Synthesis, complexation behavior and application of a new diphosphite ligand in rhodium-catalyzed hydroformylation

Article abstract of DOI:10.1016/j.jorganchem.2011.05.004

Oxidative coupling of 3-(3-tert-butyl-4-hydroxyphenyl)propionic acid methyl ester (2) gave dimethyl 3,3′-(5,5′-di-tert-butyl-6,6′- dihydroxybiphenyl-3,3′-diyl)-dipropionate (1c), which upon phosphorylation/transesterification with a phosphochloridite derived from (R)-binaphthol, formed the new unsymmetrical binaphthol-bridged diphosphite 4. A rhodium catalyst based on 4 as ligand gave predominantly iso-selectivity in the hydroformylation of selected styrenes but opposite regioselectivity with 2,6-disubstituted derivatives. New chelate metal complexes (acac)RhL, PdCl ₂L and PtCl₂L have been synthesized by reacting 4 with (acac)Rh(CO)₂, PdCl₂(MeCN)₂ and PtCl ₂(COD), respectively. The structure of obtained compounds is determined based on ¹H, ¹³C, ³¹P and ¹⁹⁵Pt NMR spectroscopy and mass spectrometry data.

Full text of DOI:10.1016/j.jorganchem.2011.05.004

Journal of Organometallic Chemistry 696 (2011) 3050e3057
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, complexation behavior and application of a new diphosphite ligand
in rhodium-catalyzed hydroformylation
,
Igor S. Mikhel a, Natalia V. Dubrovina a, Ivan A. Shuklov a, Wolfgang Baumann a, Detlef Selent a
**
,
,c,
Haijun Jiao a, Andrea Christiansen b, Robert Franke b, Armin Börner a
*
a Leibniz-Institut für Katalyse an der Universität Rostock e.V., Albert-Einstein-St. 29a, 18059 Rostock, Germany
b Evonik Oxeno GmbH, Paul-Baumann-Str. 1, 45 772 Marl, Germany
c Institut für Chemie der Universität Rostock, Albert-Einstein-St. 3a, 18059 Rostock, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Oxidative coupling of 3-(3-tert-butyl-4-hydroxyphenyl)propionic acid methyl ester (2) gave dimethyl
3,30-(5,50-di-tert-butyl-6,60-dihydroxybiphenyl-3,30-diyl)-dipropionate (1c), which upon phosphoryla-
Received 16 March 2011
Received in revised form
29 April 2011
tion/transesterification with
a phosphochloridite derived from (R)-binaphthol, formed the new
unsymmetrical binaphthol-bridged diphosphite 4. A rhodium catalyst based on 4 as ligand gave
predominantly iso-selectivity in the hydroformylation of selected styrenes but opposite regioselectivity
with 2,6-disubstituted derivatives. New chelate metal complexes (acac)RhL, PdCl2L and PtCl2L have been
synthesized by reacting 4 with (acac)Rh(CO)2, PdCl2(MeCN)2 and PtCl2(COD), respectively. The structure
of obtained compounds is determined based on 1H, 13C, 31P and 195Pt NMR spectroscopy and mass
spectrometry data.
Accepted 5 May 2011
Keywords:
Homogeneous catalysis
Diphosphite
Rhodium
Ó 2011 Elsevier B.V. All rights reserved.
Palladium
Platinum
Hydroformylation
1. Introduction
Unfortunately, the other substituents on the phenols are not suit-
able for further chemical transformations desired in catalysis, such
Hydroformylation of olefins is a fundamental transformation in
organic synthesis and one of the most powerful tools for the
formation of carbonecarbon bonds [1]. Large amounts of
commodity oxo products are produced per year by the use of
homogeneous rhodium catalysts. Some of these catalysts show
high chemo- and regioselectivity towards the formation of
commercially preferred linear aldehydes and are very active under
less severe conditions, compared to cobalt catalysis.
as anchoring of the ligand to a solid surface or incorporation of
more polar groups.
Particularly useful for fine tuning of Rh-catalysts are trivalent P-
ligands, such as phosphites. A frequently used motif for the
construction of industrially relevant diphosphites is the biphenol
subunit [2,3]. The required biphenols e.g. 1a,b serving as starting
material are commercially available. They can be purchased in large
quantities, because they are primarily employed for the ton-scale
production of phosphate based flame retardants [4].
As a part of our ongoing search for industrially relevant catalytic
systems [2f,i,5], we looked for a biphenol which is more susceptible
for chemical alteration. Compound 1c, bearing two methyl propi-
onate groups in para-position to the hydroxyl group revealed
therefore an interesting candidate. This biphenol should be avail-
able by arylearyl coupling of the relevant mono-phenol. The latter
is commercially available in a large scale [6].
* Corresponding author. Leibniz-Institut für Katalyse an der Universität Rostock
e.V., Albert-Einstein-St. 29a, 18059 Rostock, Germany. Tel.: þ49 381 1281 202;
fax: þ49 381 1281 51202.
Herein we will report our results on the synthesis of 1c.
Subsequently trials on the transformation of this diol in a chiral
diphosphite ligand will be reported. Finally some complexation
studies and results in the hydroformylation of styrenes as model
substrates will be likewise detailed.
** Corresponding author.
E-mail addresses: detlef.selent@catalysis.de (D. Selent), armin.boerner@
catalysis.de (A. Börner).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.05.004

I.S. Mikhel et al. / Journal of Organometallic Chemistry 696 (2011) 3050e3057
3051
Scheme 1. Methods for arylearyl couplings.
2. Results and discussion
2.1. Phenol coupling
For the coupling of phenols several methods have been sug-
gested in the literature. Thus, Waldvogel and co-workers used the
anodic oxidation [7] for the selective synthesis of 2,20-biphenols
under solvent-free conditions and in fluorinated alcohols [8]. Also
enzyme catalyzed oxidations of related phenols by air gave desired
coupling products [9]. 2,20-Biphenols could be synthesized as well
as by Ullmann-type coupling of corresponding arylbromides cata-
lyzed by Cu or Ni [10].
We investigated two routes (Scheme 1) for the synthesis of
biphenol 1c from 3-(3-tert-butyl-4-hydroxyphenyl)propionic acid
methyl ester (2) as a starting material, an Ullmann-type coupling
and the direct oxidative CeC bond coupling.
As starting material for the Cu-catalyzed coupling bromo
compound, 3 was synthesized via ortho-bromination of 2 in 87%
yield. Unfortunately, the subsequent Ullmann-coupling of 3 affor-
ded the desired product 1c in only 11% yield. Mainly, dehalogena-
tion of 3 was observed as a side reaction.
Alternatively the direct oxidative ortho-phenol coupling was
investigated in detail. In the literature several heterogeneous
oxidants such as (tert-BuO)2 [11], FeCl3/H2O/O2 [12], H2O2/Cu-
complexes [13], Fe-salts [14], FeSO4/Na2S2O8 [15] or K2S2O8 [16] are
recommended. As oxidants for the homogeneous phenol coupling
Fe- or Cu-salts/O2, m-chloroperbenzoic acid/FeCl3 [17], K3[Fe(CN)6]
[18] and the strong oxidant K2Cr2O7/H2SO4 [19] are reported.
Some typical results of the homogeneously oxidative ortho-
phenol coupling are listed in Table 1. K3[Fe(CN)6], H2O2, FeSO4/
H2O2, CuCl2/O2, FeSO4/Na2S2O8 or K2S2O8 did not work. Also the use
of sodium phenolates did not enhance the poor yields by applica-
tion of H2O2 and K3[Fe(CN)6].
Scheme 2. Synthesis of the diphosphite.
Unfortunately, prolongation of the reaction time or an increase of
the temperature did not enhance the yield, but led to over-
oxidation.
2.2. Synthesis of the diphosphite
Phosphorylation of diol 1c was accomplished with the phos-
phochloridite of (R)-binaphthol in THF in the presence of triethyl-
amine (Scheme 2). Surprisingly, not the intended symmetrical
diphosphite 40 was obtained, but the unsymmetrical structure 4.
The structure of 4 was evidenced by NMR spectroscopy. Thus,
the 31P NMR of the reaction solution in THF was dominated by two
doublets centered at dP 145.1 and 137.4 with a JPP coupling of
w3.7 Hz covering about 75% of the overall integral intensity
together with a singlet at dP 137.1 (15%) and some other resonances
in the range of dP 14e0 corresponding to products of degradation.
At first it was attempted to obtain pure ligand by column chro-
matography of the corresponding borane adduct [4(BH3)2] (5),
which was expected to be more stable towards air in comparison
with 4, and should be deprotected easily by treatment with amine
(Scheme 3).
This concept worked, however, 5 was found to be in equilibrium
in CD2Cl2 solution with a small amount of 4 and additionally, two
Highest yield was achieved by employment of a modified
procedure of Wang and co-workers [17] using benzoyl peroxide as
oxidants (Run 2) or m-chloroperbenzoic acid (¼MCPBA)/FeCl3 (Run
3), which hitherto was used only for the para-coupling of phenols.
MCPBA alone did not work. Compound 1c was obtained in the best
case with 32% isolated yield. The product was purified by column
chromatography,
followed
by
bulb-to-bulb
distillation.
Table 1
Oxidative ortho-phenol coupling of 2.
Run
Reagent
Method
GC yield (%)
Isolated yield (%)
1
2
3
K2Cr2O7/H2SO4
Benzoyl peroxide
MCPBA/FeCl3
A
B
C
30
34
36
22
28
32
Scheme 3. Purification of the diphosphite.

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I.S. Mikhel et al. / Journal of Organometallic Chemistry 696 (2011) 3050e3057
monoborane adducts which sum up to a 20% fraction. Monoborane
adducts have also been detected by mass spectrometry (see
experimental part for all details). This mobile solution equilibrium
complicated flash-chromatography and reduced the overall yield
down to 28%.
Finally, crude 4 was directly purified chromatographically with
71% yield. The 31P spectrum of the pure compound in CD2Cl2
exhibits two doublets with parameters dP 144.7 and 137.2 and
JPP ¼ 3.7 Hz 31P-31P COSY NMR spectroscopy proved the intra-
molecular “through space” coupling constant [20] between the
different phosphorus atoms. The low field chemical shift could be
easily assigned to the binaphthol phosphorus center [5g]. Thus it
can be unambiguously concluded that diol 1c reacts under our
conditions with binaphtholchlorophosphite under ring intercon-
version to give the unsymmetrical diphosphite 4. Such processes
are rarely described in ligand synthesis, only Beller and co-workers
reported recently on a related transformation [21].
It is interesting to note, that there is only one set of resonances in
the 31P NMR spectrum of 4, consistent with either formation of
a single diastereoisomer or two diastereoisomers undergoing rapid
interconversion. To clarify this question we measured 31P and 1H
NMR spectra of 4 in d8-toluene in the range of ꢀ86 to þ100 ꢁC. Upon
cooling to ꢀ67 ꢁC, the 31P NMR spectrum of 4 measured in toluene-
D8 showed four singlets of almost equal intensity resonating at dP
147.6, 146.0, 137.7 and 137.4 which is in accordance with a 1:1
mixture of (R,R,R) and (R,R,S) rotamers of 4, differing in the config-
uration of the biphenol moiety. It should be also pointed out that the
JPP coupling is much smaller in d8-toluene compared to CD2Cl2 even
at room temperature, but could be registered by 31Pe31P COSY NMR.
At low temperature, PeP coupling is not longer observed.
2.3. Complexation studies
As a first precursor to study the coordination behavior of 4
(acac)Rh(CO)2 was selected. 31P NMR spectroscopy proved that the
reaction in d8-toluene (or in CD2Cl2) at room temperature sponta-
neously affords the complex 60 with mono-coordinated ligand 4 as
the main product, characterized by two broad resonances at dP
145.8 (d, 1JPRh ¼ 289.7 Hz) and 139.1 (s, br) (Scheme 4). The broad
singlet observed clearly corresponds to the uncoordinated biphenol
phosphorus atom because the chemical shift of the non-
coordinating phosphorus has changed only slightly compared to
the free ligand. Furthermore, 17% of overall signal intensity can be
assigned to the dinuclear complex (acac)(CO)RhPXPRh(acac)(CO)
which shows absorptions at dP 145.6 (d, 1JPRh ¼ 293.3 Hz) and 132.8
(d, 1JPRh ¼ 295.3 Hz), revealing the interesting bridging ability of the
diphosphite.
Scheme 4. Synthesis of Rh-complexes.
due to the influence of the bulky ligand with two unequivalent
phosphorus atoms, which causes a distortion of the geometry of the
metal complex.
After a few minutes the final complex 6 evolves in the reaction
solution. Storage of the reaction mixture at r.t. for several days, or
for 10 h in toluene at 80 ꢁC, led to the substitution of the second CO.
Finally, we have found an alternative method. The slow addition of
ligand 4 under strongly diluted conditions in CH2Cl2 to the rhodium
dicarbonyl complex followed by the evaporation of the solution to
dryness under reduced pressure allowed the desired complex 6 to
be prepared directly in nearly quantitative yield and high purity.
The 31P NMR spectrum of 6 after redissolution in CD2Cl2 shows two
doublets of doublets placed at dP 139.3 (1JPRh ¼ 307.3 Hz) and 129.6
A cis-complexation of ligand 4 was achieved also with other d8
metal fragments. In contrast to the carbonyl rhodium complex,
Pd(MeCN)2Cl2 and Pt(COD)Cl2 reacted smoothly already at room
temperature with full substitution of acetonitrile or cyclooctadiene,
respectively, and the formation of Pd(4)Cl2 (7) and Pt(4)Cl2 (8)
(Scheme 5).
For 7, the 31P NMR spectrum in CD2Cl2 solutions contains two
doublets at dP 115.2 (2JPP ¼ 65.9 Hz) and 81.8 (2JPP ¼ 66.5 Hz) and
two doublets of pseudotriplets for 8 at dP 88.8 (1JPPt ¼ 5989.1 Hz,
2
(1JPRh ¼ 304.8 Hz) with a large JPP coupling of 113.2 Hz. The
measured 1JPRh as well as 2JPP coupling constants are characteristic
of coordinated diphosphites with a cis-configuration for the phos-
phorus atoms [22]. The proposed solution structure of complex 6 is
also consistent with the results of 13C and 1H NMR studies. Note-
worthy is the pronounced asymmetric arrangement of the acac
ligand, which is manifested in the fact that each carbon atom
exhibits its own signal (see Experimental Part). This seems to be
2JPP ¼ 16.2 Hz) and 57.6 (1JPPt ¼ 5973.6 Hz, JPP ¼ 19.3 Hz). Inter-
2
estingly, the resonances which correspond to the binaphthol
phosphorus center are reasonably broadened in both complexes.
This is probably due to the steric repulsion between two parts of
the bulky ligand, which prevents them from stable occupying two
adjacent coordination sites. The magnitude of the 1JPPt is typical of
a phosphite phosphorus atom bonded to the PtCl2 fragment with

I.S. Mikhel et al. / Journal of Organometallic Chemistry 696 (2011) 3050e3057
3053
Table 2
Rhodium-catalyzed hydroformylation of styrenes.a
Run Substrate
1c Styrene
T (ꢁC) Conversion (%)b Selectivity for the b:lb
formation
of aldehyde (%)
60
80
90
98
99
99
99
99
99
99
99
99
99
99
99
99
98
99
99
4:1
2
3
Styrene
Styrene
2:1
1.2:1
2.2:1
1.2:1
2.9:1
1.6:1
2.3:1
1.6:1
2.5:1
1.6:1
2.5:1
1.3:1
1.1:1
100 100
4d Styrene
80
80
60
80
60
99
99
99
98
96
5e Styrene
6c p-Fluorostyrene
7
p-Fluorostyrene
8c p-Methoxystyrene
9
p-Methoxystyrene
80 100
10c p-Methylstyrene
11 p-Methylstyrene
12c o-Methylstyrene
13 o-Methylstyrene
60
80
60
80
98
97
90
95
3
Scheme 5. Synthesis of metal complexes.
14 2,4,6-Trimethylstyrene 80
15 2,4,6-Trimethylstyrene. 100
10
1:1.7
cis-configuration of the Cl atoms [23]. This fact is supported by the
195Pt NMR spectroscopy of 8 in CD2Cl2; the spectrum displayed
a broad triplet with dPt ꢀ4215 (1JPtP ¼ ca. 5980 Hz). The 13C and 1H
NMR spectroscopic data are also in good agreement with structures
of complexes 7 and 8 (see Experimental Part).
FAB mass spectrometric examination of compounds 6, 7 and 8
revealed the mononuclear nature of the complexes with the detec-
tion of molecular ions (m/z (I, %)): 1302(38) [M þ H]þ and 1203(54)
[M ꢀ acac þ H]þ; 1242(85) [M ꢀ Cl þ H]þ and 1206(21)
[M ꢀ 2Cl þ H]þ; 1294(14) [M ꢀ 2Cl þ H]þ, respectively. Intense peaks
for the [M ꢀ Cl]þ and [M ꢀ 2Cl þ H]þ ions are typical of manychloride
complexes of palladium and platinum [24]. HR ESI mass spectrom-
etry additionally confirmed the elemental composition of all
complexes. Unfortunately, numerous attemptstogrowsinglecrystals
of the new complexes suitable for an X-ray diffraction study failed.
a
Reaction conditions: substrate/Rh(acac)(CO)2/ligand 2800:1:2.2; 50 bar CO/H2
(ratio 1:1), in 5 mL of toluene, 3 h.
b
Determined by GC, HP 5 (Agilent).
18 h.
c
d
L/Rh ¼ 1.
e
L/Rh ¼ 6.
3. Conclusion
In summary, a new P,P-bidentate diphosphite ligand has been
synthesized within two steps starting from a commercially avail-
able and functionalized phenol based on an intramolecular trans-
esterification. This approach gives
straightforward synthesis of unsymmetrical diphosphites bearing
different phosphorus atoms.
a
new access to the
Some metal complexes were synthesized and characterized as
well. In a study of the Rh-catalyzed hydroformylation of styrenes
steric effects of the aromatic olefins dominate the regioselectivity
as well as the rate of the conversion, more than the properties of
the ligand [2e,25b]. Further investigations concerned to the
synthesis of related P,P0-bidentate diphosphites and their use in
hydroformylation are currently in progress.
2.4. Hydroformylation studies
In order to assess the catalytic properties of ligand 4 it was used in
the Rh-catalyzed hydroformylation of styrenes. Results are listed in
Table 2. As known from the literature selectivity and yield in the
hydroformylation of styrenes can be dominated by the electronic and
steric effects of the substrate [25]. In the hydroformylation with the
catalyst based on ligand 4 the formation of the branched aldehyde is
predominantly observed (Runs 1e5). Obviously the steric bulk of the
ligand is not sufficient to compensate the substrate-directed forma-
tionof the branched(iso)aldehyde. Onlytwoortho-substituents inthe
substrate force the formation of linear aldehydes and decrease the
reaction rates (Runs 14,15). Substituents with different electronic
properties on the aromatic ring affect the regioselectivity slightly
(Runs 6e11). The reaction temperature influences the regioselectivity
as well. Linear products are favorably formed at higher temperatures.
Forexampletheamountofthebranchedaldehydedrops from2.5:1at
60 ꢁC to 1.6 at 80 ꢁC with p-methylstyrene (Runs 10,11). The same
behavior can be observed with 2,4,6-trimethylstyrene as substrate.
Here the ratioofb:l increases from1.1:1 at60ꢁC to 1:1.7at 80ꢁC (Runs
14,15). The load of ligand has an impact on the observed regiose-
lectivity (compare runs 2, 4, 5). Increased amount of ligand improved
the formation of the linear product. Noteworthy, although an enan-
tiopure ligand was used, no stereoselection was observed.
4. Experimental part
4.1. General
Unless otherwise stated, all reactions were carried out under
a dry argon atmosphere using standard Schlenk-line techniques. All
reagents, unless otherwise mentioned, were purchased from
commercial sources and used without additional purification.
Solvents were dried and freshly distilled under argon before use.
Thin-layer chromatography was performed on pre-coated TLC
plates (silica gel 60 F254, Merck). Flash-chromatography was
carried out with silica gel 60 (230e400 mesh ASTM). PCl3 and NEt3
were distilled immediately before use. Pd(MeCN)2Cl2 and Pt(COD)
Cl2 were purchased from Aldrich and Rh(acac)(CO)2 was obtained
from Umicore. All other reagents were used as received from
Aldrich and Acros. NMR 1H (250.1, 300.1 and 400.1 MHz), 31P (101.3
and 162.0 MHz), 13C (62.9 and 75.5 MHz) and 195Pt (64.2 MHz)

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I.S. Mikhel et al. / Journal of Organometallic Chemistry 696 (2011) 3050e3057
spectra were recorded on a Bruker Avance 250, Bruker Avance 300
and Bruker Avance 400, respectively. Chemical shifts are quoted in
parts per million (ppm) downfield of tetramethylsilane. 31P NMR
chemical shifts were referenced externally to 85% H3PO4 0.0).
Coupling constants J are given in Hz. CI and FAB mass spectra were
measured on a Finnigan MAT 95-XP mass spectrometer (Thermo
Electron Corporation). HRMS was performed on MAT 95-XP (EI)
and Agilent 6210 Time-of-Flight LC/MS (ESI). GCeMS was per-
formed on Agilent 5973 chromatograph mass selective detector. GC
was performed on Agilent 6890 chromatograph with a 30 m HP5
column.
4.2.2.3. Method C. To a solution of 2 (4.720 g, 0.02 mol) in CH2Cl2
(100 mL) was added anhydrous FeCl3 (6.5 mg, 0.04 mmol) and
MCPBA (meta-chloroperoxybenzoic acid) (3.440 g, 0.02 mol) at
0 ꢁC. The reactions mixture was stirred for 1 h at room temperature
(GC-control), and then poured into water (200 mL). The mixture
was extracted with CH2Cl2 (3 ꢂ 75 mL). The combined organic
layers were neutralized with aqueous NaHCO3, dried with Na2SO4
and the solvents were removed in vacuo. The crude 1c was purified
by the same method. Yield 1.48 g (31.5%).
d
(d
4.2.2.4. Ullmann-coupling. To a solution of 3 (0.5 g, 0.016 mol) in
DMF (20 mL) was added Cu0 powder (0.32 g, 0.05 mol). The mixture
was vigorously stirred at 170 ꢁC (GC-control), and then diluted with
diethyl ether (30 mL) and filtered. The filter cake was washed with
diethyl ether. The combined organic layers were washed with water
(5 ꢂ 50 mL), and then dried with Na2SO4 and the solvents were
removed in vacuo to give a mixture of product 1c and 2. The crude 1c
was purified as described above. Yield 0.041 g (11%).
4.2. Phenol coupling
4.2.1. Synthesis of 3-(3-bromo-5-tert-butyl-4-hydroxyphenyl)
propionic acid methyl ester (3) [26]
A solution of bromine (1.6 g, 0.512 mL, 0.01 mol) in CH2Cl2
(2 mL) was added dropwise to a solution of phenol 3-(3-tert-butyl-
4-hydroxyphenyl)propionic acid methyl ester (2) (2.2 g, 0.01 mol)
in CH2Cl2 (10 mL) over 10 min at 0 ꢁC, then poured into water
(50 mL). The organic layer was diluted with CH2Cl2 (50 mL), sepa-
rated and washed with water (6 ꢂ 50 mL), dried with MgSO4. The
solvent was removed in vacuo to give crude 3. The product was
purified by flash column chromatography (silica gel, n-hexane/
AcOEt 5:1, Rf ¼ 0.55). Yield 2.740 g (87%). HRMS (EI): Calcd for
C10H1281BrO3 316.0491, found 316.0490 [M]þ; Calcd for
C10H1279BrO3 314.0512, found 314.0509 [M]þ. MS (CI, m/z (I, %)):
316(44) [M]þ, 314(44) [M]þ, 302(96), 299(98), 243(22), 242(30),
227(100), 225(97). 1H NMR (300.1 MHz, CDCl3): 1.38 (s, 9H, t-Bu),
2.58 (t, J ¼ 7.8, 2H, CH2), 2.85 (t, J ¼ 7.7, 2H, CH2), 3.68 (s, 3H, OCH3),
5.69 (s, 1H, OH), 7.03 (d, J ¼ 2.0, 2H, ArH), 7.17 (d, J ¼ 2.0, 2H, ArH).
13C NMR (75.5 MHz, CDCl3): 29.3 (C(CH3)3), 30.2 (CH2), 35.5
(C(CH3)3, 35.9 (CH2), 51.7 (OCH3), 112.0, 126.7, 128.9, 133.0, 137.5,
148.8 (CeO), 173.2 (C]O).
4.3. Synthesis of dimethyl 3,30-(4,8-di-tert-butyl-6-((1R)-20-
((11bR)-dinaphtho[2,1-d:10,20-f] [1,3,2]-dioxaphosphepin-4-yloxy)-
1,10-binaphthyl-2 yloxy)dibenzo[d,f] [1,3,2]dioxaphosphepine-2,10-
diyl)dipropionate (4)
4.3.1. Synthesis without intermediate P-protection
1-Methylpyrrolidin-2-one (0.01 g, 0.1 mmol) was added to
a stirred mixture of (R)-binaphthol (1 g, 3.492 mmol) and PCl3
(5 mL). The mixture was refluxed for 10 min until it became
completely homogeneous. All volatiles were then removed under
vacuum (0.1 Torr). Toluene (20 mL) was added and the solvent was
evaporated on a vacuum line to remove traces of PCl3. The obtained
product was dried on vacuum (0.05 Torr) for 1 h.
To a stirred solution of the whole of the synthesized binaph-
tholchlorophosphite in THF (20 mL) was slowly added dropwise
a solution of 1c (0.756 g, 1.606 mmol) and NEt3 (1 mL, 0.726 g,
7.17 mmol) in THF (25 mL) at 0 ꢁC and the resulting mixture was
stirred for 2 h. The reaction mixture was allowed to warm to r.t. and
stored overnight. The reaction solution was filtered, the filter cake
was washed with THF (2 ꢂ 15 mL) and the solution was evaporated.
The product was dried in vacuum for 2 h (0.05 Torr). The crude
ligand thus obtained was purified by flash-chromatography:
Rf ¼ 0.3 (CH2Cl2). Yield: 1.250 g (71%).
4.2.2. Synthesis of (dimethyl 3,30-(5,50-di-tert-butyl-6,60-
dihydroxybiphenyl-3,30-diyl)-dipropionate) (1c)
4.2.2.1. Method A. To the solution of 2 (9.450 g, 0.04 mol) in
CH3COOH (34 mL) a solution of K2Cr2O7 (4.000 g, 0.0136 mol) in
H2O (24 mL) and H2SO4 (8 mL) was added dropwise during 40 min
at 55 ꢁC. The reactions mixture was stirred for 60 min at 55 ꢁC and
then overnight at room temperature (GC-control). The resulting
mixture was poured into ice (100 mL) and extracted with CHCl3
(3 ꢂ 100 mL). The combined organic layers were neutralized with
aqueous NaHCO3, and then dried with Na2SO4 and the solvents
were removed in vacuo. The crude product was purified by chro-
matography (silica gel, n-hexane/AcOEt 5:1, Rf ¼ 0.4) and bulb-to-
bulb distillation at 160 ꢁC, 4e6 ꢂ 10ꢀ3 bar to give pure 1c. Yield:
2.050 g (21.8%). HRMS (ESI): Calcd for C28H39O6 471.2741, found
471.2745 [M þ H]þ. MS (CI, m/z (I, %)): 470(100) [M]þ, 399(35),
335(53), 293(30). 1H NMR (300.1 MHz, CDCl3): 1.42 (s, 18H, t-Bu),
2.63 (t, J ¼ 7.9, 2H, CH2), 2.90 (t, J ¼ 7.9, 2H, CH2), 3.67 (s, 3H, OCH3),
5.24 (s, 2H, OH), 6.90 (d, J ¼ 2.0, 2H, ArH), 7.16 (d, J ¼ 2.0, 2H, ArH).
13C NMR (62.9 MHz, CDCl3): 29.6 (C(CH3)3), 30.5 (CH2), 35.0
(C(CH3)3, 36.1 (CH2), 51.7 (OCH3), 122.6, 127.8, 128.0, 132.4, 137.4,
150.4 (CeO), 173.5 (C]O).
White powder. HRMS (ESI): Calcd for C68H60NaO10P2 1121.3554,
found 1121.3551 [M þ Na]þ; Calcd for C68H61O10P2 1099.3734, found
1099.3730 [M þ H]þ. 31P NMR (101.3 MHz, CD2Cl2): 144.7 (d,
JPP ¼ 3.7 Hz), 137.2 (d, JPP ¼ 3.7 Hz). 13C NMR (62.9 MHz, CD2Cl2):
173.4 (s, CO2Me), 148.5 (d, JCP ¼ 3.7, POC), 148.4 (d, JCP ¼ 7.8, POC),
147.9 (d, JCP ¼ 4.6, POC), 147.4 (d, JCP ¼ 2.3, POC), 146.3 (d, JCP ¼ 19.2,
POC), 146.2 (d, JCP ¼ 17.4, POC), 141.7 (d, JCP ¼ 1.8, Carom), 141.6 (d,
JCP ¼ 1.4, Carom),136.9 (s, Carom), 136.8 (s, Carom),134.6 (s, Carom), 134.3
(s, Carom), 133.2 (s, Carom), 133.15 (s, Carom), 133.1 (d, JCP ¼ 1.4, Carom),
132.9 (d, JCP ¼ 3.7, Carom), 132.7 (d, JCP ¼ 1.4, Carom), 131.9 (s, Carom),
131.5 (s, Carom), 131.3 (s, Carom), 131.2 (s, Carom), 130.6 (s, Carom), 130.3
(s, Carom), 130.1 (s, Carom), 129.9 (s, Carom), 129.3 (d, JCP ¼ 3.7, Carom),
128.6 (d, JCP ¼ 2.7, Carom), 128.5 (s, Carom), 128.3 (s, Carom), 127.7 (d,
JCP ¼ 3.2, Carom), 127.3 (s, Carom), 127.1 (s, Carom), 127.0 (s, Carom), 126.6
(s, Carom), 126.4 (s, Carom), 126.3 (s, Carom), 125.6 (s, Carom), 125.4 (s,
Carom),125.3 (s, Carom),125.1 (s, Carom),124.6 (d, JCP ¼ 5.5, Carom),123.0
(s, Carom), 122.9 (s, Carom), 122.71 (d, JCP ¼ 1.4, Carom), 122.67 (s, Carom),
122.0 (d, JCP ¼ 1.4, Carom), 121.97 (s, Carom), 121.9 (s, Carom), 121.8 (s,
Carom), 121.1 (s, Carom), 120.9 (s, Carom), 51.8 (s, OCH3), 36.0 (s, CH2),
35.98 (s, CH2), 35.09 (s, C(CH3)3), 35.07 (s, C(CH3)3), 30.87 (s, CH2),
30.82 (s, C(CH3)3), 30.79 (s, C(CH3)3). 1H NMR (400.1 MHz, CD2Cl2):
8.11 (1H, d, JHH ¼ 9.0, ArH), 8.04 (1H, d, JHH ¼ 8.1, ArH), 7.95e7.88 (4H,
m, ArH), 7.85 (1H, d, JHH ¼ 8.0, ArH), 7.63 (1H, d, JHH ¼ 9.0, ArH), 7.58
4.2.2.2. Method B. To a solution of 2 (0.221 g, 0.001 mol) in toluene
(5 mL) was added benzoyl peroxide (0.242 g, 0.001 mol) at 0 ꢁC. The
reaction mixture was stirred for 18 h at room temperature (GC-
control), and then poured into water (50 mL). The mixture was
extracted with diethyl ether (3 ꢂ 30 mL). The combined organic
layers were washed with aqueous NaHCO3, dried with Na2SO4 and
the solvents were removed in vacuo. The crude 1c was purified as
described above. Yield 0.066 g (28%).

I.S. Mikhel et al. / Journal of Organometallic Chemistry 696 (2011) 3050e3057
3055
1
2
(1H, d, JHH ¼ 8.8, ArH), 7.49e7.15 (14H, m, ArH), 7.06 (2H, d, JHH ¼ 2.0,
ArH), 6.87 (2H, d, JHH ¼ 2.0, ArH), 6.07 (1H, d, JHH ¼ 8.8, ArH), 3.65
(3H, s, CH3), 3.64 (3H, s, CH3), 2.91e2.86 (4H, m, CH2), 2.62e2.55 (4H,
m, CH2), 1.00 (9H, s, t-Bu), 0.98 (9H, s, t-Bu).
139.3 (dd, JPRh
¼
307.3 Hz, JPP
¼
113.2 Hz), 129.6 (dd,
1JPRh ¼ 304.8 Hz, 2JPP ¼ 113.2 Hz). 13C NMR (62.9 MHz, CD2Cl2): 185.5
(s, COacac), 185.0 (s, COacac), 173.4 (s, CO2Me), 173.3 (s, CO2Me), 148.5
(d, JCP ¼ 14.2, POC), 147.8 (d, JCP ¼ 2.7, POC), 147.7 (d, JCP ¼ 8.7, POC),
147.4 (s, POC), 147.0 (d, JCP ¼ 4.1, POC), 146.7 (d, JCP ¼ 14.6, POC), 141.0
(d, JCP ¼ 3.2, Carom), 140.8 (d, JCP ¼ 4.6, Carom), 136.9 (d, JCP ¼ 0.9,
Carom), 136.7 (s, Carom), 134.2 (s, Carom), 133.4 (s, Carom), 133.12 (d,
JCP ¼ 1.8, Carom), 133.1 (d, JCP ¼ 1.4, Carom),132.2 (s, Carom), 132.14 (s,
Carom), 132.1 (s, Carom), 131.7 (d, JCP ¼ 1.8, Carom), 131.5 (s, Carom), 131.0
(s, Carom), 130.9 (s, Carom), 130.7 (s, Carom), 130.4 (s, Carom), 129.8 (s,
Carom),129.3 (s, Carom),128.7 (s, Carom),128.5 (d, JCP ¼ 3.2, Carom),128.3
(s, Carom), 128.2 (s, Carom), 127.2 (s, Carom), 127.2 (s, Carom), 126.9 (s,
Carom), 126.6 (s, Carom), 126.4 (s, Carom), 126.36 (s, Carom), 126.3 (s,
Carom), 125.5 (s, Carom), 125.4 (s, Carom), 125.39 (d, JCP ¼ 1.4, Carom),
124.3 (d, JCP ¼ 1.8, Carom), 124.1 (d, JCP ¼ 2.7, Carom), 123.1 (d, JCP ¼ 2.3,
Carom), 122.9 (d, JCP ¼ 2.7, Carom), 123.0 (d, JCP ¼ 6.0, Carom), 122.6 (d,
JCP ¼ 6.0, Carom), 120.9 (s, Carom),120.2 (s, Carom), 120.1 (s, Carom), 119.9
(s, Carom), 99.9 (s, CHacac), 51.9 (s, OCH3), 51.7 (s, OCH3), 36.5 (s,
C(CH3)3), 36.0 (s, CH2), 35.96 (s, CH2), 34.9 (s, C(CH3)3), 32.8 (s,
C(CH3)3), 31.0 (s, C(CH3)3), 30.8 (s, CH2), 30.7 (s, CH2), 26.8 (d,
JCP ¼ 9.2, CH3acac), 25.7 (d, JCP ¼ 9.2, CH3acac). 1H NMR (250.1 MHz,
CD2Cl2): 8.50 (1H, d, JHH 9.0, ArH), 8.25 (1H, d, JHH ¼ 9.0, ArH),
8.08e7.80 (9H, m, ArH), 7.63 (1H, d, JHH ¼ 8.6, ArH), 7.53e7.14 (12H,
m, ArH), 7.06 (1H, d, JHH ¼ 2.2, ArH), 7.02 (1H, d, JHH ¼ 2.2, ArH), 6.93
(1H, d, JHH ¼ 8.5, ArH), 6.90 (1H, d, JHH ¼ 2.2, ArH), 5.05 (1H, s,
CH(acac)), 3.71 (3H, s, CH3), 3.53 (3H, s, CH3), 3.02 (2H, t, JHH ¼ 7.6,
CH2), 2.84 (2H, t, JHH ¼ 7.6, CH2), 2.71 (2H, t, JHH ¼ 7.6, CH2), 2.55 (1H,
t, JHH ¼ 7.9, CH2), 2.53 (1H, t, JHH ¼ 7.9, CH2), 1.92 (9H, s, t-Bu), 1.36
(3H, s, CH3(acac)), 0.68 (3H, s, CH3(acac)), 0.67 (9H, s, t-Bu).
4.3.2. Purification via diborane adduct 5
4.3.2.1. Synthesis of diborane adduct [4-(BH3)2] (5). To a solution of
the whole of synthesized diphosphite 4 in THF (30 mL) BH3 ꢂ THF
(9 mL, 1 M in THF) was added dropwise at 0 ꢁC. The resulting
solution was stirred at r.t. for 24 h. Then the reaction solution was
evaporated up to w1 mL and the product was precipitated with
pentane. The obtained solid was washed twice with pentane
(2 ꢂ 10 mL) and dried in vacuum. The product was purified by flash-
chromatography. Rf ¼ 0.45 (CH2Cl2, silica gel). Yield: 0.645 g (36%).
White powder. HRMS (ESI): Calcd for C68H66B2NaO10P2
1149.4230, found 1149.4222 [M þ Na]þ; Calcd for C68H64BO10P2
1113.4073, found 1113.4072 [M ꢀ BH3 þ H]þ; C68H63BNaO10P2
1135.3893, found 1135.3888 [M
ꢀ
BH3
þ
Na]þ; Calcd for
C68H60NaO10P2 1121.3554, found 1121.3556 [M þ Na]þ; Calcd for
C68H61O10P2 1099.3734, found 1099.3711 [M þ H]þ. 31P NMR
(101.3 MHz, CD2Cl2):144.7(d, JPP ¼ 3.7 Hz, 0.5%),144.5 (s, 4%),137.6 (s,
6%),137.2 (d, JPP ¼ 3.7 Hz, 0.5%),126.5 (br. s, 45%),116.8 (br. s, 44%).13
C
NMR (62.9 MHz, CD2Cl2): 173.4 (s, CO2Me),173.3 (s, CO2Me),146.9 (d,
JCP ¼ 6.4, POC),146.8 (d, JCP ¼ 8.2, POC),146.7 (d, JCP ¼ 10.5, POC),146.5
(d, JCP ¼ 1.8, POC),145.05 (d, JCP ¼ 14.2, POC),145.0 (d, JCP ¼ 11.0, POC),
141.2 (d, JCP ¼ 3.7, Carom), 141.0 (d, JCP ¼ 3.7 Carom), 138.1 (d, JCP ¼ 0.9,
Carom),137.8 (d, JCP ¼ 0.9, Carom),134.0 (s, Carom),133.7 (s, Carom),132.7
(d, JCP ¼ 1.4, Carom), 132.3 (s, Carom), 132.2 (d, JCP ¼ 1.4, Carom), 131.4 (s,
Carom),131.2 (s, Carom),130.9 (d, JCP ¼ 2.3, Carom),130.5 (s, Carom),130.4
(s, Carom), 130.1 (s, Carom), 129.8 (s, Carom), 129.0 (s, Carom), 128.8 (s,
Carom),128.7 (s, Carom),128.4 (s, Carom),128.3 (s, Carom),128.2 (s, Carom),
127.6 (s, Carom),127.3 (s, Carom),127.1 (s, Carom),127.05 (s, Carom),127.0
(s, Carom), 126.8 (s, Carom), 126.4 (s, Carom), 126.2 (s, Carom), 126.1 (s,
Carom), 125.8 (s, Carom), 122.33 (s, Carom), 122.3 (s, Carom), 122.1 (s,
Carom),121.8 (d, JCP ¼ 2.7, Carom),121.3 (s, Carom),121.26 (s, Carom),120.5
(d, JCP ¼ 1.4, Carom),120.2 (d, JCP ¼ 2.3, Carom),120.1 (d, JCP ¼ 2.3, Carom),
51.9 (s, OCH3), 51.87 (s, OCH3), 36.0 (s, CH2), 35.9 (s, CH2), 35.2 (s,
C(CH3)3), 35.0 (s, C(CH3)3), 31.0 (s, C(CH3)3), 30.9 (s, CH2), 30.84 (s,
C(CH3)3), 30.8 (s, CH2). 1H NMR (250.1 MHz, CD2Cl2): 8.12e7.65 (9H,
m, ArH), 7.58e7.22 (11H, m, ArH), 7.14e7.00 (5H, m, ArH), 6.68 (1H, d,
JHH ¼ 2.1, ArH), 6.54 (1H, d, JHH ¼ 2.1 ArH), 6.15 (1H, dd, JHH ¼ 8.8, JHH
1.0, ArH), 3.69 (3H, s, CH3), 3.67 (3H, s, CH3), 2.97e2.85 (4H, m, CH2),
2.69e2.58 (4H, m, CH2),1.05 (9H, s, t-Bu), 0.89 (9H, s, t-Bu),1.20e0.00
(6H, v. br., BH3).
4.4.2. Synthesis of Pd(4)Cl2 complex (7)
To a stirred solution of Pd(MeCN)2Cl2 (25.9 mg, 0.1 mmol) in
CH2Cl2 (1 mL) a solution of the ligand 4 (109.9 mg, 0.1 mmol) in
CH2Cl2 (2 mL) was added dropwise and the reaction mixture was
stirred for 2 h. Then the solvent was evaporated and the obtained
solid was dried in vacuum. Yield was nearly quantitative.
Yellow powder. HRMS (ESI): Calcd for C68H61Cl2O10P2Pd
1275.2163, found 1275.2443 [M þ H]þ. MS (FAB, m/z (I, %)): 1242(85)
[M ꢀ Clþ H]þ,1206(21) [M ꢀ 2Cl þ H]þ. 31P NMR (101.3 MHz, CD2Cl2):
2
2
115.2 (br. d, JPP ¼ 65.9 Hz) and 81.8 (d, JPP ¼ 66.5 Hz). 13C NMR
(62.9 MHz, CD2Cl2): 173.1 (s, CO2Me),147.5 (d, JCP ¼ 13.7, POC), 147.3 (d,
JCP ¼ 3.7, POC),147.2 (d, JCP ¼ 11.9, POC), 146.9 (d, JCP ¼ 3.7, POC),146.89
(d, JCP ¼ 16.5, POC), 146.2 (d, JCP ¼ 6.4, POC),145.9 (br. s, Carom),140.8 (d,
JCP ¼ 4.1, Carom),140.7(d, JCP ¼ 4.1, Carom),139.6 (d, JCP ¼ 1.4, Carom),138.6
(d, JCP ¼ 0.9, Carom), 134.5 (s, Carom), 133.8 (s, Carom), 133.0 (s, Carom),
132.9 (s, Carom),132.64 (s, Carom),132.6 (s, Carom),132.58 (s, Carom),132.2
(d, JCP ¼ 0.9, Carom), 132.1 (d, JCP ¼ 3.2, Carom), 131.8 (s, Carom), 131.5 (s,
Carom), 131.3 (s, Carom), 131.1 (s, Carom), 131.0 (s, Carom), 130.4 (s, Carom),
130.1 (s, Carom),129.5 (s, Carom),129.2 (s, Carom),129.1 (s, Carom),128.7 (s,
Carom), 128.2 (s, Carom), 127.9 (s, Carom), 127.8 (s, Carom), 127.5 (s, Carom),
127.4 (s, Carom),127.2 (s, Carom),127.1 (s, Carom),126.8 (s, Carom),126.6 (s,
Carom), 126.4 (s, Carom), 126.2 (s, Carom), 123.1 (d, JCP ¼ 1.8, Carom), 122.9
(d, JCP ¼ 2.7, Carom), 121.7 (d, JCP ¼ 7.8, Carom), 121.5 (d, JCP ¼ 2.3, Carom),
121.1 (d, JCP ¼ 6.0, Carom),120.1(s,Carom),120.0(s,Carom),119.0(s,Carom),
51.9 (s, OCH3), 51.8 (s, OCH3), 36.1 (s, C(CH3)3), 36.0 (s, CH2), 35.7 (s,
CH2), 35.4 (s, C(CH3)3), 31.4 (s, C(CH3)3), 30.9 (s, CH2), 30.6 (s, CH2). 1H
NMR (250.1 MHz, CD2Cl2): 8.44 (1H, d, JHH ¼ 9.5, ArH), 8.40 (1H, d,
JHH ¼ 9.4, ArH), 8.27 (1H, d, JHH ¼ 9.1, ArH), 8.20 (1H, d, JHH ¼ 9.2, ArH),
8.07 (2H, t, JHH ¼ 8.0, ArH), 7.98 (1H, d, JHH ¼ 9.0, ArH), 7.89e7.84 (2H,
m, ArH), 7.78 (1H, d, JHH ¼ 8.2, ArH), 7.71 (1H, d, JHH ¼ 9.2, ArH), 7.64
(1H, d, JHH ¼ 1.7, ArH), 7.60e7.23 (8H, m, ArH), 7.17e7.02 (5H, m, ArH),
6.93 (1H, d, JHH ¼ 2.2, ArH), 6.86 (1H, d, JHH ¼ 8.7, ArH), 6.37 (1H, d,
JH,H ¼ 9.0, ArH), 3.73 (3H, s, CH3), 3.60 (3H, s, CH3), 3.13 (2H, t, JHH ¼ 7.6,
CH2), 2.89 (2H, t, JHH ¼ 7.7, CH2), 2.79 (2H, t, JHH ¼ 7.6, CH2), 2.59 (2H, t,
JHH ¼ 7.9, CH2), 1.90 (9H, s, t-Bu), 0.58 (9H, s, t-Bu).
4.3.2.2. Deprotection of diborane adduct 5. To a solution of 5
(0.483 g, 0.428 mmol) in toluene (15 mL) NEt3 (0.26 g, 0.36 mL,
2.57 mmol) was added and the resulting mixture was stirred for
72 h. Then the reaction mixture was evaporated and the obtained
solid was dried in vacuum. The product 4 was then purified by
flash-chromatography (CH2Cl2, silica gel). Yield: 0.370 g (79%).
4.4. Synthesis of metal complexes
4.4.1. Synthesis of Rh(acac)(4) complex (6)
To a stirred solution of Rh(acac)(CO)2 (25.8 mg, 0.1 mmol) in
CH2Cl2 (10 mL) a solution of the ligand (0.1099 g, 0.1 mmol) in
CH2Cl2 (10 mL) was added dropwise in 10 min and the reaction
mixture was stirred for 2 h. Then the solvent was evaporated on
a vacuum pump and the obtained solid was dried in vacuum. Yield
was nearly quantitative.
Yellowebrown powder. HRMS (ESI): Calcd for C73H67NaO12P2Rh
1323.3055, found 1323.3072 [M þ Na]þ; Calcd for C73H68O12P2Rh
1301.3236, found 1301.3237 [M þ H]þ. MS (FAB, m/z (I, %)): 1302(38)
[M þ H]þ, 1203(54) [M ꢀ acac þ H]þ. 31P NMR (101.3 MHz, CD2Cl2):

3056
I.S. Mikhel et al. / Journal of Organometallic Chemistry 696 (2011) 3050e3057
(b) M. Beller, B. Cornils, C.D. Frohning, C.W. Kohlpaintner, J. Mol. Cat. A Chem. 104
4.4.3. Synthesis of Pt(4)Cl2 complex (8)
(1995) 17e85;
To a stirred suspension of Pt(COD)Cl2 (37.4 mg, 0.1 mmol) in
CH2Cl2 (1 mL) a solution of ligand 4 (109.9 mg, 0.1 mmol) in CH2Cl2
(2 mL) was added dropwise and the reaction mixture was stirred
for 2 h. The reaction solution was reduced up to w1 mL and the
complex was precipitated by pentane. The obtained solid was
washed carefully three times with a small amount of ether and
pentane and dried in air and then in vacuum. Yield: 0.128 g (94%).
White powder. HRMS (ESI): Calcd for C68H60Cl2NaO10P2Pt
1386.2584, found 1386.2584 [M þ Na]þ. MS (FAB, m/z (I, %)):
1294(14) [M ꢀ 2Cl þ H]þ. 31P NMR (101.3 MHz, CD2Cl2): 88.8 (br. d,
(c) C.D. Frohning, C.W. Kohlpaintner, in: B. Cornils, W.A. Herrmann (Eds.), Applied
Homogeneous Catalysis with Organometallic Compounds: A Comprehensive
Handbook in Two Volumes, vol. 1, VCH Verlagsgesellschaft, Weinheim, 1996, pp.
27e104;
(d) P.W.N.M. van Leeuwen, C. Claver (Eds.), Rhodium Catalyzed Hydro-
formylation, Kluwer, Dordrecht, 2000;
(e) G. Protzmann, K.-D. Wiese, Erdöl, Erdgas, Kohle 117 (2001) 235e240;
(f) K.-D. Wiese, D. Obst, Top. Organomet. Chem. 18 (2006) 1e33.
[2] (a) E. Billig, A.G. Abatjoglou, D.R. Bryant, (UCC), EP 213639 (1987), EP
214622(1987), US 4769498 (1988).
(b) S. Keiichi, Y. Kawaragi, M. Takai, T. Ookoshi (Mitsubishi Kasei), EP 518241
(1992). (c) G.D. Cuny, S.L. Buchwald, J. Am. Chem. Soc. 115 (1993) 2066e2068;
(d) B. Moasser, W.L. Gladfelter, D.C. Roe, Organometallics 14 (1995) 3832e3838;
(e) A. van Rooy, P.C.J. Kamer, P.W.N.M. van Leeuwen, J. Organomet. Chem. 535
(1997) 201e207;
(f) D. Röttger, A. Börner, D. Selent, D. Hess (Oxeno), DE 10031493 (2002).
(g) M.A. Brammer, W.-J. Peng, J.M. Maher (Dow Chemica), WO 2008124468
(2008).
(h) T.C. Eisenschmid, R.R. Peterson, G.A. Miller, A. G. Abatjoglou (UCC), WO
2008115740 (2008).
(i) Selent, A. Börner, B. Kreidler, D. Hess, K.-D. Wiese (Oxeno), WO 2008071508
(2008).
1JPPt ¼ 5989.1 Hz, JPP ¼ 16.2 Hz) and 57.6 (d, JPPt ¼ 5973.6 Hz,
2JPP ¼ 19.3 Hz). 195Pt NMR (64.2 MHz, CD2Cl2): ꢀ4215 (br. t,
1JPtP ¼ ca. 5971 Hz). 13C NMR (62.9 MHz, CD2Cl2): 173.2 (s, CO2Me),
147.4 (d, JCP ¼ 13.3, POC),147.2 (d, JCP ¼ 2.3, POC), 146.9 (d, JCP ¼ 11.4,
POC), 146.8 (d, JCP ¼ 2.3, POC), 146.4 (d, JCP ¼ 14.2, POC), 146.3 (br. s,
Carom), 146.0 (d, JCP ¼ 6.7, POC), 140.9 (d, JCP ¼ 3.2, Carom), 140.8 (d,
JCP ¼ 2.8, Carom), 139.5 (d, JCP ¼ 1.4, Carom), 138.4 (d, JCP ¼ 1.4, Carom),
134.5 (s, Carom), 133.8 (s, Carom), 132.8 (s, Carom), 132.6 (d, JCP ¼ 1.4,
Carom), 132.1 (d, JCP ¼ 0.9, Carom), 132.0 (d, JCP ¼ 2.7, Carom), 131.6 (s,
Carom), 131.5 (s, Carom), 131.3 (s, Carom), 131.1 (s, Carom), 131.0 (s,
Carom), 130.4 (s, Carom), 130.0 (d, JCP ¼ 0.9, Carom), 129.4 (s, Carom),
129.14 (s, Carom), 129.1 (s, Carom), 129.0 (s, Carom), 128.7 (s, Carom),
128.2 (s, Carom), 127.8 (s, Carom), 127.6 (s, Carom), 127.5 (s, Carom), 127.3
(s, Carom), 127.2 (s, Carom), 127.15 (s, Carom), 127.1 (s, Carom), 126.7 (s,
Carom), 126.6 (s, Carom), 126.3 (s, Carom), 126.1 (s, Carom), 123.3 (d,
JCP ¼ 2.3, Carom), 122.8 (d, JCP ¼ 2.7, Carom), 121.7 (d, JCP ¼ 2.3, Carom),
121.5 (d, JCP ¼ 7.3, Carom), 121.0 (d, JCP ¼ 5.5, Carom), 120.3 (s, Carom),
120.2 (s, Carom), 120.1 (s, Carom), 119.1 (s, Carom), 51.9 (s, OCH3), 51.7
(s, OCH3), 36.1 (s, C(CH3)3), 36.0 (s, CH2), 35.7 (s, CH2), 35.4 (s,
C(CH3)3), 31.5 (s, C(CH3)3), 31.4 (s, C(CH3)3), 30.9 (s, CH2), 30.6 (s,
CH2). 1H NMR (250.1 MHz, CD2Cl2): 8.45 (1H, d, JHH ¼ 9.2, ArH), 8.38
(1H, d, JHH ¼ 9.1, ArH), 8.26 (1H, d, JHH ¼ 9.2, ArH), 8.21 (1H, d,
JHH ¼ 9.3, ArH), 8.10e7.96 (3H, m, ArH), 7.87 (2H, d, JHH ¼ 8.5, ArH),
7.78 (1H, d, JHH ¼ 8.2, ArH), 7.70 (1H, d, JHH ¼ 9.2, ArH), 7.64 (1H, d,
JHH ¼ 1.6, ArH), 7.60e7.22 (8H, m, ArH), 7.16e7.01 (5H, m, ArH), 6.92
(1H, d, JHH ¼ 2.2, ArH), 6.84 (1H, d, JHH ¼ 8.7, ArH), 6.36 (1H, d,
JH,H ¼ 9.0, ArH), 3.73 (3H, s, CH3), 3.59 (3H, s, CH3), 3.13 (2H, t,
JHH ¼ 7.6, CH2), 2.88 (2H, t, JHH ¼ 7.6, CH2), 2.78 (2H, t, JHH ¼ 7.6,
CH2), 2.57 (2H, t, JHH ¼ 7.9, CH2), 1.91 (9H, s, t-Bu), 0.56 (9H, s, t-Bu).
2
1
(j) W.-J. Peng, C.L. Rand (Dow Chemical), WO 2008134326 (2008).
[3] For related ligands, which have been used widely in asymmetric hydro-
formylation, see the following review A. Gual, C. Godard, S. Castillon, C. Claver,
Tetrahedron: Asymmetry 21 (2010) 1135e1146 and ref. cited therein.
[4] K.H. Pawlowski, B. Schartel, Polym. Int. 56 (2007) 1404e1414.
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Angew. Chem. Int. Ed. 39 (2000) 1639e1641;
(b) D. Selent, D. Hess, K.-D. Wiese, D. Röttger, C. Kunze, A. Börner, Angew.
Chem. Int. Ed. 40 (2001) 1696e1698;
(c) C. Kunze, D. Selent, R. Schmutzler, I. Neda, A. Spannenberg, A. Börner,
Heteroatom Chem. 12 (2001) 577e585;
(d) C. Kunze, D. Selent, I. Neda, R. Schmutzler, W. Baumann, A. Börner,
Z. Allgem. Anorg. Chem. 628 (2002) 779e787;
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A. Börner, Organometallics 22 (2003) 4265e4271;
(f) D. Selent, K.D. Wiese, A. Börner, O-Acylphosphites: new and promising
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Taylor & Francis, Boca Raton, 2005, pp. 459e469;
(g) D. Selent, W. Baumann, K.-D. Wiese, A. Börner, Chem. Commun. (2008)
6203e6205;
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[6] Delivered by UFC Corporation, Taiwan.
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4.5. General procedure for hydroformylation
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0.0038 mmol) and toluene (5 mL). The mixture was stirred for
60 min then the olefinic substrate (10.8 mmol) was added. The
yellow reaction mixture was transferred in a 25 mL Parr auto-
clave under argon. The autoclave was purged with syngas three
times and subsequently charged with syngas (CO/H2 ¼ 1:1,
50 atm). The autoclave was warmed up to 80 ꢁC and the reaction
was started by stirring. After 3 h, the autoclave was cooled and
the gases were carefully released in a well-ventilated hood. The
reaction mixture was analyzed by GC to determine conversion
and regioselectivity.
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Acknowledgments
We would like to thank Dr. Christine Fisher for mass spec-
trometry measurements.
[17] K. Wang, M. Lü, A. Yu, X. Zhu, Q. Wang, J. Org. Chem. 74 (2009) 935e938.
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