Phosphine-phosphite ligands: Chelate ring size vs. activity and enantioselectivity relationships in asymmetric hydrogenation

Article abstract of DOI:10.1039/c2dt30386h

A series of new phosphine-phosphite ligands P(C)_nOP (n = 1-4) have been synthesized and used for rhodium-catalyzed asymmetric hydrogenation of prochiral olefins in order to study the effect of the chelate ring size. Excellent ees (up to 97.5%) were obtained in the hydrogenation of dimethyl itaconate and an increase of activity and enantioselectivity was observed in the hydrogenation of (Z)-α-acetamidocinnamic acid methyl ester with the increasing length of the backbone of the ligands.

Full text of DOI:10.1039/c2dt30386h

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PAPER
Phosphine–phosphite ligands: chelate ring size vs. activity and
enantioselectivity relationships in asymmetric hydrogenation
Gergely Farkas,a Szabolcs Balogh,a József Madarász,a Áron Szöllősy,b Ferenc Darvas,c László Ürge,c
Maryse Gouygoud,e and József Bakos*a
Received 17th February 2012, Accepted 15th June 2012
DOI: 10.1039/c2dt30386h
A series of new phosphine–phosphite ligands P(C)nOP (n = 1–4) have been synthesized and used for
rhodium-catalyzed asymmetric hydrogenation of prochiral olefins in order to study the effect of the
chelate ring size. Excellent ees (up to 97.5%) were obtained in the hydrogenation of dimethyl
itaconate and an increase of activity and enantioselectivity was observed in the hydrogenation of
(Z)-α-acetamidocinnamic acid methyl ester with the increasing length of the backbone of the ligands.
demands of the catalyst, and substituent controlled electronic-
Introduction
tuning of the chiral ligands.7 Less common are instances of the
Among bifunctional ligands, phosphine–phosphites are a par-
ticularly interesting class of compounds due to their unique elec-
tronic properties. They possess two strongly coordinating
phosphorus functionalities, one of them being a good π-acceptor
group. After the pioneering work of Takaya et al.1 reporting
excellent results in the asymmetric hydroformylation of olefins
with BINAPHOS, the scope of phosphine–phosphites has
greatly been increased. In recent years, a new series of phos-
phine–phosphite ligands have been developed and have been
found to have unique catalytic properties in asymmetric hydro-
genation and in other homogeneous catalytic transformations.2
In the past few decades, the exploration of ligand effects in
transition metal catalysis became a very powerful tool for fine
tuning of the efficiency of the catalytic system in homogeneous
catalysis. Variation of the electronic3 and steric features and the
“natural” bite angle4 of bidentate ligands has been used to opti-
mize many catalytic reactions. These ligand parameters have
been proven to control key features of catalysts, like activity,
selectivity and stability. It is also important to note that these sys-
tematic modifications resulted in a better understanding of ligand
effects in catalysis. Furthermore, supramolecular strategies5 and
the application of heteromonodentate systems6 should also be
mentioned as impressive tools in catalyst design. In asymmetric
hydrogenation, the majority of reports of ligand modification for
catalysis have followed systematic variation of the spatial
manipulation of the chelate ring size, despite the fact that such
changes can be, in many cases, readily implemented resulting in
steric and electronic alteration and producing similarly dramatic
improvements in catalyst activity and enantioselectivity. A quan-
titative comparison measurement of equilibrium constants for
binding of the olefinic substrates and of the catalytic hydrogen-
ation rates is reported for Ph2P(CH2)nPPh2 (n = 2–5) by Halpern
and Landis.8 A noteworthy conclusion of their study is that all
rate constants (i.e. the C–H reductive elimination step as well as
the H2 oxidative addition step) appear to increase with increasing
chelate ring size. A general trend of increasing overall catalytic
rate with increasing diphosphine chelate ring size also has been
noted by Kagan et al.9
In this contribution we report a comparison of the perform-
ance of directly analogous heterodiphos systems with a P(C)nOP
backbone (n = 1–4) that has not been made before. In addition,
we describe full results about the application of a new family of
phosphine–phosphites PCnOP(S)-Hx (n = 1–4, x = 0 or 8)
(Fig. 1), covering their synthesis, coordination chemistry and a
comparison of their catalytic activity and selectivity.
Results and discussion
Ligand synthesis methods
The synthetic route developed for the synthesis of the phos-
phine–phosphites (PCnOP) depends on the length (n) of the
bridge (Scheme 1) and only differs in the synthesis of the corres-
ponding hydroxyphosphine: (a) nucleophilic addition of HPPh2
to formaldehyde (n = 1),10 (b) reaction of an ω-halogenoalcohol
with two equivalents of LiPPh2 followed by the hydrolysis of
the resulting Li-salt (n = 2, 3),11 and (c) ring opening reaction of
cyclic ethers (e.g. THF) by LiPPh2 and the subsequent hydroly-
sis of the Li-alcoholate (n = 4).12 Then these valuable intermedi-
ate hydroxyphosphines can be combined with chlorophosphites
aDepartment of Organic Chemistry, University of Pannonia, H-8200
Veszprém, Egyetem u. 10, Hungary. E-mail: bakos@almos.vein.hu;
Fax: +36886244469; Tel: +3688624544
bDepartment of General and Analytical Chemistry, Budapest University
of Technology and Economics, H-1111 Budapest, Szent Gellért tér 4,
Hungary
cThalesNano Nanotechnology Inc., 1031 Budapest, Záhony u. 7,
Graphisoft Park, Hungary
dCNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de
Narbonne, BP 44099F-31077 Toulouse Cedex 4, France
eUniversité de Toulouse, UPS, INPT, F-31077 Toulouse Cedex 4, France
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Fig. 1 Novel chiral phosphine–phosphite ligands.
Scheme 1 Strategies for preparation of hydroxyalkyl-phosphines, conditions: (i) HPPh2; (ii) LiPPh2; (iii) H2O; (iv) chlorophosphite, Et3N.
Table 1 31P NMR data of ligands PCnOP(S)-Hx and their [Rh(COD)(PCnOP(S)-Hx)]BF4 complexesa
δ(PA)
(ppm)
1J(RhPA)
(Hz)
δ(PB)
(ppm)
1J(RhPB)
(Hz)
1J(PAPB)
(Hz)
δlig(PA)
(ppm)
δlig(PB)
(ppm)
Δδ (PA)
(ppm)
Δδ (PB)
(ppm)
Ligand
PC1OP(S)-H0
PC2OP(S)-H0
PC3OP(S)-H0
PC4OP(S)-H0
PC1OP(S)-H8
PC2OP(S)-H8
PC3OP(S)-H8
PC4OP(S)-H8
164.3
132.8
145.9
139.4
161.3
128.3
138.7
132.3
261.7
251.7
259.5
258.4
259.5
249.5
258.4
256.2
62.4
10.8
15.6
15.4
64.3
12.7
15.7
14.7
148.1
136.0
140.3
140.3
149.8
139.2
141.4
141.5
41.2
59.0
49.0
44.6
42.3
60.1
49.0
45.1
140.3
140.2
141.6
141.1
134.9
136.9
138.4
139.0
−13.1
−23.5
−16.2
−16.2
−14.0
−23.9
−16.2
−15.3
24.0
−7.4
4.3
−1.7
26.4
−8.6
0.3
75.5
34.3
31.8
31.6
78.3
36.6
31.9
29.9
−6.7
a All spectra measured in CDCl3 at 20 °C with chemical shifts to high frequency of 85% H3PO4. PA is in the phosphite group and PB is in the
phosphino group. The coordination chemical shift: Δδ = δ(complex) − δ(ligand).
in the presence of a proton acceptor to give the desired C1-sym-
metric phosphine–phosphites.
treatment of chiral ligands with 1 or 0.5 equiv. of [Rh(COD)2]-
BF4 were evaluated by 31P{1H} NMR spectroscopy. At a 1 : 1
ligand–metal ratio, two double doublets were observed in the
31P{1H} NMR spectra of compounds 1 (Scheme 2, a). The
rhodium complexes of PCnOP(S)-Hx showed large positive
chemical coordination shifts regarding the phosphine group, but
in the case of the phosphite moieties both positive and negative
shifts were observed.
When a ratio of 2 : 1 was applied, two double triplets were
obtained (Scheme 2, b) in those cases when n > 1. This pattern
cannot be attributed to the cis-[Rh(PCnOP(S)-H0)2]BF4 com-
plexes. The observed NMR characteristics rather correspond to
the structure of 2, where the phosphorus atoms of similar chemi-
cal environment are in trans position exhibiting a simple A2X2
spin system (by coupling with the 103Rh nucleus).
Stereo-electronic characterization of the ligands
The new ligands mentioned above are moderately air-sensitive
solids but are indefinitely stable in an inert atmosphere. Their
31P-NMR spectra were particularly informative for purity: in
each case, two singlets were observed, one for the phosphorus in
the phosphite (PA) and one in the phosphine (PB), except in the
case of PC1OP(S)-H8 and PC1OP(S)-H0, where two doublets
3
could be found with a J(P,P) coupling constant of about 6 Hz
(Table 1). From δ(PA) data it can be concluded that ligands
possessing the H8-biaryl moiety have phosphite groups of stron-
ger σ-donor ability compared to their H0-analogues.
The coordination chemistry of ligands PCnOP(S)-Hx with
rhodium was investigated because of its relevance to the asym-
metric catalysis described below. The products formed upon
However, when PC1OP(S)-H0 was used as a ligand a yellow
precipitate formed immediately. The residue of the mixture was
partly soluble in CH2Cl2 and acetone, but readily soluble in
DMSO. Despite the fact that DMSO is a good coordinating
9494 | Dalton Trans., 2012, 41, 9493–9502
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Scheme 2 Coordination features of the ligands (depicted 31P{1H}NMR spectra belong to the corresponding complexes of ligand PC3OP(S)-H0).
agent, d6-DMSO was chosen as a solvent for 31P{1H} NMR
studies of the complex formed. Interestingly, besides the
expected A2X2 spin system the 31P{1H} NMR spectrum of the
latter exhibited a much more complicated AA′XX′ multiplet
(Fig. 2). This second species can be identified as [Rh(PC1OP-
(S)-H0)2]BF4 where phosphines and phosphites of the two
ligands are in mutual cis positions as indicated by the large
2J(PO,PC) = 393 Hz. According to the measured 31P{1H} NMR
spectrum, the DMSO solution of the complex contains a
4 : 1 mixture of cis and trans isomers of [Rh(PC1OP(S)-H0)2]BF4.
In order to exclude the possible influence of DMSO on the
complex formation, the 31P{1H} NMR spectrum of a rhodium
complex with a ligand of a longer backbone, [Rh(PC2OP(S)-
H0)2]BF4, was also recorded in d6-DMSO. The resulting spin
system was the same (A2X2) as observed in CDCl3. Based on
studies by Reek and Pizzano et al.,13 the formation of cis chelate
Rh-complexes of hybrid phosphorus ligands is already known.
However, the bis chelate complex formed in their work at a
ligand–metal ratio of 1 : 1. Contrary to this, such a complex
could not be observed in our case. To our knowledge the only
study about the addition of a C1-symmetry hybrid phosphorus
ligand to [Rh(COD)2]BF4 in a 2 : 1 molar ratio was reported by
Pringle et al.14 However, in this case, the cis isomer was ident-
ified as the only product of the reaction.
On the basis of our results and of studies mentioned above, it
might be hypothesized that the coordination mode of binol-
based hybrid phosphorus ligands in bis chelate complexes
depends on (i) π-stacking interactions between binol-moieties,
(ii) chelate ring size as a steric factor and (iii) the electronic
features of coordinating phosphorus atoms.
A simple way of evaluating the σ-donor ability of the phos-
phorus functionalities is by measuring the magnitude of the
1J(77Se–31P) coupling constant in the 77Se isotopomer of the cor-
responding seleno-phosphate and phosphine-selenide. The mag-
nitude of lJ(77Se–3lP) is very much dependent upon the nature of
the organic groups bound to phosphorus, electron-withdrawing
groups causing the coupling constant to increase whereas elec-
tron-donating and bulky groups cause it to decrease.15
The synthesis of diselenides was performed by simply reacting
the corresponding ligand with elemental selenium. According to
the preparation method developed by Pizzano et al., the reaction
proceeds in a stepwise manner and needs a prolonged reaction
time (2–8 days) for completion at 100 °C in toluene.16 In con-
trast to this, we found that PCnOP(S)-H0 ligands react readily
with selenium powder producing the desired diselenides in
benzene after 24 h at room temperature (Table 2). It is also inter-
esting to note that the 31P{1H} NMR spectrum of 3(1) exhibited
a spectacular pattern due to the coupling between the two phos-
phorus atoms (Fig. 3).
1
It can be concluded from the data in Table 2 that J(77P–31Se)
coupling constants decrease with increasing values of n. Conse-
quently, the longer backbone makes the phosphine and phosphite
moieties in the ligand more electron donating. The electronic
differences between the phosphorus functionalities of the same
type decrease with the length of the backbone as expressed
in the decreasing differences in their appropriate coupling
constants.
Catalytic experiments
The variation in catalytic activity and enantioselectivity with the
length of the backbone shows the sensitivity of the catalysts to
the chelate ring size (Table 3) in the asymmetric hydrogenation
of dimethyl itaconate. Under similar reaction conditions (0 °C,
1 bar H2 and 25 °C, 1 bar) the five-membered Rh(I)-chelate has
no catalytic activity, and from six to eight-membered Rh(I)-
chelates a significant enhancement in rate is observed. Interest-
ingly, the PC3OP(S)-H8 ligand exhibits the highest ee. The
hydrogen pressure had a slight effect on the observed trend in
enantioselectivity, but a profound effect on the reaction rate.
In the catalytic experiments the catalytic systems were evalu-
ated in two different ways: using in situ formed catalysts starting
from [Rh(COD)2]BF4 and the corresponding chiral ligand or
applying preformed complexes 1 as catalysts. It is clearly visible
from the data of Chart 1 that complexes 1 provide higher ees in
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Fig. 2 Calculated (top and bottom for cis and trans isomers, respectively) and measured (middle) 31P{1H} NMR spectra for [Rh(PC1OP(S)-H8)2]-
BF4. Coupling constants used for simulated spectra; for the cis isomer: J(Rh,PC) = 125 Hz, J(Rh,PO) = 223 Hz, J(PC,PO)trans = 393 Hz, J(PC,PO)cis
= −54 Hz, J(PC,PC) = 29 Hz, J(PO,PO) = 36 Hz; for the trans isomer: J(Rh,PC) = 124 Hz, J(Rh,PO) = 219 Hz, J(PC,PO) = 43 Hz.
Table 2 31P–77Se coupling constants in compounds 3
Compound (n)
1J(77Se–31P)A (Hz)
1J(77Se–31P)B (Hz)
3(1)
3(2)
3(3)
3(4)
1053.6
1035.8
1038.3
1032.7
762.9
755.1
750.5
749.0
All spectra measured in benzene, at 20 °C at 121.495 MHz with chemical shifts to high frequency of 85% H3PO4. 1J(P–Se)A is the coupling constant
in the phosphite group and 1J(P–Se)B in the phosphino group.
each case. When the catalyst used was in situ made by addition
of 1 equiv. of ligand to [Rh(COD)2]BF4 instead of preformed
[Rh(COD)(PCnOP(S)-Hx)]BF4 (n = 1–4), the ees were lower.
It can also be seen that H8-ligands provide higher enantio-
selectivities than their H0-analogues. The most interesting
finding in this case is that the enantioselectivities increase mono-
tonously with the increasing chelate ring size. Using preformed
complexes 1 the ee rises from the value of 75.6 to 92.7. Since
the ligands only differ in the length of the backbone, we con-
cluded that the enantioselectivity was predominantly controlled
by the length of the backbone, i.e. by the increasing basicity of
the phosphine and phosphite moieties. It was also noted that the
enantioselectivity of the catalyst [Rh(COD)(PC4OP(S)-H8)]BF4
was sensitive to the solvent used. Higher ees were achieved in
CH2Cl2 (92.7%) and THF (90.1%) than in EtOAc (82.7%). Pre-
vious results by Pringle et al. with optically active, C1-symmetric
diphosphines also show that a larger chelate ring can provide
better enantioselectivity in the hydrogenation reaction of certain
substrates (e.g. (Z)-α-acetamidocinnamic acid methyl ester).17
An interesting effect has been described by Börner et al.18 and
is based on the observation in nonasymmetric hydrogenation of
imines. Five- and six-membered Rh(I)-chelates afforded the
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Fig. 3 31P{1H} NMR spectrum of 3(1).
Table 3 Asymmetric hydrogenation of dimethyl itaconate: a comparative study
0 °C, 1 bar
Time (min)
25 °C, 1 bar
Time (min)
25 °C, 5 barb
Ligand
ee (%)
Conv. (%)
ee (%)
Conv. (%)
Time (min)
ee (%)
PC1OP(S)-H8
PC2OP(S)-H8
PC3OP(S)-H8
PC4OP(S)-H8
—
—
—
—
—
—
120
120
120
60
90.1 (R)
89.9 (R)
96.9 (R)
86.8 (R)
1380
480
80
92.8 (R)
97.5 (R)
88.4 (R)
76.5
97.5
97.5
1380
360
120
93.2 (R)
96.9 (R)
87.2 (R)
94.2
100
95.4
Reaction conditions: 2.5 mmol of substrate in 5 mL of CH2Cl2; catalyst: 0.0055 mmol of chiral ligand and 0.005 mmol of [Rh(COD)2]BF4.
a Conversion was complete.
Chart 2 TOF vs. chelate ring size diagram. Reaction conditions:
2.5 mmol of substrate in 5 mL of CH2Cl2; catalyst: 0.0055 mmol of
PCnOP(S)-H0 and 0.005 mmol of [Rh(COD)2]BF4; temperature: 25 °C;
pressure: 5 bar; substrate: (Z)-α-acetamidocinnamic acid methyl ester.
(For further information about reaction conditions, see the Experimental
section.)
Chart 1 ee vs. chelate ring size diagram, catalyst: □ in situ prepared
catalyst using PCnOP(S)-H0 ligand,
in situ prepared catalyst using
PCnOP(S)-H8 ligand, preformed [Rh(PCnOP(S)-H8)(COD)]BF4
complex. Reaction conditions: 2.5 mmol of substrate in 5 mL of
CH2Cl2; S/C molar ratio: 500; temperature: 25 °C; pressure: 5 bar; sub-
strate: (Z)-α-acetamidocinnamic acid methyl ester. The configuration of
the product is (R) in each case. In the case of PCnOP(S)-H8 ligands con-
version was 100% in 1 h. (For reaction times for PCnOP(S)-H0 ligands,
see the Experimental section.)
functionalities proved to be very significant when (Z)-α-acetami-
docinnamic acid methyl ester was used as the substrate. The
turnover frequency ranges from 267 to 2961 h−1 when 5 to
8 membered chelate rings are varied. An opposite trend was
observed for P–Se coupling constants which decrease from
762.9 to 749 Hz and from 1053.6 to 1032.7 Hz in the phosphino
and in the phosphite group, respectively, indicating an increasing
basicity of both coordinating moieties.
It is worth noting that the conclusions drawn in this paper
could be extrapolated to Pd catalyzed asymmetric allylic alkyl-
ation. Conformational preferences will certainly be important,
but inevitably more difficult to predict. Further mechanistic
studies aimed at understanding these important features are
currently in progress.
desired amine in poor (20 h, conv. 16%) and modest yield (20 h,
conv. 86%), respectively. In contrast, the more flexible seven-
membered Rh(I)-chelate based on dppb (1,4-bis(diphenylphos-
phino)butane) as the ligand converted the imine within 2 h into
the desired product.
In order to compare the catalytic activity of the novel phos-
phine–phosphite ligands, the turnover frequencies (TOF) were
calculated (Chart 2). The dependence of catalytic activity on
chelate ring size and/or the electronic nature of the phosphorus
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(yield: 76.3%) of a white foam. [α]2D0 = 207.17° (c = 1.115,
CH2Cl2), mp. 45–46 °C. Anal. calcd for C33H32O3P2: C 73.60,
Conclusion
1
Several chiral heterobidentate ligands and their Rh-complexes
have been synthesized, characterized by 31P{1H} NMR spec-
troscopy and tested in the hydrogenation of dimethyl itaconate
and Z-(α)-acetamidocinnamic acid methyl ester. The rate and the
enantioselectivity of the asymmetric hydrogenation with a series
of new hybrid phosphine–phosphite ligands P(C)nOP (n = 1–4)
were strongly sensitive to the size of the formed chelate ring.
A monotonous increase in enantioselectivity and activity with
chelate ring size suggests that the increasing basicity of the phos-
phine and phosphite moieties with the increasing chelate ring
size is one of the key elements in determining activity and selec-
tivity, however, the role of the chelate conformation cannot be
neglected. Since the BINOL and H8-BINOL based ligands have
been widely used in catalytic reactions, the substantial improve-
ments of enantioselectivities and catalytic activities by simply
changing the length of the backbone of the ligands clearly indi-
cate the high potential of this new strategy. We believe this can
be applied to other catalytic reactions.
H 5.99%; found: C 73.37, H 5.97%. H NMR (300.130 MHz,
CDCl3): δ = 1.55 (m, 2H, CH2), 1.79 (m, 6H, CH2), 2.28 (m,
2H, CH2), 2.64 (m, 2H, CH2), 2.82 (m, 4H, CH2), 4.30 (m,
diast. 1H, CH2), 4.63 (m, diast. 1H, CH2), 6.70–7.50 ppm (aro-
matic 14H). 13C{1H} NMR (75.468 MHz, CDCl3): δ = 22.50 (s,
1C, CH2), 22.60 (s, 1C, CH2), 22.68 (s, 1C, CH2), 22.73 (s, 1C,
CH2), 27.74 (s, 1C, CH2), 27.78 (s, 1C, CH2), 29.20 (s, 2C,
1
2
CH2, overlapped), 64.54 (dd, J(P,C) = 13.6 Hz, J(P–O,C) =
4.3 Hz, 1C, CH2), 118.7–146.9 ppm (aromatic 24C). 31P{1H}
3
NMR (161.976 MHz, CDCl3): δ = −14.03 ppm (d, J(P,P) =
5.6 Hz), 134.93 (d, 3J(P,P) = 5.6 Hz).
[Rh(COD)(PC1OP(S)-H8)]BF4. PC1OP(S)-H8 (119.3 mg,
0.2216 mmol) dissolved in CH2Cl2 (5 mL) was added dropwise
to a solution of [Rh(COD)2]BF4 (90 mg, 0.2216 mmol) in
CH2Cl2 (5 mL). The resulting orange solution was stirred for
20 min, concentrated, filtered and finally treated with Et2O (3 ×
5 mL) to give 171 mg of [Rh(COD)(PC1OP(S)-H8)]BF4 as an
orange powder. Yield: 92%. mp. 230–236 °C. 1H NMR
(300.130 MHz, CDCl3): δ = 1.51 (m, 2H, CH2), 1.76 (m, 6H,
CH2), 2.13–2.71 (m, 12H, CH2, overlapped), 2.86 (m, 4H, CH2),
4.64 (m, 2H), 4.80 (m, 1H), 5.00 (m, 1H), 5.75 (m, 2H),
7.06–7.83 ppm (aromatic 14H). 13C{1H} NMR (75.468 MHz,
CDCl3): δ = 22.25 (s, 1C, CH2), 22.33 (s, 1C, CH2), 22.39 (s,
1C, CH2), 22.43 (s, 1C, CH2), 27.67 (s, 1C, CH2), 27.82 (s, 1C,
CH2), 28.57 (s, 1C, CH2), 29.08 (s, 1C, CH2), 29.14 (s, 1C,
CH2), 29.61 (s, 1C, CH2), 30.05 (s, 1C, CH2), 30.85 (s, 1C,
CH2), 68.06 (dd, J(P,C) = 30.1 Hz, 18.4 Hz, 1C, CH2), 100.76
(m, 1C, CH COD), 107.09 (m, 1C, CH COD), 108.80 (m, 1C,
CH COD), 111.94 (m, 1C, CH COD), 118.5–145.9 ppm (aro-
matic 24C). 31P{1H} NMR (121.495 MHz, CDCl3): δ = 64.29
Experimental
General experimental details
All manipulations were carried out under argon using Schlenk
techniques. Solvents were purified, dried and deoxygenated by
standard methods. (S)-Chloro-dinaphtho[2,1-d:1′,2′-f][1,3,2]-
dioxaphosphepine and (S)-chloro-5,5′,6,6′,7,7′,8,8′-octahydrodi-
naphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine,19,20 1-diphenyl-
phosphino-1-{(S)-dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-
2-yloxy}-methane (PC1OP(S)-H0),21 hydroxymethyl-,8 hydro-
xyethyl-,9 hydroxypropyl-,9 and hydroxybutyl-diphenylphos-
phine10 were prepared according to the literature methods.
31P{1H}-, 1H- and 13C{1H}-NMR spectra were recorded on
either a VARIAN UNITY 300 spectrometer operating at
121.42 MHz, 300.15 MHz and 75.43 MHz, respectively, on a
Bruker Avance 400 spectrometer (NMR Laboratory, University
of Pannonia) operating at 161.98 MHz, 400.13 MHz and
100.61 MHz, respectively, or on a Bruker DRX-500 spec-
trometer operating at 202.45 MHz, 500.13 MHz and
125.76 MHz, respectively. ESI mass spectra were recorded on
either a Thermo Finnigan LCQ Duo spectrometer or on an
Agilent 1100 LC/MSD SL Quadrupole mass spectrometer (Uni-
versity of Pannonia). Diethyl ether, THF and CH2Cl2 were
freshly distilled prior to use. All other starting materials were
purchased from Aldrich.
1
2
(dd, J(Rh,P) = 149.2 Hz, J(P,P) = 42.3 Hz), 161.34 ppm (dd,
1J(Rh,P) = 259.5 Hz, J(P,P) = 42.3 Hz). ESI mass spectrum:
2
m/z 748.93 [M+ − BF4], 640.93 [M+ − BF4 − COD] (calculated
749.18 [M+ − BF4], 641.09 [M+ − BF4 − COD]).
1-Diphenylphosphino-2-{(S)-5,5′,6,6′,7,7′,8,8′-octahydro-dinaphtho-
[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-2-yloxy}-ethane (PC2OP-
(S)-H8). This product was prepared by following the procedure
described for PC1OP(S)-H8. White foam (yield: 78.1%). [α]D20
=
178.65° (c = 1.405, CH2Cl2), mp. 42–44 °C. Anal. calcd for
C34H34O3P2: C 73.90, H 6.20%; found: C 73.79, H 6.41%.
1H NMR (300.130 MHz, CDCl3): δ = 1.57 (m, 2H, CH2), 1.80
(m, 6H, CH2), 2.27 (m, 2H, CH2), 2.44 (m, 2H, CH2PPh2), 2.66
(m, 2H, CH2), 2.82 (m, 4H, CH2), 3.89 (m, diast. 1H, OCH2),
4.00 (m, diast. 1H, OCH2), 6.80–7.40 ppm (aromatic 14H).
13C{1H} NMR (75.468 MHz, CDCl3): δ = 22.51 (s, 1C, CH2),
22.57 (s, 1C, CH2), 22.68 (s, 1C, CH2), 22.72 (s, 1C, CH2),
27.76 (s, 1C, CH2), 27.78 (s, 1C, CH2), 29.21 (s, 2C, CH2, over-
1-Diphenylphosphino-1-{(S)-5,5′,6,6′,7,7′,8,8′-octahydro-di-
naphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-2-yloxy}-methane
(PC1OP(S)-H8). Hydroxymethyldiphenylphosphine (0.79 g,
3.67 mmol) and triethylamine (0.567 g, 0.78 mL, 5.57 mmol)
were dissolved in 30 mL of ether at room temperature.
H8-chlorophosphite (2.0 g, 5.57 mmol) was dissolved in 30 mL
of ether at −10 °C. The solution of the phosphine was added to
the solution of the chlorophosphite at −10 °C and stirred for a
further 30 min. The mixture was filtered through a pad of acti-
vated Al2O3 and washed with 4 × 10 mL of ether. The solvent of
the filtrate was removed under reduced pressure to obtain 1.50 g
1
3
lapped), 30.48 (dd, J(P,C) = 14.9 Hz, J(P–O,C) = 4.3 Hz, 1C,
2
2
CH2PPh2), 62.26 (dd, J(P–O,C) = 27.9 Hz, J(P,C) = 9.30 Hz,
1C, OCH2), 118.7–146.5 ppm (aromatic 24C). 31P{1H} NMR
(161.976 MHz, CDCl3): δ = −24.14 (s), 136.58 ppm (s).
[Rh(COD)(PC2OP(S)-H8)]BF4. This product was prepared
by following the procedure described for [Rh(COD)(PC1OP(S)-
H8)]BF4. Orange powder (yield: 92%). mp. 179–181 °C.
1H NMR (500.130 MHz, CDCl3): δ = 1.43 (m, 2H, CH2), 1.71
9498 | Dalton Trans., 2012, 41, 9493–9502
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(m, 6H, CH2), 1.91 (m, 1H, CHH), 2.12 (m, 3H, CH2, over-
lapped), 2.20 (m, 2H, CH2), 2.31–2.58 (m, 6H, CH2), 2.72 (m,
5H, CH2, overlapped), 2.94 (m, 1H, CH2), 3.97 (m, 1H), 4.28
(m, 1H), 4.43 (m, 1H), 4.74 (m, 1H), 5.23 (m, 1H), 5.62 (m,
1H), 6.9–7.9 (aromatic 14H). 13C{1H} NMR (75.468 MHz,
CDCl3): δ = 22.27 (s, 1C, CH2), 22.34 (s, 1C, CH2), 22.42 (s,
2C, CH2), 27.18 (d, J(P,C) = 5.6 Hz, 1C, CH2), 27.59 (s, 1C,
CH2), 27.74 (s, 1C, CH2), 28.39 (s, 1C, CH2 COD), 29.09 (s,
1C, CH2), 29.12 (s, 1C, CH2), 29.62 (s, 1C, CH2 COD), 30.61
(s, 1C, CH2 COD), 31.45 (s, 1C, CH2 COD), 64.54 (m, 1C,
CH2), 98.20 (m, 1C, CH2), 104.51 (m, 1C, CH2), 108.12 (m,
1C, CH2), 111.90 (m, 1C, CH2), 126.3–145.7 ppm (aromatic
24C). 31P{1H} NMR (121.495 MHz, CDCl3): δ = 12.65 (dd,
1J(Rh,P) = 139.2 Hz, 2J(P,P) = 60.1 Hz), 128.30 ppm (dd,
186.55° (c = 1.19, CH2Cl2), mp. 42–43 °C. Anal. calcd for
C36H38O3P2: C 74.47, H 6.60%; found: C 74.35, H 6.94%.
1H NMR (300.130 MHz, CDCl3): δ = 1.58 (m, 4H, CH2 and
CH2CH2PPh2), 1.80 (m, 8H, 3CH2 and OCH2CH2), 2.07 (m,
2H, CH2PPh2), 2.29 (m, 2H, CH2), 2.67 (m, 2H, CH2), 2.83 (m,
4H, CH2), 3.78 (m, diast. 1H, OCH2), 3.92 (m, diast. 1H,
OCH2), 6.7–7.5 ppm (aromatic 14H). 13C{1H} NMR
(75.468 MHz, CDCl3): δ = 22.31 (d, J = 16.7 Hz, 1C, CH2),
22.52 (s, 1C, CH2), 22.59 (s, 1C, CH2), 22.71 (s, 1C, CH2),
22.75 (s, 1C, CH2), 27.68 (d, J = 11.2 Hz, 1C, CH2), 27.79 (s,
1C, CH2), 27.82 (s, 1C, CH2), 29.20 (s, 1C, CH2), 29.23 (s, 1C,
CH2), 32.47 (dd, J = 12.4 Hz, J = 4.3 Hz, 1C, CH2), 64.37 (d,
J = 10.5 Hz, 1C, CH2), 118.6–146.6 ppm (aromatic 24C).
31P{1H} NMR (161.976 MHz, CDCl3): δ = −15.26 (s),
139.01 ppm (s).
2
1J(Rh,P) = 249.5 Hz, J(P,P) = 60.14 Hz). ESI mass spectrum:
m/z 763.07 [M+ − BF4], 655.20 [M+ − BF4 − COD] (calculated
763.20 [M+ − BF4], 655.10 [M+ − BF4 − COD]).
[Rh(COD)(PC4OP(S)-H8)]BF4. This product was prepared by
following the procedure described for [Rh(COD)(PC1OP(S)-
H8)]BF4. Orange powder (yield: 95%). mp. 164–166 °C. 1H
NMR (500.130 MHz, CDCl3): δ = 1.44 (m, 2H, CH2), 1.70 (m,
6H, CH2), 1.80 (m, 2H, CH2), 1.97 (m, 2H, CH2), 2.14 (m, 6H,
CH2), 2.45 (m, 6H, CH2), 2.73 (m, 6H, CH2), 4.10 (m, 1H),
4.21 (m, 1H), 4.82 (m, 1H), 5.00 (m, 1H), 5.16 (m, 1H), 5.48
(m, 1H), 6.9–7.8 ppm (aromatic 14H). 13C{1H} NMR
(75.468 MHz, CDCl3): δ = 21.98 (s, 1C, CH2), 22.27 (s, 1C,
CH2), 22.35 (s, 1C, CH2), 22.39 (s, 1C, CH2), 22.47 (s, 1C,
CH2), 27.60 (s, 1C, CH2), 27.63 (s, 1C, CH2), 28.87 (s, 1C,
CH2), 29.04 (s, 1C, CH2), 29.13 (s, 1C, CH2), 29.39 (s, 1C,
CH2), 29.74 (s, 1C, CH2), 29.77 (s, 1C, CH2), 30.58 (s, 1C,
CH2), 31.15 (s, 1C, CH2), 69.60 (m, 1C, CH2), 96.87 (m, 1C,
CH COD), 99.35 (m, 1C, CH COD), 107.90 (m, 1C, CH COD),
111.79 (m, 1C, CH COD), 126.6–146.5 ppm (aromatic 24C).
31P{1H} NMR (121.495 MHz, CDCl3): δ = 14.65 (dd,
1J(Rh,P) = 141.5 Hz, 2J(P,P) = 45.7 Hz), 132.34 ppm (dd,
1-Diphenylphosphino-3-{(S)-5,5′,6,6′,7,7′,8,8′-octahydro-dinaphtho-
[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-2-yloxy}-propane (PC3OP-
(S)-H8). This product was prepared by following the procedure
described for PC1OP(S)-H8. White foam (yield: 47.3%). [α]D20
=
189.7° (c = 1.165, CH2Cl2), mp. 45–48 °C. Anal. calcd for
C35H36O3P2: C 74.19, H 6.40%; found: C 74.14, H 6.32%.
1H NMR (300.130 MHz, CDCl3): δ = 1.59 (m, 2H, CH2), 1.81
(m, 8H, 3CH2 and OCH2CH2, overlapped), 2.12 (m, 2H,
CH2PPh2), 2.32 (m, 2H, CH2), 2.67 (m, 2H, CH2), 2.83 (m, 4H,
CH2), 3.86 (m, diast. 1H, OCH2), 4.01 (m, diast. 1H, OCH2),
6.82–7.45 ppm (aromatic 14H). 13C{1H} NMR (75.468,
CDCl3): δ = 22.51 (s, 1C, CH2), 22.58 (s, 1C, CH2), 22.70 (s,
1C, CH2), 22.75 (s, 1C, CH2), 24.19 (d, J = 11.8 Hz, 1C, CH2),
27.79 (s, 1C, CH2), 27.82 (s, 1C, CH2), 29.23 (s, 2C, CH2, over-
lapped), 29.45 (d, J = 18.6 Hz, 1C, CH2), 65.32 (dd, J = 14.3 Hz,
J = 10.6 Hz, 1C, CH2), 118.7–146.9 ppm (aromatic 24C). 31P{1H}
NMR (121.495 MHz, CDCl3): δ = −16.21 (s), 138.45 ppm (s).
2
1J(Rh,P) = 256.2 Hz, J(P,P) = 45.7 Hz). ESI mass spectrum:
m/z 791.1 [M+ − BF4], 683.0 [M+ − BF4 − COD] (calculated
791.23 [M+ − BF4], 683.54 [M+ − BF4 − COD]).
[Rh(COD)(PC3OP(S)-H8)]BF4. This product was prepared
by following the procedure described for [Rh(COD)(PC1OP(S)-
H8)]BF4. Orange powder (yield: 94%). mp. 220–225 °C.
1H NMR (300.130 MHz, CDCl3): δ = 1.54 (m, 2H, CH2), 1.78
(m, 8H, CH2, overlapped), 2.25 (m, 8H, CH2, overlapped),
2.54–3.01 (m, 10H, CH2, overlapped), 3.96 (m, 1H), 4.24 (m,
1H), 4.94 (m, 1H), 4.98 (m, 1H), 5.78 (m, 2H, overlapped),
6.9–7.7 ppm (aromatic 14H). 13C{1H} NMR (75.468, CDCl3):
δ = 22.28 (s, 1C, CH2), 22.34 (s, 1C, CH2), 22.40 (s, 1C, CH2),
22.47 (s, 1C, CH2), 24.85 (s, 1C, CH2), 27.08 (d, J(P,C) =
27.4 Hz, 1C, CH2), 27.64 (s, 1C, CH2), 27.71 (s, 1C, CH2),
28.17 (s, 1C, CH2), 29.13 (s, 2C, CH2), 29.64 (s, 1C, CH2), 31.06 (s,
1C, CH2), 31.61 (s, 1C, CH2), 65.87 (m, 1C, CH2), 97.55 (m, 1C,
CH2), 103.25 (m, 1C, CH2), 109.08 (m, 1C, CH2), 111.74 (m, 1C,
CH2), 126.5–145.7 ppm (aromatic 24C). 31P{1H} NMR
(121.495 MHz, CDCl3): δ = 15.66 (dd, 1J(Rh,P) = 141.5 Hz, 2J(P,P)
= 49.0 Hz), 138.71 ppm (dd, 1J(Rh,P) = 258.4 Hz, 2J(P,P) = 49.0 Hz).
ESI mass spectrum: m/z 776.87 [M+ − BF4], 668.93 [M+ − BF4 −
COD] (calculated 777.21 [M+ − BF4], 669.12 [M+ − BF4 − COD]).
[Rh(COD)(PC1OP(S)-H0)]BF4. This product was prepared
by following the procedure described for [Rh(COD)(PC1OP(S)-
H8)]BF4. Orange powder (yield: 92%). mp. 175–180 °C.
1H NMR (300.130 MHz, CDCl3): δ = 1.95–1.69 (m, 8H, CH2
COD, overlapped), 4.76 (m, 1H, CHH), 4.93 (m, 1H, CH COD),
5.05 (m, 1H, CHH), 5.60 (m, 1H, CH COD), 5.74 (m, 2H,
CH COD, overlapped), 7.1–8.3 ppm (aromatic 22H). 13C{1H}
NMR (75.468 MHz, CDCl3): δ = 28.55 (s, 1C, CH2), 29.64 (s,
1C, CH2), 29.97 (s, 1C, CH2), 30.71 (s, 1C, CH2), 68.08 (m, 1C,
CH2), 100.93 (m, 1C, CH), 106.82 (m, 1C, CH), 109.08 (m, 1C,
CH), 112.31 (m, 1C, CH), 212.4–147.1 ppm (aromatic 32C).
31P{1H} NMR (121.495 MHz, CDCl3): δ = 62.44 (dd,
1J(Rh,P) = 148.1 Hz, 2J(P,P) = 41.2 Hz), 164.3 ppm (dd,
2
1J(Rh,P) = 261.7 Hz, J(P,P) = 41.2 Hz). ESI mass spectrum:
m/z 740.93 [M+ − BF4], 632.93 [M+ − BF4 − COD] (calculated
741.12 [M+ − BF4], 633.03 [M+ − BF4 − COD]).
[Rh(PC1OP(S)-H0)2]BF4. This product was prepared by
addition of PC1OP(S)-H0 (29.4 mg, 0.0554 mmol) to [Rh-
(COD)2]BF4 (11.25 mg, 0.0272 mmol) in CDCl3. After for-
mation of a yellow precipitate the solvent was removed in vacuo
and the residue was dissolved in d6-DMSO. 31P{1H} NMR
1-Diphenylphosphino-4-{(S)-5,5′,6,6′,7,7′,8,8′-octahydro-dinaphtho-
[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-2-yloxy}-butane (PC4OP-
(S)-H8). This product was prepared by following the procedure
described for PC1OP(S)-H8. White foam (yield: 38.6%). [α]D20
=
This journal is © The Royal Society of Chemistry 2012
Dalton Trans., 2012, 41, 9493–9502 | 9499

View Article Online
(161.976 MHz, d6-DMSO): trans isomer δ = 63.8 (dt, 1J(Rh,PC)
= 124 Hz, J(P,P) = 43 Hz), 184.6 (dt, J(Rh,PO) = 219 Hz,
2J(PO,PC) = 43 Hz), cis isomer 62.4 (m, J(PC,Rh) = 125 Hz,
J(PC,PO)trans = 393 Hz, J(PC,PO)cis = −54 Hz, J(PC,PC) =
δ = 26.72 (1J(P,Se) = 755.1 Hz, P–C), 77.73 ppm (1J(P,Se) =
1035.8 Hz, P–O).
2
1
1-Diphenylphosphino-3-{(S)-dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxa-
phosphepin-2-yloxy}-propane (PC3OP(S)-H0). This product was
prepared by following the procedure described for PC1OP(S)-H8.
White foam (yield: 53.1%). [α]2D0 = 394.0° (c = 1.00, CH2Cl2),
mp. 53–55 °C. Anal. calcd for C35H28O3P2: C 75.26, H 5.05%;
found: C 75.22, H 4.94%. 1H NMR (300.130 MHz, CDCl3): δ =
1.76 (m, 2H, CH2PPh2), 2.12 (m, 2H, CH2), 3.86 (m, diast. 1H,
OCH2), 4.06 (m, diast. 1H, OCH2), 7.29–8.06 ppm (aromatic
22H). 13C{1H} NMR (75.468 MHz, CDCl3): δ = 24.12 (d, J =
11.8 Hz, CH2), 27.64 (dd, J = 17.7 Hz, J = 3.72 Hz, CH2),
65.64 (dd, J = 14.88 Hz, J = 6.82 Hz, CH2), 121.65–
148.72 ppm (m, aromatic 32C). 31P{1H} NMR -(121.495 MHz,
CDCl3): δ = −16.25 (s), 141.64 ppm (s).
29 Hz), 181.9 ppm (m, J(PO,Rh) = 223 Hz, J(PO,PC)trans
393 Hz, J(PO,PC)cis = −54 Hz, J(PO,PO) = 36 Hz).
=
Diselenide of PC1OP(S)-H0. To a mixture of PC1OP(S)-H0
(40 mg, 0.075 mmol) and elemental selenium (15 mg,
0.19 mmol) benzene (2.5 mL) was added and the resulting
slurry was stirred for 24 h. After stirring, the unreacted selenium
was left to be deposited and the required quantity of the solution
was added into an NMR tube. 31P{1H} NMR (121.495 MHz,
benzene): δ = 27.16 (dd, 1J(P,Se) = 762.9 Hz, 3J(P,P) =
25.5 Hz), 77.58 ppm (dd, 1J(P,Se) = 1053.6 Hz, 25.5 Hz).
1-Diphenylphosphino-2-{(S)-dinaphtho[2,1-d:1′,2′-f][1,3,2]-
dioxaphosphepin-2-yloxy}-ethane (PC2OP(S)-H0). This product
was prepared by following the procedure described for PC1OP-
(S)-H8. White foam (yield: 37.3%). [α]2D0 = 364.0° (c = 1.00,
CH2Cl2), mp. 56–58 °C. Anal. calcd for C35H28O3P2: C 75.00,
[Rh(COD)(PC3OP(S)-H0)]BF4. This product was prepared
by following the procedure described for [Rh(COD)(PC1OP(S)-
H8)]BF4. Orange powder (yield: 90%). mp. 174–178 °C.
1H NMR (500.130 MHz, CDCl3): δ = 1.73 (m, 1H), 1.88 (m,
1H), 2.10 (m, 2H), 2.17 (m, 2H), 2.28 (m, 2H), 2.35 (m, 1H),
2.72 (m, 1H), 2.91 (m, 2H), 4.19 (m, 1H), 4.35 (m, 1H), 5.00
(m, 2H), 5.17 (m, 1H), 5.79 (m, 1H), 7.3–8.2 ppm (aromatic
22H). 13C{1H} NMR (75.468 MHz, CDCl3): δ = 24.83 (s, 1C,
CH2), 27.19 (d, J(P,C) = 27.2 Hz, 1C, CH2), 27.37 (s, 1C, CH2),
28.45 (s, 1C, CH2 COD), 29.91 (s, 1C, CH2 COD), 30.71 (s,
1C, CH2 COD), 31.26 (s, 1C, CH2 COD), 66.03 (s, 1C, CH2),
97.72 (m, 1C, CH COD), 103.27 (m, 1C, CH COD), 109.76 (m,
1C, CH COD), 112.18 (m, 1C, CH COD), 120.7–147.1 ppm
(aromatic 32C). 31P{1H} NMR (121.495 MHz, CDCl3): δ =
1
H 4.81%; found: C 74.58, H 5.15%. H NMR (400.130 MHz,
CDCl3): δ = 2.40 (m, 2H, CH2PPh2), 3.86 (m, diast. 1H, OCH2),
4.04 (m, diast. 1H, OCH2), 7.29–8.06 ppm (aromatic 22H).
1
13C{1H} NMR (100.613 MHz, CDCl3): δ = 20.04 (d, J(P,C) =
3.3 Hz, CH2PPh2), 69.61 (d, 2J(P–O,C) = 6.7 Hz), 119.00–
132.74 ppm (aromatic 32C). 31P{1H} NMR (121.495 MHz,
CDCl3): δ = −23.54 (s), 140.16 ppm (s).
[Rh(COD)(PC2OP(S)-H0)]BF4. This product was prepared
by following the procedure described for [Rh(COD)(PC1OP(S)-
H8)]BF4. Orange powder (yield: 89%). mp. 170–174 °C.
1H NMR (300.130 MHz, CDCl3): δ = 2.05 (m, 2H, CH2), 2.19
(m, 4H, CH2, overlapped), 2.47 (m, 2H, CH2), 2.78 (m, 1H,
CHH), 3.04 (m, 1H, CHH), 4.23 (m, 1H), 4.35 (m, 1H), 4.59
(m, 1H), 4.87 (m, 1H), 5.38 (m, 1H), 5.68 (m, 1H),
7.16–8.27 ppm (aromatic 22H). 13C{1H} NMR (75.468 MHz,
CDCl3): δ = 27.26 (d, J(P,C) = 38.2 Hz, 1C, CH2), 28.55 (m,
1C, CH2 COD), 29.79 (m, 1C, CH2 COD), 30.38 (m, 1C, CH2
COD), 31.20 (m, 1C, CH2 COD), 64.75 (m, 1C, CH2), 98.32
(m, 1C, CH COD), 104.05 (m, 1C, CH COD), 108.90 (m, 1C,
CH COD), 112.50 (m, 1C, CH COD), 120.7–146.7 ppm (aro-
matic 32C). 31P{1H} NMR (121.495 MHz, CDCl3): δ = 10.82
2
15.58 (dd, 1J(Rh,P) = 140.3 Hz, J(P,P) = 49.0 Hz), 145.93 ppm
1
2
(dd, J(Rh,P) = 259.5 Hz, J(P,P) = 49.0 Hz). ESI mass spec-
trum: m/z 768.80 [M+ − BF4], 660.93 [M+ − BF4 − COD] (cal-
culated 769.15 [M+ − BF4], 661.06 [M+ − BF4 − COD]).
[Rh(PC3OP(S)-H0)2]BF4. This product was prepared by fol-
lowing the procedure described for [Rh(PC1OP(S)-H0)2]BF4.
1
31P{1H} NMR (120.495 MHz, CDCl3): δ = 9.52 (dt, J(Rh,P) =
120.3 Hz, 2J(P,P) = 53.5 Hz), 164.66 ppm (dt, 1J(Rh,P) =
213.8 Hz, 2J(P,P) = 53.5 Hz).
Diselenide of PC3OP(S)-H0. Diselenide of PC3OP(S)-H0 was
prepared by following the procedure described for the diselenide
of PC1OP(S)-H0. 31P{1H} NMR (121.495 MHz, benzene):
δ = 32.52 (1J(P,Se) = 750.5 Hz, P–C), 77.96 ppm (1J(P,Se) =
1038.3 Hz, P–O).
1
2
(dd, J(Rh,P) = 136.0 Hz, J(P,P) = 59.0 Hz), 132.81 ppm (dd,
1J(Rh,P) = 251.7 Hz, J(P,P) = 59.0 Hz). ESI mass spectrum:
2
m/z 754.80 [M+ − BF4], 646.87 [M+ − BF4 − COD] (calculated
755.14 [M+ − BF4], 647.04 [M+ − BF4 − COD]).
1-Diphenylphosphino-4-{(S)-dinaphtho[2,1-d:1′,2′-f][1,3,2]-
dioxaphosphepin-2-yloxy}-butane (PC4OP(S)-H0). This product
was prepared by following the procedure described for PC1OP-
(S)-H8. White foam (yield: 42.6%). [α]2D0 = 319.0° (c = 1.11,
CH2Cl2), mp. 45–47 °C. Anal. calcd for C35H28O3P2: C 75.52,
[Rh(PC2OP(S)-H0)2]BF4. This product was prepared by fol-
lowing the procedure described for [Rh(PC1OP(S)-H0)2]BF4.
1
31P{1H} NMR (121.495 MHz, CDCl3): δ = 7.68 (dt, J(Rh,P) =
123.6 Hz, 2J(P,P) = 55.7 Hz), 153.34 ppm (dt, 1J(Rh,P) =
204.9 Hz, 2J(P,P) = 55.7 Hz). 31P{1H} NMR (121.495 MHz,
d6-DMSO): δ = 10.30 (dt, 1J(Rh,P) = 122.5 Hz, 2J(P,P) =
54.6 Hz), 156.47 ppm (dt, 1J(Rh,P) = 207.2 Hz, 2J(P,P) =
54.6 Hz).
1
H 5.28%; found: C 75.03, H 5.38%. H NMR (400.130 MHz,
CDCl3): δ = 1.51 (m, 2H, CH2CH2PPh2), 1.71 (m, 2H,
OCH2CH2), 2.02 (m, 2H, CH2PPh2), 3.73 (m, diast. 1H, OCH2),
3.93 (m, diast. 1H, OCH2), 7.19–8.05 ppm (aromatic 22H).
13C{1H} NMR (100.613 MHz, CDCl3): δ = 22.19 (d, J(P,C) =
16.7 Hz, 1C, CH2), 27.50 (d, J(P,C) = 11.37 Hz, 1C, CH2),
32.24 (dd, J(P,C) = 13.0, J(P,C) = 4.0, 1C, CH2), 64.68 (d,
J(P,C) = 6.1 Hz, 1C, CH2), 118.87–138.44 ppm (m, aromatic
Diselenide of PC2OP(S)-H0. Diselenide of PC2OP(S)-H0 was
prepared by following the procedure described for the diselenide
of PC1OP(S)-H0. 31P{1H} NMR (121.495 MHz, benzene):
9500 | Dalton Trans., 2012, 41, 9493–9502
This journal is © The Royal Society of Chemistry 2012

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32C). 31P{1H} NMR (161.976 MHz, CDCl3): δ = −16.24 (s),
(25 m × 0.25 mm, df = 0.12 μm), N2 as carrier gas, a split/split-
less injector at 250 °C, and a FID at 250 °C. Temperature
program: 2 min at 140 °C; 2 °C min−1 from 140 °C to 180 °C;
40 min at 180 °C.
TOF vs. chelate ring size diagram (Chart 2) was calculated by
using the data compiled in Table 4.
141.13 ppm (s).
[Rh(COD)(PC4OP(S)-H0)]BF4. This product was prepared by
following the procedure described for [Rh(COD)(PC1OP(S)-
H8)]BF4. Orange powder (yield: 90%). mp. 166–168 °C. 1H NMR
(400.130 MHz, CDCl3): δ = 1.91–2.34 (m, 8H, overlapped),
2.58 (m, 4H), 2.80 (m, 1H), 2.91 (m, 1H), 4.38 (m, 1H), 4.53
(m, 1H), 4.99 (m, 1H), 5.12 (m, 1H), 5.26 (m, 1H), 5.62 ppm
(m, 1H), 6.9–8.3 (aromatic 22H). 13C{1H} NMR (100.613 MHz,
CDCl3): δ = 15.18 (s, 1C, CH2), 21.88 (s, 1C, CH2), 28.37 (d,
J(P,C) = 27.0 Hz, 1C, CH2), 29.18 (s, 1C, CH2 COD), 29.4 (s,
1C, CH2 COD), 29.67 (s, 1C, CH2 COD), 30.73 (s, 1C, CH2
COD), 69.85 (s, 1C, CH2), 97.00 (m, 1C, CH COD), 99.05 (m,
1C, CH COD), 108.43 (m, 1C, CH COD), 112.24 (m, 1C,
CH COD), 120.8–147.1 ppm (aromatic 32C). 31P{1H} NMR
Acknowledgements
The authors thank the National Office for Research and Techno-
logy (KMOP 1.1.4) for financial support. This article was partly
made under the project TÁMOP-4.2.1/B-09/1/KONV-2010-
0003, TÁMOP-4.2.2/B-10/1-2010-0025 and PHC Balaton/
17320ZA. These projects are supported by the European Union
and co-financed by the European Social Fund. We thank Mr
Béla Édes for skillful assistance in synthetic and catalytic
experiments.
1
(121.495 MHz, CDCl3): δ = 15.41 (dd, J(Rh,P) = 140.3 Hz,
2J(P,P) = 44.6 Hz), 139.42 ppm (dd, 1J(Rh,P) = 258.4 Hz,
2J(P,P) = 44.6 Hz). ESI mass spectrum: m/z 783.0 [M+ − BF4],
675.0 [M+ − BF4 − COD] (calculated 783.17 [M+ − BF4],
675.07 [M+ − BF4 − COD]).
References
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Reaction time
(min)
Conversion
(%)
TOF
Ligand
ee (%)
(1 h−1
)
PC1OP(S)-H0
PC2OP(S)-H0
PC3OP(S)-H0
PC4OP(S)-H0
45.0
5.0
5.0
5.1
39.1
33.5
43.1
49.0
63.5
77.3
81.0
88.4
261
2010
2586
2882
Reaction conditions: 2.5 mmol of substrate in 5 mL of CH2Cl2; catalyst:
0.0055 mmol of PCnOP(S)-H0 and 0.005 mmol of [Rh(COD)2]BF4;
temperature: 25 °C; pressure: 5 bar; substrate: (Z)-α-acetamidocinnamic
acid methyl ester.
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9502 | Dalton Trans., 2012, 41, 9493–9502
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