Adaptative biaryl phosphite-oxazole and phosphite-thiazole ligands for asymmetrie Ir-catalyzed hydrogenation of alkenes

Article abstract of DOI:10.1002/chem.200903350

A library of readily available phosphite-oxazole/thiazole ligands (L1a-g-L7a-g) was applied in the Ir-catalyzed asymmetric hydrogenation of several largely unfunctionalized E- and Z-trisubstituted and 1,1-disubstituted terminal alkenes. The ability of the catalysts to transfer chiral information to the product could be tuned by choosing suitable ligand components (bridgelength, the substituents in the heterocyclic ring and the alkyl backbone chain, the configuration of the ligand backbone, and the substituents/ configurations in the biaryl phosphite moiety),so that enantioselectivities could be maximized for each substrate as required. Enantioselectivities were therefore excellent (enantiomeric excess (ee) values up to >99%) for a wide range of E- and Z-trisubstituted and 1,1-disubstituted terminal alkenes. The biaryl phosphite moiety was a very advantageous ligand component in terms of substrate versatility.

Full text of DOI:10.1002/chem.200903350

FULL PAPER
DOI: 10.1002/chem.200903350
Adaptative Biaryl Phosphite–Oxazole and Phosphite–Thiazole Ligands for
Asymmetric Ir-Catalyzed Hydrogenation of Alkenes
Javier Mazuela,[a] Alexander Paptchikhine,[b] Oscar Pꢀmies,[a] Pher G. Andersson,*[b] and
Montserrat Diꢁguez*[a]
Abstract: A library of readily available
phosphite–oxazole/thiazole ligands
length, the substituents in the heterocy-
clic ring and the alkyl backbone chain,
the configuration of the ligand back-
bone, and the substituents/configura-
tions in the biaryl phosphite moiety),
so that enantioselectivities could be
maximized for each substrate as re-
quired. Enantioselectivities were there-
fore excellent (enantiomeric excess
(ee) values up to >99%) for a wide
range of E- and Z-trisubstituted and
1,1-disubstituted terminal alkenes. The
biaryl phosphite moiety was a very ad-
vantageous ligand component in terms
of substrate versatility.
(L1a–g–L7a–g) was applied in the Ir-
catalyzed asymmetric hydrogenation of
several largely unfunctionalized E- and
Z-trisubstituted and 1,1-disubstituted
terminal alkenes. The ability of the cat-
alysts to transfer chiral information to
the product could be tuned by choosing
suitable ligand components (bridge
Keywords: alkenes
·
asymmetric
catalysis · hydrogenation · iridium ·
P,N ligands
Introduction
plementary to those of Rh– and Ru–diphosphine com-
plexes.[1,2] The first chiral ligands developed for this process
were the phosphine–oxazolines, which are chiral mimics of
Crabtreeꢀs catalyst. These ligands were successfully used for
the asymmetric hydrogenation of a limited range of al-
kenes.[3] Since then, the composition of the ligands has been
extended by the discovery of new mixed P,N ligands that
have considerably broadened the scope of Ir-catalyzed hy-
drogenation.[4] Of them all, the most successful ligands con-
tain a phosphine or phosphinite moiety as a P-donor group
and either an oxazoline,[4b,g] oxazole,[4d] thiazole,[4i] or pyridi-
ne[4c] as an N-donor group (1–4). However, the iridium-cata-
lyzed asymmetric hydrogenation of unfunctionalized olefins
is still highly substrate-dependent and the development of
efficient chiral ligands that tolerate a broader range of sub-
strates remains a challenge.
The preparation of enantiomerically enriched compounds
currently plays a key role in such important areas as phar-
maceuticals, agrochemicals, fine chemicals, and natural prod-
uct chemistry.[1] As a consequence of its high efficiency,
atom economy, and operational simplicity, asymmetric hy-
drogenation of properly selected prochiral starting materials
is one of the most powerful synthetic tools for preparing
these compounds.[1] Whereas the rhodium and ruthenium-
catalyzed asymmetric hydrogenations of chelating olefins
have a long history, the asymmetric hydrogenations of un-
functionalized olefins are less developed because these sub-
strates lack an adjacent polar group to direct the reaction.[1]
In recent years, iridium complexes with chiral P,N ligands
have become established as efficient catalysts for the hydro-
genation of unfunctionalized olefins, and their scope is com-
[a] J. Mazuela, O. Pꢁmies, M. Diꢂguez
Departament de Quꢃmica Fꢃsica i Inorgꢁnica.
Universitat Rovira i Virgili. C/Marcel·li Domingo
s/n. 43007 Tarragona (Spain)
Fax : (+34)977559563
E-mail: montserrat.dieguez@urv.cat
[b] A. Paptchikhine, P. G. Andersson
Department of Biochemistry and Organic Chemistry
Uppsala University, BOX 576
751 23 Uppsala (Sweden)
E-mail: pher.andersson@kemi.uu.se
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In this context, we have recently discovered that the pres-
ence of biaryl phosphite moieties in ligand design is highly
advantageous.[5] Ir/phosphite–oxazoline catalytic systems
provided greater substrate versatility than previous Ir/phos-
phinite–oxazoline systems, and high activities and enantiose-
lectivities for several largely unfunctionalized E- and Z-tri-
substituted and 1,1-disubstituted olefins.[5a,c] Despite this suc-
cess, little attention has been paid to this new class of highly
efficient phosphite-containing ligands for this process[5a,c]
and their potential as new ligands still needs to be systemati-
cally studied. To fully investigate this potential, we therefore
decided to go one step further and study whether the biaryl
phosphite moiety maintains its effectiveness in combination
with N-donor groups other than oxazolines. For this pur-
pose, we took two of the most successful ligand families
used in this process (2 and 3) and replaced their phosphinite
or phosphine moieties with biaryl phosphite groups to give
ligands L1a–g–L7a–g.[6] Ligands 2 and 3 proved to be highly
able alcohols.[11] As well as containing biaryl phosphite moi-
eties in their design, these ligands have a flexible ligand
scaffold that enables several parameters to be tuned. Thus,
the effect of ligand structure on catalytic performance can
be explored. We systematically varied the bridge length (li-
gands L1 and L5), the substituent in the heterocyclic ring (li-
gands L1–L4) and the alkyl backbone chain (ligands L5 and
L6), the configuration of the alkyl backbone chain (ligands
L6 vs. L7), and the substituents and configurations in the
biaryl phosphite moiety (a–g) in these ligands and examined
their effects on asymmetric hydrogenation. By selecting the
best ligand elements, we achieved high enantioselectivities
and activities in the reduction of a wide range of E- and Z-
trisubstituted and 1,1-disubstituted olefins.
Results and Discussion
Synthesis of the Ir-catalyst pre-
cursors: The catalyst precursors
were made by refluxing a di-
chloromethane solution of the
appropriate ligand (L1a–g–
L7a–g) in the presence of 0.5
equivalents of [{IrClACHTUNGTRENNUNG(cod)}2]
(cod=1,5-cyclooctadiene) for
2 h and then exchanging the
counterion
with
sodium
tetrakis[3,5-bis(trifluorome-
AHCTUNGTRENNUNG
thyl)phenyl]borate (NaBArF;
1 equiv), in the presence of
water (Scheme 1). All com-
plexes were isolated as air-
stable orange solids and were
used without further purifica-
tion.
The complexes were charac-
terized by elemental analysis
1
and H, 13C, and 31P NMR spec-
troscopy. The spectral assign-
efficient in the hydrogenation of unfunctionalized aryl–alkyl
E-trisubstituted olefins (including those containing weakly
coordinating groups),[4d,i] but they provided low-to-moderate
enantioselectivities for the Z analogues[7] and enol phosphi-
nates.[8] Moreover, although ligand 2 provided high enantio-
selectivities for the terminal substrate 2-(4-methoxyphenyl)-
1-butene, only moderate enantioselectivities were achieved
for other terminal 2-arylbut-1-enes.[9] Therefore, with this
new biaryl phosphite–oxazole and phosphite–thiazole design
we expect to increase substrate versatility in the hydrogena-
tion of largely unfunctionalized olefins. Interestingly, these
ligands combine a priori the advantages of the oxazole/thia-
zole moieties with those of the phosphite moiety. So they
are more stable than their oxazoline counterparts,[10] less
sensitive to air and other oxidizing agents than phosphines
and phosphinites, and easy to synthesize from readily avail-
Scheme 1. Synthesis of catalyst precursors [IrACTHNUGTRENNU(G cod)ACHTUNTGNER(NUGN P-N)]BArF (P-N=
L1a–g–L7a–g).
ments (see the Experimental Section) were based on infor-
mation from 1H–1H and 13C–1H correlation measurements
and were as expected for these C1 iridium complexes. The
VT-NMR spectra indicate that only one isomer is present in
solution. One singlet in the 31P{1H} NMR spectra was ob-
tained in all cases.
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Chem. Eur. J. 2010, 16, 4567 – 4576

Asymmetric Ir-Catalyzed Hydrogenation of Alkenes
FULL PAPER
Asymmetric hydrogenation of trisubstituted olefins
effect between the configuration of the biaryl moiety and
the configuration of the ligand backbone on enantioselectiv-
ity. This led to a matched combination for ligand L1d,
which contains an S-binaphthyl moiety (entries 4 and 5).
This effect was less pronounced for phosphite–thiazole li-
gands L5 (entries 14 and 15). In addition, a comparison of
the absolute stereochemistry obtained by using ligand L1c
with those obtained upon using the related binaphthyl li-
gands L1d and L1e (entries 3–5) shows that the atropoiso-
meric biphenyl moiety in ligands L1a–c adopts an S configu-
ration upon forming a complex with iridium.[12]
In summary, activities and enantioselectivities (enantio-
meric excess (ee) values up to 98%) were high with ligands
L5a–L7a (Table 1, entries 11, 16, and 17), which contain the
optimal combination of ligand parameters (bridge length,
the substituents in the heterocyclic ring, and the substituents
and configurations in the biaryl phosphite moiety). In addi-
tion, both enantiomers of the hydrogenated product can be
accessed in high enantioselectivity simply by changing the
configuration of the ligand backbone (entries 16 and 17).
These findings clearly show the efficiency of highly modular
scaffolds in ligand design.
Asymmetric hydrogenation of unfunctionalized trisubstituted
olefins: In a first set of experiments, we used the Ir-cata-
lyzed hydrogenation of trans-a-methylstilbene (S1) to study
the potential of ligands L1a–g–L7a–g. S1 was chosen as the
substrate because it has been hydrogenated by a wide range
of catalysts, which enabled the efficiency of the various
ligand systems to be compared directly. The results are sum-
marized in Table 1. We found that enantioselectivities were
highly affected by the bridge length, the substituents in the
heterocyclic ring, and the substituents and configurations in
the biaryl phosphite moiety (a–g), but not by the substitu-
ents in the alkyl backbone chain.
Table 1. Selected results for the Ir-catalyzed hydrogenation of S1 by
using the ligand library L1a–g–L7a–g.[a]
Entry
Ligand
Conv. [%][b]
ee [%][c]
1
2
3
4
5
6
7
8
L1a
L1b
L1c
L1d
L1e
L1 f
L1g
L2a
L3a
L4a
L5a
L5b
L5c
L5d
L5e
L6a
L7a
100
100
100
100
100
8
90 (S)
90 (S)
85 (S)
84 (S)
37 (S)
50 (S)
12 (S)
89 (S)
82 (S)
83 (S)
98 (S)
97 (S)
95 (S)
85 (S)
90 (S)
98 (S)
98 (R)
We then studied the asymmetric hydrogenation of other
E- and Z-trisubstituted olefins (S2–S6) by using the phos-
phite–oxazole/thiazole ligand library L1a–g–L7a–g. The
most noteworthy results are shown in Table 2. The enantio-
selectivities are among the best observed for these sub-
strates. In general, the hydrogenation of E-trisubstituted ole-
fins (S2–S3) followed the same trends as the hydrogenation
8
100
100
42
100
100
100
100
100
100
100
9
10
11
12
13
14
15
16
17
Table 2. Selected results for the Ir-catalyzed hydrogenation of largely un-
functionalized E- and Z-trisubstituted olefins by using the ligand library
L1a–g–L7a–g.[a]
[a] Reactions carried out by using 1 mmol of S1 and 0.2 mol% of Ir-cata-
1
lyst precursor at 50 bar of H2. [b] Conversion measured by H NMR spec-
troscopy after 2 h. [c] Enantiomeric excesses determined by chiral GC
analysis.
Entry
Substrate
Ligand
Conv. [%][b]
ee [%][c]
1
2
3
L5a
L6a
L7a
100
100
100
99 (S)
99 (S)
98 (R)
The influence of the bridge length indicates that ligands
L5–L7, which form a seven-membered chelate ring, provid-
ed higher enantioselectivity than ligands L1–L4, which form
a six-membered chelate ring (Table 1, entries 1 and 8–10 vs.
11 and 16–17).
In the heterocyclic ring, electron-withdrawing substituents
had a negative effect on enantioselectivity (Table 1, entries 9
vs. 1 and 8), and bulky substituents at this position de-
creased activity (entries 10 vs. 1).
4
5
6
L5a
L6a
L7a
100
100
100
99 (S)
99 (S)
99 (R)
7
L5e
100
90 (R)
8
9
10
L5a
L6a
L7a
100
100
100
78 (R)
93 (R)
93 (S)
Bulky ortho substituents in the biaryl phosphite moiety
were highly advantageous for both activity and enantioselec-
tivity (Table 1, entries 1–5 vs 6 and 7). However, substituents
in the para positions also play a small but crucial role.
Therefore, if enantioselectivities have to be high the para
position needs to be substituted (entries 1 and 2 vs. 3). For
phosphite–oxazole ligands L1, we also found a cooperative
11
L5a
100
99 (R)
[a] Reactions carried out by using 1 mmol of substrate and 0.2 mol% of
Ir-catalyst precursor at 50 bar of H2. [b] Conversion measured by
1H NMR spectroscopy or GC analysis after 2 h. [c] Enantiomeric excesses
determined by chiral GC analysis.
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4569

M. Diꢂguez et al.
of S1. Again, the catalyst precursors containing ligands
L5a–L7a provided the best enantioselectivities (ee values
up to 99%; Table 2, entries 1–6). It should be noted that if
ligands are appropriately tuned, high enantioselectivities (ee
values up to 99%) could also be obtained for the more de-
manding Z-trisubstituted olefins (S4–S6), which are usually
hydrogenated less enantioselectively than the corresponding
E isomers (Table 2, entries 7–11). Interestingly, when these
excellent results are compared with the moderate enantiose-
lectivity obtained for Z-trisubsituted olefins with the related
ligands 2 and 3,[7] we can conclude that the introduction of a
biaryl phosphite moiety has been highly advantageous.
the enantioselectivity was best with ligand L1a (entries 15
and 17). Once again, these results clearly show the efficiency
of using modular scaffolds in ligand design and are among
the best that have been reported for this type of substrates.[2]
They also show that the introduction of a biaryl phosphite
moiety in the ligand design is highly advantageous because
it overcomes a substrate limitation of the related ligands 2
and 3 by hydrogenating enol phosphinates.[8]
Asymmetric hydrogenation of 1,1-disubstituted terminal
olefins
Asymmetric hydrogenation of unfunctionalized 1,1-disubsti-
tuted terminal olefins: To further study the potential of the
phosphite–oxazole/thiazole ligand library L1a–g–L7a–g, we
also screened it in the Ir-catalyzed hydrogenation of more
demanding substrates: terminal olefins. Enantioselectivity is
more difficult to control in these substrates than in trisubsti-
tuted olefins. There are two main reasons for this:[2d] 1) the
two substituents in the substrate can easily exchange posi-
tions in the chiral environment formed by the catalysts, thus
reversing the face selectivity and 2) the terminal double
bond can isomerize to form the more stable internal alkene,
which usually leads to the predominant formation of the op-
posite enantiomer of the hydrogenated product. Few known
catalytic systems provide high enantioselectivities for these
substrates, and those that do are usually limited in substrate
scope.[13,14] Pfaltz found that in the hydrogenation of termi-
nal alkenes, the selectivity is highly pressure dependent. Hy-
drogenation at an atmospheric pressure of H2 gave signifi-
cantly higher ee values than at higher pressures.[4b,13a]
Asymmetric hydrogenation of trisubstituted olefins containing
a neighboring polar group: We then applied the phosphite–
oxazole/thiazole ligand library L1a–g–L7a–g in the asym-
metric hydrogenation of several trisubstituted olefins con-
taining a neighboring polar group. These substrates are in-
teresting because they allow for further functionalization.
The results are summarized in Table 3. Again, enantioselec-
Table 3. Selected results for the Ir-catalyzed hydrogenation of trisubsti-
tuted weakly coordinating functionalized olefins by using the ligand li-
brary L1a–g–L7a–g.[a]
Entry
Substrate
Ligand
Conv. [%][b]
ee [%][c]
1
2
3
4
5
6
7
8
L1a
L5a
L6a
L7a
L1a
L5a
L6a
L7a
L5a
L6a
L7a
L5a
L6a
L7a
65
100
100
100
100
100
100
100
100
100
100
100
100
100
99 (S)
99 (S)
98 (S)
98 (R)
84 (S)
96 (S)
96 (S)
96 (R)
95 (S)
94 (S)
94 (R)
98 (S)
97 (S)
97 (R)
In a first set of experiments, we examined the Ir-catalyzed
asymmetric hydrogenation of 2-phenylbut-1-ene (S13). Ta-
ble 4shows the results obtained by using the ligand library
L1a–g–L7a–g in optimized conditions. We were again able
to fine-tune ligand parameters to produce high activities and
enantioselectivities (ee values up to 94%) in the hydrogena-
9
10
11
12
13
14
15[d]
16[d]
L1a
L5a
100
100
91 (S)
20 (R)
Table 4. Selected results for the Ir-catalyzed hydrogenation of S13 by
using the ligands L1a–g–L7a–g.[a]
17[e]
L1a
45
92 (S)
[a] Reactions carried out by using 1 mmol of substrate, dichloromethane
as solvent, and 0.2 mol% of Ir-catalyst precursor at 50 bar of H2 and at
room temperature. [b] Conversion measured by H NMR spectroscopy or
GC analysis after 2 h. [c] Enantiomeric excesses determined by chiral GC
analysis or HPLC. [d] t=12 h. [e] 100 bar of H2, t=12 h.
Entry
Ligand
Conv. [%][b]
ee [%][c]
1
1
2
3
4
5
6
7
8
L1a
L2a
L3a
L4a
L5a
L5b
L5c
L5d
L5e
L6a
L7a
100
100
100
100
100
100
100
100
100
100
100
53 (R)
50 (R)
43 (R)
5 (R)
94 (R)
94 (R)
90 (R)
89 (R)
3 (R)
tivities in both enantiomers of the hydrogenation product
were excellent (ee values up to 99%) under mild reaction
conditions. Hydrogenation of a,b-unsaturated ester S7, allyl-
ic alcohol S8, allylic acetate S9, and vinylsilane S10 followed
the same trends as those observed for the previous E-trisub-
stituted substrates S1–S3. Therefore, enantioselectivities
were best with ligands L5a–L7a (Table 3, entries 2–4 and 6–
14). However, for trisubsituted enol phosphinates S11–S12,
9
10
11
90 (R)
90 (S)
[a] Reactions carried out by using 1 mmol of S13 and 0.2 mol% of Ir-cat-
alyst precursor at 1 bar of H2. [b] Conversion measured by GC analysis
after 2 h. [c] Enantiomeric excesses determined by chiral GC analysis.
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Asymmetric Ir-Catalyzed Hydrogenation of Alkenes
FULL PAPER
Table 5. Selected results for the Ir-catalyzed hydrogenation of largely un-
tion of this substrate. In contrast to the hydrogenation of E-
trisubstituted olefins (S1–S3 and S7–S10), among the other
ligand parameters, activities and enantioselectivities were
also affected by the subsitutents in the alkyl backbone
chain. Therefore, ligand L5 provided better enantioselectivi-
ties than ligands L6 and L7 that contain methyl substitutents
at the alkyl backbone chain (Table 4, entries 5 vs. 10 and
11). Interestingly, the effect of bridge length was more pro-
nounced in this reaction than in the reduction of E-trisubsti-
tuted olefins. The ligands that formed seven-membered che-
late rings (L5) provided much higher enantioselectivities
than the one that formed a six-membered chelate ring (L1).
The effect of the substituents in the biaryl phosphite moiety
followed the same trend as those observed for E-trisubstitut-
ed olefins. However, by using ligands L5d and L5e, we
found an important cooperative effect between the configu-
ration of the biaryl moiety and the configuration of the
ligand backbone on enantioselectivity. Ligand L5d, which
contains an S-binaphthyl moiety, performed better than L5e
(Table 4, entries 8 and 9). In addition, a comparison of the
results obtained upon using ligand L5c with those from the
related binaphthyl ligands L5d and L5e (Table 4, entries 7–
9) shows that the atropoisomeric biphenyl moieties in li-
gands L5a–c adopt an S configuration upon coordination to
iridium.[12]
functionalized 1,1-disubstituted terminal olefins by using ligand L5a.[a]
Entry
1
Substrate
Conv. [%][b]
100
ee [%][c]
95 (R)
2
3
4
5
100
100
100
100
94 (R)
85 (R)
95 (R)
94 (R)
6
7
100
100
97 (R)
94 (R)
In summary, enantioselectivities were best when phos-
phite–thiazole ligands L5a and L5b were used. Once again,
it was possible to access both enantiomers of the hydrogena-
tion product. These results, which again clearly show the ef-
ficiency of using modular scaffolds in ligand design, are
among the best that have been reported for this demanding
substrate class.[13,14]
8
9
100
100
90 (+)
99 (À)
We then studied the asymmetric hydrogenation of other
1,1-disubstituted aryl–alkyl substrates (S14–S20) and 1,1-dis-
ubstituted heteroaryl–alkyl olefins (S21–S23) by using the
phosphite–oxazole/thiazole ligand library L1a–g–L7a–g.
The most noteworthy results are shown in Table 5. They
follow the same trends as the hydrogenation of S13. Again,
the catalyst precursor containing the phosphite–thiazole li-
gands L5a and L5b provided the best enantioselectivities
(ee values up to 99%).
10
100
96 (À)
[a] Reactions carried out by using 1 mmol of substrate and 0.2 mol% of
Ir-catalyst precursor at 1 bar of H2. [b] Conversion measured by H NMR
spectroscopy or GC analysis. [c] Enantiomeric excesses determined by
chiral GC analysis.
1
The hydrogenations of 1,1-disubstituted aryl–alkyl sub-
strates bearing increasingly bulky alkyl substituents (S14–
S18) all gave similar high activities and enantioselectivities
(full conversion, ee values up to 95%; Table 5, entries 1–5).
Our results with several para-substituted 2-phenylbut-2-enes
(S13, S19–S20) indicated that enantioselectivity (ee values
up to 97%) is relatively insensitive to the electronic nature
of the substrate phenyl ring (Table 4, entry 5 and Table 5,
entries 6 and 7). This is, therefore, one of only two catalytic
systems able to hydrogenate a wide range of a-alkylstyrenes
in high enantioselectivities.[5c]
Under standard conditions, our catalyst systems were also
able to hydrogenate several 1,1-heteroaromatic alkenes with
high activities and enantioselectivities (ee values up to 99%;
Table 5, entries 8–10).
Asymmetric hydrogenation of 1,1-disubstituted terminal ole-
fins containing a neighboring polar group: Encouraged by
the excellent results obtained up to this point, we examined
the asymmetric hydrogenation of 1,1-disubstituted terminal
olefins containing a polar neighboring group (S24–S27). The
results are summarized in Table 6.
We then decided to apply this ligand library in the asym-
metric hydrogenation of 1,1-heteroaromatic alkenes (S21–
S23) because heterocycles are used in industry and because
the heterocyclic part can be modified post-hydrogenation.
Despite this, only one previous study has been made.[5c]
We initially tested the ligand library in the hydrogenation
of the allylic alcohol S24. Derivatives of the hydrogenation
product 2-phenylpropanol are frequently used as compo-
nents of fragrance mixtures (i.e. commercial odorants Mu-
guesia and Pamplefleur) and also as intermediates for the
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4571

M. Diꢂguez et al.
Table 6. Selected results for the Ir-catalyzed hydrogenation of 1,1-disub-
stituted terminal olefins containing a neighboring polar group by using
the ligand library L1a–gL7a–g.[a]
Conclusion
A library of readily available phosphite–oxazole/thiazole li-
gands (L1a–g–L7a–g) was applied in the Ir-catalyzed asym-
metric hydrogenation of several largely unfunctionalized E-
and Z-trisubstituted and 1,1-disubstituted terminal alkenes.
This ligand library combines the advantages of the oxazole/
thiazole moieties with those of the phosphite moiety. They
are more stable than their oxazoline counterparts, less sensi-
tive to air and other oxidizing agents than phosphines and
phosphinites, and easy to synthesize from readily available
alcohols. Moreover, the highly modular nature of the ligand
library enables the bridge length, the substituents in the het-
erocyclic ring and the alkyl backbone chain, the configura-
tion of the ligand backbone, and the substituents/configura-
tions in the biaryl phosphite moiety to be easily and system-
atically varied. We found that the effectiveness at transfer-
ring the chiral information in the product can be tuned by
choosing suitable ligand components, so that enantioselec-
tivities can be maximized for each substrate as required.
Enantioselectivities were therefore excellent (ee values up
to >99%) in a wide range of E- and Z-trisubstituted and
1,1-disubstituted terminal alkenes. It should be noted that
these catalytic systems also have a high tolerance to the
presence of a neighboring polar group and, therefore, tri-
and disubstituted allylic alcohols, acetates, esters, silanes,
and enol phosphinates can be hydrogenated in high enantio-
selectivities (ee values up to 99%). We also demonstrated
that the introduction of a biaryl phosphite moiety into the
ligand design is highly advantageous in terms of substrate
versatility. Therefore, these Ir–phosphite–oxazole/thiazole
catalytic systems provided higher enantioselectivities for a
wider range of E- and Z-trisubstituted and 1,1-disubstituted
substrates than their related phosphinite–oxazole (2) and
phosphine–thiazole (3) counterparts. These results show that
these catalytic systems are among the few alternatives that
provide high substrate versatility for E- and Z-trisubstituted
and 1,1-disubstituted terminal alkenes.
Entry
Substrate
Ligand
Conv. [%][b]
ee [%][c]
1
2
3
L5a
L6a
L7a
100
100
100
87 (S)
90 (S)
90 (R)
4
5
6
L5a
L6a
L7a
100
100
100
83 (S)
87 (S)
87 (R)
7[d]
L1a
L5a
100
100
82 (R)
93 (R)
8
[a] Reactions carried out by using 1 mmol of substrate and 0.5 mol% of
Ir-catalyst precursor at 50 bar of H2. [b] Conversion measured by
1H NMR spectroscopy measured after 2 h. [c] Enantiomeric excesses de-
termined by chiral GC or HPLC analysis. [d] t=12 h.
synthesis of natural products and drugs (i.e. modulators of
dopamine D3 receptors).[15] Iridium complexes containing li-
gands L5a–L7a proved to be the most selective catalysts,
giving 90% ee at room temperature in both enantiomers of
the hydrogenation product (Table 6, entries 1–3). Similarly,
the hydrogenation of the allylic acetate S25 also proceeds
with high activity and enantioselectivity with the catalyst
systems containing ligands L5a–L7a (Table 6, entries 4–6).
These results are among the best that have been reported
for these substrate types.[5c,13a]
We next screened ligands L1a–g–L7a–g in the asymmetric
hydrogenation of the enol phosphinate S26 and the allylic
silane S27. The hydrogenation of these compounds gave rise
to important chiral organic intermediates and a number of
innovative new organosilicon[16] drugs are being developed.
As previously observed for the trisubstituted enol phosphi-
nates, if ee values have to be high for substrate S26, phos-
phite–oxazole ligand types (L1) need to be used. Enantiose-
lectivities (ee values up to 82%) were best with catalyst pre-
cursor Ir–L1e (Table 6, entry 7). However, for the hydroge-
nation of S27, the best result (ee values up to 93%) was ob-
tained with the Ir–L5a catalyst precursor (Table 6, entry 8).
This is, therefore, one of the two catalytic systems able to
hydrogenate allylic silane S27 in high enantioselectivities.[5c]
It is also noteworthy that phosphite–oxazole ligands L1 pro-
vide better conversions and enantioselectivities than those
obtained with related phosphinite–oxazole ligands 2 in the
hydrogenation of enol phosphinate S26.[8] This shows once
again the benefits of incorporating a biaryl phosphite
moiety into the ligand design for the hydrogenation of enol
phosphinates.
Experimental Section
General considerations: All reactions were carried out by using standard
Schlenk techniques under an atmosphere of argon. Solvents were purified
and dried by standard procedures. Phosphite–oxazole/thiazole ligands
L1a–g–L7a–g were prepared as previously described.[6] 1H, 13C{1H}, and
31P{1H} NMR spectra were recorded by using a 400 MHz spectrometer.
Chemical shifts are relative to that of SiMe4 (1H and 13C) as an internal
standard or H3PO4 (31P) as an external standard. 1H and 13C assignments
were made on the basis of 1H–1H gCOSY and 1H–13C gHSQC experi-
ments.
Typical procedure for the preparation of [Ir
sponding ligand (0.074 mmol) was dissolved in CH2Cl2 (2 mL) and [{IrCl-
(cod)}2] (25 mg, 0.037 mmol) was added. The reaction was refluxed at
508C for 1 h. After 5 min at room temperature, NaBArF (77.1 mg,
0.082 mmol) and water (2 mL) were added and the reaction mixture was
stirred vigorously for 30 min at room temperature. The phases were sepa-
rated and the aqueous phase was extracted twice with CH2Cl2. The com-
bined organic phases were filtered through a Celite plug, dried with
ACHTUNGERTN(NUNG cod)(L)]BArF: The corre-
AHCTUNGTRENNUNG
4572
www.chemeurj.org
ꢄ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2010, 16, 4567 – 4576

Asymmetric Ir-Catalyzed Hydrogenation of Alkenes
FULL PAPER
À
MgSO4, and the solvent was evaporated to give the product as an orange
solid.
8.4 Hz; CH2), 61.3 (d, JCÀP =4.2 Hz; CH O), 70.0 (CH=, cod), 70.4 (CH=
, cod), 97.8 (d, JCÀP =20.4 Hz; CH=, cod), 106.8 (d, JCÀP =9.6 Hz; CH=,
[IrACHTUNGTRENNUNG(cod)ACHTUNGTRENNUNG
(L1a)]BArF: Yield: 127 mg (93%); 31P NMR (CDCl3): d=
cod), 117.8 (brs; CH=, BArF), 119–134 (aromatic carbon atoms), 135.0
(brs; CH=BArF), 136–153 (aromatic carbon atoms), 161.9 (q, JCÀB
1
108.9 ppm; 1H NMR (CDCl3): d=1.08 (s, 3H; CH3), 1.28 (s, 3H; CH3),
=
49.2 Hz; C-B, BArF), 168.1 ppm (C=N); elemental analysis calcd (%) for
C81H68BF24IrNO4PSi2: C 52.15, H 3.67, N 0.75; found: C 52.17, H 3.69, N
0.74.
1.37 (s, 9H; CH3, tBu), 1.39 (s, 9H; CH3, tBu), 1.51 (s, 9H; CH3, tBu),
2
1.59 (s, 9H; CH3, tBu), 1.68 (m, 4H; CH2, cod), 1.81 (dd, 1H, JHÀH
=
18.1, 3JHÀH =8.8 Hz; CH2), 2.04 (m, 1H; CH2), 2.35 (m, 4H; CH2, cod),
2.54 (d, 1H, 2JHÀH =17.4 Hz; CH2 C=), 2.68 (d, 1H, 2JHÀH =17.1 Hz;
(L1e)]BArF: Yield: 134 mg (97%); 31P NMR (CDCl3): d=
[IrACTHNGUTRENNU(G cod)ACHTGNUTRENNUNG
À
1
À
À
CH2 C=), 4.03 (m, 1H; CH=, cod), 4.39 (brs, 2H; CH=, cod), 5.35 (brs,
108.0 ppm; H NMR (CDCl3): d=0.23 (s, 9H, CH3 Si), 0.60 (s, 9H;
À
À
1H; CH=, cod), 5.61 (s, 1H; CH O), 6.90–8.20 ppm (m, 21H; CH=);
CH3 Si), 1.09 (s, 3H; CH3), 1.20 (s, 3H; CH3), 1.58 (m, 4H; CH2, cod),
1.73 (dd, 1H, JHÀH =14.1, JHÀH =5.7 Hz; CH2), 2.07 (m, 2H; CH2 +CH2,
2
3
13C NMR (CDCl3): d=24.6 (CH2, cod), 27.1 (CH2, cod), 28.4 (CH3), 29.2
(CH3), 31.1 (CH3, tBu), 31.2 (CH3, tBu), 31.5 (CH3, tBu), 32.6 (CH3, tBu),
34.6 (CH2, cod), 35.0 (CH2-C=), 35.1 (brs; C, tBu), 35.6 (brs; C, tBu),
cod), 2.16 (m, 1H; CH2, cod), 2.27 (m, 2H; CH2, cod), 2.58 (d, 1H,
2JHÀH =17.3 Hz; CH2 C=), 2.67 (d, 1H, 2JHÀH =17.5 Hz; CH2 C=), 3.81
(m, 1H; CH=, cod), 4.22 (brs, 2H; CH=, cod), 5.36 (brs, 1H; CH=, cod),
À
À
À
36.0 (CMe2), 37.5 (brs; CH2, cod), 42.2 (brs; CH2), 69.5 (brs; CH O),
À
70.1 (CH=, cod), 70.9 (CH, cod), 91.7 (d, JCÀP =23.6 Hz; CH=, cod,),
105.5 (brs; CH=, cod), 113–116 (aromatic carbon atoms), 117.7 (brs;
CH=, BArF), 119–134 (aromatic carbon atoms), 135.0 (brs, CH=BArF),
136–157 (aromatic carbon atoms), 161.9 (q, 1JCÀB =49.5 Hz; C-B, BArF),
165.9 ppm (C=N); elemental analysis calcd (%) for C83H80BF24IrNO4P: C
54.02, H 4.37, N 0.76; found: C 53.98, H 4.48, N 0.77.
5.51 (s, 1H; CH O), 7.20–8.10 ppm (m, 27H; CH=); 13C NMR (CDCl3):
d=0.5 (CH3 Si), 0.9 (CH3 Si), 25.6 (CH2, cod), 29.9 (CH2, cod), 30.1
(CH3), 30.8 (CH3), 32.2 (CH2, cod), 33.4 (CH2 C=), 35.2 (CMe2), 36.1 (d,
CÀP =6.8 Hz; CH2, cod), 42.9 (d, JCÀP =9.1 Hz; CH2), 61.4 (d, JCÀP
À
À
À
J
=
À
3.7 Hz; CH O), 69.5 (CH=, cod), 70.1 (CH=, cod), 97.1 (d, JCÀP
=
22.5 Hz; CH=, cod), 107.3 (d, JCÀP =10.8 Hz; CH=, cod), 117.7 (brs; CH=
, BArF), 119–134 (aromatic carbon atoms), 135.0 (brs; CH=BArF), 136–
153 (aromatic carbon atoms), 161.9 (q, 1JCÀB =49.2 Hz; C-B, BArF),
167.9 ppm (C=N); elemental analysis calcd (%) for C81H68BF24IrNO4PSi2:
C 52.15, H 3.67, N 0.75; found: C 52.13, H 3.70, N 0.73.
[IrACHTUNGTRENNUNG(cod)ACHTUNGTRENNUNG
(L1b)]BArF: Yield: 126 mg (95%); 31P NMR (CDCl3): d=
111.6 ppm; 1H NMR (CDCl3): d=1.06 (s, 3H; CH3), 1.08 (s, 3H; CH3),
1.49 (s, 9H; CH3, tBu), 1.56 (s, 9H; CH3, tBu), 1.65 (m, 4H; CH2, cod),
2
1.81 (dd, 1H, 2JHÀH =14.1, 3JHÀH =6.6 Hz; CH2), 2,07 (dd, 1H, JHÀH
=
14.4, 3JHÀH =6.6 Hz; CH2), 2.22 (m, 2H; CH2, cod), 2.43 (m, 2H; CH2,
(L1 f)]BArF: Yield: 120 mg (94%); 31P NMR (CDCl3): d=
[IrACTHNGUTRENNU(G cod)ACHTGNUTRENNUNG
cod), 2.53 (d, 1H, 2JHÀH =17.4 Hz; CH2 C=), 2.67 (d, 1H, JHÀH
=
104.2 ppm (s); 1H NMR (CDCl3): d=0.92 (s, 3H; CH3), 1.12 (s, 3H;
CH3), 1.52 (m, 4H; CH2, cod), 1.62 (dd, 1H, 2JHÀH =14, 3JHÀH =5.6 Hz;
CH2), 1.92 (dd, 1H, 2JHÀH =14, 3JHÀH =5.4 Hz; CH2), 2.09 (m,1H; CH2
cod), 2.15 (m, 1H; CH2, cod), 2.25 (m, 2H; CH2, cod), 2.53 (m, 1H,
2
À
À
À
À
17.1 Hz; CH2 C=), 3.84 (s, 3H; CH3 O), 3.86 (s, 3H; CH3 O), 4.02 (m,
1H; CH=, cod), 4.44 (brs, 1H; CH=, cod), 4.59 (brs, 1H; CH=, cod),
À
5.34 (brs, 1H; CH=, cod), 5.58 (s, 1H; CH O), 6.60–8.20 ppm (m, 21H;
CH=); 13C NMR (CDCl3): d=24.5 (CH2, cod), 27.1 (CH2, cod), 28.4
(CH3), 29.1 (CH3), 31.1 (CH3, tBu), 32.2 (CH3, tBu), 34.7 (CH2, cod), 35.0
2JHÀH =16 Hz; CH2 C=), 2.61 (d, 1H, 2JHÀH =16 Hz; CH2 C=), 3.80 (m,
1H; CH=, cod), 4.20 (brs, 2H; CH=, cod), 5.32 (brs, 1H; CH=, cod),
À
À
À
À
(CH2 C=), 35.6 (brs; C, tBu), 36.0 (CMe2), 37.6 (CH2, cod), 42.4 (brs;
5.59 (m, 1H; CH O), 6.90–8.30 ppm (m, 29H; CH=); 13C NMR (CDCl3):
d=24.3 (CH2, cod), 29.1 (CH3), 29.9 (CH2, cod), 30.4 (CH3), 32.5 (CH2,
À
À
CH2), 55.8 (CH3 O), 69.6 (brs; CH O), 70.5 (CH=, cod), 70.9 (CH=,
cod), 91.2 (d, JCÀP =23.6 Hz; CH=, cod), 105.5 (brs; CH=, cod), 113–116
(aromatic carbon atoms), 117.7 (brs; CH=, BArF), 119–134 (aromatic
carbon atoms), 135.0 (brs; CH=BArF), 136–157 (aromatic carbon atoms),
À
cod), 33.1 (CH2 C=), 35.4 (CMe2), 36.5 (CH2), 43.1 (d, JCÀP =9.4 Hz;
À
CH2), 61.9 (d, JCÀP =3.1 Hz; CH O), 69.9 (CH=, cod), 70.2 (CH=, cod),
97.3 (d, JCÀP =18.9 Hz; CH=, cod), 107.8 (d, JCÀP =9.9 Hz; CH=, cod),
117.6 (brs; CH=, BArF), 119–134 (aromatic carbon atoms), 135.0 (brs;
CH=BArF), 136–159 (aromatic carbon atoms), 161.8 (q, 1JCÀB =49.2 Hz;
C-B, BArF), 167.4 ppm (C=N); elemental analysis calcd (%) for
C75H52BF24IrNO4P: C 52.34, H 3.05, N 0.81; found: C 52.36, H 3.07, N
0.79.
1
161.9 (q, JCÀB =49.5 Hz; C-B, BArF), 165.7 ppm (C=N); elemental analy-
sis calcd (%) for C77H68BF24IrNO3PSSi2: C 51.57, H 3.82, N 0.78; found:
C 51.62, H 3.85, N 0.75.
[IrACHTUNGTRENNUNG(cod)ACHTUNGTRENNUNG
(L1c)]BArF: Yield: 120 mg (92%); 31P NMR (CDCl3): d=
1
À
107.6 ppm; H NMR (CDCl3): d=0.28 (s, 9H; CH3 Si), 0.50 (s, 9H;
À
CH3 Si), 1.06 (s, 3H; CH3), 1.07 (s, 3H; CH3), 1.61 (m, 4H; CH2, cod),
1.81 (dd, 1H, JHÀH =14.1, JHÀH =5.7 Hz; CH2), 2,07 (m, 2H; CH2 +CH2,
(L1 g)]BArF: Yield: 118 mg (93%); 31P NMR (CDCl3): d=
[IrACTHNGUTRENNU(G cod)ACHTGNUTRENNUNG
103.9 ppm (s); 1H NMR (CDCl3): d=0.89 (s, 3H; CH3), 1.11 (s, 3H;
CH3), 1.53 (m, 4H; CH2, cod), 1.72 (dd, 1H, 2JHÀH =14.4, 3JHÀH =6.0 Hz;
CH2), 1.88 (dd, 2JHÀH =14.4, 3JHÀH =5.6 Hz, 1H; CH2), 2.11 (m,1H; CH2,
cod), 2.14 (m, 1H; CH2, cod), 2.23 (m, 2H; CH2, cod), 2.48 (m, 1H,
2
3
cod), 2.16 (m, 1H; CH2, cod), 2.43 (m, 2H; CH2, cod), 2.53 (d, 1H,
2JHÀH =17.4 Hz; CH2 C=), 2.67 (d, 1H, 2JHÀH =17.5 Hz; CH2 C=), 4.07
(m, 1H; CH=, cod), 4.27 (brs, 1H; CH=, cod), 4.41 (brs, 1H; CH=, cod),
À
À
À
À
À
5.50 (brs, 1H; CH=, cod), 5.64 (s, 1H; CH O), 7.20–8.10 ppm (m, 23H;
2JHÀH =16 Hz; CH2 C=), 2.63 (d, 1H, 2JHÀH =16 Hz; CH2 C=), 3.81 (m,
1H; CH=, cod), 4.22 (brs, 2H; CH=, cod), 5.28 (brs, 1H; CH=, cod),
13
À
À
CH=); C NMR (CDCl3): d=0.34 (CH3 Si), 0.86 (CH3 Si), 24.6 (CH2,
À
cod), 27.4 (CH2, cod), 28.4 (CH3), 28.8 (CH3), 34.3 (CH2, cod), 35.2
5.63 (m, 1H; CH O), 6.90–8.30 ppm (m, 29H; CH=); 13C NMR (CDCl3):
d=24.1 (CH2, cod), 28.9 (CH2, cod), 29.7 (CH3), 30.6 (CH3), 32.4 (CH2,
À
(CH2 C=), 36.0 (CMe2), 37.7 (d, JCÀP =6.8 Hz; CH2, cod), 42.4 (d, JCÀP
=
À
9.1 Hz; CH2), 65.6 (d, JCÀP =3.7 Hz; CH O), 70.3 (CH=, cod), 70.5 (CH=
, cod), 93.4 (d, JCÀP =22.5 Hz; CH=, cod), 107.1 (d, JCÀP =10.8 Hz; CH=,
cod), 33.0 (CH2-C=), 35.6 (CMe2), 36.8 (CH2), 43.2 (d, JCÀP =8.4 Hz;
À
CH2), 61.8 (d, JCÀP =2.8 Hz; CH O), 68.3 (CH=, cod), 70.1 (CH=, cod),
cod), 117.7 (brs; CH=, BArF), 119–134 (aromatic carbon atoms), 135.0
96.2 (d, JCÀP =16.5 Hz; CH=, cod), 103.6 (d, JCÀP =10.2 Hz; CH=, cod),
117.6 (brs; CH=, BArF), 119–134 (aromatic carbon atoms), 135.0 (brs;
CH=BArF), 136–159 (aromatic carbon atoms), 161.8 (q, 1JCÀB =49.2 Hz;
C-B, BArF), 167.7 ppm (C=N); elemental analysis calcd (%) for
C75H52BF24IrNO4P: C 52.34, H 3.05, N 0.81; found: C 52.32, H 3.08, N
0.80.
1
(brs; CH=BArF), 136–153 (aromatic carbon atoms), 161.9 (q, JCÀB
=
49.2 Hz; C-B, BArF), 165.9 ppm (C=N); elemental analysis calcd (%) for
C73H64BF24IrNO3PSSi2: C 49.66, H 3.65, N 0.79; found: C 49.68, H 3.69,
N 0.78.
[IrACHTUNGTRENNUNG(cod)ACHTUNGTRENNUNG
(L1d)]BArF: Yield: 130 mg (94%); 31P NMR (CDCl3): d=
1
À
107.7 ppm; H NMR (CDCl3): d=0.21 (s, 9H; CH3 Si), 0.54 (s, 9H;
(L2a)]BArF: Yield: 132 mg (96%); 31P NMR (CDCl3): d=
[IrACTHNGUTRENNU(G cod)ACHTGNUTRENNUNG
À
CH3 Si), 1.04 (s, 3H; CH3), 1.18 (s, 3H; CH3), 1.49 (m, 2H; CH2, cod),
104.7 ppm (s); 1H NMR (CDCl3): d=0.86 (s, 3H; CH3), 0.99 (s, 3H;
CH3), 1.26 (s, 9H; CH3, tBu), 1.29 (s, 9H; CH3, tBu), 1.43 (s, 9H; CH3,
1.53 (m, 2H; CH2, cod), 1.78 (dd, 1H, 2JHÀH =14.2, 3JHÀH =5.6 Hz; CH2),
2.09 (brs, 2H; CH2 +CH2 cod), 2.14 (m, 1H; CH2, cod), 2.25 (m, 2H;
tBu), 1.52 (s, 9H; CH3, tBu), 1.64 (m, 4H; CH2, cod), 1.73 (dd, 1H,
2
3
CH2, cod), 2.56 (d, 1H, 2JHÀH =17.2 Hz; CH2 C=), 2.63 (d, 1H, JHÀH
=
2JHÀH =14.2, 3JHÀH =6 Hz; CH2), 2.02 (dd, 1H, 2JHÀH =14.2, JHÀH
=
À
À
17.2 Hz; CH2 C=), 3.81 (m, 1H; CH=, cod), 4.20 (brs, 2H; CH=, cod),
6.4 Hz; CH2), 2.13 (m, 2H; CH2, cod), 2.19 (m, 2H; CH2, cod), 2.29 (s,
5.41 (brs, 1H; CH=, cod), 5.49 (s, 1H; CH O), 7.20–8.10 ppm (m, 27H;
CH=); C NMR (CDCl3): d=0.3 (CH3 Si), 1.2 (CH3 Si), 25.4 (CH2,
cod), 29.7 (CH2, cod), 30.0 (CH3), 31.2 (CH3), 32.3 (CH2, cod), 33.6
3H; CH3 Ph), 2.43 (d, 1H, 2JHÀH =19.2 Hz; CH2 C=), 2.50 (d, 1H,
À
À
À
13
2JHÀH =19.2 Hz; CH2 C=), 3.85 (m, 1H; CH=, cod), 4.31 (brs, 2H; CH=,
À
À
À
À
cod), 5.11 (brs, 1H; CH=, cod), 5.45 (m, 1H; CH O), 7.10–8.20 ppm (m,
20H; CH=); C NMR (CDCl3): d=21.9 (CH3 Ph), 23.2 (CH2, cod), 25.6
13
À
À
(CH2 C=), 35.4 (CMe2), 36.2 (d, JCÀP =7.2 Hz; CH2, cod), 42.8 (d, JCÀP
=
Chem. Eur. J. 2010, 16, 4567 – 4576
ꢄ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
4573

M. Diꢂguez et al.
(CH3), 27.3 (CH2, cod), 27.9 (CH3), 30.2 (CH3, tBu), 30.8 (brs; CH3, tBu),
31.2 (CH3, tBu), 31.6 (C, tBu), 31.8 (C, tBu), 33.4 (C, tBu), 33.9 (CH2,
[IrACTHNGUTRENNU(G cod)ACHTGNUTRENNUNG
1
96.4 ppm (s); H NMR (CDCl3): d=1.41 (s, 9H; CH3, tBu), 1.47 (m, 2H;
À
À
cod), 34.5 (CH2, cod), 34.9 (CMe2), 36.7 (d, JCÀP =8.0 Hz; CH2 C=), 41.2
CH2, cod), 1.52 (m, 1H; CH2 CH), 1.63 (s, 9H; CH3, tBu), 1.81 (m, 1H;
À
À
(d, JCÀP =9.2 Hz; CH2), 68.4 (CH O), 69.8 (CH=, cod), 70.5 (CH=, cod),
CH2 CH), 1.86 (m, 1H; CH2), 1.96 (m, 1H; CH2), 2.08 (m, 4H; CH2,
À
89.7 (d, JCÀP =21.2 Hz; CH=, cod), 103.9 (d, JCÀP =9.2 Hz; CH=, cod),
117.7 (brs; CH=, BArF), 119–134 (aromatic carbon atoms), 135.0 (brs,
CH=BArF), 136–153 (aromatic carbon atoms), 161.9 (q, 1JCÀB =49.2 Hz;
C-B, BArF), 161.9 ppm (C=N), elemental analysis calcd (%) for
C84H82BF24IrNO4P: C 54.26, H 4.44, N 0.75; found: C 54.30, H 4.46, N
0.76.
cod), 2.24 (m, 2H; CH2, cod), 2.71 (m, 1H; CH2 C=), 2.96 (dd, 1H,
2JHÀH =17.7, JHÀH =4.8 Hz; CH2 C=), 3.46 (m, 1H; CH=, cod), 3.77 (brs,
3
À
À
À
2H; CH, CH=+cod), 3.82 (s, 3H; CH3 O), 3.87 (s, 3H; CH3 O), 4.48
À
À
(m, 1H; CH2 O), 4.59 (m, 1H; CH2 O), 4.76 (brs, 1H; CH=, cod), 5.19
(brs, 1H; CH=, cod), 6.50–8.50 ppm (m, 21H; CH=); 13C NMR (CDCl3):
À
d=23.4 (CH2 C=), 23.5 (CH2), 24.8 (CH2, cod), 29.1 (CH2, cod), 30.0
(CH2 CH), 30.6 (CH3, tBu), 31.3 (CH3, tBu), 33.8 (CH2, cod), 35.7 (C,
tBu), 36.0 (C, tBu), 37.0 (CH2, cod), 55.9 (CH3 O), 61.3 (CH=, cod), 69.9
(CH=, cod), 71.6 (brs; CH+CH2 O), 96.0 (d, JCÀP =23.0 Hz; CH=, cod),
105.1 (d, JCÀP =12.5 Hz; CH=, cod), 117.7 (brs; CH=, BArF), 119–134 (ar-
omatic carbon atoms), 135.0 (brs; CH=BArF), 136–158 (aromatic carbon
atoms), 161.9 (q, 1JCÀB =49.5 Hz; C-B, BArF), 169.6 ppm (s; C=N); ele-
mental analysis calcd (%) for C76H66BF24IrNO5PS: C 50.84, H 3.71, N
0.78; found: C 50.89, H 3.79, N 0.75.
[IrACHTUNGTRENNUNG(cod)ACHTUNGTRENNUNG
(L3a)]BArF: Yield: 130 mg (92%); 31P NMR (CDCl3): d=
À
108.8 ppm; 1H NMR (CDCl3): d=0.95 (s, 3H; CH3), 0.97 (s, 3H; CH3),
À
À
1.28 (s, 9H; CH3, tBu), 1.29 (s, 9H; CH3, tBu), 1.41 (s, 9H; CH3, tBu),
2
1.49 (s, 9H; CH3, tBu), 1.59 (m, 4H; CH2, cod), 1.72 (dd, 1H, JHÀH
=
14.0, JHÀH =6 Hz; CH2), 1.98 (dd, 1H, 2JHÀH =14.0, JHÀH =6.4 Hz; CH2),
3
3
2
2.16 (m, 2H; CH2, cod), 2.20 (m, 2H; CH2, cod), 2.40 (d, 1H, JHÀH
=
18.8 Hz; CH2 C=), 2.54 (d, 1H, 2JHÀH =16.8 Hz; CH2 C=), 3.81 (m, 1H;
CH=, cod), 4.33 (brs, 2H; CH=, cod), 5.23 (brs, 1H; CH=, cod), 5.51 (m,
À
À
1H; CH O), 7.10–8.20 ppm (m, 20H; CH=); 13C NMR (CDCl3): d=23.3
(L5c)]BArF: Yield: 124 mg (95%); 31P NMR (CDCl3): d=
[IrACTHNGUTRENNU(G cod)ACHTGNUTRENNUNG
À
(CH2, cod), 25.8 (CH3), 27.1 (CH2, cod), 27.8 (CH3), 30.0 (CH3, tBu), 30.3
(brs; CH3, tBu), 31.1 (CH3, tBu), 31.9 (brs; C, tBu), 33.4 (C, tBu), 33.7
(brs; C, tBu; CH2, cod), 34.3 (CH2, cod), 34.7 (CMe2), 36.5 (d, JCÀP
98.6 ppm (s); 1H NMR (CDCl3): d=0.06 (s, 9H; CH3-Si), 0.52 (s, 9H;
À
CH3-Si), 1.30 (m, 2H; CH2, cod), 1.44 (m, 1H; CH2 CH), 1.85 (m, 1H;
CH2 CH), 1.89 (m, 1H; CH2), 2.01 (m, 1H; CH2), 2.19 (m, 4H; CH2,
À
=
À
À
À
7.8 Hz; CH2 C=), 40.9 (d, JCÀP =8.5 Hz; CH2), 68.1 (brs; CH O), 69.8
(CH=, cod), 70.5 (CH=, cod), 89.4 (d, JCÀP =23.3 Hz; CH=, cod), 104.2
(d, JCÀP =10.8 Hz; CH=, cod), 117.7 (brs; CH=, BArF), 119–134 (aromatic
carbon atoms), 135.0 (brs; CH=BArF), 136–153 (aromatic carbon atoms),
cod), 2.39 (m, 2H; CH2, cod), 2.73 (m, 1H; CH2 C=), 2.99 (dd, 1H,
2JHÀH =17.4, JHÀH =5.5; CH2 C=), 3.47 (m, 1H; CH=, cod), 3.93 (m, 1H;
3
À
CH), 4.04 (brs, 1H; CH=, cod), 4.42 (brs, 1H; CH=, cod), 4.66 (m, 1H;
À
À
CH2 O), 4.76 (m, 1H; CH2 O), 5.16 (brs, 1H; CH=, cod), 7.20–
8.50 ppm (m, 23H; CH=); C NMR (CDCl3): d=À0.33 (CH3 Si), 0.74
1
13
À
161.9 (q, JCÀB =49.2 Hz; C-B, BArF), 162.7 ppm (C=N); elemental analy-
sis calcd (%) for C84H79BF27IrNO4P: C 52.73, H 4.16, N 0.73; found: C
À
À
(CH3 Si), 23.4 (CH2 C=), 23.5 (CH2), 24.7 (CH2, cod), 29.1 (CH2, cod),
À
52.70, H 4.18, N 0.71.
29.9 (CH2 CH), 33.3 (CH2, cod), 37.1 (CH2, cod), 61.7 (CH=, cod), 67.2
(CH=, cod), 70.8 (brs; CH+CH2 O), 97.2 (d, JCÀP =21.9 Hz; CH=, cod),
105.3 (d, JCÀP =12.5 Hz; CH=, cod), 117.7 (brs; CH=, BArF), 119–134 (ar-
omatic carbon atoms), 135.0 (brs; CH=BArF), 136–154 (aromatic carbon
atoms), 161.9 (q, 1JCÀB =49.5 Hz; C-B, BArF), 169.6 ppm (s; C=N); ele-
mental analysis calcd (%) for C72H62BF24IrNO3PSSi2: C 48.93, H 3.54, N
0.79; found: C 48.95, H 3.56, N 0.78.
[IrACHTUNGTRENNUNG(cod)ACHTUNGTRENNUNG
(L4a)]BArF: Yield: 127 mg (94%); 31P NMR (CDCl3): d=
À
115.8 ppm; 1H NMR (CDCl3): d=0.90 (s, 3H; CH3), 1.03 (s, 3H; CH3),
1.25 (s, 9H; CH3, tBu), 1.29 (s, 9H; CH3, tBu), 1.37 (s, 9H; CH3, tBu),
1.47 (s, 9H; CH3, tBu), 1.49 (m, 1H; CH2), 1.54 (s, 9H; CH3, tBu), 1.62
(m, 2H; CH2, cod), 1.82 (dd, 2JHÀH =14.4, 3JHÀH =6 Hz, 1H; CH2), 1.99
2
(m, 3H; CH2, cod+CH2), 2.20 (m, 4H; CH2, cod), 2.32 (d, 1H, JHÀH
=
17.2 Hz; CH2 C=), 2.43 (d, 1H, 2JHÀH =16.8 Hz; CH2 C=), 4.32 (brs,
1H; CH=, cod), 4.46 (m, 1H; CH=, cod), 4.76 (brs, 1H; CH=, cod), 5.32
[Ir
93.8 ppm (s); H NMR (CDCl3): d=0.01 (s, 9H; CH3 Si), 0.61 (s, 9H;
(L5d)]BArF: Yield: 133 mg (96%); 31P NMR (CDCl3): d=
ACHUTNGREN(NUG cod)ACHTUNGTRENNUGN
À
À
1
À
À
À
À
(brs, 1H; CH=, cod), 5.47 (m, 1H; CH O), 6.90–8.30 ppm (m, 16H;
CH3 Si), 1.15 (m, 2H; CH2, cod), 1.41 (m, 1H; CH2 CH), 1.73 (brs, 2H;
CH=); 13C NMR (CDCl3): d=21.7 (CH3), 23.1 (CH2, cod), 26.4 (CH2,
cod), 27.5 (CH3), 29.3 (CH3, tBu), 29.7 (brs; CH3, tBu), 30.3 (CH3, tBu),
30.7 (CH3, tBu), 31.6 (brs; C, tBu), 33.6 (C, tBu), 33.7 (brs; C, tBu), 34.3
CH2, cod), 1.85 (m, 1H; CH2 CH), 1.96 (m, 1H; CH2), 2.06 (m, 1H;
À
CH2), 2.13 (m, 2H; CH2, cod), 2.33 (m, 2H; CH2, cod), 2.73 (m, 1H;
CH2 C=), 2.97 (dd, 2JHÀH =18, 3JHÀH =4.8 Hz, 1H; CH2 C=), 3.15 (m,
1H; CH=, cod), 3.71 (brs, 1H; CH=, cod), 4.16 (m, 1H; CH), 4.23 (brs,
À
À
À
(CH2, cod), 34.8 (CMe2), 33.9 (s; CH2 C=), 34.2 (C, tBu), 34.7 (CH2),
34.9 (C, tBu), 36.5 (CH2, cod), 40.7 (d, JCÀP =9.3 Hz; CH2, cod), 68.4
(brs; CH O+CH=, cod), 70.4 (CH=, cod), 85.7 (d, JCÀP =27.9 Hz; CH=,
À
À
1H; CH=, cod), 4.62 (brs, 1H; CH2 O), 4.73 (m, 1H; CH2 O), 4.94 (brs,
1H; CH=, cod), 6.70–8.30 ppm (m, 27H; CH=); 13C NMR (CDCl3): d=
À
À
À
À
cod), 101.2 (d, JCÀP =8.6 Hz; CH=, cod), 117.7 (brs; CH=, BArF), 119–
134 (aromatic carbon atoms), 135.0 (brs; CH=BArF), 136–153 (aromatic
carbon atoms), 161.9 (q, 1JCÀB =49.2 Hz; C-B, BArF), 174.4 ppm (C=N);
elemental analysis calcd (%) for C81H84BF24IrNO4P: C 53.29, H 4.64, N
0.77; found: C 53.26, H 4.65, N 0.78.
(L5a)]BArF: Yield: 128 mg (94%); 31P NMR (CDCl3): d=
[IrACHTUNGTRENNUNG(cod)ACHTUNGTRENNUNG
100.2 ppm (s); H NMR (CDCl3): d=1.28 (s, 9H; CH3, tBu), 1.32 (s, 9H;
CH3, tBu), 1.41 (s, 9H; CH3, tBu), 1.47 (m, 2H; CH2, cod), 1.55 (m, 1H;
À0.0 (CH3 Si), 0.4 (CH3 Si), 23.7 (CH2 C=), 24.4 (CH2), 26.1 (CH2,
À
cod), 28.4 (CH2, cod), 31.2 (CH2 CH), 34.3 (CH2, cod), 36.6 (CH2, cod),
À
68.1 (CH=, cod), 70.7 (CH+CH=, cod), 71.9 (CH2 O), 95.3 (d, JCÀP
=
22.7 Hz; CH=, cod), 104.2 (brs; CH=, cod), 117.7 ppm (brs; CH=, BArF),
119–134 (aromatic carbon atoms), 135.0 (brs; CH=BArF), 136–154 (aro-
matic carbon atoms), 161.9 (q, 1JCÀB =49.5 Hz; C-B, BArF), 169.3 ppm (s,
C=N); elemental analysis calcd (%) for C80H66BF24IrNO3PSSi2: C 51.45,
H 3.56, N 0.75; found: C 51.47, H 3.59, N 0.74.
1
(L5e)]BArF: Yield: 130 mg (94%); 31P NMR (CDCl3): d=
ACHUTGTNRENNUG(cod)ACHTUTGNRENNUGN
À
À
CH2 CH), 1.60 (s, 9H; CH3, tBu), 1.76 (m, 1H; CH2 CH), 1.92 (m, 1H;
[Ir
103.8 ppm; H NMR (CDCl3): d=0.14 (s, 9H; CH3 Si), 0.60 (s, 9H;
1
À
CH2), 1.99 (m, 1H; CH2), 2.09 (m, 4H; CH2, cod), 2.22 (m, 2H; CH2,
cod), 2.69 (m, 1H; CH2 C=), 2.99 (dd, 1H, 2JHÀH =17.7, 3JHÀH =4.8 Hz;
CH3 Si), 1.17 (m, 2H; CH2, cod), 1.44 (m, 1H; CH2 CH), 1.86 (m, 1H;
CH2 CH), 1.90 (m, 1H; CH2), 1.99 (m, 1H; CH2), 2.10 (m, 4H; CH2,
cod), 2.32 (m, 2H; CH2, cod), 2.74 (m, 1H; CH2 C=), 3.00 (dd, 1H,
2JHÀH =23, 3JHÀH =5.4 Hz; CH2 C=), 3.49 (m, 1H; CH=, cod), 3.85 (m,
1H; CH), 3.97 (brs, 1H; CH=, cod), 4.23 (brs, 1H; CH=, cod), 4.72 (brs,
2H; CH2 O), 5.17 (brs, 1H; CH=, cod), 6.60–8.30 ppm (m, 27H; CH=);
À
À
À
À
À
CH2 C=), 3.41 (m, 1H; CH=, cod), 3.79 (brs, 2H; CH, CH=+cod), 4.51
(m, 1H; CH2 O), 4.56 (m, 1H; CH2 O), 4.78 (brs, 1H; CH=, cod), 5.19
(brs, 1H; CH=, cod), 6.50–8.50 ppm (m, 21H; CH=); 13C NMR (CDCl3):
d=23.1 (CH2 C=), 23.9 (CH2), 24.7 (CH2, cod), 29.2 (CH2, cod), 30.2
(CH2 CH), 30.4 (CH3, tBu), 31.1 (CH3, tBu), 33.9 (CH2, cod), 35.5 (C,
tBu), 36.1 (C, tBu), 37.4 (CH2, cod), 61.5 (CH=, cod), 70.2 (CH=, cod),
71.3 (brs; CH+CH2 O), 96.1 (d, JCÀP =22.0 Hz; CH=, cod), 104.7 (d,
À
À
À
À
À
À
À
13
À
À
C NMR (CDCl3): d=À0.4 (CH3 Si), 0.9 (CH3 Si), 23.4 (brs; CH2 +
À
À
CH2-C=), 24.7 (CH2, cod), 29.2 (CH2, cod), 31.2 (CH2 CH), 33.3 (CH2,
J
CÀP =11.2 Hz; CH=, cod), 117.7 (brs; CH=, BArF), 119–134 ppm (aro-
cod), 37.1 (CH2, cod), 61.6 (brs; CH=cod+CH), 67.2 (CH=, cod), 71.1
À
matic carbon atoms), 135.0 (brs; CH=BArF), 136–158 (aromatic carbon
atoms), 161.9 (q, 1JCÀB =49.5 Hz; C-B, BArF), 168.6 ppm (s, C=N), ele-
mental analysis calcd (%) for C82H78BF24IrNO3PS: C 53.31, H 4.26, N
0.76; found: C 53.28, H 4.28, N 0.75.
(CH2 O), 97.6 (d, JCÀP =21.6 Hz; CH=, cod), 105.5 (brs; CH=, cod),
117.7 (brs; CH=, BArF), 119–134 (aromatic carbon atoms), 135.0 (brs;
CH=BArF), 136–154 (aromatic carbon atoms), 161.9 (q, 1JCÀB =49.2 Hz;
C-B, BArF), 169.6 ppm (s; C=N); elemental analysis calcd (%) for
4574
www.chemeurj.org
ꢄ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2010, 16, 4567 – 4576

Asymmetric Ir-Catalyzed Hydrogenation of Alkenes
FULL PAPER
C80H66BF24IrNO3PSSi2: C 51.45, H 3.56, N 0.75; found: C 51.46, H 3.58,
N 0.75.
cobsen, A. Pfaltz, H. Yamamoto), Springer, Berlin, 1999; e) R.
Noyori, Asymmetric Catalysis in Organic Synthesis, Wiley, New
York, 1994.
[IrACHTUNGTRENNUNG(cod)ACHTUNGTRENNUNG
(L6a)]BArF: Yield: 129 mg (93%); 31P NMR (CDCl3): d=
1
[2] For recent reviews, see: a) K. Kꢆllstrçm, I. Munslow, P. G. Ander-
sson, Chem. Eur. J. 2006, 12, 3194; b) S. J. Roseblade, A. Pfaltz, Acc.
Chem. Res. 2007, 40, 1402; c) T. L. Church, P. G. Andersson, Coord.
Chem. Rev. 2008, 252, 513; d) X. Cui, K. Burgess, Chem. Rev. 2005,
105, 3272.
[3] See, for instance: a) W. Tang, W. Wang, X. Zhang, Angew. Chem.
2003, 115, 973; Angew. Chem. Int. Ed. 2003, 42, 943; b) D.-R. Hou,
J. Reibenspies, T. J. Colacot, K. Burgess, Chem. Eur. J. 2001, 7, 5391;
c) P. G. Cozzi, F. Menges, S. Kaiser, Synlett 2003, 0833; d) A. Light-
foot, P. Schnider, A. Pfaltz, Angew. Chem. 1998, 110, 3047; Angew.
Chem. Int. Ed. 1998, 37, 2897; e) F. Menges, M. Neuburger, A.
Pfaltz, Org. Lett. 2002, 4, 4713; f) D. Liu, W. Tang, X. Zhang, Org.
Lett. 2004, 6, 513.
[4] See, for instance: a) M. C. Perry, X. Cui, M. T. Powell, D.-R. Hou,
J. H. Reibenspies, K. Burgess, J. Am. Chem. Soc. 2003, 125, 5391;
b) J. Blankenstein, A. Pfaltz, Angew. Chem. 2001, 113, 4577; Angew.
Chem. Int. Ed. 2001, 40, 4445; c) S. Kaiser, P. S. Smidt, A. Pfaltz,
Angew. Chem. 2006, 118, 5318; Angew. Chem. Int. Ed. 2006, 45,
5194; d) K. Kꢆllstrçm, C. Hedberg, P. Brandt, P. Bayer, P. G. Ander-
sson, J. Am. Chem. Soc. 2004, 126, 14308; e) M. Engman, J. S.
Diesen, A. Paptchikhine, P. G. Andersson, J. Am. Chem. Soc. 2007,
129, 4536; f) A. Trifonova, J. S. Diesen, P. G. Andersson, Chem. Eur.
J. 2006, 12, 2318; g) F. Menges, A. Pfaltz, Adv. Synth. Catal. 2002,
344, 4044; h) W. J. Drury III, N. Zimmermann, M. Keenan, M. Hay-
ashi, S. Kaiser, R. Goddard, A. Pfaltz, Angew. Chem. 2004, 116, 72;
Angew. Chem. Int. Ed. 2004, 43, 70; i) C. Hedberg, K. Kꢆllstrçm, P.
Brandt, L. K. Hansen, P. G. Andersson, J. Am. Chem. Soc. 2006,
128, 2995.
92.1 ppm (s); H NMR (CDCl3): d=0.94 (s, 3H; CH3), 1.26 (s, 3H; CH3),
1.34 (s, 9H; CH3, tBu), 1.35 (s, 9H; CH3, tBu), 1.37 (s, 9H; CH3, tBu),
À
1.46 (m, 2H; CH2, cod), 1.52 (m, 1H; CH2 CH), 1.63 (s, 9H; CH3, tBu),
À
1.73 (m, 1H; CH2 CH), 1.77 (m, 1H; CH2), 1.94 (m, 1H; CH2), 2.09 (m,
À
4H; CH2, cod), 2.27 (m, 2H; CH2, cod), 2.79 (m, 2H; CH2 C=), 3.26 (m,
1H; CH=, cod), 3.82 (brs, 1H; CH=, cod), 4.67 (brs, 2H; CH+CH=,
cod), 4.89 (brs, 1H; CH=, cod), 6.50–8.50 ppm (m, 21H; CH=);
13
À
C NMR (CDCl3): d=19.8 (CH3), 23.1 (CH3), 24.6 (CH2 C=), 25.4
À
(CH2), 26.7 (CH2, cod), 28.9 (CH2, cod), 29.9 (CH2 CH), 31.1 (CH3, tBu),
31.2 (CH3, tBu), 31.6 (CH3, tBu), 31.8 (CH3, tBu), 34.2 (brs; C, tBu; CH2,
cod), 34.9 (C, tBu), 35.7 (C, tBu), 36.1 (C, tBu), 36.8 (CH2, cod), 53.7
(CH), 60.9 (CH=, cod), 70.1 (CH=, cod), 93.4 (d, JCÀP =24.2 Hz; CH=,
cod), 94.1 (CMe2), 103.5 (m; CH=, cod), 117.7 (brs; CH=, BArF), 119–
134 (aromatic carbon atoms), 135.0 (brs; CH=BArF), 136–158 (aromatic
1
carbon atoms), 161.9 (q, JCÀB =49.5 Hz; C-B, BArF), 170.4 ppm (s, C=N);
elemental analysis calcd (%) for C84H80BF24IrNO3PS: C 53.79, H 4.41, N
0.75; found: C 53.78, H 4.43, N 0.74.
[IrACHTUNGTRENNUNG(cod)ACHTUNGTRENNUNG
(L7a)]BArF: Yield: 133 mg (96%); 31P NMR (CDCl3): d=
1
92.5 ppm (s); H NMR (CDCl3): d=0.93 (s, 3H; CH3), 1.26 (s, 3H; CH3),
1.35 (s, 9H; CH3, tBu), 1.38 (s, 18H; CH3, tBu), 1.46 (m, 2H; CH2, cod),
À
À
1.52 (m, 1H; CH2 CH), 1.63 (s, 9H; CH3, tBu), 1.73 (m, 1H; CH2 CH),
1.76 (m, 1H; CH2), 1.94 (m, 1H; CH2), 2.09 (m, 4H; CH2, cod), 2.27 (m,
À
2H; CH2, cod), 2.79 (m, 2H; CH2 C=), 3.26 (m, 1H; CH=, cod), 3.82
(brs, 1H; CH=, cod), 4.67 (brs, 2H; CH+CH=, cod), 4.89 (brs, 1H;
CH=, cod), 6.50–8.50 ppm (m, 21H; CH=); 13C NMR (CDCl3): d=19.9
À
(CH3), 23.1 (CH3), 24.6 (CH2 C=), 25.4 (CH2), 26.7 (CH2, cod), 28.9
À
(CH2, cod), 30.1 (CH2 CH), 31.1 (CH3, tBu), 31.2 (CH3, tBu), 31.6 (CH3,
tBu), 31.7 (CH3, tBu), 34.2 (brs; C, tBu; CH2, cod), 34.9 (C, tBu), 35.7 (C,
tBu), 36.1 (C, tBu), 36.9 (CH2, cod), 53.7 (CH), 60.9 (CH=, cod), 70.1
(CH=, cod), 93.4 (d, JCÀP =24.2 Hz; CH=, cod), 94.2 (CMe2), 103.5 (m;
CH=, cod), 117.7 (brs; CH=, BArF), 119–134 (aromatic carbon atoms),
135.0 (brs; CH=BArF), 136–158 (aromatic carbon atoms), 161.9 (q,
1JCÀB =49.5 Hz; C-B, BArF), 170.6 ppm (s, C=N); elemental analysis calcd
(%) for C84H80BF24IrNO3PS: C 53.79, H 4.41, N 0.75; found: C 53.71, H
4.43, N 0.76.
[5] a) M. Diꢂguez, J. Mazuela, O. Pꢁmies, J. J. Verendel, P. G. Ander-
sson, J. Am. Chem. Soc. 2008, 130, 7208; b) M. Diꢂguez, J. Mazuela,
O. Pꢁmies, J. J. Verendel, P. G. Andersson, Chem. Commun. 2008,
3888; c) J. Mazuela, J. J. Verendel, M. Coll, B. Schꢆffner, A. Bçrner,
P. G. Andersson, O. Pꢁmies, M. Diꢂguez, J. Am. Chem. Soc. 2009,
131, 12344.
[6] J. Mazuela, A. Paptchikhine, P. Tolstoy, O. Pꢁmies, M. Diꢂguez, P. G.
Andersson, Chem. Eur. J. 2010, 16, 620.
[7] The only success in hydrogenating highly unfunctionalized Z-trisub-
stituted olefins by using ligands 2 and 3 can be found with the less-
Typical procedure for the hydrogenation of olefins: The alkene (1 mmol)
and Ir complex (0.2 mol%) were dissolved in CH2Cl2 (2 mL) in a high-
pressure autoclave. The autoclave was purged four times with hydrogen.
Then, it was pressurized at the desired pressure. After the desired reac-
tion time, the autoclave was depressurized and the solvent evaporated
off. The residue was dissolved in Et2O (1.5 mL) and filtered through a
short Celite plug. The enantiomeric excess was determined by chiral GC
or chiral HPLC and conversions were determined by 1H NMR spectros-
copy. The enantiomeric excesses of the hydrogenated products were de-
termined by using the conditions previously described.[4d,5c]
demanding
6-methoxy-1-methylene-1,2,3,4-tetrahydronaphthalene
(S6), see references [4d,4i].
[8] P. Cheruku, S. Gohil, P. G. Andersson, Org. Lett. 2007, 9, 1659.
[9] Unpublished results (i.e., for substrate S13, ee values up to 41%).
[10] J. A. Joule, K. Mills, Heterocyclic Chemistry, 4th ed., Blackwell Sci-
ence, Oxford, 2000.
[11] For some representative examples, see: a) “Chiral Diphosphinites,
Diphosphonites, Diphosphites and Mixed PO-Ligands”: C. Claver,
O. Pꢁmies, M. Diꢂguez in Phosphorous Ligands in Asymmetric Cat-
alysis, Vol. 2 (Ed.: A. Bçrner), Wiley-VCH, Weinheim, 2008, Chap-
ter 3; b) M. Diꢂguez, O. Pꢁmies, Acc. Chem. Res. 2010, 43, 312;
c) M. Diꢂguez, A. Ruiz, C. Claver, J. Org. Chem. 2002, 67, 3796;
d) M. T. Reetz, G. Mehler, Angew. Chem. 2000, 112, 4047; Angew.
Chem. Int. Ed. 2000, 39, 3889; e) M. Yan, Z. Y. Zhou, A. S. C. Chan,
Chem. Commun. 2000, 115; f) M. Diꢂguez, A. Ruiz, C. Claver, Tet-
rahedron: Asymmetry 2001, 12, 2895; g) O. Pꢁmies, M. Diꢂguez, C.
Claver, J. Am. Chem. Soc. 2005, 127, 3646; h) M. Diꢂguez, O.
Pꢁmies, C. Claver, Chem. Commun. 2005, 1221; i) Y. Mata, O.
Pꢁmies, M. Diꢂguez, Chem. Eur. J. 2007, 13, 3296.
Acknowledgements
We thank the Spanish Government (Consolider-Ingenio CSD2006-0003,
CTQ2007-62288/BQU, 2008PGIR/07 to O.P. and 2008PGIR/08 to M.D.),
the Catalan Government (2009SGR116), COST D40, Vetenskapsrꢅdet
(VR), and Astra Zeneca for support. Knut and Alice Wallenbergs Stif-
telse is also gratefully acknowledged for generous financial support. We
are grateful to Johan J. Verendel for providing us the terminal substrates.
[12] The rapid ring inversions (atropoisomerization) in the biaryl phos-
phite moiety is usually stopped upon coordination to the metal
center. See, for example: a) G. J. H. Buisman, van der Veen, L. A.;
A. Klootwijk, W. G. J. de Lange, P. C. J. Kamer, P. W. N. M. van
Leeuwen, D. Vogt, Organometallics 1997, 16, 2929; A. Klootwijk,
W. G. J. de Lange, P. C. J. Kamer, P. W. N. M. van Leeuwen, D. Vogt,
Organometallics 1997, 16, 2929; b) M. Diꢂguez, O. Pꢁmies, A. Ruiz,
C. Claver, S. Castillꢇn, Chem. Eur. J. 2001, 7, 3086; c) O. Pꢁmies, M.
Diꢂguez, G. Net, A. Ruiz, C. Claver, J. Org. Chem. 2001, 66, 8364;
[1] See for instance: a) Catalytic Asymmetric Synthesis, 2nd ed. (Ed.: I.
Ojima), Wiley-VCH, Weinheim, 2000; b) Applied Homogeneous
Catalysis with Organometallic Compounds, 2nd ed. (Eds.: B. Cornils,
W. A. Herrmann), Wiley-VCH, Weinheim, 2002; c) Asymmetric Cat-
alysis on Industrial Scale : Challenges, Approaches and Solutions
(Eds.: H. U. Blaser, E. Schmidt), Wiley-VCH, Weinheim, 2004;
d) Comprehensice Asymmetric Catalysis, Vols. 1–3 (Eds.: E. N. Ja-
Chem. Eur. J. 2010, 16, 4567 – 4576
ꢄ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
4575

M. Diꢂguez et al.
d) M. Diꢂguez, O. Pꢁmies, Chem. Eur. J. 2008, 14, 3653; e) O.
Pꢁmies, M. Diꢂguez, Chem. Eur. J. 2008, 14, 944.
[15] See, for instance: a) A. Abate, E. Brenna, C. Fuganti, G. G. Gatti, T.
Givenzana, L. Malpezzi, S. Serra, J. Org. Chem. 2005, 70, 1281;
b) K. Drescher, A. Haupt, L. Unger, S. C. Rutner, W. Braje, R.
Grandel, C. Henry, G. Backfisch, A. Beyerbach, W. Bisch, WO
Patent 2006/040182A1.
[16] See, for instance: a) I. Fleming, A. Barbero, D. Walter, Chem. Rev.
1997, 97, 2063; b) G. R. Jones, Y. Landais, Tetrahedron 1996, 52,
7599; c) W. Bains, R. Tacke, Curr. Opin. Drug Discovery Dev. 2003,
6, 526.
[13] For successful applications of Ir catalysts, see: a) S. McIntyre, E.
Hçrmann, F. Menges, S. P. Smidt, A. Pfaltz, Adv. Synth. Catal. 2005,
347, 282; b) reference [4b]; c) reference [4d]; d) reference [5c].
[14] For successful applications of Sm, Ru, and Rh complexes, see:
a) V. P. Conticello, L. Brard, M. A. Giardello, Y. Tsuji, M. Sabat,
C. L. Stern, T. J. Marks, J. Am. Chem. Soc. 1992, 114, 2761; b) M. A.
Giardello, V. P. Conticello, L. Brard, M. R. Gagnꢂ, T. J. Marks, J.
Am. Chem. Soc. 1994, 116, 10241; c) G. S. Forman, T. Ohkuma, W. P.
Hems, R. Noyori, Tetrahedron Lett. 2000, 41, 9471; d) T. T. Co, T. J.
Kim, Chem. Commun. 2006, 3537.
Received: December 7, 2009
Published online: March 12, 2010
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Chem. Eur. J. 2010, 16, 4567 – 4576