef-
Hydroformylation (HF)[1] represents one of the most impor-
tant homogeneously catalyzed industrial processes with mil-
lions of tons of oxo products being produced worldwide per
year. Catalytic asymmetric hydroformylation (AHF) is an
atom-economic one-carbon homologation reaction that con-
verts in a single step olefins and syngas (CO/H2) into chiral
aldehydes, which can be used as important chiral synthons
for a variety of pharmaceutical products and fine chemi-
cals.[1–3] Despite the considerable interest from both industry
[a] Dr. B. Zhao, X. Peng, Prof. Dr. Z. Wang, Prof. Dr. K. Ding
State Key Laboratory of Organometallic Chemistry
Shanghai Institute of Organic Chemistry
Chinese Academy of Sciences
354 Fenglin Road, Shanghai 200032 (China)
Fax : (+86)216-416-6128
E-mail: kding@mail.sioc.ac.cn
[b] X. Peng, Prof. Dr. C. Xia
State Key Laboratory of Oxo Synthesis and Selective Oxidation
Lanzhou Institute of Chemical Physics
Chinese Academy of Sciences
Lanzhou 730000 (China)
Fax : (+86)931-827-7088
E-mail: cgxia@lzb.ac.cn
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.200800388.
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Results and Discussion
Ligand design: Based on the
observation that the phosphites
can be highly effective ligands
for the reaction with excellent
reactivities,[5,6] and that the
chiral ligands bearing a 1,2-di-
phosphinoethane or 1,2-diphos-
phinobenzene moiety often
demonstrated excellent regio-
or enantioselective control in
the reaction,[6c,7,10,11] it was envi-
sioned that incorporation of
both structural features into
one ligand molecule might
result in a combination of these
advantages in a best scenario.
During the course of our inves-
tigation on modular chiral cata-
lysts for asymmetric catalysis, a
wide variety of modular mono-
dentate phosphoramide ligands,
DpenPhos (7)[12a,b] and Cydam-
Phos (8)[12c] based on chiral 1,2-
phenylethlene-1,2-diamine and
1,2-diaminocyclohexane, respec-
tively, have been developed.
Dual steric tuning of the sub-
stituents on the ligands is criti-
Scheme 1. Representative examples of chiral ligands for RhI-catalyzed AHF of olefins.
fective for AHF of vinyl acetate, but quite unselective
toward hydroformylation of styrene.[7] The discovery of the
Rh/binaphos (4) catalysts by Takaya, Nozaki and co-workers
in 1993 is widely regarded as a breakthrough in this field. A
variety of olefins were hydroformylated with generally high
levels of regio- and enantioselectivity using this versatile cat-
alyst.[8] Very recently, Zhang and Yan reported phosphine–
phosphoramidite (5), a ligand structurally related to (R,S)-
binaphos (4) in which an oxygen atom was replaced by an
NEt fragment, which significantly improved the enantiose-
lectivities over (R,S)-binaphos in AHF of vinyl arenes and
vinyl acetate[9] The diazaphospholane 6 and its analogues,
reported by Klosin and co-workers in 2005, also demonstrat-
ed very effective control of regio- and enantioselectivities in
the AHF of styrene, vinyl acetate, and allyl cyanide sub-
strates, with remarkable features of high catalytic activity at
elevated temperatures.[10] Overall chiral ligands with a new
skeleton for this important asymmetric catalytic reaction
would be highly desirable.[11] Herein, we report the results
on the design and synthesis of a new class of modular C2-
symmetric chiral bidentate phosphonite ligands, as well as
their application in the RhI-catalyzed asymmetric hydrofor-
mylation of styrene derivatives, vinyl acetate, and allyl cya-
nide with the effective control of the regio- and stereoselec-
tivities. The solid-state structure of the catalyst precursor
has also been elucidated to shed some light on the origin of
the selectivity control of the reaction.
cally important for achieving excellent enantioselectivity in
RhI-catalyzed hydrogenations of a variety of functionalized
olefin derivatives, such as dehydro-a-amino acid derivatives,
enamides, methyl (Z)-b-substituted a-acetoxyacrylates, or
(E)-b-aryl itaconate derivatives. The drastic impact of sub-
stituents on the ligands on the enantioselectivity of the reac-
tions can be addressed on the basis of their spatial orienta-
tions in the RhI complexes, which constitute an integral part
of the chiral environment around the RhI center. By taking
the advantages of the structural diversity and remote stereo-
control capability of the substituents on the backbone of 7
and 8, the privileged skeleton of 1,2-diphosphinoethane or
1,2-diphosphinobenzene, as well as the high activity of phos-
phite ligands, we decided to prepare a series of bidentate
phosphonite ligands (9 and 10) (Scheme 2) containing all of
the elements above for the RhI-catalyzed AHF reaction of
olefin derivatives.
Ligand synthesis: As shown in Scheme 3, the synthesis of
modular bidentate phosphonite ligands 9 and 10 was quite
straightforward and was accomplished in a convergent
manner. The diphenol derivative (R,R)-11, which is a key in-
termediate in the preparation of DpenPhos and can be read-
ily prepared from (1R,2R)-1,2-bis(2-methoxyphenyl)ethane-
1,2-diamine,[12a–b] was allowed to react with 1,2-bis(dichloro-
phosphino)ethane (12) or 1,2-bis(dichlorophosphino)ben-
zene (13) in THF in the presence of Et3N as HCl scavenger
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Modular Chiral Bidentate Phosphonites
FULL PAPER
(18), and allyl cyanide (21) (Scheme 4). The reaction was
performed in a Parr autoclave under a pressure of 20 bar
CO/H2 (1/1) in toluene at 608Cin the presence of 0.2 mol%
of RhI complexes, and the conversions of the substrates, and
the regio- and enantioselectivities of the reactions were de-
I
termined by GCanalysis. The Rh complexes were formed
in situ by reaction of one equivalent of [Rh(acac)(CO)2]
G
with 1.5 equivalents of ligands 9 or 10 in toluene. The pre-
liminary examination of the AHF of the substrates with RhI
complexes of 9a,b indicated that the catalyst composed of
ligand 9b bearing a 1,2-phenylene backbone gave relatively
higher regio- and enantioselectivities than that of 9a with a
1,2-ethylene skeleton (entry 1 vs. 2, Table 1), affording the
corresponding branched aldehydes regioselectively with 51–
73% ee. These results clearly indicate the feasibility of the
ligand design concept shown in Scheme 2. Therefore, we
subsequently switched our attention to the ligand modifica-
tion on the basis of the 1,2-phenylene backbone with the
readily available diphenols 14 as the chiral modifiers. Ac-
cordingly, a family of modular ligands 10a–l was designed
and synthesized as discussed above.
For the optimization of the reaction conditions, ligand
10b was first chosen to examine various reaction parame-
ters, such as substrate concentration, syngas partial pressure,
solvent, temperature, and ligand-to-rhodium ratio. The opti-
mization began with a preliminary examination of the sub-
strate concentration effect on the reactivity/selectivities of
the AHF in the presence of the RhI/10b complex. After
screening the concentration ranges from 1.0 to 4.3m for all
three substrates, a concentration of 3.0m was found to be
optimal for both styrene and vinyl acetate, whereas 1.0m
worked best for allyl cyanide (see Table S1 in the Support-
ing Information). Significant impact of the CO/H2 partial
pressures on the catalytic activities was observed, as reflect-
ed in the conversion data listed in Tables S2 and S3 in the
Supporting Information. Remarkably, increasing the H2 par-
tial pressure or lowering the CO partial pressure demon-
strated a beneficial effect on the conversions, which is con-
sistent with the mechanistic understanding that an enhanced
rate of H2 oxidation addition to Rh can be expected at
higher H2 pressure, whereas the dissociation of CO from the
Rh center to give the active species (dissociation mecha-
nism) would be facilitated under lower CO pressures.[13]
Within the pressure range examined for the reactions,
50 atm of H2/CO (4:1) was found to be optimal for the reac-
tion of styrene and vinyl acetate, whereas 40 atm of 3:1 H2/
CO turned out to be best for the reaction of allyl cyanide
with the RhI/10b system. Subsequent examination of the sol-
vent effects using both ligands 10b and 10c under similar
conditions revealed that the reactions performed best in
tBuOMe for all three olefins in terms of the catalytic activi-
ties and selectivities (see Table S4 in the Supporting Infor-
mation).
Scheme 2. The concept of ligand design for RhI-catalyzed AHF of olefins.
at room temperature. This afforded the corresponding bi-
dentate phosphonite ligands 9a,b having an ethylene and
phenylene backbone, respectively, in reasonably good yields
(66–71%). These two compounds were purified by column
chromatography on silica gel without special precaution
against air or trace amounts of water in the solvent. Consid-
ering the ready availability and facile modification of diphe-
nol 14,[12c] we decided to further extend the bisphosphonite
ligand diversity with this skeleton. Thus, the key diphenol
intermediates 14a–l were conveniently prepared in good
yields (76–85%) from readily available enantiopure 1,2-di-
A
through a three-step reaction sequence developed in our
laboratory. Similarly, the reaction of 14 with 0.5 equivalents
of 13 in dry THF at room temperature in the presence of
2 equivalents of Et3N afforded the corresponding bidentate
phosphonite ligands 10a–l in moderate to good yields. These
chiral phosphonite ligands were stable enough to allow pu-
rification by silica gel column chromatography in the open
air, and could be stored under argon without degradation
for long periods (>6 months).
Optimization of reaction conditions: With the novel chiral
bidentate phosphonite ligands 9a,b and 10a–l in hand, we
then proceeded to examine their asymmetric induction abili-
ty in the RhI-catalyzed AHF of the three most commonly
used model substrates, namely styrene (15a), vinyl acetate
The impacts of reaction temperature and ligand/Rh ratios
on the catalysis are summarized in Table 2. Enhancement of
the reaction temperatures from 40 to 608Cled to an im-
provement of the reaction rate and an essentially constant
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7849

K. Ding, C. Xia et al.
in much difference in selectivi-
ties, albeit with a minor nega-
tive effect on the activities.
Overall, the optimized condi-
tions turned out to be 50 bar
(4:1) or 40 bar (3:1) pressure of
H2/CO for the reaction of sty-
rene/vinyl acetate (3.0m) or
allyl cyanide (1.0m), respective-
ly, in tBuOMe as solvent at
608Cin the presence of 0.2
mol% of the RhI complex of
10b (1:1.5) for 2 h or 4 h
(entry 3, Table 2).
The substituent effect of the li-
gands: The modular nature of
the bidentate chiral phosphon-
ite ligands 10 allows a facile
fine-tuning of the catalytic per-
formance through modifications
of the stereoelectronic proper-
ties of the two sets of substitu-
ents on the ligand backbone, R
and R’ (Scheme 3). Under the
optimized reaction conditions,
the impacts of the R and R’
substituents in ligands 10a–l on
the regio- and enantioselectivi-
ties were subsequently investi-
gated for the RhI-catalyzed
asymmetric hydroformylation
of vinyl acetate, styrene, and
allyl cyanide. As can be seen
from Table 3, increasing the
steric bulkiness of N-arylacyl
substituents in the ligand was
found to be beneficial to both
the regio- and enantioselectivi-
ties for all the three kinds of
substrates, albeit with a some-
what drop in reactivity for allyl
cyanide (entries 1–3, Table 3).
For the ligands with R’=H
(10a, 10d,e, and 10h,i), the
steric property of R exhibited a
Scheme 3. Synthesis of bidentate phosphonite ligands 9 and 10.
Scheme 4. RhI-catalyzed AHF of styrene (15a), vinyl acetate (18), and allyl cyanide (21) in the presence of
RhI complexes of 9 or 10b.
ee for all the three substrates, albeit with a slight lowering of
b/l ratios (branching/linear ratios; entries 1–3, Table 2).
However, a further increase of the temperature to 708Cre-
sulted in a significant decrease in both regio- and enantiose-
lectivities (entry 4, Table 2). The 10b/Rh ratios, which can
affect the concentrations of the active species through the
coordination equilibrium, are found to exhibit a considera-
ble effect on both the regio- and enantioselectivities of the
hydroformylations, with a threshold value of 1.5/1 being op-
timal for all the three substrates (entries 3 and 5–8, Table 2).
Further increase of the ligand/RhI ratio to 2/1 did not result
hard-to-predict influence on the regio- and enantioselectivi-
ties of the reactions, depending on both the position and the
steric bulkiness of R. Whereas modification of the R group
at the 3-position from H to Me resulted in considerable deg-
radation in both reactivity and selectivities for the reactions
(entry 1 vs. 4, Table 3), the reverse is true for a similar modi-
fication at the 4-position on the phenoxy moieties in the li-
gands (entry 1 vs. 5, Table 3). However, further increasing
the steric bulkiness of the 4-substituent by changing Me to
iPr or tBu led to somewhat lowered regio- and enantioselec-
tivities of the three reactions (entry 5 vs. 8 and 9, Table 3).
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Modular Chiral Bidentate Phosphonites
FULL PAPER
Table 1. AHF of styrene (15a), vinyl acetate (18) and allyl cyanide (21) under the catalysis of RhI/9a,b.
allyl cyanide, both substituents
are beneficial to the selectivity
control (entries 1 vs. 10 and 11,
Table 3). In short, these obser-
vations suggested that the ste-
reocontrol capabilities of li-
gands 10 are highly sensitive to
the subtle changes in the struc-
tural moieties (R, R’). This can
Entry
9
15a[a]
18[a]
b/l[c]
21[b]
b/l[c]
conv.
[%][c]
b/l[c]
ee
conv.
[%][c]
ee
conv.
ee
[%][c]
[%][c]
[%][c]
[%][c]
1
2
9a
9b
66
42
4.5
6.3
44.6 (R)
51.1 (R)
82
27
38
19.7
50.0 (S)
51.8 (S)
>99
>99
3.1
4.4
44.0 (R)
73.4 (R)
[a] Reaction conditions: [Rh]/9=1:1.5, sub./cat.=500, P(H2)=10 bar, P(CO)=10 bar, [substrate]=0.68m, tolu-
ene, 608C, 5 h. [b] Reaction conditions: [Rh]/9=1:1.5, sub./cat.=500, P(H2)=30 bar, P(CO)=10 bar, [sub-
strate]=1.8m, tBuOMe, 608C, 4 h. [c] Conversions, branched/linear (b/l) ratios and ee values were determined
by GCanalysis. The absolute configuration for the products 16a, 19, and 22 were assigned by comparing the
sign of the optical rotations with those in the literature.[18,19]
be better understood by
a
closer examination of the X-ray
single-crystal structure of the
Table 2. The impact of reaction temperature and ratios of 10b/[Rh] on the AHF of styrene (15a), vinyl acetate
(18), and allyl cyanide (21) in the presence of RhI/10b.
catalyst
[Rh(2R,3R,5S,6S,2’R,3’R,5’S,6’
S)-10b(acac)] (Figure 1). Re-
markably, whereas the
precursor
[b]
Entry 10b/Rh T [8C]
15a[a]
18 [a]
21
conv.[%][c] b/l[c] ee[%][c] conv.[%][c] b/l[c] ee[%][c] conv.[%][c] b/l[c] ee[%][c]
AHCTREUNG
R
1
2
3
4
5
6
7
8
1.5:1
1.5:1
1.5:1
1.5:1
1.0:1
1.2:1
1.8:1
2.0:1
40
50
60
70
60
60
60
60
29
64
99
99
99
99
99
95
6.6
5.8
5.7
3.7
7.8
6.7
5.7
5.5
66
64
64
51
22
40
63
63
55
71
99
99
99
99
99
94
80.0 87
61.5 87
36.0 86
32.3 81
24.0 71
26.8 79
36.0 86
37.5 86
8
24
99
99
99
99
99
98
3.5
3.4
3.2
3.2
3.3
3.3
3.3
3.3
70
70
73
70
62
66
72
70
groups are spatially located
near to the reaction site and are
expected to exert influences on
the reaction, two of the four R’
groups bonded remotely at the
ligand backbone, also exhibit a
similar spatial orientation.
A
[a] Reaction conditions: sub./cat.=500, P(H2)=40 bar, P(CO)=10 bar, [substrate]=3.0m, tBuOMe, 2 h.
[b] Reaction conditions: P(H2)=30 bar, P(CO)=10 bar, [substrate]=1.0m, 4 h. Other reaction conditions
were same as those of [a]. [c] See footnote [c] in Table 1.
complex interaction of these
factors seems to play a key role
in determining the catalytic per-
formance of the Rh complex.
These facts along with the mod-
ular nature of this type of li-
gands suggest that their asym-
metric induction capabilities in
AHF could be readily tuned by
judicious modifications of the R
and R’ substituents on the skel-
eton of the ligands, which rep-
resents a valuable feature for
ligand optimization. Within the
ligand series, 10c turns out to
be the best for AHF of vinyl
acetate (up to 91% ee with b/
l=40.7) and styrene (up to
79% ee with b/l=12.2) in terms
of regio- and enantioselectivity,
whereas 10j is optimal for the
reaction of allyl cyanide (up to
79% ee with b/l=4.4).
Table 3. RhI-catalyzed AHF of styrene (15a), vinyl acetate (18), and allyl cyanide (21) in the presence of vari-
ous ligands 10a–l.
Entry Ligand[a]
15a[b]
18[b]
21[c]
conv.[%][d] b/l[d] ee[%][d] conv.[%][d] b/l[d] ee[%][d] conv.[%][d] b/l[d] ee[%][d]
1
2
3
4
5
6
7
8
10a
10b
10c
10d
10e
10 f
10g
10h
10i
99
99
99
42
99
99
95
97
98
99
98
99
7.8
5.7
56 (R)
64 (R)
97
99
99
66
99
99
85
81
83
99
93
99
38.5 81 (S)
36.0 86 (S)
40.7 91 (S)
15.3 71 (R)
42.1 88 (R)
37.5 88 (R)
34.5 72 (R)
29.3 63 (R)
19.0 54 (R)
32.3 80 (S)
34.7 84 (S)
23.4 75 (S)
99
99
80
88
37
40
99
99
99
99
99
99
4.1
3.2
3.2
0.9
3.8
2.9
2.9
3.8
3.3
4.4
4.2
2.4
55 (R)
73 (R)
77 (R)
30 (S)
71 (S)
68 (S)
62 (S)
48 (S)
26 (S)
79 (R)
77 (R)
56 (R)
12.2 79 (R)
4.2 6 (R)
15.3 71 (S)
9.2 56 (S)
13.5 37 (S)
16.9 35 (S)
16.8 20 (S)
7.1
6.3
6.4
9
10
11
12
10j
10k
10l
46 (R)
59 (R)
50 (R)
[a] The configuration of ligands 10a–c and 10j–l is (2R,3R,5S,6S,2’R,3’R,5’S,6’S); the configuration of 10d–i is
(2S,3S,5R,6R,2’S,3’S,5’R,6’R). [b] Reaction conditions: [Rh]/10=1:1.5, sub./cat.=500, P(H2)=40 bar, P(CO)=
10 bar, [substrate]=3.0m, tBuOMe, 608C, 2 h. [c] Reaction conditions: [Rh]/10=1:1.5, sub./cat.=500, P(H2)=
30 bar, P(CO)=10 bar, [substrate]=1.0m, tBuOMe, 608C, 4 h. [d] See footnote [c] in Table 1.
In the case of R=4-Me, increasing the steric bulkiness of
the N-acylaryl group is unfavorable for the reactions, and
generally leads to deterioration in both the reactivity and se-
lectivities (entries 5–7, Table 3). Intriguingly, for ligands with
R=H, changing the 4-R’ from Me to tBu gave rise to lower
catalytic performance (entry 2 vs. 12). Moreover, modifica-
tion of 4-R’ by changing from H to the electron-withdrawing
chloro substituent led to a slight lowering of the selectivities
for the reactions of styrene and vinyl acetate. On the other
hand, for the ligand with R’=4-MeO, the reverse is true
(entries 1 vs. 10 and 11, Table 3). For the reaction involving
Substrate adaptability: To investigate the substrate adapta-
bility of the RhI catalyst containing ligand 10c, a series of
olefin derivatives was hydroformylated in the presence of
[Rh(acac)(CO)2]/10c under the optimized reaction condi-
A
tions. These afforded the corresponding products in moder-
ate to excellent regioselectivities and enantioselectivities
(entries 1–7, Table 4). Remarkably, hydroformylation of
vinyl acetate using the RhI/10c catalyst demonstrated high
reactivity (92% conversion after 12 h) and excellent regio-
(b/l=44.5) and enantioselectivity (90% ee) (entry 8,
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K. Ding, C. Xia et al.
diffusion of hexane into an
equimolar solution of [Rh-
(acac)(CO)2] and 10b in chloro-
form at room temperature. X-
ray crystallographic analysis
(Figure 1) revealed that [Rh-
A
N
its solid state, with a square-
planar coordination geometry
around the Rh center. The
value of the P1-Rh-P1A bite
angle is 84.428, which is close to
an inherent bite angle of 908
for four-coordinate Rh com-
plexes.[6c] The rigid 1,2-diphos-
phinobenzene moiety formed a
five-membered ring by the che-
lating coordination of phospho-
rus atoms with the Rh atom,
whereas the phenoxy rings A
and Care close to the catalytic
active site (Rh center), and
thus are expected to exert an
impact on both reactivity and
selectivities. Interestingly, the
N-acyl aromatic rings, located
at the “remote” site of the
ligand backbone, were also
found to protrude into the vi-
Figure 1. Structure of complex [Rh(2R,3R,5S,6S,2’R,3’R,5’S,6’S)-10b
for clarity. Selected interatomic distances [Š], and angles and torsion angles [8] in the complex: Rh P1
N
À
À
À
2.1212(15), P1 O1 1.610(4), P1 O2 1.632(4), P1 C1 1.818(5); P1-Rh-P1A 84.42(9), O1-P1-O2 101.3(2), O1-
P1-C1 105.5(2), O2-P1-C1 99.7(2), O1-P1-Rh 112.33(17), O2-P1-Rh 121.56(15), C1-P1-Rh, 114.35(17), O5-Rh-
P1-O1 64.1(2), O5-Rh-P1-O1 62(2), P1-Rh-P1-O1 119.22(18).
Table 4. AHF of olefins under the catalysis of optimized catalyst Rh(I)/
cinity of the Rh center by virtue of the orientation of the
acyl group, which has a profound implication on the selec-
tivity control. It can be expected that this conformation will
be preserved in solution to some extent, owing to the rigidi-
ty of the amide bond.[12c]
10c or Rh(I)/10j.[a]
Asymmetric induction pathway: On the basis of the absolute
configurations of the products observed in the experiment,
Entry
R
Conv.[%]
b/l
ee[%][d]
1
2
3
4
5
6
C6H5 (15a)
99
99
98
87
99
99
99
92
12.2
10.9
9.9
9.1
8.9
40.7
4.4
44.5
79 (R)
68 (–)
75 (–)
72 (–)
70 (–)
91 (S)
79 (R)
90 (S)
the
crystal
structure
of
the
complex
[Rh
4-FC6H5 (15b)
4-MeC6H5 (15c)
4-MeOC6H5 (15d)
6-MeOC10H6 (15e)
AcO (18)
(2R,3R,5S,6S,2’R,3’R,5’S,6’S)-10b
assumption that the selectivity-determining transition state
(alkene insertion into the Rh H bond) would adopt a trigo-
nal-bipyramidal coordination geometry with equatorial and
axial phosphorus atoms (since the bite angle of P1-Rh-P1A
here (84.42(9)8) is close to 908), the plausible models for
asymmetric induction in the hydroformylation of terminal
olefin derivatives with the present catalyst system are pro-
posed. As can be seen from the crystal structure of the com-
AHCTREUNG
À
7[b]
8[c]
NCCH2 (21)
AcO (18)
[a] Unless otherwise noted, the reaction conditions are identical to those
in Table 3. [b] Ligand 10j is used. P(H2)=30 bar, P(CO)=10 bar.
[c] Substrate/Rh=10000/1, t=12 h. [d] The absolute configurations for
the products were assigned by comparing the signs of their optical rota-
tions with those in the literature.[18, 19]
plex [Rh(2R,3R,5S,6S,2’R,3’R,5’S,6’S)-10b(acac)], the phenyl
A
moieties A and Cextend more significantly away from the
plane defined by the phenyl backbone of the ligand than
phenyl moieties B and D (see Figure 1). Accordingly, the
steric environment developed by the ligands can be depicted
with a simplified model shown in Scheme 5. Obviously, the
transition-state model (a) is more favorable than (b), since
the steric congestion between the equatorially coordinated
olefin and the phenyl moiety A of the equatorial P atom in
model (a) is less serious than that of the equatorial olefin
Table 4) under a low catalyst loading (substrate/catalyst=
10000/1).
Crystal structure of the catalyst precursor [Rh
N
N
To probe the origin of the selectivity control of the present
catalyst system, we succeeded in obtaining the single crystals
of the catalyst precursor [Rh
N
N
7852
www.chemeurj.org
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2008, 14, 7847 – 7857

Modular Chiral Bidentate Phosphonites
FULL PAPER
remote stereocontrol capability of the backbone substitu-
ents, will stimulate future studies to explore their applica-
tions in other transition-metal-catalyzed asymmetric reac-
tions.
Experimental Section
General comments: All the experiments that were sensitive to moisture
or air were carried out under an argon atmosphere using standard
Schlenk techniques. NMR spectra were recorded in CDCl3 or [D6]DMSO
on a Varian Mercury 300 (1H 300 MHz; 13C75 MHz; 31P 121 MHz) spec-
trometer. Chemical shifts are expressed in ppm with an internal standard:
TMS (0 ppm), CDCl3 (d=7.26 ppm), and [D6]DMSO (d=2.50 ppm) for
1H, and CDCl3 (d=77.0 ppm) and [D6]DMSO (d=39.5 ppm) for 13C.
31P NMR spectra were recorded with 85% H3PO4 as an external refer-
ence. The IR spectra were measured on a Rio-Rad FTS-185 spectrometer
in KBr pellets. EI (70 eV) and ESI mass spectra were obtained on
HP5989 A and Mariner LC-TOF spectrometers, respectively. HR-MS
were determined on an IonSpect 4.7 TESLA FTMS. Elemental analyses
were performed with an Elemental VARIO EL apparatus. Optical rota-
tions were measured on a Perkin–Elmer 341 automatic polarimeter.
HPLCanalyses were carried out on a JASCO 1580 liquid chromatograph
with a JASCO CD-1595 detector and AS-1555 autosampler. GC analyses
were measured on Agilent 6890N system. trans-1S,2S-Diaminocyclohex-
ane was obtained by optical resolution with tartaric acid,[14] and 3-methyl-
salicylaldehyde, 4-methylsalicylaldehyde, and 5-methylsalicylaldehyde
were prepared by following the literature method.[15] The key intermedi-
ate diphenol (R,R)-11 was synthesized from (1R,2R)-1,2-bis(2-methoxy-
Scheme 5. The proposed asymmetric induction pathway for RhI-catalyzed
AHF of terminal olefin derivatives.
with the phenyl moiety C of the axial P atom in model (b).
In the favored transition state model (a), the R group of the
olefin substrates at the equatorial position of the Rh com-
plex will extend to the less hindered equatorial CO moiety.
On the basis of this transition model, the absolute configura-
tions of the branched hydroformylation products of vinyl
acetate, styrene, and allyl cyanide will be S, R, and R, re-
spectively. In fact, the absolute configurations of the corre-
sponding products attained in the catalysis with ligand
(2R,3R,5S,6S,2’R,3’R,5’S,6’S)-10b support the prediction
mentioned above, which indicates that the formal addition
of formaldehyde across the C=Cdouble bond occurs at the
same enantioface for all substrates. Moreover, the sense of
asymmetric induction expected according to this model with
all ligands 9–10 is consistent with that observed in the ex-
periments except for the reaction of styrene under the catal-
ysis of the RhI/10d complex (Table 3, entry 4). In this case,
the Me groups at the ortho position of phenoxy moieties (B
and D rings) probably have caused subtle changes in the
steric hindrance of the ligand, and as a result influence the
coordination of the olefin substrates, leading to changes of
reactivity and the sense of asymmetric induction. In fact, rel-
atively low catalytic activity was observed with the RhI com-
plex of the ligand 10d.
phenyl)ethane-1,2-diamine according
a
literature procedure,[12a–b] and
14a–e were prepared from (1S, 2S)-1,2-diaminocyclohexane and various
salicylaldehyde derivatives by a three-step reaction sequence developed
previously in our laboratory.[12c] 1,2-Bis(dichlorophosphino)ethane (12) is
commercially available. 1,2-Bis(dichlorophosphino)benzene (13) was pre-
pared by a modified literature procedure reported by Reetz et al.[16] (see
Supporting Information). Dichloromethane was freshly distilled from cal-
cium hydride; 2-propanol from magnesium filings; THF, benzene,
tBuOMe, and toluene from sodium benzophenone ketyl; ethyl acetate
and acetonitrile from P2O5.
Ligand synthesis
Preparation of (3R,4R,3’R,4’R)-9a: A solution of diphenol (R,R)-11
(324 mg, 0.72 mmol) and Et3N (0.20 mL, 1.44 mmol) in dry THF was
added dropwise to a solution of 1,2-bis(dichlorophosphino)ethane (12;
83.5 mg, 0.36 mmol) in dry toluene (1.0 mL) at room temperature over
20 min, and the resulting mixture was stirred overnight. The reaction
mixture was concentrated under reduced pressure, and the residue was
purified by flash column chromatography on silica gel with chloroform/
ethyl acetate (20/1) as eluent to give the corresponding bidentate phos-
phonite ligand (3R,4R,3’R,4’R)-9a as a white solid in 66% yield. M.p.
180–1828C ; a[ ]2D0 =À414 (c=0.5, CHCl3); 1H NMR (300 MHz, CDCl3):
d=6.97–7.32 (m, 32H), 6.82 (t, J=8.4 Hz, 2H), 6.64 (d, J=8.1 Hz, 2H),
5.34 (d, J=15.3 Hz, 2H), 5.01 (d, J=15.6 Hz, 2H), 4.45 (d, J=3.3 Hz,
2H), 4.34 (d, J=3.3 Hz, 2H), 3.86 (d, J=15.3 Hz, 2H), 3.58 (d, J=
15.3 Hz, 2H), 1.81–1.85 (m, 2H), 1.62–1.69 ppm (m, 2H); 31P NMR
(121.46 MHz, CDCl3): d=177.87 ppm (s); IR (KBr pellet): n˜ =3030,
Conclusion
In summary, a new class of C2-symmetric chiral bidentate
phosphonite ligands has been developed and successfully ap-
plied to the RhI-catalyzed AHF of vinyl acetate, allyl cya-
nide, styrene, and its derivatives with high efficiency. The X-
ray structural analysis of the catalyst precursor suggested
that the steric hindrance caused by the protrusion of the
remote substituents of the ligands into the vicinity of the
metal center might be an important factor for the enantio-
control of the catalysis, whereas the sense of the asymmetric
induction can be rationalized on the basis of a trigonal-bi-
pyramidal transition state diagram. The salient features of
this type of ligands, such as cheap starting material, facile
preparation, air-stability, structural diversity as well as the
1699, 1601, 1584, 1481, 1452, 1268, 1219, 1203, 1094, 877 cmÀ1
.
Preparation of (3R,4R,3’R,4’R)-9b: A solution of 1,2-bis(dichlorophos-
phino)benzene (93.3 mg, 0.333 mmol) in dry toluene (1.0 mL) was added
dropwise to a solution of diphenol (R,R)-11 (300 mg, 0.67 mmol) and
Et3N (0.18 mL, 1.33 mmol) in dry THF at room temperature over 20 min,
and the resulting mixture was stirred overnight. The reaction mixture was
concentrated under reduced pressure, and the residue was purified by
flash column chromatography on silica gel with chloroform/ethyl acetate
(20/1) as eluent to give the corresponding bidentate phosphonite ligand
(3R,4R,3’R,4’R)-9b as a white solid in 71% yield. M.p. 132–1348C;
[a]2D0 =À142 (c=0.5, CHCl3); 1H NMR (300 MHz, CDCl3): d=6.96–7.38
(m, 36H), 6.72 (t, J=8.3 Hz, 2H), 5.83 (d, J=7.8 Hz, 2H), 5.32 (d, J=
Chem. Eur. J. 2008, 14, 7847 – 7857
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
7853

K. Ding, C. Xia et al.
15.3 Hz, 2H), 5.05 (d, J=15.3 Hz, 2H), 4.65 (d, J=3.3 Hz, 2H), 4.50 (d,
J=3.3 Hz, 2H), 3.89 (d, J=15.0 Hz, 2H), 3.60 ppm (d, J=15.6 Hz, 2H);
31P NMR (121.46 MHz, CDCl3): d=150.58 ppm (s); IR (KBr pellet): n˜ =
3030, 2919, 1700, 1602, 1584, 1481, 1453, 1267, 1216, 1093, 875, 771,
699 cmÀ1; ESI-MS: m/z: 1035.4 ([M+H+]); HRMS (MALDI/DHB): m/
z: calcd for C64H53N4O6P2 ([M+H+]): 1035.3434; found: 1035.3443.
(2S,3S,5R,6R)-14 f: Yield=76% ; white solid; m.p. 256–2588C ; a[ ]D20
=
À77.0 (c=0.5, DMF); 1H NMR (300 MHz, [D6]DMSO): d=1.51–1.37
(m, 4H), 1.75 (s, 2H), 2.23 (s, 6H), 2.29 (s, 6H), 2.69 (d, J=8.1 Hz, 2H),
3.88 (d, J=4.5 Hz, 2H), 5.86 (s, 2H), 6.54 (s, 2H), 6.77 (d, J=7.8 Hz,
2H), 6.90 (d, J=7.2 Hz, 4H), 7.01 (d, J=8.1 Hz, 4H), 7.54 (d, J=7.5 Hz,
2H), 8.94 ppm (s, 2H); 13CNMR (75 MHz, [D 6]DMSO): d=172.7, 153.4,
138.9, 137.0, 133.4, 127.9, 127.6, 126.1, 122.9, 119.1, 115.2, 60.2, 54.5, 30.7,
24.5, 20.4, 20.3 ppm; IR (KBr): n˜ =3422, 2928, 2861, 1608, 1419, 1336,
1113, 831 cmÀ1; ESI-MS: m/z: 589.2 ([M+H+]); HRMS (MALDI/DHB):
m/z: calcd for C38H41N2O4 ([M+H+]): 589.3061; found: 589.3064.
A typical procedure for the preparation of diphenol 14: The syntheses of
key diphenol intermediates 14a–e were reported in previous work.[12c]
The preparation of 14 f–l were carried out by following a similar proce-
dure. A typical procedure for the synthesis of 14a was as follows: a solu-
tion of salicylaldehyde (46.4 g, 0.38 mol) in EtOH (200 mL) was added
(2S,3S,5R,6R)-14g: Yield=90%; white solid; m.p. 266–2688C ; a[ ]D20
=
À58.0 (c=0.3, DMF); 1H NMR (300 MHz, [D6]DMSO): d=1.23–1.78
(m, 6H), 2.06 (s, 12H), 2.32 (s, 6H), 2.68 (s, 2H), 3.84 (s, 2H), 5.76 (s,
2H), 6.55 (s, 6H), 6.78–6.92 (m, 4H), 7.50 (s, 2H), 8.92 ppm (s, 2H);
13CNMR (75 MHz, [D 6]DMSO): d=173.0, 153.5, 137.0, 136.1, 130.5,
127.6, 124.0, 122.9, 118.9, 115.2, 66.6, 59.9, 54.9, 30.0, 24.4, 20.4, 20.3 ppm;
IR (KBr): n˜ =2919, 1653, 1628, 1614, 1420, 1342, 1331, 1117, 863,
821 cmÀ1; ESI-MS: m/z: 617.3 ([M+H+]); elemental analysis (%) calcd
for C40H44N2O4: C77.89, H 7.19, N 4.54; found: C77.47, H 7.54, N 4.16.
dropwise to
a solution (400 mL) of trans-1S,2S-diaminocyclohexane
(21.7 g, 0.19 mol) in ethanol at room temperature over 1 h. After stirring
at reflux temperature for 12 h, the mixture was cooled to room tempera-
ture and the solvent was removed by vacuum evaporation. The oil-like
residue was dissolved in a mixture of dry acetonitrile (1700 mL) and tolu-
ene (190 mL). To this solution was added manganese powder[17,12c]
(325 mesh; 20.9 g, 0.38 mol), and the resulting mixture was cooled to 08C
before trifluoroacetic acid (58.3 mL, 0.76 mol) was added dropwise over
a period of 30 min under an Ar atmosphere. The reaction mixture was
stirred vigorously at 208Cfor 24 h followed by addition of two additional
equivalents of trifluoroacetic acid at 08C. After the mixture was left to
stand at that temperature for 2 h, the resulting mixture was filtered and
the residue was washed with petroleum ether (b.p. 60–908C, 2”50 mL)
to afford a white solid. The solid was dissolved in H2O (100 mL) and neu-
tralized with saturated NaHCO3 solution to pH 8. The aqueous solution
was extracted with dichloromethane (3”200 mL). The combined organic
layer was washed with H2O (100 mL), dried over anhydrous Na2SO4, and
concentrated. The resulting white solid was recrystallized with a mixture
of petroleum and ethyl acetate (1:1) to afford the desired aminophenol
compound as colorless needles in 85% yield (52.3 g). M.p. 226–2278C
(2S,3S,5R,6R)-14h: Yield=90%; white solid; m.p. 180–1828C ; a[ ]D20
=
À56.6 (c=0.5, CHCl3); 1H NMR (300 MHz, CDCl3): d=1.23 (d, J=
6.3 Hz, 12H), 1.43–1.73 (m, 6H), 2.81–2.68 (m, 4H), 4.08 (s, 2H), 5.54 (d,
J=4.8 Hz, 2H), 6.48 (s, 2H), 6.82–7.17 (m, 14H), 7.46 ppm (s, 2H);
13CNMR (75 MHz, CDCl 3): d=175.2, 152.5, 150.3, 135.6, 130.2, 128.0,
126.8, 126.5, 122.7, 118.6, 114.1, 56.7, 33.6, 32.3, 25.0, 23.9, 23.8 ppm; IR
(KBr): n˜ =3441, 2959, 2932, 1624, 1426, 1339 cmÀ1; ESI-MS: m/z: 617.3
([M+H+]); elemental analysis (%) calcd for C40H44N2O4: C77.89, H
7.19, N 4.54; found: C77.67, H 7.04, N 4.22.
(2S,3S,5R,6R)-14i: Yield=98%; white solid; m.p. 190–1928C ; a[ ]D20
=
À20.2 (c=0.5, DMF); 1H NMR (300 MHz, CDCl3): d=1.33 (s, 18H),
1.53–1.40 (m, 4H), 1.74 (s, 2H), 2.69 (br, 2H), 3.37 (s, 2H), 3.86 (s, 2H),
5.86 (s, 2H), 6.76 (s, 2H), 6.97 (s, 4H), 7.34–7.16 (m, 6H), 7.55 (s, 2H),
8.92 ppm (s, 2H); 13CNMR (75 MHz, CDCl 3): d=172.7, 153.2, 150.5,
136.3, 129.3, 127.4, 127.1, 126.0, 122.8, 114.8, 112.0, 60.0, 54.9, 33.6, 30.8,
[15]
[15]
(Lit.
m.p. 2158C); [a]2D0 =À5.5 (c=1.00, CHCl3) [Lit.
[a]2D0 =À7.2
(c=1.7, CHCl3)]; 1H NMR (300 MHz, CDCl3): d=1.41–1.46 (m, 4H),
1.76–1.82 (m, 4H), 2.41 (br, 2H), 2.67–2.70 (m, 2H), 4.15 (s, 2H), 6.12
(dd, J=1.8, 7.5 Hz, 2H), 6.42 (dt, J=1.2, 7.5 Hz, 2H), 6.83 (dd, J=1.2,
8.1 Hz, 2H,), 7.07 (dt, J=1.8, 7.8 Hz, 2H,), 10.86 ppm (br. s, 2H);
13CNMR (75 MHz, CDCl 3): d=156.7, 130.0, 128.8, 123.1, 118.4, 116.4,
63.2, 59.5, 31.4, 24.2 ppm; EI-MS: m/z: 324 ([M+], 11), 203 (43), 122
(100).
30.5, 24.3 ppm; IR (KBr): n˜ =3422, 2963, 1619, 1578, 1415, 1338 cmÀ1
;
ESI-MS: m/z: 645.3 ([M+H+]); elemental analysis (%) calcd for
C42H48N2O4: C78.23, H 7.50, N 4.34; found: C78.34, H 7.66, N 4.19.
(2R,3R,5S,6S)-14j: Yield=99% ; white solid; m.p. 294–2958C ; a[ ]D20
=
+107 (c=0.3, THF); 1H NMR (300 MHz, [D6]DMSO): d=1.39–1.53 (m,
4H), 1.73 (br, 2H), 2.65 (d, J=10.2 Hz, 2H), 3.83 (d, J=5.1 Hz, 2H),
5.89 (s, 2H), 6.74 (d, J=7.8 Hz, 2H), 6.99–6.92 (m, 6H), 7.19 (t, J=
7.2 Hz, 2H), 7.29 (d, J=8.7 Hz, 4H), 7.64 (d, J=6.9 Hz, 2H), 9.18 ppm
(s, 2H); 13CNMR (75 MHz, [D 6]DMSO): d=171.6, 153.4, 134.7, 134.2,
128.3, 127.8, 127.7, 127.6, 125.1, 118.5, 114.8, 60.1, 54.7, 30.6, 24.4 ppm;
To a solution of the above-prepared aminophenol compound (1.0 g,
3.1 mmol) and NEt3 (1.72 mL, 12.3 mmol) in dry toluene (8 mL), benzoyl
chloride (1.42 mL, 12.3 mmol) was added dropwise at room temperature
over 10 min. The reaction mixture was stirred at 608Covernight. After
removal of toluene under reduced pressure, 20% KOH aqueous solution
(15 mL) and ethanol (15 mL) were added. After the mixture had been
stirred at room temperature for 6 h, ethanol was removed under vacuum,
and the resulting residue was neutralized with 6n HCl aqueous solution
to pH 8–9. The resulting solid was collected by filtration, washed with
water (3”30 mL), and dried under vacuum. The desired compound
(2S,3S,5R,6R)-14a (1.6 g) was obtained in 97% yield as a white solid,
which could be used directly for the next step without further purifica-
tion.
IR (KBr): n˜ =3430, 2935, 1623, 1597, 1458, 1336, 1091, 837, 755 cmÀ1
;
ESI-MS: m/z: 601.3 ([M+H+]); elemental analysis (%) calcd for
C34H30Cl2N2O4: C67.89, H 5.03, N 4.66; found: C67.94, H 5.24, N 4.41.
(2R,3R,5S,6S)-14k: Yield=99%; white solid; m.p. 280–2828C ; a[ ]D20
=
+68.6 (c=0.5, DMF); 1H NMR (300 MHz, [D6]DMSO): d=1.37–1.50
(m, 4H), 1.72 (s, 2H), 2.61 (d, J=6.9 Hz, 2H), 3.66 (s, 6H), 3.86 (d, J=
6.3 Hz, 2H), 6.01 (s, 2H), 6.73–6.69 (m, 6H), 6.98–6.93 (m, 6H), 7.16 (t,
J=7.2 Hz, 2H), 7.66 (d, J=7.2 Hz, 2H), 9.09 ppm (s, 2H); 13CNMR
(75 MHz, [D6]DMSO): d=172.3, 160.0, 153.6, 128.2, 128.0, 127.9, 127.7,
125.8, 118.3, 114.7, 112.7, 60.4, 54.6, 30.7, 24.4 ppm; IR (KBr): n˜ =3245,
2934, 1604, 1511, 1458, 1335, 1253, 1174, 840 cmÀ1; ESI-MS: m/z: 593.3
([M+H+]); elemental analysis (%) calcd for C36H36N2O4: C72.95, H
6.12, N 4.73; found: C72.86, H 6.00, N 4.42.
(2R,3R,5S,6S)-14a: Colorless prisms, Yield=97%, m.p. 264–2658C;
[a]2D0 =+15.6 (c=1.00, CH3OH); 1H NMR (300 MHz, CDCl3): d=1.56–
1.79 (m, 8H), 2.77 (br, 2H), 4.12 (br, 2H), 5.61 (br, 2H), 6.60 (d, J=
8.1 Hz, 2H), 6.87 (d, J=7.2 Hz, 4H), 7.02–7.09 (m, 6H), 7.16–7.24 (m,
4H), 7.63 ppm (d, J=7.5 Hz, 2H); 13CNMR (75 MHz, [D 6]DMSO): d=
173.1, 154.0, 136.6, 129.9, 128.6, 128.1, 127.9, 126.5, 126.0, 118.8, 115.2,
60.6, 55.1, 31.1, 24.9 ppm; IR (KBr): n˜ =3236, 2934, 1625, 1602, 1579,
1485, 1388, 1337, 1239, 1110, 905, 755, 701 cmÀ1; EI-MS: m/z: 532 ([M]+,
2.7), 427 (11.5), 306 (5.5), 105 (100); HRMS (MALDI/DHB): m/z: calcd
for C34H32N2O4Na ([M + Na+]): 555.2254; found: 555.2272; elemental
analysis (%) calcd for C34H32N2O4: C76.67, H 6.06, N 5.26; found: C
76.42, H 6.09, N 5.04.
(2R,3R,5S,6S)-14l: Yield=98%; white solid; m.p. 272–2748C ; a[ ]D20
=
+52.4 (c=1.0, CH3OH); 1H NMR (300 MHz, [D6]DMSO): d=1.15 (s,
18H), 1.48–1.36 (m, 4H), 1.62 (s, 2H), 2.65 (br, 2H), 4.04 (s, 2H), 5.87 (s,
2H), 6.57 (d, J=8.1 Hz, 2H), 7.00–6.92 (m, 6H), 7.16–7.10 (m, 6H),
7.59 ppm (s, 2H); 13CNMR (75 MHz, CDCl 3): d=175.3, 153.6, 152.8,
132.8, 129.1, 127.3, 126.7, 125.5, 125.0, 120.4, 116.3, 56.3, 34.6, 32.1, 31.0,
24.8 ppm; IR (KBr): n˜ =33352, 3287, 2962, 2866, 1658, 1626, 1457, 1408,
1336, 1292, 754 cmÀ1; ESI-MS: m/z: 645.3 ([M+H+]); elemental analysis
(%) calcd for C42H48N2O4: C78.23, H7.50, N 4.34; found: C77.62, H
7.43, N 4.02.
The key intermediates 14 f–l were prepared in good to excellent yields by
following a similar procedure mentioned above. Their characterization
data are summarized as follows.
7854
www.chemeurj.org
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2008, 14, 7847 – 7857

Modular Chiral Bidentate Phosphonites
FULL PAPER
Typical procedure for preparation of 10: The preparation of
(2R,3R,5S,6S, 2’R,3’R,5’S,6’S)-10a was described here as a typical proce-
1166, 1107, 888, 873, 757 cmÀ1; ESI-MS: m/z: 1255.0 ([M+H+]); elemen-
tal analysis (%) calcd for C78H72N4O8P2: C74.63, H 5.78, N 4.46; found:
C74.24, H 6.08, N 4.00.
dure.
A
solution of 1,2-bis(dichlorophosphino)benzene (125 mg,
0.446 mmol) in dry toluene (1.6 mL) was added dropwise to a solution of
diphenol (2R,3R,5S,6S)-14a (500 mg, 0.892 mmol) and Et3N (0.25 mL,
1.784 mmol) in dry THF at room temperature over 20 min, and the re-
sulting mixture was stirred overnight. The reaction mixture was concen-
trated under the reduced pressure, and the residue was purified by flash
column chromatography on silica gel with chloroform/ethyl acetate (20/1)
as eluent to give the corresponding bidentate phosphonite ligands
(2R,3R,5S,6S,2’R,3’R,5’S,6’S)-10a in 62% yield as a white solid. M.p. 212–
2148C ; a[ ]2D0 =+194 (c=0.5, CHCl3); 1H NMR (300 MHz, CDCl3): d=
7.73–7.77 (m, 2H), 7.58 (d, J=7.8 Hz, 2H), 6.91–7.34 (m, 32H), 6.63–6.66
(m, 2H), 6.14 (d, J=7.8 Hz, 2H), 5.84 (s, 2H), 5.52 (t, J=3.3 Hz, 2H),
4.37–4.41 (m, 2H), 4.20–4.27 (m, 2H), 3.03–3.07 (m, 2H), 2.34–2.37 (m,
2H), 1.50–1.98 ppm (m, 12H); 31P NMR (121.46 MHz, CDCl3): d=
151.82 ppm (s); 13CNMR (75 MHz, CDCl3): d=175.9, 175.0, 152.04,
152.00, 151.96, 149.9, 143.6, 137.1, 136.3, 135.8, 133.0, 130.7, 130.2, 129.7,
129.0, 128.2, 128.1, 127.9, 127.7, 126.8, 126.7, 125.9, 125.2, 124.8, 124.5,
122.1, 121.4, 63.9, 59.4, 57.7, 57.5, 32.6, 31.8, 25.5, 24.7 ppm; IR (KBr
pellet): n˜ =3062, 2931, 1656, 1602, 1580, 1477, 1454, 1326, 1215, 1108,
1093, 874, 699 cmÀ1; ESI-MS: m/z: 1199.7 ([M+H+]); HRMS (MALDI/
DHB): m/z calcd for C74H65N4O8P2 ([M+H+]): 1199.4272; found:
1199.4263.
(2S,3S,5R,6R,2’S,3’S,5’R,6’R)-10e: Yield=49%; white solid; m.p. 196–
1988C ; a[ ]2D0 =À191 (c=0.5, CHCl3); 1H NMR (300 MHz, CDCl3): d=
7.58 (d, J=7.5 Hz, 2H), 7.42 (d, J=7.5 Hz, 2H), 6.91–7.30 (m, 26H), 6.82
(s, 2H), 6.69–6.72 (m, 2H), 5.98 (s, 2H), 5.80 (s, 2H), 5.46–5.49 (m, 2H),
4.31–4.35 (m, 2H), 4.21–4.26 (m, 2H), 3.03–3.07 (m, 2H), 2.36 (s, 6H),
2.32–2.35 (m, 2H), 2.08 (s, 6H), 1.50–1.98 ppm (m, 12H); 31P NMR
(121.46 MHz, CDCl3): d=151.91 ppm (s); 13C NMR (75 MHz, CDCl3):
d=175.9, 175.0, 151.94, 151.91, 151.88, 149.8, 143.8, 143.7, 139.1, 137.9,
137.2, 136.4, 132.8, 130.4, 129.9, 129.7, 129.6, 128.1, 127.8, 127.6, 127.5,
126.8, 126.7, 125.4, 125.3, 125.0, 124.8, 122.6, 122.1, 63.8, 59.2, 57.7, 57.4,
32.7,31.6, 25.5, 24.7, 21.0, 20.7 ppm; IR (KBr pellet): n˜ =2928, 2860, 1657,
1617, 1496, 1447, 1403, 1326, 1244, 1108, 960, 786, 700 cmÀ1; ESI-MS: m/
z: 1255.4 ([M+H+]); HRMS (MALDI/DHB): m/z: calcd for
C78H73N4O8P2 ([M+H+]): 1255.4898; found: 1255.4898.
(2S,3S,5R,6R,2’S,3’S,5’R,6’R)-10 f: Yield=33%; white solid; m.p. 206–
2088C ; [a]2D0 =À223.8 (c=0.5, CHCl3); 1H NMR (300 MHz, CDCl3): d=
7.60 (d, J=7.8 Hz, 2H), 7.42 (d, J=8.1 Hz, 2H), 7.10–6.87 (m, 22H), 6.68
(s, 2H), 5.91 (s, 2H), 5.83 (s, 2H), 5.42 (s, 2H), 4.41 (t, J=10.8 Hz, 2H),
4.17 (t, J=8.7 Hz, 2H), 3.04 (d, J=11.1 Hz, 2H), 2.34 (s, 6H), 2.28 (s,
6H), 2.25 (s, 6H), 2.03 (s, 6H), 1.43–1.88 (m, 14H); 31P NMR
(121.46 MHz, CDCl3): d=149.72 ppm (s); 13C NMR (75 MHz, CDCl3):
d=175.9, 175.2, 151.8, 149.6, 144.0, 140.7, 139.7, 139.1, 137.6, 134.6, 133.5,
133.0, 130.4, 130.0, 128.7, 128.4, 127.4, 127.1, 126.9, 125.4, 125.3, 125.0,
124.6, 122.5, 122.0, 77.2, 63.8, 59.4, 57.7, 57.6, 32.8, 31.7, 25.6, 24.7, 21.5,
21.3, 20.9, 20.7 ppm; IR (KBr pellet): n˜ =2925, 2859, 1654, 1614, 1403,
Following a similar procedure for the preparation of 10a, ligands 10b–l
were synthesized in moderate to good yields. Their characterization data
are summarized as follows.
(2R,3R,5S,6S,2’R,3’R,5’S,6’S)-10b: Yield=62%; white solid; m.p. 214–
2168C ; [a]2D0 =+246 (c=0.36, CHCl3); 1H NMR (300 MHz, CDCl3): d=
7.71–7.74 (m, 2H), 7.56 (d, J=7.8, 1.5 Hz, 2H), 7.30–7.32 (m, 4H), 6.68–
7.14 (m, 24H), 6.63–6.66 (m, 2H), 6.11 (d, J=8.1 Hz, 2H), 5.87 (s, 2H),
5.46–5.52 (m, 2H), 4.37–4.41 (m, 2H), 4.17–4.21 (m, 2H), 3.02–3.06 (m,
1325, 1243, 1107 cmÀ1
;
HRMS (MALDI/DHB): m/z: calcd for
C82H81N4O8P2 ([M+H+]): 1311.5524; found: 1311.5555.
(2S,3S,5R,6R,2’S,3’S,5’R,6’R)-10g: Yield=78%; white solid; m.p. 182–
1848C ; a[ ]2D0 =À174 (c=0.25, CHCl3); 1H NMR (300 MHz, CDCl3): d=
7.60 (d, J=7.5 Hz, 2H), 7.43 (d, J=7.5 Hz, 2H), 7.22–7.19 (m, 2H), 7.13
(d, J=7.5 Hz, 2H), 6.93–6.90 (m, 8H), 6.78 (s, 2H), 6.64 (s, 4H), 6.52 (s,
4H), 5.91 (s, 2H), 5.73 (s, 2H), 5.35 (s, 2H), 4.34 (t, J=11.1 Hz, 2H),
4.18 (t, J=8.7 Hz, 2H), 3.70 (d, J=1.5 Hz, 2H), 3.11 (d, J=11.4 Hz, 2H),
2.36 (s, 6H), 2.12 (s, 12H), 2.05 (s, 6H), 2.03 (s, 12H), 1.72–1.85 ppm (m,
12H); 31P NMR (121.46 MHz, CDCl3): d=151.21 ppm (s); 13CNMR
(75 MHz, CDCl3): d=176.2, 175.3, 151.9, 149.5, 138.9, 137.6, 137.5, 137.4,
137.3,136.1, 133.3, 132.1, 130.8, 130.4, 129.6, 125.6, 125.1, 125.0, 124.8,
124.6, 124.4, 122.3, 121.9, 63.3, 59.1, 57.8, 57.7, 43.4, 41.8, 32.8, 31.6, 26.9,
25.6, 24.8, 24.7, 21.1 ppm; IR (KBr pellet): n˜ =2929, 1657, 1652, 1403,
1336, 1244 cmÀ1; HRMS (MALDI/DHB): m/z: calcd for C86H89N4O8P2
([M+H+]): 1367.6150; found: 1367.6171.
2H), 2.25–2.29 (m, 2H), 2.24
(s, 12H), 1.48–1.90 ppm (m, 12H); 31P NMR
G
(121.46 MHz, CDCl3): d=150.24 ppm (s); 13C NMR (75 MHz, CDCl3):
d=176.0, 175.1, 151.8, 149.8, 143.7, 140.7, 139.8, 135.9, 134.4, 133.4, 130.1,
128.9, 128.7, 128.4, 127.8, 127.5, 126.9, 126.8, 125.8, 125.1, 124.7, 124.4,
121.9, 121.4, 63.7, 59.3, 57.6, 57.5, 32.7, 31.7, 25.5, 24.6, 21.4, 21.3 ppm; IR
(KBr pellet): n˜ =2926, 1652, 1611, 1581, 1477, 1454, 1409, 1318, 1214,
1106, 874, 757 cmÀ1; ESI-MS: m/z: 1254.8 ([M+H+]); elemental analysis
(%) calcd for C78H72N4O8P2: C74.63, H 5.78, N 4.46; found: C74.43, H
6.07, N 4.16.
(2R,3R,5S,6S,2’R,3’R,5’S,6’S)-10c: Yield=66%; white solid; m.p. 168–
1708C ; a[ ]2D0 =+194 (c=0.3, CHCl3); 1H NMR (300 MHz, CDCl3): d=
7.73–7.76 (m, 2H), 7.57 (d, J=7.8 Hz, 2H), 7.30–7.34 (m, 4H), 7.11–7.20
(m, 4H), 6.88–6.99 (m, 8H), 6.71–6.75 (m, 2H), 6.62 (s, 4H), 6.49 (s, 4H),
6.12 (d, J=8.1 Hz, 2H), 5.79 (s, 2H), 5.38–5.42 (m, 2H), 4.33–4.40 (m,
2H), 4.17–4.25 (m, 2H), 3.07–3.12 (m, 2H), 2.33–2.36 (m, 2H), 2.11 (s,
12H), 2.02 (s, 12H), 1.50–1.98 ppm (m, 12H); 31P NMR (121.46 MHz,
CDCl3): d=151.52 ppm (s); 13C NMR (75 MHz, CDCl3): d=176.1, 175.2,
151.9. 151.8, 149.7, 143.9, 137.7, 137.6, 137.5, 137.2, 136.2, 136.0, 133.4,
132.2, 131.0, 129.9, 128.8, 127.6, 127.5, 125.9, 125.2, 124.6, 124.4, 124.3,
121.7, 121.0, 63.3, 59.1, 57.7, 57.6, 32.7, 31.6, 25.5, 24.7, 21.1, 20.9,
20.8 ppm; IR (KBr pellet): n˜ =2927, 2863, 1656, 1604, 1582, 1477, 1454,
1333, 1253, 1220, 1170, 875, 763 cmÀ1; ESI-MS: m/z: 1311.2 ([M+H+]);
HRMS (MALDI/DHB): m/z calcd for C82H81N4O8P2 ([M+H+]):
1311.5524; found: 1311.5550.
(2S,3S,5R,6R,2’S,3’S,5’R,6’R)-10h: Yield=27%; white solid; m.p. 179–
1818C ; a[ ]2D0 =À167.7 (c 0.5, CHCl3); 1H NMR (300 MHz, CDCl3) d=
7.63 (d, J=7.8 Hz, 2H), 7.47 (d, J=7.8 Hz, 2H), 7.31–6.95 (m, 26H), 6.85
(s, 2H), 6.74 (s, 2H), 6.05 (s, 2H), 5.77 (s, 2H), 5.45 (s, 2H), 4.42 (t, J=
8.1 Hz, 2H), 4.21 (t, J=8.7 Hz, 2H), 3.08 (d, J=11.4 Hz, 2H), 2.87–2.83
(m, 2H), 2.66–2.61 (m, 2H), 2.28 (d, J=5.1 Hz, 2H), 1.87–1.46 (m, 12H),
1.22 (d, J=6.9 Hz, 6H), 1.13 (d, J=6.9 Hz, 6H), 0.99 (d, J=7.2 Hz, 6H),
0.95 ppm (d, J=6.9 Hz, 6H); 31P NMR (121.46 MHz, CDCl3): d=
150.96 ppm (s); 13CNMR (75 MHz, CDCl 3): d=175.9, 175.0, 152.1, 150.4,
149.8, 148.8, 137.4, 136.5, 133.2, 130.6, 130.2, 129.6, 128.1, 127.9, 127.6,
126.9, 126.8, 125.5, 124.8, 123.0, 122.3, 119.8, 119.4, 109.7, 63.6, 59.5, 57.7,
33.7, 33.3, 32.8, 31.6, 25.6, 24.7, 23.9, 23.8, 23.6, 23.4 ppm; IR (KBr
pellet): n˜ =2960, 2930, 1655, 1407, 1328, 1110 cmÀ1; HRMS (MALDI/
DHB): m/z: calcd for C86H89N4O8P2 ([M+H+]): 1367.6150; found:
1367.6154.
(2S,3S,5R,6R,2’S,3’S,5’R,6’R)-10d: Yield=74%; white solid; m.p. 238–
2408C ; a[ ]2D0 =À61.9 (c=0.5, CHCl3); 1H NMR (300 MHz, CDCl3): d=
7.55 (d, J=6.9 Hz, 2H), 7.36–7.48 (m, 6H), 7.10–7.26 (m, 14H), 6.94 (d,
J=7.5 Hz, 4H), 6.89 (t, J=7.5 Hz, 4H), 6.66 (d, J=7.5 Hz, 4H), 6.44 (t,
J=7.5 Hz, 2H), 6.07 (s, 2H), 5.63 (t, J=6.3 Hz, 2H), 4.44 (t, J=9.9 Hz,
2H), 4.04 (t, J=10.2 Hz, 2H), 3.03 (d, J=12.3 Hz, 2H), 2.57 (d, J=
11.1 Hz, 2H), 1.48–1.90 ppm (m, 24H); 31P NMR (121.46 MHz, CDCl3):
d=156.16 ppm (s); 13CNMR (75 MHz, CDCl 3): d=176.6, 174.2, 151.0,
150.2, 144.8, 136.5, 136.0, 134.6, 130.7, 130.4, 130.3, 130.1, 130.0, 129.9,
129.7, 129.0, 128.5, 128.0, 127.1, 126.9, 125.4, 124.2, 124.1, 123.9, 123.2,
77.2, 65.5, 58.3, 58.0, 56.6, 33.5, 32.5, 25.2, 24.9, 17.2, 16.9 ppm; IR (KBr
pellet): n˜ =3059, 2929, 1658, 1600, 1580, 1462, 1403, 1326, 1255, 1183,
(2S,3S,5R,6R,2’S,3’S,5’R,6’R)-10i: Yield=41%; white solid; m.p. 212–
2148C ; [a]2D0 =À126.6 (c=0.5, CHCl3); 1H NMR (300 MHz, CDCl3): d=
7.64 (d, J=7.8 Hz, 2H), 7.49 (d, J=7.8 Hz, 2H), 7.32–6.95 (m, 28H), 6.96
(s, 2H), 6.22 (s, 2H), 5.78 (s, 2H), 5.44 (s, 2H), 4.43 (t, J=7.2 Hz, 2H),
4.21 (t, J=7.8 Hz, 2H), 3.07 (d, J=10.5 Hz, 2H), 2.29 (d, J=7.2 Hz, 2H),
1.87–1.44 (m, 12H), 1.19 (s, 18H), 1.04 ppm (s, 18H); 31P NMR
(121.46 MHz, CDCl3): d=150.40 ppm (d, J=24.6 Hz); 13CNMR
(75 MHz, CDCl3): d=175.9, 175.1, 152.9, 151.9, 151.2, 149.6, 137.5, 136.5,
132.7, 130.6, 130.2, 129.6, 128.1, 127.8, 127.0, 126.9, 125.2, 124.7, 121.4,
Chem. Eur. J. 2008, 14, 7847 – 7857
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
7855

K. Ding, C. Xia et al.
120.9, 119.4, 118.8, 63.6, 59.5, 57.7, 34.7, 34.3, 32.9, 31.6, 31.1, 31.0, 25.6,
24.7 ppm; IR (KBr pellet): n˜ =2962, 2865, 1655, 1402, 1327, 1213,
940 cmÀ1; HRMS (MALDI/DHB): m/z: calcd for C90H97N4O8P2 ([M+H+
]): 1423.6776; found: 1423.6733.
above was added to the catalyst solution in a glove box. The resulting
mixture was then transferred to a stainless steel autoclave under an
argon atmosphere, and then sealed. After autoclave had been purged
with syngas (H2/CO=4:1) three times, the final pressure was adjusted to
the appropriate value. The reactor was heated to the desired temperature
while stirring at 800 rpm. The reaction was stopped after 2 or 4 h then
cooled by using ice water, and then the syngas was released carefully.
Upon opening the reactor, 0.1 mL of the reaction mixture was taken out
and diluted with toluene (1.0 mL). This solution was analyzed by gas
chromatography. For analysis of the products of the reactions of styrene
and vinyl acetate, a Supelcoꢁs Beta Dex 225 column was used under a
temperature program of 1008Cfor 5 min, then 4 8Cper min to 160 8C.
Retention time: 2.35 min for vinyl acetate (18), 6.62 min for (R)-19, and
8.37 min for (S)-19, the enantiomers of the acetic acid 1-methyl-2-oxo-
ethyl ester (branched regioisomer 19), 11.28 min for acetic acid 3-oxo-
propyl ester (linear regioisomer 20); 4.59 min for styrene (15a),
12.11 min for (R)-16a and 12.34 min for (S)-16a, the enantiomers of 2-
phenylpropionaldehyde (branched regioisomer 16a), 16.08 min for 3-phe-
nylpropionaldehyde (linear regioisomer 17a), and 10.33 min for n-dodec-
ane. For the analysis of reaction product of allyl cyanide, Supelcoꢁs Beta
Dex 120 column was used under a temperature program of 808Cfor
5 min, then 108Cper min to 130 8C. This method was applied to deter-
mine the conversion of substrate 21 and the b/l ratio in the products 22
and 23. Retention time: 3.7 min for allyl cyanide (21), 11.75 min for 3-
methyl-4-oxo-butyronitrile (branched regioisomer 22), 13.61 min for 5-
oxo-pentanenitrile (linear regioisomer 23), and 12.49 min for n-dodecane.
The enantiomeric excess of the product 22 was determined by GCanaly-
sis of its methyl ester on a Supelcoꢁs Beta Dex 120 column under a tem-
perature program of 808Cfor 0 min, then 1 8Cper min to 100 8C, 1008C
for 8 min, then 48Cper min to 130 8C. Retention time: 26.3 min (S) and
26.6 min (R) for the enantiomers of the methyl-3-cyano-2-methylpropa-
noate (branched regioisomer). The methyl ester was obtained by oxida-
tion with Jones reagent to give initially carboxylic acids, followed by
esterification using CH2N2·Et2O solution.
(2R,3R,5S,6S,2’R,3’R,5’S,6’S)-10j: Yield=56%; white solid; m.p. 195–
1968C ; [a]2D0 = +222.7 (c=0.5, CHCl3); 1H NMR (300 MHz, CDCl3): d=
7.71 (d, J=6.9 Hz, 2H), 7.53 (d, J=7.5 Hz, 2H), 7.36–6.89 (m, 28H), 6.75
(s, 2H), 6.18 (d, J=8.4 Hz, 2H), 5.79 (s, 2H), 5.52 (s, 2H), 4.39 (t, J=
10.5 Hz, 2H), 4.21 (t, J=9.6 Hz, 2H), 3.05 (d, J=11.4 Hz, 2H), 2.30 (s,
2H), 1.96–1.89 (m, 4H), 1.76–1.57 ppm (m, 8H); 31P NMR (121.46 MHz,
CDCl3): d=150.86 ppm (s); 13C NMR (75 MHz, CDCl3): d=174.6, 173.7,
151.8, 149.6, 143.2, 136.4, 135.9, 135.7, 135.0, 134.5, 132.9, 130.8, 129.4,
128.5, 128.3, 128.1,127.4, 125.6, 124.8, 124.5, 122.1, 121.8, 63.8, 59.2, 57.6,
57.5, 56.6, 32.5, 31.6, 25.4, 24.6 ppm; IR (KBr pellet): n˜ =2931, 1655,
1476, 1454, 1401, 1326, 1214, 1090, 874, 759 cmÀ1; HRMS (MALDI/
DHB): m/z: calcd for C74H61Cl4N4O8P2 ([M+H+]): 1335.2713; found:
1335.2694.
(2R,3R,5S,6S,2’R,3’R,5’S,6’S)-10k: Yield=45%; white solid; m.p. 198–
2008C ; [a]2D0 =+225.4 (c=0.4, CHCl3); 1H NMR (300 MHz, CDCl3): d=
7.76 (d, J=5.4 Hz, 2H), 7.57 (d, J=7.2 Hz, 2H), 7.36–6.63 (m, 30H), 6.16
(d, J=7.8 Hz, 2H), 5.93 (s, 2H), 5.53 (s, 2H), 4.48 (t, J=10.8 Hz, 2H),
4.22 (t, J=10.8 Hz, 2H), 3.64 (s, 6H), 3.62 (s, 6H), 3.02 (d, J=10.5 Hz,
2H), 2.31 (d, J=6.3 Hz, 2H), 2.02–1.87 (m, 4H), 1.80–1.56 ppm (m, 8H);
31P NMR (121.46 MHz, CDCl3): d=150.41 ppm (s); 13CNMR (75 MHz,
CDCl3): d=175.3, 174.6, 161.1, 160.6, 151.6, 149.5, 143.3, 135.7, 133.1,
129.9, 129.3, 128.7, 128.5, 128.4, 128.1, 127.5, 125.5, 124.9, 124.4, 124.1,
121.7, 121.2, 113.1, 112.8, 76.9, 63.7, 59.9, 59.3, 57.2, 54.9, 54.7, 32.3, 31.4,
25.2, 24.4 ppm; IR (KBr pellet): n˜ =2932, 2858, 1649, 1606, 1325, 1303,
1253, 1173 cmÀ1; HRMS (MALDI/DHB): m/z: calcd for C78H73N4O8P2
([M+H+]): 1319.4695; found: 1319.4690.
(2R,3R,5S,6S,2’R,3’R,5’S,6’S)-10l: Yield=50%; white solid; m.p. 160–
1628C ; [a]2D0 =+245.5 (c=0.5, CHCl3); 1H NMR (300 MHz, CDCl3) d=
7.74 (d, J=4.5 Hz, 2H), 7.73 (d, J=7.2 Hz, 2H), 7.31–6.68 (m, 30H), 6.10
(d, J=7.8 Hz, 2H), 5.96 (s, 2H), 5.49 (s, 2H), 4.46 (t, J=10.2 Hz, 2H),
4.15 (t, J=10.8 Hz, 2H), 3.04 (d, J=10.2 Hz, 2H), 2.25 (s, 2H), 1.86–1.52
(m, 12H), 1.23 (s, 18H), 1.15 ppm (s, 18H); 31P NMR (121.46 MHz,
CDCl3): d=149.88 ppm (s); 13C NMR (75 MHz, CDCl3): d=176.0, 174.9,
153.8, 153.2, 151.9, 149.6, 143.6, 136.0, 134.5, 133.8, 133.3,130.0, 129.0,
127.8, 127.5, 127.0, 126.6, 125.6, 125.5, 124.9, 124.8, 124.7, 124.3, 121.8,
63.8, 59.4, 57.5, 34.6, 32.6, 31.6, 31.0, 29.5, 25.6, 24.6 ppm; IR (KBr
Acknowledgements
This work was supported by the National Natural Science Foundation of
China (No. 20532050, 20632060), the Chinese Academy of Sciences, the
Major Basic Research Development Program of China (Grant No.
2006CB806106), the Science and Technology Commission of Shanghai
Municipality, and Merck Research Laboratories.
pellet): n˜ =2962, 1654, 1326, 1214, 875, 768 cmÀ1
; HRMS (MALDI/
DHB): m/z: calcd for C90H97N4O8P2 ([M+H+]): 1423.6776; found:
1423.6809.
Preparation
[(2R,3R,5S,6S,2’R,3’R,5’S,6’S)-10b][Rh
and
X-ray
crystallographic
(acac)]:
analysis
of
G
[Rh(acac)(CO)2]
ACHTREUNG
(9.5 mg, 0.0368 mmol) and (2R,3R,5S,6S,2’R,3’R,5’S,6’S)-6b (46.6 mg,
0.0368 mmol) were dissolved in dry chloroform (1 mL), and hexane
(8 mL) was diffused into the solution by slow evaporation at room tem-
perature. After one week, a large amount of single crystals was obtained
as orange needles. X-ray crystallographic analysis was performed with a
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Bruker SMART CCD-APEX at 208C . CH79N4O10P2Rh, Mr =1576.72,
83
tetragonal, P4(3)2(1)2, a=14.4686(6), b=14.4686(6), c=38.287(2) Š; V=
8015.1(6) Š3, 1.50<2q<27.508; 1calcd =1.307 gcmÀ3, Z=4, Rint =0.1369,
goodness of fit indicator=0.863, final R1=0.0625, wR2=0.1269 on F2 for
observed data, Pmax, Pmin =0.604, À0.404 ŠÀ3; absolute structure parame-
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graphic data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.ccdc.cam.a-
c.uk/data_request/cif
General procedure for catalytic AHF: The styrene/vinyl acetate/dodec-
ane solution was prepared by mixing styrene (21.58 g, 0.2075 mol) and
vinyl acetate (17.85 g, 0.2075 mol) with dodecane (7.055 g, 0.0415 mol)
(as a GCinternal standard). The allyl cyanide/dodecane solution was pre-
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0.0403 mol) in toluene (9.6 mL). [Rh(acac)(CO)2] (1.1 mg, 0.0043 mmol)
A
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ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Received: March 4, 2008
Published online: July 15, 2008
Chem. Eur. J. 2008, 14, 7847 – 7857
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
7857