A new route to achiral and chiral 1,2-bis(phosphino)ethanes, 1-arsino-2-phosphinoethanes, and 1,3-bis(phosphino)propanes and the molecular structure and catalytic activity of some rhodium(I) complexes derived thereof

Article abstract of DOI:10.1039/b401585a

A series of unsymmetrical 1,2-bis(phosphino)ethanes R₂PCH ₂CH₂PR′₂ (2a-d) and 1-arsino-2- phosphinoethanes R₂AsCH₂CH₂PR′ ₂ (3a-c) mainly with bulky substituants R and

Full text of DOI:10.1039/b401585a

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F U L L P A P E R
A new route to achiral and chiral 1,2-bis(phosphino)ethanes,
1-arsino-2-phosphinoethanes, and 1,3-bis(phosphino)propanes
and the molecular structure and catalytic activity of some
rhodium(I) complexes derived thereof†
Guido Fries, Justin Wolf, Kerstin Ilg, Bernhard Walfort, Dietmar Stalke and Helmut Werner*
Institut für Anorganische Chemie der Universität Würzburg, Am Hubland, D-97074 Würzburg,
Germany. E-mail: helmut.werner@mail.uni-wuerzburg.de
Received 3rd February 2004, Accepted 13th April 2004
First published as an Advance Article on the web 10th May 2004
A series of unsymmetrical 1,2-bis(phosphino)ethanes R2PCH2CH2PR′2 (2a–d) and 1-arsino-2-phosphinoethanes
R2AsCH2CH2PR′2 (3a–c) mainly with bulky substituents R and R′ were prepared from the cyclic sulfate 1 by
stepwise cleavage of the carbon–oxygen bonds by LiPR2 and LiPR′2 or LiAsR2 and LiPR′2, respectively. Analogously,
racemic mixtures of R2PCH2CH(Me)PPh2 (R = iPr 5a, Cy 5b) as well as the enantiomers (R)-5a, (R)-5b and (R)-
tBu2PCH2CH(Me)PPh2 (R)-5c were obtained from the corresponding unsymmetrical cyclic sulfates 4 and (S)-4. On a
similar route, the racemates of the 1,3-bis(phosphino)propanes R2PCH2CH2CH(Me)PPh2 (R = iPr 7, tBu 8), optically pure
(R)-8 and (S,S)-iPr2PCH(Me)CH2CH(Me)PPh2 (S,S)-10 were prepared. The reaction of [{RhCl(4-C8H12)}2] with chelating
ligands L–L, where L–L is R2PCH2P(men)2 (R = iPr, Ph; men = (1S,2R,5S)-menthyl), Cy2AsCH2P(men)2, or (R)-5a, (R)-
5b, (R)-5c, (R)-8 and (S,S)-10, in the presence of AgPF6, gave the complexes [Rh(4-C8H12)(L–L)]PF6 (12a–h) which were
used as pre-catalysts in the hydrogenation of the methyl ester of -acetamidocinnamic acid (ACM). Depending on L–L,
the solvent, the temperature and the pressure of H2, optical yields of up to 69% ee were achieved. For two of the rhodium
complexes, 12c and 12d, the molecular structures were determined by X-ray crystallography.
Following our interest in the use of new, possibly hemilabile bi-
dentate ligands as part of d6 and d8 metal complexes,1 we recently
described the preparation of new symmetrical and unsymmetrical
bis(phosphino)methanes and arsino(phosphino)methanes with
bulky substituents R and R′ at the donor centers.2,3 The search for
these ligands was initiated by the fact that apart from the well-
known compounds Ph2PCH2PPh2 (dppm) and Me2PCH2PMe2
(dmpm) related, in particular unsymmetrical derivatives of the
general composition R2PCH2PR′2 were almost unknown.4 After we
prepared at the beginning of these studies a variety of rhodium(I)
complexes with iPr2PCH2PR2 (R = Ph, Cy) and iPr2PCH2AsR2 (R =
iPr, tBu) as ligands,2,3 we later extended this work to correspond-
ing ruthenium(II) compounds5 and included, for comparison, also
unsymmetrical 1,2-bis(phosphino)ethanes and 1-arsino-2-phosphi-
noethanes as coordinating units.6,7 In the context of these studies
we also observed that the stepwise reaction of [(6-p-cym)RuCl2]2
(cym = cymol) with Ph2PCH2CH2tPBu2 and AgPF6 leads to the
formation of a hetero-tetranuclear Ru2Ag2 compound in which the
unsymmetrical bidentate ligand binds in a bridging mode.6
Taking into consideration that rhodium complexes with opti-
cally active phosphine ligands are powerful tools not only in
hydrogenation reactions but also in other parts of asymmetric
organic synthesis, we decided to prepare a series of compounds
[Rh(4-C8H12)(L–L)]PF6 where L–L is an unsymmetrical and/or
chiral bis(phosphino)methane, 1,2-bis(phosphino)ethane, 1-arsino-
2-phosphinoethane or 1,3-bis(phosphino)propane. In this paper we
report the synthesis of the as yet not described ligands L–L, the
preparation and structural characterization of rhodium(I) complexes
derived thereof, and the catalytic activity of the new compounds
[Rh(4-C8H12)(L–L)]PF6 in hydrogenation reactions.
R2PCH2AsR′2 starts with the chlorophosphines R2PCl and proceeds
via R2PCH2SnPh3 and R2PCH2Li as intermediates,2,3 a similar pro-
cedure could not be applied to the corresponding ethane derivatives.
The already known 1,2-bis(phosphino)ethanes bearing different
substituents at the phosphorus centers, such as Me2PCH2CH2PR2
(R = Ph, CH2CMe3) and Ph2PCH2CH2PnBu2, are accessible upon
addition of dimethylvinylthiophosphorane to R2PH followed by
reduction with LiAlH4,8 or by reaction of Ph2P(CHCH2) with
LiPR2 and subsequent hydrolysis.9 The yields are usually moderate
(exception: Me2PCH2CH2PPh2), reaching rarely more than 50%.
A broader scope for compounds of the general composition
R2PCH2CH2PR′2 provides the synthetic route which we have devel-
oped and is shown in Scheme 1. The starting material for 2a–d is the
cyclic sulfate 1, which is obtained upon treatment of 1,2-ethanediol
with SOCl2 followed by catalytic oxidation with NaIO4.10 Similar
cyclic sulfates, but with four carbon atoms in the bridge, were used
by Burk et al. for the synthesis of 1,2-bis(phospholano)benzene
derivatives known as DUPHOS.11 The cleavage of one of the C–O
bonds in 1 and the concomitant opening of the five-membered ring
occurs rapidly and quantitatively by addition of the lithium phos-
phide LiPR2 to a solution of 1 in THF at −70 °C. After warming the
solution to room temperature and renewed cooling to −70 °C, the
addition of the second P-nucleophile LiPR′2 leads to the substitution
of the sulfate group by the PR′2 unit. Subsequent hydrolysis affords
an oily, very air-sensitive residue, which can be eventually distilled
by using a Kugelrohr at 2.5 mbar. Compounds 2a, 2b and 2d are
isolated as highly viscous liquids, while 2c, after crystallization
from methanol, is obtained as a colorless microcrystalline solid. The
yields range from 30% for 2d to 65–75% for 2a–c. Whereas the 31P
NMR spectrum of the non-isolated intermediates shows a singlet at
nearly the same position ( 10.5) as PiPr3, the correponding spectra
of 2a–d display in each case two doublets with a 3J(P,P) coupling
constant of ca. 30–34 Hz.
Results and discussion
Preparation of the ligands
The one-pot procedure for the new unsymmetrical 1,2-
bis(phosphino)ethanes is not only remarkable because of its easy
synthetic approach, short reaction times and efficiency (except
for 2d), but also because it can be extended to related 1-arsino-2-
phosphinoethanes (see Scheme 1). As far as we know, up to now
only two compounds of the general composition R2AsCH2CH2PR′2,
Whilethepreparationoftheunsymmetricalbis(phosphino)methanes
R2PCH2PR′2 and the related arsino(phosphino)methanes
†Dedicated to Professor Wolfdieter A. Schenk, a respected colleague and
creative scientist, on the occasion of his 60th birthday.
T h i s j o u r n a l i s
©
T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 4
D a l t o n T r a n s . , 2 0 0 4 , 1 8 7 3 – 1 8 8 1
1 8 7 3

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lysts for the enantioselective hydrogenation of (Z)-acetamidocin-
namic acid.17 Moreover, Gulyas, Arva and Bakos prepared the
chiral sulfate Ph2PCH(Me)CH2CH(Me)OSO3Li, which is soluble
in water and has been employed as co-catalyst in a biphasic reac-
tion for the rhodium-catalyzed hydroformylation of 1-octene.18 The
composition of this chiral sulfate is related to that of the (non-iso-
lated) intermediate being formed upon treatment of 6 with LiPiPr2
or LiPtBu2 or of (S)-6 with LiPtBu2, respectively. Finally, it should
be mentioned that similarly to (R)-8, also the diastereoisomer (S,S)-
10 is accessible from (R,R)-9 by stepwise addition of LiPiPr2 and
LiPPh2 (see Scheme 3). The value for the optical rotation []20D of
(S,S)-10 in CH2Cl2 is −102°.
Scheme 1
namely Ph2AsCH2CH2PPh212 and Me2AsCH2CH2PPh213 have been
reported in the literature; however, for the latter of those no detailed
preparative procedure and analytical data were given. The new
method described herein furnishes the bidentate systems 3a–c in
good yields. For the preparation of 2a–c as well as of 3a and 3c it is
only important to note that the stronger nucleophile (for example,
LiPiPr2 for 2a or LiAstBu2 for 3a) is added first and the weaker
nucleophile (LiPPh2 for 2a and 3a) second. If this order is reversed,
mixtures of products are obtained.
The method used for the preparation of 2a–d and 3a–c is also
suitable for the synthesis of chiral bidentate P,P-donors of the type
R2PCH(R″)CH2PR′2. In Scheme 2 three examples are shown. In a
test experiment we initially treated the racemic mixture of the cyclic
sulfate 4 stepwise with LiPR2 (R = iPr, Cy) and LiPPh2 and isolated
the corresponding product in an analogous way to that described for
2a–d. By using the (S) enantiomer of 4, the (R) enantiomers 5a–c
are obtained in a completely regioselective fashion by inversion of
configuration at the stereogenic centre. Although the yields of 5a
and 5b are moderate (and that of 5c is low), they are similar to those
reported for PROPHOS14 and CYCPHOS15. These compounds were
prepared from the corresponding chiral bis(tosylate) and two equiv-
alents of LiPPh2. The chiral 1,2-bis(phosphino)ethanes 5a–c are
colorless, air-sensitive oils, which are readily soluble in all common
organic solvents and can be stored under argon at −20 °C for weeks.
As expected, the 31PNMR spectra of 5a–c display two doublets with
31P–31P coupling constants (19–20 Hz) that are almost identical to
the 3J(P,P) value of Ph2PCH(Me)CH2PPh2 (20.6 Hz).16 We note that
the optical rotation []20D of 5a and 5b (+201° and +167° in CH2Cl2,
respectively) is comparable to that of PROPHOS ([]20D = 186°).14
To explore the application of the new synthetic methodology fur-
Scheme 3
Preparation and molecular structure of the rhodium
complexes
With [{RhCl(4-C8H12)}2] (11) as the starting material, the syn-
thesis of the cationic chelate complexes 12a–h occurs stepwise
(see Scheme 4). Treatment of a suspension of 11 in acetone with
AgPF6 furnishes in situ the bis(acetone) compound [Rh(4-
C8H12)(acetone)2]PF6 which is separated by filtration from the pre-
cipitated AgCl. Addition of one equivalent of the ligand L–L to the
filtrate leads to a quick change of color from yellow to orange and
after partial removal of the solvent and addition of diethyl ether gave
the products in 65–88% yield. The chelate complexes 12a–h are
yellow to orange, moderately air-stable solids which are soluble in
polar organic solvents and, in nitromethane, show the conductivity
of 1:1 electrolytes. The 31P NMR spectra show (with the exception
of 12c) apart from the signal for PF6− two doublets of doublets for
the 31P nuclei of the non-equivalent PR2 units with 31P–31P coupling
constants that are ca. 22–27 Hz for 12d–f but larger (ca. 34–40 Hz)
for 12g,h and even larger (ca. 52–62 Hz) for 12a and 12b.
To obtain more information about the detailed structural as-
pects of 12c (which is, as far as we know, the first structurally
characterized mononuclear transition-metal complex bearing an
arsino(phosphino)methane as a chelating ligand), an X-ray crystal
structure investigation was carried out. Compound 12c as well as
the related compound 12d crystallize in chiral space groups (see
Table 5 later) and, based on the Flack parameter,19 their absolute
structures were determined unambigously.19 As shown in Fig. 1 for
12c, the rhodium centre of the cation is coordinated in a square-pla-
nar fashion. Similarly to the analogous phosphino(stibino)methane
compound20 [Rh(4-C8H12)(2-iPr2PCH2SbtBu2)]+, the four-mem-
bered RhAsCP ring is perfectly planar with an intraligand angle
As(1)–C(20)–P(1) of 96.7(3)°. The bite angle As(1)–Rh(1)–P(1) of
73.80(4)° is relatively small but comparable to the bite angle Sb–Rh–
P of [Rh(4-C8H12)(2-iPr2PCH2SbtBu2)]+ and to that of neutral and
cationic rhodium complexes with bulky bis(phosphino)methanes as
ligands.3,21,22 While the Rh(1)–P(1) bond length lies in the expected
range,3,21 the distance Rh(1)–As(1) of 2.4533(8) Å is significantly
Scheme 2
ther, we also prepared the racemic mixtures of 7 and 8 (see Scheme
3) as well as the chiral unsymmetrical 1,3-bis(phosphino)propane
(R)-8. These compounds are high-boiling, air-sensitive liquids
which have been characterized by elemental analysis and mass
spectra. The enantiopure (R)-8 displays in CH2Cl2 an optical rotation
[]20D of +39°. With regard to related 1,3-bis(phosphino)propanes,
we note that recently Huttner and co-workers reported the syn-
thesis of enantiopure compounds of the general composition
R2PCH2CH(X)CH2PR′2 (where X is an OH or OR functionality)
from epichlorhydrins and used the corresponding cationic rhodium
complexes [Rh(4-C8H12){R2PCH2CH(X)CH2PR′2}]+ as precata-
1 8 7 4
D a l t o n T r a n s . , 2 0 0 4 , 1 8 7 3 – 1 8 8 1

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Scheme 4
longer than in the dinuclear compound [(4-C8H12)Rh(-Cl)2Rh(2-
iPr2PCH2AstBu2)] (2.306(2) Å).2 The bond lengths between Rh(1)
and the carbon atoms C(50) and C(51) (see Table 1) are somewhat
longer than those between Rh(1) and C(54) and C(55), which is
probably a consequence of the stronger trans influence of phospho-
rus compared with arsenic.
Table 1 Selected bond lengths (Å) and angles for the cation of compound
12c
Rh–P(1)
2.321(2)
2.4533(8)
1.859(6)
1.980(6)
2.271(7)
2.216(6)
Rh–C(54)
Rh–C(55)
P(1)–C(1)
P(1)–C(10)
As(1)–C(30)
As(1)–C(40)
2.190(5)
2.182(5)
1.882(6)
1.875(6)
1.981(5)
1.991(5)
Rh–As(1)
P(1)–C(20)
As(1)–C(20)
Rh–C(50)
Rh–C(51)
P(1)–Rh–As(1)
P(1)–C(20)–As(1)
73.80(4)
96.7(3)
C(20)–P(1)–Rh
C(20)–As(1)–Rh
98.4(2)
91.0(2)
Table 2 Selected bond lengths (Å) and angles for the cation of compound
12d
Rh(1)–P(1)
Rh(1)–P(2)
P(1)–C(1)
P(2)–C(2)
Rh(1)–C(40)
Rh(1)–C(41)
2.3074(14)
2.2917(13)
1.832(5)
1.849(6)
2.273(6)
2.220(6)
Rh(1)–C(44)
Rh(1)–C(45)
P(1)–C(30)
P(1)–C(31)
P(2)–C(10)
P(2)–C(20)
2.270(5)
2.225(5)
1.839(6)
1.833(7)
1.808(6)
1.816(6)
P(1)–Rh(1)–P(2)
P(1)–C(1)–C(2)
C(1)–C(2)–P(2)
C(40)–Rh(1)–C(41)
84.16(5)
111.1(4)
105.4(4)
35.0(3)
C(44)–Rh(1)–C(45)
P(2)–C(2)–C(3)
C(1)–C(2)–C(3)
35.6(3)
115.9(4)
112.8(5)
Fig. 1 Solid-state structure of cation of 12c; anisotropic displacement
parameters are depicted at the 50% probability level; hydrogen atoms are
omitted for clarity.
The molecular structure of 12d has also been determined crystal-
lographically and the result is shown in Fig. 2. Similarly to 12c,
the coordination geometry around rhodium is square-planar with
the C(40)–C(41) double bond of the cyclooctadiene trans to the
PiPr2 and the C(44)–C(45) double bond trans to the PPh2 moiety.
According to the absolute structure parameter19 x of −0.06(4), the
(R) configuration of the bis(phosphino)ethane ligand is maintained.
The distances Rh–(P1) and Rh–P(2) are practically identical (see
Table 2) and quite similar to the Rh–P distance found in 12c. As
expected, the bite angle P(1)–Rh(1)–P(2) of 12d is significantly
larger (84.16(5)°) than the bite angle As(1)–Rh(1)–P(1) of 12c
owing to the presence of a five-membered chelate ring. Since the
torsional angles Rh(1)–P(1)–C(1)–C(2)(40.18°) and Rh(1)–P(2)–
C(2)–C(1)(41.17°) are nearly the same, an almost ideal “half-chair”
conformation results. The perspective view of the cation shows, that
the phenyl group with the ipso-carbon atom C(10) occupies a quasi-
equatorial and the phenyl group with the ipso-carbon atom C(20) a
quasi-axial position. The five-membered ring thus forms a -chelate
structure, in analogy to various transition-metal complexes contain-
ing (R)-PROPHOS as ligand.16,23
Fig. 2 Solid-state structure of cation of 12d; anisotropic displacement
parameters are depicted at the 50% probability level; hydrogen atoms are
omitted for clarity.
performed, one in isopropanol at 40 °C and 60 °C and the other in
THF at 25 °C and 50 °C, respectively. From the results obtained at a
hydrogen pressure of 1 bar (see Table 3), the following conclusions
can be drawn:
(i) Only with 12a and 12b as pre-catalysts, which contain an un-
symmetrical bis(phosphino)methane with two (1S,2R,5S)-menthyl
groups at one phosphorus atom, is the (R)-isomer of N-acetylphe-
nylalanine methylester generated. In all other reactions, the (S)-
isomer is formed.
Catalytic studies
In order to get some information about the possible role of the new
chiral bidentate ligands reported both in this paper and in previous
work,3 the catalytic hydrogenation of the methyl ester of -acet-
amidocinnamic acid (ACM) with the rhodium complexes 12a–h as
catalyst precursors has been investigated. Two series of runs were
(ii) With the exception of 12a and 12b, a higher enantiomeric
excess (although not exceptional) is obtained in THF compared to
D a l t o n T r a n s . , 2 0 0 4 , 1 8 7 3 – 1 8 8 1
1 8 7 5

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Table 3 Results for the hydrogenation of -acetamidocinnamic acid
methylester (ACM) at 1 bar pressure of H2 in iPrOH (entry 1–16) and in
THF (entry 17–32) with complexes 12a–h as catalyst precursorsa
Table 4 Results for the hydrogenation of -acetamidocinnamic acid meth-
ylester (ACM) at different pressure of H2 in THF at 25 °C with complexes
12d–h as catalyst precursorsa
Entry
Complex
T/°C
Time/h
ee (%)
Entry
Complex
Pressure/bar
Time/h
ee (%)
1
2
3
4
5
6
7
8
9
12a
12a
12b
12b
12c
12c
12d
12d
12e
12e
12f
40
60
40
60
40
60
40
60
40
60
40
60
40
60
40
60
25
50
25
50
25
50
25
50
25
50
25
50
25
50
25
50
1
1
8
8
1
1
6
6
6
60(R)
69(R)
32(R)
38(R)
4(S)
1
2
3
4
5
6
7
8
9
10
11
12
13
12d
12d
12d
12d
12d
12e
12e
12f
5
10
20
40
60
5
10
5
10
5
1
1
0.5
0.5
0.2
1
1
6
4
0.2
0.1
0.2
0.1
56(S)
57(S)
53(S)
56(S)
57(S)
42(S)
48(S)
29(S)
30(S)
20(S)
20(S)
58(S)
52(S)
3(S)
52(S)
36(S)
28(S)
27(S)
20(S)
13(S)
12(S)
9(S)
53(S)
44(S)
50(R)
57(R)
29(R)
31(R)
16(S)
14(S)
59(S)
58(S)
35(S)
37(S)
30(S)
21(S)
20(S)
16(S)
66(S)
55(S)
12f
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
6
12g
12g
12h
12h
12
12
1
1
1
1
1
1
8
8
1
1
6
6
6
6
10
5
10
12f
12g
12g
12h
12h
12a
12a
12b
12b
12c
12c
12d
12d
12e
12e
12f
a Conditions see Table 3.
In contrast to some related systems,25 the increase of the hydrogen
pressure does not lead, with none of the pre-catalysts, to an inver-
sion of configuration of the product.
In summary the results reported in this paper illustrate that, by
using cyclic sulfates such as 1, 4 or 6 as starting materials, a variety
of unsymmetrical 1,2-bis(phosphino)ethanes, 1-phosphino-2-ar-
sinoethanes and 1,3-bis(phosphino)propanes can be prepared. The
one-pot procedure is not only effective but can also be extended to
the synthesis of corresponding chiral bidentate P,P-donors with one
or two chiral centers in the bridge between the phosphorus atoms.
The new ligands as well as some related bis(phosphino)methanes,
described in earlier work from our group,3 readily afford rhodium
complexes of the general composition [Rh(4-C8H12)(L–L)]PF6
(12a–h), in which the coordination sphere around rhodium is
square-planar. Moreover, the X-ray crystal structure analysis of
12d confirmed that upon complexation the (R) configuration of the
bis(phosphino)ethane ligand is maintained. As expected, the chiral
rhodium complexes 12a–h are pre-catalysts in the hydrogenation of
the methylester of -acetamidocinnamic acid giving the methylester
of N-acetylphenylalanine in moderate enantiomeric excess.
12
12
1
1
1
12f
12g
12g
12h
12h
1
a Conditions: [Rh] = 2.5 mM; [ACM]/[Ru] = 100; volume of solvent = 10
cm3; yields determined by 1H NMR; all chemical yields are 100 %; ee values
determined as described by Brunner et al.24
isopropanol. We assume that the better donor capability of THF pos-
sibly increases the stability of one (or more) intermediate(s) formed
in the catalytic cycle.
Experimental
(iii) The increase in temperature effects the ee values only mar-
ginally. Apart from entries 1/2, 3/4 and 17/18, the trend is that the
optical yield is slightly better in isopropanol at 40 °C and in THF at
25 °C than at 60 °C or 50 °C in the same solvents.
All experiments were carried out under an atmosphere of argon
by Schlenk techniques. The starting materials iPr2PH,26 tBu2PH,27
Cy2PH,28 Ph2PH,29 tBu2AsH,30 Cy2AsH,31 1,10 iPr2PCH2P(men)2,3
Ph2PCH2P(men)2,3 Cy2AsCH2P(men)2,3 rac-4-methyl-(1,3,2)-di-
oxathian-2-oxide,32 and 11,33 were prepared as described in the
literature. Compounds (S)-4, rac-6, (S)-6 and (4R,6R)-4,6-dimethyl-
(1,3,2)-dioxathian-2-oxide were gifts from Dr R. Schmid and Dr W.
Burkart, Hoffmann-La Roche AG. NMR spectra were recorded at
room temperature on Bruker AC 200 and Bruker AMX 400 instru-
ments, mass spectra on a Finnigan 90 MAT instrument. Melting
points were measured by differential thermal analysis (DTA) with
a Thermoanalyzer Du Pont 900. Abbrevations used: iPr, isopropyl;
tBu, t-butyl; Cy, cyclohexyl; Ph, phenyl; men, (1S,2R,5S)-menthyl;
s, singlet; d, doublet; t, triplet; sept, septet; m, multiplet; br, broad-
ened signal; coupling constants J in Hz.
(iv) The type of the chelating ligand influences the rate of the
hydrogenation reaction significantly. A quantitative conversion of
the substrate to the product takes place with 12a, 12c, 12g and 12h
as catalyst precursors both in isopropanol and THF within 1 h, with
12b within 8 h, with 12d and 12e within 6 h and with 12f within
12 h. While by comparing 12a and 12b, an increase of the steric
bulk (iPr for Ph) also leads to an increase in rate, the opposite is
found by comparing 12d and 12e with 12f. The comparison of 12f
and 12g illustrates that, although the substituents at the phosphorus
atoms are the same, the increase in size of the chelate ring increases
the rate considerably.
(v) The introduction of a second chiral center in the backbone of
the chelate ring leads to a significant increase of the optical yield.
Whereas with 12g as the pre-catalyst (THF, 25 °C) 20% ee of the
(S)-isomer has been obtained, with 12h as the pre-catalyst the
enantiomeric excess is 66% under the same conditions. A similar
increase results in THF at 50 °C and also in isopropanol (both at
40 °C and 60 °C) as the solvent.
Table 4 summarizes the results which have been obtained in THF
at 25 °C by changing the hydrogen pressure. By comparing the data
(for example, entry 23 of Table 3 and entries 1–5 of Table 4, or entry
27 of Table 3 and entries 8 and 9 of Table 4), the general conclusion
is that the increase of the pressure of H2 influences the rate of forma-
tion but not the optical yield of the product. Only in the case of 12e
(see entry 25 of Table 3 and entry 7 of Table 4) has a noteworthy
increase of ee (from 35% at 1 bar to 48% at 10 bar) been observed.
Preparations
iPr2PCH2CH2PPh2 2a. AsolutionofiPr2PH(1.68g, 14.24 mmol)
in THF (25 cm3) was treated at −70 °C with a 1.76 M solution of
nBuLi (8.1 cm3, 14.24 mmol) in THF and slowly warmed to room
temperature. After the solution was stirred for 30 min, it was cooled
to −70 °C, and then added dropwise to a solution (also cooled
to −70 °C) of 1 (1.77 g, 14.24 mmol) in THF (45 cm3). The reaction
mixture was slowly brought to room temperature and stirred for
30 min. After it was cooled again to −70 °C, a solution of LiPPh2
was added, which was prepared from Ph2PH (2.63 g, 14.11 mmol)
and a 1.76 M solution of nBuLi (8.0 cm3, 14.11 mmol) in THF.
The reaction mixture was then brought to room temperature and
1 8 7 6
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stirred for 3 h at 60 °C. After it was cooled to 20 °C, the solvent was
evaporated in vacuo and the residue was dissolved in diethyl ether
(50 cm3). The ether solution was treated with water (20 cm3) and
the aqueous phase was separated. The organic phase was washed
twice with 10 cm3 portions of water, carefully dried with Na2SO4
and then filtered. The filtrate was brought to dryness in vacuo and
the remaining oil distilled using a Kugelrohr at 2.5 mbar. A color-
less, highly viscous liquid was obtained: yield 3.55 g (76%), bp
200 °C (2.5 mbar) (Found: C, 72.61; H, 8.35. C20H28P2 requires C,
72.71; H, 8.54%). MS (CI, isobutane, 150 eV): m/z 331 ([M + 1]+),
187 ([Ph2P + 1]+), 119 ([iPr2P + 1]+). NMR (CDCl3): H (200 MHz)
7.52–7.30 (10 H, m, C6H5), 2.16 (2 H, m, PCH2), 1.73 (2 H, m,
PCHCH3), 1.47 (2 H, m, PCH2), 1.08, 1.02 [6 H each, dd, J(P,H) =
9.0, J(H,H) = 7.0 Hz, PCHCH3]; C (50.3 MHz) 138.2 [d, J(P,C) =
13.9 Hz, ipso-C of C6H5], 132.5 [d, J(P,C) = 18.5 Hz, ortho-C
of C6H5], 128.1 (s, para-C of C6H5), 128.0 [d, J(P,C) = 12.0 Hz,
meta-C of C6H5], 26.3 [dd, J(P,C) = 20.4, J(P′,C) = 12.9 Hz, PCH2],
23.0 [d, J(P,C) = 12.9 Hz, PCHCH3], 19.8 [d, J(P,C) = 14.8 Hz,
PCHCH3], 18.7 [d, J(P,C) = 10.2 Hz, PCHCH3], 17.2 [dd, J(P,C) =
19.4, J(P′,C) = 15.7 Hz, PCH2]; P (81.0 MHz) 10.3 [d, J(P,P) =
33.0 Hz, iPr2P], −11.9 [d, J(P,P) = 33.0 Hz, Ph2P].
J(P,C) = 26.8, J(P′,C) = 18.5 Hz, PCH2], 19.8 [d, J(P,C) = 14.5 Hz,
PCHCH3], 19.2 [dd, J(P,C) = 29.2, J(P′,C) = 10.3 Hz, PCH2], 18.7
[d, J(P,C) = 9.2 Hz, PCHCH3]; P (81.0 MHz) 36.9 [d, J(P,P) =
30.5 Hz, tBu2P], 10.7 [d, J(P,P) = 30.5 Hz, iPr2P].
tBu2AsCH2CH2PPh2 3a. This compound was prepared as
described for 2a, from tBu2AsH (2.70 g, 14.18 mmol), a 1.77 M
solution of nBuLi (8.00 cm3, 14.18 mmol) in THF, 1 (1.76 g, 14.18
mmol) and LiPPh2, prepared from Ph2PH (2.61 g, 14.02 mmol) and
a 1.77 M solution of nBuLi (7.92 cm3, 14.02 mmol) in THF. Color-
less, highly viscous liquid: yield 3.05 g (54%), bp 210 °C (2.5 mbar)
(Found: C, 65.35; H, 7.71. C22H32AsP requires C, 65.67; H, 8.02%).
MS (CI, isobutane, 150 eV): m/z 403 ([M + 1]+), 191 ([tBu2As +
1]+), 187 ([Ph2P + 1]+). NMR (CDCl3): H (200 MHz) 7.58–7.25
(10 H, m, C6H5), 2.37, 1.53 (2 H each, both m, PCH2 and AsCH2),
1.16 (18 H, s, AsCCH3); C (50.3 MHz) 138.4 [d, J(P,C) = 13.9 Hz,
ipso-C of C6H5], 132.6 [d, J(P,C) = 17.6 Hz, ortho-C of C6H5], 128.3
[d, J(P,C) = 11.1 Hz, meta-C of C6H5], 128.2 (s, para-C of C6H5),
32.5 (s, AsCCH3), 29.7 (s, AsCCH3), 28.0, 16.1 [both d, J(P,C) =
13.9 Hz, PCH2 and AsCH2]; P (81.0 MHz) − 11.7 (s).
tBu2AsCH2CH2PiPr2 3b. This compound was prepared as de-
scribed for 2a, from tBu2AsH (1.76 g, 9.26 mmol), a 1.76 M solu-
tion of nBuLi (5.25 cm3, 9.26 mmol) in THF, 1 (1.15 g, 9.26 mmol)
and LiPiPr2, prepared from iPr2PH (1.08 g, 9.20 mmol) and a 1.76 M
solution of nBuLi (5.22 cm3, 9.20 mmol) in THF. Colorless, highly
viscous liquid: yield 1.89 g (62%), bp 140 °C (2.5 mbar). MS (CI,
isobutane, 150 eV): m/z 351 ([iPr2P(O)CH2CH2AstBu2 + 1]+). NMR
(CDCl3): H (400 MHz) 1.67 (2 H, m, PCH2 or AsCH2), 1.48 (4 H,
m, PCHCH3 and PCH2 or AsCH2), 1.09 (18 H, s, AsCCH3), 1.01
(12 H, m, PCHCH3); C (100.6 MHz) 32.5 (s, AsCCH3), 29.9 (s,
AsCCH3), 23.2 [d, J(P,C) = 13.4 Hz, PCHCH3], 21.7 [d, J(P,C) =
19.1 Hz, PCH2], 20.1 [d, J(P,C) = 14.3 Hz, PCHCH3], 19.1 [d,
J(P,C) = 18.1 Hz, AsCH2], 19.0 [d, J(P,C) = 9.5 Hz, PCHCH3]; P
(162.0 MHz) 10.9 (s).
tBu2PCH2CH2PPh2 2b. This compound was prepared as de-
scribed for 2a, from tBu2PH (1.54 g, 10.53 mmol), a 1.79 M solution
of nBuLi (5.9 cm3, 10.54 mmol) in THF, 1 (1.31 g, 10.53 mmol) and
LiPPh2, prepared from Ph2PH (1.95 g, 10.50 mmol) and a 1.79 M
solution of nBuLi (5.8 cm3, 10.50 mmol) in THF. Colorless, highly
viscous liquid: yield 2.62 g (70%), bp 190 °C (2.5 mbar) (Found: C,
74.39; H, 8.86. C22H32P2 requires C, 73.72; H, 9.00%). MS (CI, iso-
butane, 150 eV): m/z 359 ([M + 1]+), 187 ([Ph2P + 1]+), 147 ([tBu2P +
1]+). NMR (CDCl3): H (200 MHz) 7.51–7.30 (10 H, m, C6H5),
2.27 (2 H, m, PCH2), 1.45 (2 H, m, PCH2), 1.07 [18 H, d, J(P,H) =
11.0 Hz, PCCH3]; C (50.3 MHz) 138.4 [d, J(P,C) = 13.9 Hz, ipso-C
of C6H5], 132.7 [d, J(P,C) = 18.5 Hz, ortho-C of C6H5], 128.4 (s,
para-C of C6H5), 128.3 [d, J(P,C) = 12.9 Hz, meta-C of C6H5], 31.4
[d, J(P,C) = 21.3 Hz, PCCH3], 29.4 [d, J(P,C) = 12.9 Hz, PCCH3],
28.9 [dd, J(P,C) = 20.0, J(P′,C) = 12.9 Hz, PCH2], 16.7 [dd, J(P,C) =
22.2, J(P′,C) = 15.7 Hz, PCH2]; P (81.0 MHz) 36.4 [d, J(P,P) =
34.3 Hz, tBu2P], −12.3 [d, J(P,P) = 34.3 Hz, Ph2P].
Cy2AsCH2CH2PPh2 3c. This compound was prepared as
described for 2a, from Cy2AsH (3.28 g, 13.54 mmol), a 1.81 M
solution of nBuLi (7.50 cm3, 13.54 mmol) in THF, 1 (1.68 g, 13.54
mmol) and LiPPh2, prepared from Ph2PH (2.52 g, 13.54 mmol) and
a 1.81 M solution of nBuLi (7.50 cm3, 13.54 mmol) in THF. Color-
less, highly viscous liquid: yield 3.44 g (56%), bp 245 °C (2.5 mbar)
(Found: C, 69.24; H, 7.64. C26H36AsP requires C, 68.71; H, 7.98%).
MS (CI, isobutane, 150 eV): m/z 455 ([M + 1]+), 243 ([Cy2As +
1]+), 187 ([Ph2P + 1]+). NMR (CDCl3): H (200 MHz) 7.49–7.29
(10 H, m, C6H5), 2.26–1.20 (26 H, m, AsCH2, PCH2 and C6H11);
C (50.3 MHz) 138.6 [d, J(P,C) = 13.9 Hz, ipso-C of C6H5], 132.7
[d, J(P,C) = 18.5 Hz, ortho-C of C6H5], 128.4 [d, J(P,C) = 11.1 Hz,
meta-C of C6H5], 128.3 (s, para-C of C6H5), 33.8, 31.0, 30.0, 27.6,
26.6 (all s, CH and CH2 of C6H11), 26.6, 15.3 [both d, J(P,C) =
14.8 Hz, AsCH2 and PCH2]; P (81.0 MHz) −11.6 (s).
Cy2PCH2CH2PPh2 2c. Thiscompoundwaspreparedas described
for 2a, from Cy2PH (2.73 g, 13.80 mmol), a 1.81 M solution of
nBuLi (7.60 cm3, 13.80 mmol) in THF, 1 (1.71 g, 13.80 mmol) and
LiPPh2, prepared from Ph2PH (2.56 g, 13.80 mmol) and a 1.81 M
solution of nBuLi (7.60 cm3, 13.80 mmol) in THF. After recrys-
tallization of the colorless, highly viscous liquid a colorless solid
was obtained: yield 3.67 g (65%), bp 240 °C (2.5 mbar), mp 54 °C
(Found: C, 75.99; H, 8.62. C26H36P2 requires C, 76.07; H, 8.84%).
MS (CI, isobutane, 150 eV): m/z 411 ([M + 1]+), 199 ([Cy2P + 1]+),
187 ([Ph2P + 1]+). NMR (CDCl3): H (200 MHz) 7.51–7.00 (10 H,
m, C6H5), 2.20–0.90 (26 H, m, PCH2 and C6H11); C (50.3 MHz)
138.6 [d, J(P,C) = 12.9 Hz, ipso-C of C6H5], 132.8 [d, J(P,C) =
18.5 Hz, ortho-C of C6H5], 128.5 (s, para-C of C6H5), 128.4 [d,
J(P,C) = 12.0 Hz, meta-C of C6H5], 33.3 [d, J(P,C) = 13.0 Hz, CH
of C6H11], 30.2 [d, J(P,C) = 13.0 Hz, CH2 of C6H11], 29.1 [d, J(P,C) =
7.4 Hz, CH2 of C6H11], 27.3 [dd, J(P,C) = 19.6, J(P′,C) = 11.1 Hz,
PCH2], 26.5 (s, CH2 of C6H11), 17.0 [dd, J(P,C) = 19.2, J(P′,C) =
9.8 Hz, PCH2]; P (81.0 MHz) 2.3 [d, J(P,P) = 30.5 Hz, Cy2P], −11.9
[d, J(P,P) = 30.5 Hz, Ph2P].
rac-4-methyl-(1,3,2)-dioxathian-2,2-dioxide 4. A solution of
rac-4-methyl-(1,3,2)-dioxathian-2-oxide (6.81 g, 50.0 mmol) in
acetonitrile (50 cm3) was treated at 0 °C with RuCl3·3H2O (100 mg,
0.38 mmol), NaIO4 (16.0 g, 75.0 mmol) and water (75 cm3, 0 °C).
The reaction mixture was stirred for 5 min at 0 °C and, after it was
warmed under stirring (15 min) to room temperature, treated with
ethyl acetate (200 cm3) and a saturated aqueous solution of K2CO3
(50 cm3). The aqueous phase was separated and extracted twice
with ethyl acetate (100 cm3 each). The combined organic phases
were washed with water (100 cm3), carefully dried with Na2SO4 and
then filtered. The filtrate was evaporated in vacuo and the remain-
ing oil distilled using a Kugelrohr at 2.5 mbar. A colorless, highly
viscous liquid was obtained, which after cooling to 20 °C afforded
a colorless solid: yield 6.24 g (82%), bp 88 °C (2.5 mbar), mp 46 °C
(Found: C, 31.59; H, 5.23; S, 20.92. C4H8O4S requires C, 31.57;
H, 5.30; S, 21.07%). NMR (CDCl3): H (200 MHz) 4.92 (1 H, m,
OCH), 4.57 (2 H, m, OCH2CH2), 1.94 (2 H, m, OCH2), 1.36 [3 H,
d, J(H,H) = 6.3 Hz, OCHCH3]; C (50.3 MHz) 83.4 (s, OCH2), 77.5
(s, OCH), 30.6 (s, OCHCH2), 20.5 (s, OCHCH3).
iPr2PCH2CH2PtBu2 2d. This compound was prepared as de-
scribed for 2a, from iPr2PH (870 mg, 7.36 mmol), a 1.76 M solution
of nBuLi (4.18 cm3, 7.36 mmol) in THF, 1 (913 mg, 7.36 mmol) and
LiPtBu2, prepared from tBu2PH (1.07 g, 7.36 mmol) and a 1.76 M
solution of nBuLi (4.17 cm3, 7.36 mmol) in THF. Colorless, highly
viscous liquid: yield 630 mg (30%), bp 120 °C (2.5 mbar). MS
(CI, isobutane, 150 eV): m/z 323 ([iPr2P(O)CH2CH2P(O)tBu2 +
1]+). NMR (CDCl3): H (200 MHz) 1.55 (2 H, m, PCH2), 1.36 (2
H, m, PCH2), 0.96 [18 H, d, J(P,H) = 10.6 Hz, PCCH3], 0.95–0.85
(14 H, m, PCHCH3 and PCHCH3); C (50.3 MHz) 31.0 [d, J(P,C) =
21.3 Hz, PCCH3], 29.3 [d, J(P,C) = 12.9 Hz, PCCH3], 22.5 [dd,
D a l t o n T r a n s . , 2 0 0 4 , 1 8 7 3 – 1 8 8 1
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rac-iPr2PCH2CH(Me)PPh2 5a. This compound was prepared as
described for 2a, from iPr2PH (1.54 g, 13.00 mmol), a 1.81 M solu-
tion of nBuLi (7.20 cm3, 13.00 mmol) inTHF, 4 (1.80 g, 13.00 mmol)
and LiPPh2, prepared from Ph2PH (2.40 g, 12.90 mmol) and a
1.81 M solution of nBuLi (7.10 cm3, 12.90 mmol) in THF. Color-
less, highly viscous liquid: yield 1.66 g (37%), bp 200 °C (2.5 mbar)
(Found: C, 72.85; H, 8.60. C21H30P2 requires C, 73.23; H, 8.78%).
MS (CI, isobutane, 150 eV): m/z 345 ([M + 1]+), 187 ([Ph2P + 1]+),
119 ([iPr2P + 1]+). NMR (CDCl3): H (200 MHz) 7.62–7.13 (10 H,
m, C6H5), 2.36 (1 H, m, PCHCH2), 1.74–1.44 (4 H, m, PCH2 and
PCHCH3), 1.23 [3 H, dd, J(P,H) = 15.4, J(H,H) = 6.9 Hz, PCHCH3],
1.03–0.80 (12 H, m, PCH(CH3)CH2 and PCHCH3); C (50.3 MHz)
137.1 [d, J(P,C) = 13.9 Hz, ipso-C of C6H5], 136.6 [d, J(P,C) =
14.8 Hz, ipso-C of C6H5], 133.8 [d, J(P,C) = 14.8 Hz, C6H5], 133.4
[d, J(P,C) = 15.7 Hz, C6H5], 128.7 [d, J(P,C) = 4.6 Hz, C6H5], 128.2
[d, J(P,C) = 2.8 Hz, C6H5], 128.1 [d, J(P,C) = 3.7 Hz, C6H5], 29.6
[dd, J(P,C) = 18.5, J(P′,C) = 10.2 Hz, PCH2], 25.4 [dd, J(P,C) =
J(P′,C) = 18.5 Hz, PCH], 23.6 [d, J(P,C) = 12.9 Hz, PCHCH3],
22.9 [d, J(P,C) = 12.0 Hz, PCHCH3], 19.9 [d, J(P,C) = 15.7 Hz,
PCHCH3], 19.4 [d, J(P,C) = 13.9 Hz, PCHCH3], 18.5 [dd, J(P,C) =
11.1, J(P′,C) = 1.4 Hz, PCH(CH3)CH2], 17.7 [d, J(P,C) = 12.0 Hz,
PCHCH3], 17.4 [d, J(P,C) = 11.1 Hz, PCHCH3]; P (81.0 MHz) 1.9
[d, J(P,P) = 19.1 Hz, iPr2P], 0.2 [d, J(P,P) = 19.1 Hz, Ph2P].
1.25 [3 H, dd, J(P,H) = 15.1, J(H,H) = 6.8 Hz, PCH(CH3)CH2],
1.06 [9 H, d, J(P,H) = 11.3 Hz, PCCH3), 0.87 [9 H, d, J(P,H) =
11.0 Hz, PCCH3); C (50.3 MHz) 137.1, 136.1 [both d, J(P,C) =
14.8 Hz, ipso-C of C6H5], 133.8, 133.4 [both d, J(P,C) = 11.1 Hz,
C6H5], 132.8 [d, J(P,C) = 21.3 Hz, C6H5], 128.1 [d, J(P,C) = 7.4 Hz,
C6H5], 127.9 [d, J(P,C) = 6.5 Hz, C6H5], 31.3, 30.8 [both d, J(P,C) =
20.3 Hz, PCCH3], 30.5 [dd, J(P,C) = 21.7, J(P′,C) = 16.2 Hz, PCH2],
29.5 [d, J(P,C) = 6.5 Hz, PCCH3], 29.2 [d, J(P,C) = 7.4 Hz, PCCH3],
24.8 [dd, J(P,C) = 24.0, J(P′,C) = 18.5 Hz, PCH], 17.5 [dd, J(P,C) =
16.2, J(P′,C) = 12.5 Hz, PCH(CH3)CH2]; P (81.0 MHz) 22.1 [d,
J(P,P) = 20.3 Hz, tBu2P], 2.5 [d, J(P,P) = 20.3 Hz, Ph2P].
rac-iPr2PCH2CH2CH(Me)PPh2 7. This compound was pre-
pared as described for 2a, from iPr2PH (1.20 g, 10.20 mmol),
a 1.76 M solution of nBuLi (5.77 cm3, 10.20 mmol) in THF,
6 (1.55 g, 10.20 mmol) and LiPPh2, prepared from Ph2PH
(1.89 g, 10.20 mmol) and a 1.76 M solution of nBuLi (5.77 cm3,
10.20 mmol) in THF. Colorless, highly viscous liquid: yield 1.52 g
(42%), bp 195 °C (2.5 mbar) (Found: C, 73.36; H, 8.64. C22H32P2
requires C, 73.72; H, 9.00%). MS (CI, isobutane, 150 eV): m/z
359 ([M + 1]+). NMR (CDCl3): H (200 MHz) 7.50–7.26 (10 H,
m, C6H5), 2.46 (1 H, m, PCHCH2), 1.70–0.92 (21 H, m, PCH2,
PCH2CH2, PCH(CH3)CH2, PCHCH3 and PCHCH3); C (50.3 MHz)
137.4 [d, J(P,C) = 13.9 Hz, ipso-C of C6H5], 137.3 [d, J(P,C) =
14.8 Hz, ipso-C of C6H5], 133.9 [d, J(P,C) = 9.2 Hz, C6H5], 133.5 [d,
J(P,C) = 8.3 Hz, C6H5], 128.7 (s, C6H5), 128.4 [d, J(P,C) = 1.8 Hz,
C6H5], 128.3 [d, J(P,C) = 2.8 Hz, C6H5], 32.0–31.2 (m, PCHCH2
and PCH2), 23.3 [d, J(P,C) = 8.3 Hz, PCHCH3], 23.1 [d, J(P,C) =
17.4 Hz, PCHCH3], 20.3 [d, J(P,C) = 11.1 Hz, PCHCH3], 20.0 [d,
J(P,C) = 10.2 Hz, PCHCH3], 19.5 [dd, J(P,C) = 17.6, J(P′,C) =
12.0 Hz, PCH2CH2], 19.0, 18.9 [both d, J(P,C) = 8.8 Hz, PCHCH3],
16.0 [d, J(P,C) = 15.7 Hz, PCH(CH3)CH2]; P (81.0 MHz) 3.4 (s,
iPr2P), −1.9 (s, Ph2P).
rac-Cy2PCH2CH(Me)PPh2 5b. This compound was prepared as
described for 2a, from Cy2PH (1.54 g, 7.74 mmol), a 1.74 M solu-
tion of nBuLi (4.50 cm3, 7.74 mmol) in THF, 4 (1.07 g, 7.74 mmol)
and LiPPh2, prepared from Ph2PH (1.44 g, 7.74 mmol) and a 1.74 M
solution of nBuLi (4.50 cm3, 7.74 mmol) in THF. Colorless, highly
viscous liquid: yield 1.19 g (36%), bp 235 °C (2.5 mbar) (Found:
C, 76.23; H, 8.82. C27H38P2 requires C, 76.39; H, 9.02%). NMR
(CDCl3): H (200 MHz) 7.58–7.21 (10 H, m, C6H5), 2.33 (1 H, m,
PCH), 1.89–0.85 (27 H, m, PCH2, PCH(CH3)CH2 and C6H11); C
(50.3 MHz) 137.1, 136.8 [both d, J(P,C) = 26.8 Hz, ipso-C of C6H5],
133.9, 133.4 [both d, J(P,C) = 19.4 Hz, C6H5], 128.7–127.9 (br m,
C6H5), 33.7 [d, J(P,C) = 13.9 Hz, CH of C6H11], 32.7 [d, J(P,C) =
12.9 Hz, CH of C6H11], 30.1 [dd, J(P,C) = 18.0, J(P′,C) = 11.6 Hz,
PCH2], 29.7–24.6 (m, CH2 of C6H11 and PCH(CH3)CH2), 17.5 [dd,
J(P,C) = 16.6, J(P′,C) = 11.1 Hz, PCH]; P (81.0 MHz) 1.2 [d,
J(P,P) = 19.1 Hz, Cy2P], −8.2 [d, J(P,P) = 19.1 Hz, Ph2P].
rac-tBu2PCH2CH2CH(Me)PPh2 8. This compound was pre-
pared as described for 2a, from tBu2PH (1.48 g, 10.10 mmol), a
1.76 M solution of nBuLi (5.74 cm3, 10.10 mmol) in THF, 6 (1.54 g,
10.10 mmol) and LiPPh2, prepared from Ph2PH (1.88 g, 10.10
mmol) and a 1.76 M solution of nBuLi (5.74 cm3, 10.10 mmol)
in THF. Colorless, highly viscous liquid: yield 2.03 g (52%), bp
200 °C (2.5 mbar) (Found: C, 74.33; H, 9.19. C24H36P2 requires
C, 74.58; H, 9.39%). MS (CI, isobutane, 150 eV): m/z 387 ([M +
1]+). NMR (CDCl3): H (400 MHz) 7.44–7.19 (10 H, m, C6H5),
2.39 (1 H, m, PCHCH2), 1.70–1.04 (7 H, m, PCH2, PCH2CH2
and PCH(CH3)CH2), 0.99, 0.96 [9 H each, both d, J(P,H) = 3.2
Hz, PCCH3]; C (100.6 MHz) 137.1 [d, J(P,C) = 14.3 Hz, ipso-C
of C6H5], 133.7, 133.4 [both d, J(P,C) = 14.3 Hz, C6H5], 128.5
[d, J(P,C) = 3.8 Hz, C6H5], 128.2, 128.1 (both s, C6H5), 128.0 [d,
J(P,C) = 4.8 Hz, C6H5], 34.1 [dd, J(P,C) = 26.7, J(P′,C) = 17.2 Hz,
PCH2], 31.7 [dd, J(P,C) = 12.0, J(P′,C) = 11.9 Hz, PCHCH2],
31.2, 31.0 [both d, J(P,C) = 10.5 Hz, PCCH3], 29.6, 29.4 [both
d, J(P,C) = 1.9 Hz, PCCH3], 18.9 [dd, J(P,C) = 20.0, J(P′,C) =
11.4 Hz, PCH2CH2], 16.2 [d, J(P,C) = 16.2 Hz, PCH(CH3)CH2]; P
(81.0 MHz) 28.3 (s, tBu2P), −2.4 (s, Ph2P).
(R)-iPr2PCH2CH(Me)PPh2 (R)-5a. This compound was pre-
pared as described for 2a, from iPr2PH (735 mg, 6.22 mmol), a
1.74 M solution of nBuLi (3.60 cm3, 6.22 mmol) in THF, (S)-4
(842 mg, 6.22 mmol) and LiPPh2, prepared from Ph2PH (1.56 g,
6.22 mmol) and a 1.74 M solution of nBuLi (3.60 cm3, 6.22 mmol)
in THF. Colorless, highly viscous liquid: yield 0.79 g (37%), bp
200 °C (2.5 mbar), []20D = +201° (c 0.73, CH2Cl2). MS (CI, isobu-
tane, 150 eV): m/z 345 ([M + 1]+), 187 ([Ph2P + 1]+), 119 ([iPr2P +
1]+).
(R)-Cy2PCH2CH(Me)PPh2 (R)-5b. This compound was pre-
pared as described for 2a, from Cy2PH (2.14 g, 10.80 mmol),
a 1.75 M solution of nBuLi (6.20 cm3, 10.80 mmol) in THF,
(S)-4 (1.49 g, 10.80 mmol) and LiPPh2, prepared from Ph2PH
(1.99 g, 10.80 mmol) and a 1.75 M solution of nBuLi (6.20 cm3,
10.80 mmol) in THF. Colorless, highly viscous liquid: yield 1.65 g
(36%), bp 235 °C (2.5 mbar), []20D = +167° (c 0.73, CH2Cl2). MS
(CI, isobutane, 150 eV): m/z 426 ([M + 1]+), 199 ([Cy2P + 1]+), 187
([Ph2P +1 ]+).
(R)-tBu2PCH2CH2CH(Me)PPh2 (R)-8. This compound was
prepared as described for 2a, from tBu2PH (2.19 g, 14.96 mmol),
a 1.76 M solution of nBuLi (8.50 cm3, 14.96 mmol) in THF,
(S)-6 (2.28 g, 14.96 mmol) and LiPPh2, prepared from Ph2PH
(2.79 g, 14.96 mmol) and a 1.76 M solution of nBuLi (8.50 cm3,
14.96 mmol) in THF. Colorless, highly viscous liquid: yield 3.06 g
(53%), bp 200 °C (2.5 mbar), []20D = +39° (c 0.86, CH2Cl2)
(Found: C, 74.55; H, 9.13. C24H36P2 requires C, 74.58; H, 9.39%).
MS (CI, isobutane, 150 eV): m/z 387 ([M + 1]+).
(R)-tBu2PCH2CH(Me)PPh2 (R)-5c. This compound was pre-
pared as described for 2a, from tBu2PH (1.17 g, 8.00 mmol), a
1.80 M solution of nBuLi (4.40 cm3, 8.00 mmol) in THF, (S)-4
(1.10 mg, 8.00 mmol) and LiPPh2, prepared from Ph2PH (1.49 g,
8.00 mmol) and a 1.80 M solution of nBuLi (4.40 cm3, 8.00 mmol)
in THF. Colorless, highly viscous liquid: yield 574 mg (20%), bp
150 °C (2.5 mbar), []20D = +25° (c 0.73, CH2Cl2) (Found: C, 74.02;
H, 8.89. C23H34P2 requires C, 74.17; H, 9.20%). MS (CI, isobutane,
150 eV): m/z 373 ([M + 1]+). NMR (CDCl3): H (200 MHz) 7.48–
7.22 (10 H, m, C6H5), 2.37 (1 H, m, PCHCH2), 1.60 (2 H, m, PCH2),
(4R,6R)-4,6-dimethyl-(1,3,2)-dioxathian-2,2-dioxide (R,R)-9.
This compound was prepared as described for 4, from (4R,6R)-
4,6-dimethyl-(1,3,2)-dioxathian-2-oxide (7.50 g, 50.0 mmol),
RuCl3·3H2O (100 mg, 0.38 mmol) and NaIO4 (16.0 g, 75.0 mmol).
Colorless, highly viscous liquid: yield 7.39 g (89%), bp 97 °C
(2.5 mbar), []20D = +38° (c 1.05, CH2Cl2) (Found: C, 36.41; H,
1 8 7 8
D a l t o n T r a n s . , 2 0 0 4 , 1 8 7 3 – 1 8 8 1

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5.48; S, 19.18. C5H10O4S requires C, 36.14; H, 6.07; S, 19.29%).
NMR (CDCl3): H (200 MHz) 5.00 (2 H, m, OCH), 1.98 [2 H,
t, J(H,H) = 5.6 Hz, OCHCH2), 1.51 [6 H, d, J(H,H) = 6.6 Hz,
OCHCH3]; C (50.3 MHz) 80.5 (s, OCH), 35.1 (s, OCHCH2), 19.9
(s, OCHCH3).
men), 36.8 [dd, J(P,C) = 19.2, J(P′,C) = 18.5 Hz, PCH2P], 35.2 [d,
J(P,C) = 5.1 Hz, CH of men], 35.0 [d, J(P,C) = 7.1 Hz, CH of men],
34.6 (s, CH2 of men), 34.1 (s, CH of men), 34.0 (s, CH2 of men),
33.3 [d, J(P,C) = 9.1 Hz, CH of men], 33.2, 31.5 (both br s, CH2 of
C8H12), 30.2 [d, J(P,C) = 7.1 Hz, CH of men], 28.9, 28.8 (both br s,
CH2 of C8H12), 25.9 [d, J(P,C) = 11.2 Hz, CH2 of men], 25.4 [d,
J(P,C) = 10.2 Hz, CH2 of men], 22.6, 22.4, 22.2, 21.1, 17.4, 15.5 (all
s, CH3 of men); P (162.0 MHz) −34.3 [dd, J(Rh,P) = 117.7, J(P,P) =
61.5 Hz, Ph2P], −43.2 [dd, J(Rh,P) = 136.2, J(P,P) = 61.5 Hz,
(S,S)-iPr2PCH(Me)CH2CH(Me)PPh2 (S,S)-10. This com-
pound was prepared as described for 2a, from iPr2PH (1.98 g,
16.76 mmol), a 1.76 M solution of nBuLi (9.52 cm3, 16.76 mmol)
in THF, (R,R)-9 (2.79 g, 16.76 mmol) and LiPPh2, prepared from
Ph2PH (3.12 g, 16.76 mmol) and a 1.76 M solution of nBuLi
(9.52 cm3, 16.76 mmol) in THF. Colorless, highly viscous liquid:
yield 749 g (12%), bp 200 °C (2.5 mbar), []20D = −102° (c 0.97,
CH2Cl2) (Found: C, 74.83; H, 9.38. C23H34P2 requires C, 74.17; H,
9.20%). MS (CI, isobutane, 150 eV): m/z 373 ([M + 1]+). NMR
(CDCl3): H (200 MHz) 7.52–7.23 (10 H, m, C6H5), 2.58–0.95
(24 H, br m, PCHCH2, PCHCH2, PCH(CH3)CH2, PCHCH3 and
PCHCH3); C (50.3 MHz) 137.3 [d, J(P,C) = 3.5 Hz, C6H5], 136.9 [d,
J(P,C) = 2.7 Hz, C6H5], 133.8, 133.5 [both d, J(P,C) = 5.5 Hz, C6H5],
128.7 (s, C6H5), 128.3 [d, J(P,C) = 7.4 Hz, C6H5], 37.7 [dd, J(P,C) =
18.5, J(P′,C) = 13.8 Hz, PCHCH2], 27.5 [dd, J(P,C) = 9.2, J(P′,C) =
8.5 Hz, PCHCH2], 23.9, 23.5 [both d, J(P,C) = 12.0 Hz, PCHCH3],
21.6–20.6 (br m, PCHCH2 and PCHCH3), 16.4 [d, J(P,C) = 10.2 Hz,
PCH(CH3)CH2], 15.6 [d, J(P,C) = 15.7 Hz, PCH(CH3)CH2]; P
(81.0 MHz) 21.7 (s, iPr2P), 0.4 (s, Ph2P).
−
(men)2P], −143.6 [sept, J(F,P) = 710.6 Hz, PF6 ].
[Rh(4-C8H12){2-Cy2AsCH2P(men)2}]PF6 12c. This compound
was prepared as described for 12a, from 11 (192 mg, 0.39 mmol),
AgPF6 (197 mg, 0.78 mmol) and Cy2AsCH2P(men)2 (441 mg,
0.78 mmol). Orange–yellow solid: yield 631 mg (88%); mp 130 °C
(decomp.), M = 65.9 cm2 −1 mol−1 (Found: C, 53.36; H, 7.97; Rh,
10.76. C41H74AsF6P2Rh requires C, 53.18; H, 8.10; Rh, 11.18%).
NMR (CD2Cl2): H (400 MHz) 5.60, 5.41, 4.69, 3.82 (1 H each,
all br s, CH of C8H12), 3.24 (2 H, m, AsCH2P), 2.50–0.57 (68 H,
br m, CH2 of C8H12, C6H11 and menthyl protons); C (100.6 MHz)
95.7 [dd, J(Rh,C) = 8.6, J(P,C) = 8.6 Hz, CH of C8H12], 94.9 [dd,
J(Rh,C) = 10.0, J(P,C) = 7.2 Hz, CH of C8H12], 92.2 [d, J(Rh,C) =
9.5 Hz, CH of C8H12], 87.2 [d, J(Rh,C) = 8.6 Hz, CH of C8H12],
47.0, 43.1 (both s, CH of men), 40.7, 40.2 (both s, CH of C6H11),
40.1 [dd, J(Rh,C) = 6.1, J(P,C) = 13.2 Hz, ipso-C of men], 37.0 (s,
CH2 of men), 34.8 [d, J(P,C) = 5.8 Hz, CH of men], 34.6, 34.2 (both
s, CH2 of men), 34.0, 33.8 [both d, J(P,C) = 6.7 Hz, CH of men],
33.2 [d, J(P,C) = 7.1 Hz, CH of men], 32.8 [d, J(P,C) = 1.7 Hz, CH2
of C8H12), 31.4 [d, J(P,C) = 19.6 Hz, AsCH2P], 31.3, 31.0, 30.8,
30.2, 29.2 (all s, CH2 of C8H12 and C6H11), 29.1 [d, J(P,C) = 1.8 Hz,
CH2 of C8H12], 28.1, 27.9, 27.8, 26.2, 26.0 (all s, CH2 of C8H12 and
C6H11), 25.8, 25.5 [both d, J(P,C) = 9.5 Hz, CH2 of men], 22.7 [d,
J(P,C) = 4.8 Hz, CH3 of men], 22.5 [d, J(P,C) = 8.6 Hz, CH3 of men],
17.7, 16.4 (both s, CH3 of men); P (162.0 MHz) −22.9 [d, J(Rh,P) =
[Rh(4-C8H12){2-iPr2PCH2P(men)2}]PF6 12a. A suspension of
11 (93 mg, 0.19 mmol) in acetone (3 cm3) was treated with a solu-
tion of AgPF6 (97 mg, 0.38 mmol) in acetone (3 cm3) and stirred
for 20 min at room temperature. The reaction mixture was filtered
(to remove AgCl), the filtrate was cooled at −78 °C, and a solution
of iPr2PCH2P(men)2 (170 mg, 0.38 mmol) in acetone (3 cm3) was
added. After the solution was slowly warmed under stirring to room
temperature (30 min), it was concentrated in vacuo to ca. 5 cm3.
The addition of diethyl ether (15 cm3) led to the precipitation of an
orange–yellow solid, which was separated from the mother liquor,
washed twice with 3 cm3 portions of diethyl ether and dried: yield
205 mg (68%); mp 153 °C (decomp.), M = 71.2 cm2 −1 mol−1
(Found: C, 52.28; H, 7.94. C35H66F6P3Rh requires C, 52.76; H,
8.35%). NMR (CD2Cl2): H (400 MHz) 5.66, 5.23, 5.05, 4.87 (1 H
each, all br s, CH of C8H12), 3.44–0.70 (62 H, br m, CH2 of C8H12,
PCH2P, PCHCH3 and menthyl protons); C (100.6 MHz) 101.1 [dd,
J(Rh,C) = 8.6, J(P,C) = 7.6 Hz, CH of C8H12], 95.5 [dd, J(Rh,C) =
9.2, J(P,C) = 6.7 Hz, CH of C8H12], 94.1 [dd, J(Rh,C) = 8.1,
J(P,C) = 8.1 Hz, CH of C8H12], 92.5 [dd, J(Rh,C) = 10.2, J(P,C) =
6.0 Hz, CH of C8H12], 45.0, 44.7 (both s), 40.8, 39.2 [both d,
J(P,C) = 8.6 Hz], 38.0 [d, J(P,C) = 4.7 Hz], 36.8 (s), 34.7–32.8
(br m), 31.8–30.8 (m), 29.7 (s), 28.7–25.8 (br m), 22.7–15.4 (br
m), an exact assignment for the signals between 45.0 and 15.4 is
not possible; P (162.0 MHz) −18.5 [dd, J(Rh,P) = 128.6, J(P,P) =
52.2 Hz, iPr2P], −37.3 [dd, J(Rh,P) = 117.7, J(P,P) = 52.2 Hz,
−
119.9 Hz, (men)2P], −142.2 [sept, J(F,P) = 710.6 Hz, PF6 ].
[Rh(4-C8H12){2-(R)-iPr2PCH2CH(Me)PPh2}]PF6 12d. This
compound was prepared as described for 12a, from 11 (544 mg,
1.10 mmol), AgPF6 (557 mg, 2.20 mmol) and (R)-5a (760 mg,
2.20 mmol). Orange–yellow solid: yield 1.30 g (84%); mp 103 °C
(decomp.), M = 67.4 cm2 −1 mol−1 (Found: C, 49.48; H, 5.99; Rh,
13.96. C29H42F6P3Rh requires C, 49.73; H, 6.04; Rh, 14.69%). NMR
(CD2Cl2): H (400 MHz) 7.92 (2 H, m, C6H5), 7.67–7.50 (6 H, m,
C6H5), 7.36 (2 H, m, C6H5), 5.73, 5.59, 4.81, 4.05 (1 H each, all br
s, CH of C8H12), 2.85–1.90 (13 H, br m, CH2 of C8H12, PCHCH3
and PCHCH2), 1.59 [3 H, dd, J(P,H) = 16.4, J(H,H) = 7.3 Hz,
PCHCH3], 1.39 [3 H, dd, J(P,H) = 12.9, J(H,H) = 7.0 Hz, PCHCH3],
1.28–1.13 (9 H, br m, PCHCH3 and PCH(CH3)CH2); C (100.6 MHz)
137.4 [d, J(P,C) = 13.4 Hz, C6H5], 133.1 [d, J(P,C) = 2.9 Hz, C6H5],
131.5 [d, J(P,C) = 1.9 Hz, C6H5], 131.1, 129.9 [both d, J(P,C) =
8.6 Hz, C6H5], 129.2 [d, J(P,C) = 10.5 Hz, C6H5], 129.0 [d, J(P,C) =
42.0 Hz, ipso-C of C6H5], 126.2 [d, J(P,C) = 41.0 Hz, ipso-C of
C6H5], 102.3, 100.1 [both dd, J(Rh,C) = 8.1, J(P,C) = 8.1 Hz, CH
of C8H12], 97.5 [dd, J(Rh,C) = 7.6, J(P,C) = 7.6 Hz, CH of C8H12],
95.9 [dd, J(Rh,C) = 8.1, J(P,C) = 8.1 Hz, CH of C8H12], 35.7, 35.4
[both dd, J(P,C) = 13.2, J(P′,C) = 2.7 Hz, PCH and PCH2], 32.0,
31.1, 30.0, 28.7 (all s, CH2 of C8H12), 27.8 [d, J(P,C) = 21.0 Hz,
PCHCH3], 25.8 [d, J(P,C) = 22.9 Hz, PCHCH3], 21.9 [d, J(P,C) =
4.8 Hz, PCHCH3], 19.0 (s, PCHCH3), 18.5 [d, J(P,C) = 1.3 Hz,
PCHCH3], 18.3 [d, J(P,C) = 3.8 Hz, PCHCH3], 15.4 [dd, J(P,C) =
17.2, J(P′,C) = 6.7 Hz, PCH(CH3)CH2]; P (162.0 MHz) 62.3 [dd,
J(Rh,P) = 150.4, J(P,P) = 26.2 Hz, Ph2P], 57.1 [dd, J(Rh,P) = 141.7,
−
(men)2P], −144.7 [sept, J(F,P) = 710.6 Hz, PF6 ].
[Rh(4-C8H12){2-Ph2PCH2P(men)2}]PF6 12b. This compound
was prepared as described for 12a, from 11 (170 mg, 0.35 mmol),
AgPF6 (174 mg, 0.69 mmol) and Ph2PCH2P(men)2 (352 mg,
0.69 mmol). Orange–yellow solid: yield 440 mg (74%); mp
155 °C (decomp.), M = 66.2 cm2 −1 mol−1 (Found: C, 56.44; H,
6.68. C41H62F6P3Rh requires C, 56.95; H, 7.23%). NMR (CD2Cl2):
H (400 MHz) 7.60–7.32 (10 H, m, C6H5), 6.15, 4.94 (2 H each,
both br s, CH of C8H12), 4.01, 3.63 (1 H each, both m, PCH2P),
3.37–0.43 (46 H, br m, CH2 of C8H12 and menthyl protons); C
(100.6 MHz) 133.1 [d, J(P,C) = 11.2 Hz, C6H5], 133.0–131.9 (br
m, C6H5), 130.3 [d, J(P,C) = 1.7 Hz, C6H5], 130.2 [d, J(P,C) =
10.2 Hz, C6H5], 130.0 [d, J(P,C) = 2.0 Hz, C6H5], 129.9 [d, J(P,C) =
10.2 Hz, C6H5], 100.1 [dd, J(Rh,C) = 7.6, J(P,C) = 7.6 Hz, CH of
C8H12], 97.5 [dd, J(Rh,C) = 9.2, J(P,C) = 7.1 Hz, CH of C8H12],
97.1 [dd, J(Rh,C) = 8.1, J(P,C) = 8.1 Hz, CH of C8H12], 94.5
[dd, J(Rh,C) = 12.2, J(P,C) = 6.1 Hz, CH of C8H12], 47.2, 42.5
(both s, CH of men), 40.1 [d, J(P,C) = 13.2 Hz, CH2 of men], 38.8
[dd, J(Rh,C) = 5.1, J(P,C) = 8.1 Hz, ipso-C of men], 37.1 (s, CH2 of
−
J(P,P) = 26.2 Hz, iPr2P], −142.2 [sept, J(F,P) = 710.6 Hz, PF6 ].
[Rh(4-C8H12){2-(R)-Cy2PCH2CH(Me)PPh2}]PF6 12e. This
compound was prepared as described for 12a, from 11 (927 mg,
1.88 mmol), AgPF6 (950 mg, 3.76 mmol) and (R)-5b (1.60 g,
3.76 mmol). Orange solid: yield 2.14 g (77%); mp 128 °C (de-
comp.), M = 73.8 cm2 −1 mol−1 (Found: C, 54.09; H, 6.37; Rh,
12.52. C35H50F6P3Rh requires C, 53.85; H, 6.45; Rh, 13.18%). NMR
(CD2Cl2): H (400 MHz) 7.95–7.33 (10 H, m, C6H5), 5.73, 5.54,
D a l t o n T r a n s . , 2 0 0 4 , 1 8 7 3 – 1 8 8 1
1 8 7 9

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4.75, 3.96 (1 H each, all br s, CH of C8H12), 2.85–1.14 (36 H, br m,
CH2 of C8H12, PCH, PCH2, PCH(CH3) and C6H11); C (100.6 MHz)
137.5 [d, J(P,C) = 12.2 Hz, C6H5], 133.1 [d, J(P,C) = 2.0 Hz, C6H5],
131.5 [d, J(P,C) = 3.1 Hz, C6H5], 131.2, 129.9 [both d, J(P,C) =
9.2 Hz, C6H5], 129.1 [d, J(P,C) = 11.2 Hz, C6H5], 128.9 [d, J(P,C) =
39.0 Hz, ipso-C of C6H5], 126.3 [d, J(P,C) = 41.0 Hz, ipso-C of
C6H5], 101.7, 101.1 [both dd, J(Rh,C) = 8.1, J(P,C) = 8.1 Hz, CH
of C8H12], 97.5 [dd, J(Rh,C) = 7.6, J(P,C) = 7.6 Hz, CH of C8H12],
95.5 [dd, J(Rh,C) = 6.6, J(P,C) = 8.6 Hz, CH of C8H12], 37.9 [d,
J(P,C) = 19.3 Hz, CH of C6H11], 35.7 [ddd, J(Rh,C) = 30.4, J(P,C) =
12.2, J(P′,C) = 3.1 Hz, PCHCH2], 35.4 [d, J(P,C) = 22.4 Hz, CH of
C6H11], 33.0 [d, J(P,C) = 3.1 Hz, CH2 of C6H11], 32.7, 32.5, 31.5,
31.4 (all s, CH2 of C8H12 and C6H11), 29.7 [d, J(P,C) = 14.2 Hz, CH2
of C6H11], 29.6, 29.1 (both s, CH2 of C8H12), 29.0 [d, J(P,C) = 4.1 Hz,
CH2 of C6H11], 28.4 [d, J(P,C) = 14.2 Hz, CH2 of C6H11], 27.2 [d,
J(P,C) = 7.1 Hz, CH2 of C6H11], 27.1 [d, J(P,C) = 8.1 Hz, CH2 of
C6H11], 26.5, 26.2 (both s, CH2 of C6H11), 25.8 [ddd, J(Rh,C) =
26.4, J(P,C) = 17.3, J(P′,C) = 2.1 Hz, PCH2], 15.4 [dd, J(P,C) =
17.3, J(P′,C) = 6.1 Hz, PCH(CH3)CH2]; P (162.0 MHz) 62.8 [dd,
J(Rh,P) = 150.4, J(P,P) = 26.2 Hz, Ph2P], 48.5 [dd, J(Rh,P) = 141.7,
J(P,C) = 3.7 Hz, PCCH3], 29.6, 29.1 (both s, CH2 of C8H12), 22.7
[dd, J(P,C) = 19.0, J(P′,C) = 5.1 Hz, PCH2CH2], 18.4 [d, J(P,C) =
7.4 Hz, PCH(CH3)CH2]; P (162.0 MHz) 33.1 [dd, J(Rh,P) =
136.1, J(P,P) = 34.3 Hz, tBu2P], 21.7 [dd, J(Rh,P) = 145.0, J(P,P) =
−
34.3 Hz, Ph2P], −143.9 [sept, J(F,P) = 712.1 Hz, PF6 ].
[Rh(4-C8H12){2-(S,S)-iPr2PCH(Me)CH2CH(Me)PPh2}]PF6
12h. This compound was prepared as described for 12a, from 11
(232 mg, 0.47 mmol), AgPF6 (240 mg, 0.95 mmol) and (S,S)-10
(355 mg, 0.95 mmol). Orange–yellow solid: yield 589 mg (85%);
mp 128 °C (decomp.), M = 68.7 cm2 −1 mol−1 (Found: C, 51.21;
H, 5.90; Rh, 14.00. C31H46F6P3Rh requires C, 51.11; H, 6.36; Rh,
14.13%). NMR (CD2Cl2): H (400 MHz) 8.10–7.35 (10 H, m, C6H5),
5.74, 5.16, 4.24, 4.13 (1 H each, all br s, CH of C8H12), 2.62–1.65
(14 H, br m, CH2 of C8H12, PCHCH3 and PCHCH2CH), 1.50 [3 H,
dd, J(P,H) = 16.1, J(H,H) = 7.0 Hz, PCHCH3 or PCH(CH3)CH2],
1.42 [3 H, dd, J(P,H) = 12.8, J(H,H) = 7.8 Hz, PCHCH3 or
PCH(CH3)CH2], 1.39 [3 H, dd, J(P,H) = 10.1, J(H,H) = 7.8 Hz,
PCHCH3 or PCH(CH3)CH2], 1.33 [3 H, dd, J(P,H) = 14.5, J(H,H) =
7.2 Hz, PCHCH3 or PCH(CH3)CH2], 1.50 [3 H, dd, J(P,H) = 16.1,
J(H,H) = 7.0 Hz, PCHCH3 or PCH(CH3)CH2], 1.24 [3 H, dd,
J(P,H) = 12.5, J(H,H) = 6.9 Hz, PCHCH3 or PCH(CH3)CH2], 1.07 [3
H, dd, J(P,H) = 12.3, J(H,H) = 7.0 Hz, PCHCH3 or PCH(CH3)CH2];
C (100.6 MHz) 136.8 [d, J(P,C) = 11.2 Hz, C6H5], 132.6 [d, J(P,C) =
3.1 Hz, C6H5], 132.0 [d, J(P,C) = 8.1 Hz, C6H5], 131.2 [d, J(P,C) =
2.0 Hz, C6H5), 129.5 [d, J(P,C) = 9.2 Hz, C6H5], 129.4 [d, J(P,C) =
40.7 Hz, ipso-C of C6H5], 129.2 [d, J(P,C) = 10.2 Hz, C6H5], 128.3
[d, J(P,C) = 41.7 Hz, ipso-C of C6H5], 101.5, 101.2 [both dd,
J(Rh,C) = 7.6, J(P,C) = 7.6 Hz, CH of C8H12], 95.8 [dd, J(Rh,C) =
8.1, J(P,C) = 8.1 Hz, CH of C8H12], 94.7 [dd, J(Rh,C) = 10.2,
J(P,C) = 7.1 Hz, CH of C8H12], 38.1 [dd, J(P,C) = 5.6, J(P′,C) =
5.6 Hz, PCH], 32.7, 31.3, 29.7, 29.1 (all s, CH2 of C8H12), 26.6 [d,
J(P,C) = 19.3 Hz, PCHCH3], 24.9 [d, J(P,C) = 20.3 Hz, PCHCH3],
24.6 [dd, J(P,C) = 24.9, J(P′,C) = 7.6 Hz, PCH], 23.9 [dd, J(P,C) =
19.8, J(P′,C) = 5.6 Hz, PCH], 22.7 [d, J(P,C) = 3.1 Hz, PCHCH3],
20.7, 19.8 (both s, PCHCH3), 18.8 [d, J(P,C) = 7.1 Hz, PCHCH3],
17.6 [d, J(P,C) = 4.1 Hz, PCH(CH3)CH2], 17.5 [d, J(P,C) = 1.9 Hz,
PCH(CH3)CH2]; P (162.0 MHz) 32.4 [dd, J(Rh,P) = 137.3, J(P,P) =
40.4 Hz, iPr2P], 25.5 [dd, J(Rh,P) = 143.8, J(P,P) = 40.4 Hz,
−
J(P,P) = 26.2 Hz, Cy2P], −144.3 [sept, J(F,P) = 710.6 Hz, PF6 ].
[Rh(4-C8H12){κ2-(R)-tBu2PCH2CH(Me)PPh2}]PF6 12f. This
compound was prepared as described for 12a, from 11 (321 mg,
0.65 mmol), AgPF6 (331 mg, 1.31 mmol) and (R)-5c (487 mg,
1.31 mmol). Orange–yellow solid: yield 640 mg (67%); mp 178 °C
(decomp.), M = 69.9 cm2 −1 mol−1 (Found: C, 50.56; H, 6.25; Rh,
14.01. C31H46F6P3Rh requires C, 51.11; H, 6.36; Rh, 14.13%). NMR
(CD3NO2): H (400 MHz) 8.14 (2 H, m, C6H5), 7.71–7.40 (8 H, m,
C6H5), 6.22, 5.98, 4.51, 3.99 (1 H each, all br s, CH of C8H12), 2.96
(1 H, m, PCH), 2.58–2.05 (10 H, br m, CH2 of C8H12 and PCH2),
1.61 [9 H, d, J(P,H) = 12.9 Hz, PCCH3], 1.31 [9 H, d, J(P,H) =
13.5 Hz, PCCH3], 1.24 [3 H, dd, J(P,H) = 11.0, J(H,H) = 6.3 Hz,
PCH(CH3)CH2]; C (100.6 MHz) 138.6 [d, J(P,C) = 12.4 Hz, C6H5],
133.4 [d, J(P,C) = 2.9 Hz, C6H5], 132.2 [d, J(P,C) = 8.6 Hz, C6H5],
132.0 [d, J(P,C) = 1.9 Hz, C6H5], 130.2 [d, J(P,C) = 9.6 Hz, C6H5],
129.4 [d, J(P,C) = 10.5 Hz, C6H5], 127.3 [d, J(P,C) = 42.9 Hz, ipso-
C of C6H5], 105.6 [dd, J(Rh,C) = 7.6, J(P,C) = 7.6 Hz, CH of
C8H12], 99.1 [dd, J(Rh,C) = 8.1, J(P,C) = 8.1 Hz, CH of C8H12],
95.3 [dd, J(Rh,C) = 9.1, J(P,C) = 6.2 Hz, CH of C8H12], 91.9 [dd,
J(Rh,C) = 8.1, J(P,C) = 8.1 Hz, CH of C8H12], 39.4 [d, J(P,C) =
12.4 Hz, PCCH3], 37.3 [d, J(P,C) = 13.4 Hz, PCCH3], 34.8 [dd,
J(P,C) = 21.0, J(P′,C) = 8.6 Hz, PCH2], 32.0 [d, J(P,C) = 3.8 Hz,
PCCH3], 31.4, 30.7, 30.0, 28.7 (all s, CH2 of C8H12), 29.6 [d,
J(P,C) = 3.8 Hz, PCCH3], 28.7 [dd, J(P,C) = 20.5, J(P′,C) = 20.5 Hz,
PCH], 15.6 [dd, J(P,C) = 15.7, J(P′,C) = 6.2 Hz, PCH(CH3)CH2]; P
(162.0 MHz) 64.8 [dd, J(Rh,P) = 139.5, J(P,P) = 21.8 Hz, tBu2P],
59.7 [dd, J(Rh,P) = 152.6, J(P,P) = 21.8 Hz, Ph2P], −144.6 [sept,
−
Ph2P], −142.2 [sept, J(F,P) = 710.6 Hz, PF6 ].
Catalytic studies
The hydrogenation reactions at a hydrogen pressure of 1 bar were
carried out in a standard apparatus from Normag; those reactions
at a hydrogen pressure of up to 60 bar were carried out in a stain-
less steel autoclave from Büchi. Other details are mentioned in
Table 3. The ee values were calculated from the optical rotation
in methanol solution using a value of []D = +16.4 (c = 2.00) for
the (S)-N-acetylphenylalanine methylester,34 and corrected to the
composition of the distillate. Optical rotations were measured with
a Perkin-Elmer 241 polarimeter. For reactions carried out in the
presence of KOH as cocatalyst, 3 mL of a 0.1 M solution of KOH in
2-propanol were added to the solution of the catalyst.
−
J(F,P) = 708.4 Hz, PF6 ].
[Rh(4-C8H12){2-(R)-tBu2PCH2CH2CH(Me)PPh2}]PF6
12g. This compound was prepared as described for 12a, from
11 (956 mg, 1.94 mmol), AgPF6 (980 mg, 3.88 mmol) and (R)-8
(1.50 g, 3.88 mmol). Orange–yellow solid: yield 1.88 g (65%);
mp 120 °C (decomp.), M = 65.5 cm2 −1 mol−1 (Found: C,
51.62; H, 6.38; Rh, 13.22. C32H48F6P3Rh requires C, 51.76; H,
6.52; Rh, 13.86%). NMR (CD2Cl2): H (400 MHz) 8.30–7.33 (10
H, m, C6H5), 6.22, 5.52, 4.32, 3.94 (1 H each, all br s, CH of
C8H12), 2.62–1.20 (13 H, br m, CH2 of C8H12 and PCHCH2CH2),
1.58 [9 H, d, J(P,H) = 13.2 Hz, PCCH3], 1.35 [9 H, d, J(P,H) =
12.8 Hz, PCCH3], 0.91 [3 H, dd, J(P,H) = 11.1, J(H,H) = 7.5 Hz,
PCH(CH3)CH2]; C (100.6 MHz) 136.9 [d, J(P,C) = 8.3 Hz, C6H5],
132.7 (s, C6H5), 131.9 [d, J(P,C) = 7.4 Hz, C6H5], 131.3 (s, C6H5),
129.6 [d, J(P,C) = 10.2 Hz, C6H5], 128.7 [d, J(P,C) = 8.3 Hz, C6H5],
127.8 (s, C6H5), 102.0 [dd, J(Rh,C) = 6.9, J(P,C) = 6.9 Hz, CH of
C8H12], 98.4 [dd, J(Rh,C) = 9.2, J(P,C) = 5.5 Hz, CH of C8H12],
91.8 [dd, J(Rh,C) = 12.5, J(P,C) = 7.9 Hz, CH of C8H12], 91.0 [dd,
J(Rh,C) = 11.6, J(P,C) = 6.9 Hz, CH of C8H12], 40.0 [dd, J(P,C) =
12.4, J(P′,C) = 3.1 Hz, PCH], 34.8, 33.1 [both d, J(P,C) = 3.7 Hz,
PCCH3], 32.7, 31.4 (both s, CH2 of C8H12), 31.3 [d, J(P,C) = 4.6 Hz,
PCCH3], 31.0 [dd, J(P,C) = 13.8, J(P′,C) = 3.7 Hz, PCH2], 30.1 [d,
Crystallography
Single crystals of 12c and 12d were grown from methanol. Crys-
tal data for the structures of 12c and 12d are presented in Table 5.
Data for both structures were collected at low temperatures using
oil-coated shock-cooled crystals35 on a Nonius CAD4 (12c) and
a Stoe IPDS (12d) diffractometer using graphite monochromated
Mo K radiation ( = 0.71073 Å). Semiempirical absorption cor-
rection was applied. The structures were solved by Patterson or
direct methods with SHELXS-97.36 All structures were refined by
full-matrix least-squares procedures on F2, using SHELXL-97.37
All non-hydrogen atoms were refined anisotropically, and a riding
model was employed in the refinement of the hydrogen atom posi-
tions. Refinement of an inversion twin parameter19 x, where x = 0
for the correct absolute structure and +1 for the inverted structure,
confirmed the absolute structures of both complexes. Both PF6 an-
1 8 8 0
D a l t o n T r a n s . , 2 0 0 4 , 1 8 7 3 – 1 8 8 1

View Article Online
Table 5 Crystal data and structure refinement for complexes 12c,d at T = 173(2) K
12c
12d
Empirical formula
M
C41H74AsF6P2Rh
920.77
C29H42F6P3Rh
700.47
Space group
P21
P212121
a/Å
b/Å
c/Å
10.642(2)
18.838(4)
11.874(2)
115.84(3)
2.1423(7), 2
1.427
12.8194(16)
15.0734(16)
16.0049(16)
/°
V/nm3, Z
3.0927(6), 4
1.479
0.760
Dc/Mg m−3
/mm−1
1.294
 range/°
2.4 to 28.0
9404/377/538
0.0477
0.1149
0.725, −1.481
0.018(12)
2.4 to 25.0
5463/48/394
0.0479
0.1072
672, −657
0.06(4)
Data/restraints/parameter
R1a [I > 2(I)]
wR2b (all data)
Largest diff. peak and hole/e nm−3
Flack-x-param.19
b
a
F2 + 2F2
w(F2 − F2 )2
Fo − F
(
)
∑
c
1
o
c
∑
o
c
R1=
.
wR2 =
with w =
; P =
.
∑
σ2 F2 + g P 2 + g2P
w(F2 )2
3
F
o
(
)
∑
(
)
o
o
1
7 G. Fries, K. Ilg, M. Pfeiffer, D. Stalke and H. Werner, Eur. J. Inorg.
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ions in 12c and 12d are disordered and were refined anisotropically
with a split site occupation factor for the fluorine atoms of 72:28
and 70:30, respectively.
CCDC reference numbers 229547 (12c) and 229548 (12d).
See http://www.rsc.org/suppdata/dt/b4/b401585a/ for crystal-
lographic data in CIF or other electronic format.
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Acknowledgements
We thank the Deutsche Forschungsgemeinschaft (SFB 347) and the
Fonds der Chemischen Industrie for financial support, the latter in
particular for a PhD grant to K.I. We are also most grateful to Dr
P. Groer (HPLC measurements), Mrs R. Schedl and Mr C. P. Kneis
(DTA measurements and elemental analyses), Dr G. Lange and Mr
F. Dadrich (mass spectra) and Mrs M.-L. Schäfer (NMR spectra).
Moreover, we acknowledge support by BASFAG and F. Hoffmann-
La Roche AG for chemicals.
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D a l t o n T r a n s . , 2 0 0 4 , 1 8 7 3 – 1 8 8 1
1 8 8 1