Synthesis and study of amino acid based phosphinite ligands

Article abstract of DOI:10.1016/S0022-328X(03)00181-5

The preparation of the five new amino acid derived phosphinites Boc-Ser(OPPh₂)-OMe (5), Boc-Thr(OPPh₂)-OMe (6), Boc-Tyr(OPPh₂)-OMe (7), Z-Ser(OPPh₂)-OMe (8), and Z-β-Ala-Tyr(OPPh₂)-OMe (9) is reported

Full text of DOI:10.1016/S0022-328X(03)00181-5

Journal of Organometallic Chemistry 674 (2003) 24ꢀ31
/
www.elsevier.com/locate/jorganchem
Synthesis and study of amino acid based phosphinite ligands
Patrycja W. Galka, Heinz-Bernhard Kraatz *
Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Sask., Canada S7N 5C9
Received 24 January 2003; received in revised form 18 March 2003; accepted 19 March 2003
Abstract
The preparation of the five new amino acid derived phosphinites Boc-Ser(OPPh2)-OMe (5), Boc-Thr(OPPh2)-OMe (6), Boc-
Tyr(OPPh2)-OMe (7), Z-Ser(OPPh2)-OMe (8), and Z-b-Ala-Tyr(OPPh2)-OMe (9) is reported together with their full spectroscopic
characterization. These ligands readily complex to Pd(II) and Pt(II) giving the corresponding complexes [Boc-Ser(OPPh2)-
OMe]2PtCl2 (10), [Boc-Tyr(OPPh2)-OMe]2PtCl2 (11), [Boc-Thr(OPPh2)-OMe]2PtCl2 (12), [Z-b-Ala-Tyr(OPPh2)-OMe]2PtCl2 (13),
[Boc-Ser(OPPh2)-OMe]2PdCl2 (14), [Boc-Tyr(OPPh2)-OMe]2PdCl2 (15), [Boc-Thr(OPPh2)-OMe]2PdCl2 (16), [Z-b-Ala-Tyr(OPPh2)-
OMe]2PdCl2 (17). The X-ray structure of 10 was determined and shows the ligands being cis coordinated around the Pt(II) center
˚
˚
with PtÃ
/
P distances of 2.2278(13) A for PtÃ
/
P(1) and 2.2235(12) A for PtÃ
/
P(2).
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Phosphinite; Amino acid; Peptide; Platinum; Palladium; X-ray; 31P-NMR
1. Introduction
gands [6]. Carbohydrates, have been exploited as chiral
starting materials for the ligand synthesis of phosphi-
nites, making use of the rich array of stereochemical and
functional group diversity of carbohydrates [7]. Prior to
this work, only proline-based phosphinito ligands were
Phosphines and phosphites are among the most
important phosphorous-based ligands in organometallic
chemistry with a wide range of steric and electronic
properties. These ligands have found wide-spread appli-
cations in transition metal catalyzed asymmetric trans-
reported in the literature [8ꢀ10]. Other amino acid
/
derived phosphinites, such as tyrosine, serine or threo-
nine phosphinites have not been reported. Here, we
report the synthesis of phosphinite ligands based on the
formations [1ꢀ5]. Phosphinites have been explored
/
extensively. They provide different chemical, electronic
and structural properties compared to phosphines.
Thus, they open many opportunities to design new
naturally occurring L-hydroxy-amino acids, serine (1),
tyrosine (2) and threonine (3). Whereas, there are some
reports of amino acid and peptide-phosphines in the
improved ligands for asymmetric catalysis. The metalꢀ
/
phosphorous bond are often stronger for phosphinites
compared to the related phosphines due to the presence
literature [18], there is a noticeable absence of peptidoꢀ
/
phosphinites.
of the electron-withdrawing PÃ/OR group. In addition,
the empty s*-orbital of the phosphinite P(OR)R2 is
stabilized and thus a better acceptor.
Biomolecules, such as amino acids, peptide and
carbohydrates, offer a particularly convenient starting
point for the synthetis of chiral ligands. They are readily
available in an enantiopure form. In particular, proline-
derived aminoalcohols have been popularized for the
synthesis of chelating aminophosphineꢀphosphinite li-
/
Here we report the synthesis of several amino acid-
based phosphinites and their palladium and platinum
complexes.
* Corresponding author. Fax.: ꢁ
E-mail address: kraatz@sask.usask.ca (H.-B. Kraatz).
/
1-306-966-4660.
0022-328X/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00181-5

P.W. Galka, H.-B. Kraatz / Journal of Organometallic Chemistry 674 (2003) 24ꢀ
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25
2. Results and discussion
This strategy is was also extended to include the
dipeptide phosphinite Z-b-Ala-Tyr(OPPh2)-OMe (9),
which was readily obtained from Z-b-Ala-Tyr-OMe
under identical conditions.
The progress of this reaction was conveniently
followed by 31P-NMR spectroscopy. The signal of the
starting material ClPPh2 at d 81.0 disappeared and a
new singlet downfield due to the phosphinite was
detected. Table 1 summarizes selected spectroscopic
properties of the new phosphinite ligands. Our result
agrees with chemical shifts for other phosphinites
The synthesis of phosphinites is conveniently achieved
by reacting alcoholic amino acid, such as serine,
threonine, and tyrosine, with one equivalent of chlor-
odiphenylphosphines in the presence of an organic base.
Other functional groups can be conveniently protected,
allowing the selective conversion of the hydroxyl group
into the corresponding phosphinites. For example, the
N,C-protected amino acid derivative Boc-Ser(OH)-OMe
(4) was reacted with diphenylphosphine chloride in the
presence of Et3N and catalytic amounts of DMAP to
give the corresponding phosphinite serine 5 (Scheme 1).
Purification of the phosphinite ligand was readily
achieved by passing the reaction solution through a
pad of basic alumina. Other bases, such as pyridine, can
be used in this procedure, but require evaporation in
vacuo at elevated temperatures and are not completely
removed by the basic alumina amounts of 4-dimethyla-
minopyridine (DMAP) followed by the filtration of the
reaction solution through basic alumina (Scheme 1).
Other phosphinites based on threonine (6) and on
tyrosine (7) were prepared under identical conditions in
high yields. Other commonly used N-protecting groups,
such as benzyloxycarbonyl (Z), do not interfere with
phosphinite formation. Z-Ser(OPPh2)-OMe (8) was
obtained under identical conditions from the corre-
sponding N,C-protected Z-Ser-OMe.
reported in the literature [7a] [8ꢀ12].
/
In general, for phosphinites the a-CH and b-CH2
signals were shifted downfield upon the phosphinite
formation compared to the N,C-protected amino acid
derivative. The 13C-NMR spectra of all phosphinito
ligands prepared here showed characteristic P-C cou-
pling constants of 1JPÃC of 10ꢀ
/
21 Hz and 2JCÃOÃP of 10ꢀ
/
17 Hz consistent with the literature data. All phosphi-
nites prepared here oxidize readily in solution upon
exposure to air which has been documented in the
literature for diarylphosphinites [13], but they can be
stored under an inert atmosphere without decomposi-
tion.
Palladium and platinum complexes of the phosphinite
ligands 5ꢀ9 were prepared in quantitative yields by
/
reacting the appropriate phosphorus ligand with either
Pd or Pt precursor as outlined in Scheme 2 for the
synthesis of [Boc-Ser(OPPh2)-OMe]2PtCl2 (10) from
(COD)PtCl2 and Boc-Ser(OPPh2)-OMe (5). The same
synthetic strategy was employed to obtain Pd and Pt
complexes of the related phosphinites of threonine,
tyrosine and of b-Ala-Tyr, which are all colorless air
stable solids.
In the 31P-NMR spectrum, complexes 10ꢀ
singlets upfield from the position of the free ligand
(Table 2). For all Pt complexes, the 31PÃ195Pt coupling
/
13 exhibit
Scheme 1. Synthesis of Boc-Ser(OPPh2)-OMe (5) from serine (1) via
the N,C-protected serine derivative Boc-Ser(OH)-OMe (4): (i) Boc2O,
CH2Cl2; (ii) ClPPh2, NEt3, CH2Cl2.
/
constants agree with a cis arrangement of the phosphi-
nite ligands around the metal center. In the solid state,
the IR spectrum in CsI for two of these complexes
supports the stereochemical assignment and gives two
bands characteristic for a cis coordination of the two
Table 1
Selected 1H and 31P{1H}-NMR chemical shift data of the diphenylꢀ
/
phosphinito ligands Boc-Ser(OPPh2)-OMe (5), Boc-Thr(OPPh2)-OMe
(6), Boc-Tyr(OPPh2)-OMe (7), Z-Ser(OPPh2)-OMe (8), and Z-b-Ala-
Tyr(OPPh2)-OMe (9) in CDCl3 (d in ppm)
Compound
1H
31P{1H}
NH
a-CH
b-CH2
5
6
7
8
9
5.31
5.35
4.61
4.65
4.58
4.61
4.81
4.10
4.43
118.3
113.3
111.1
118.3
111.5
5.06
5.63
3.06
4.21
6.02, 5.42
3.45, 3.06

26
P.W. Galka, H.-B. Kraatz / Journal of Organometallic Chemistry 674 (2003) 24ꢀ31
/
Scheme 2. Synthesis of [Boc-Ser(OPPh2)-OMe]2PtCl2 (10) from ligand
5 and (COD)PtCl2 in CH2Cl2.
Table 2
31P-NMR of the Pt and Pd phosphinito complexes[Boc-Ser(OPPh2)-
OMe]2PtCl2 (10), [Boc-Tyr(OPPh2)-OMe]2PtCl2 (11), [Boc-
Thr(OPPh2)-OMe]2PtCl2 (12), [Z-b-Ala-Tyr(OPPh2)-OMe]2PtCl2
(13),
[Boc-Ser(OPPh2)-OMe]2PdCl2
(14),
[Boc-Tyr(OPPh2)-
OMe]2PdCl2 (15), [Boc-Thr(OPPh2)-OMe]2PdCl2 (16), [Z-b-Ala-
Tyr(OPPh2)-OMe]2PdCl2 (17) in CDCl3 (d in ppm and JPtÃP in Hz)
Complex
d
JPtÃP (Hz)
Fig. 1. ORTEP view of [Boc-Ser(OPPh2)-OMe]2PtCl2 (10). Ellipsoids
are drawn at the 30% probability level. All H atoms are omitted for
[Boc-Ser(OPPh2)-OMe]2PtCl2 (10)
[Boc-Tyr(OPPh2)-OMe]2PtCl2 (11)
[Boc-Thr(OPPh2)-OMe]2PtCl2 (12)
[Z-b-Ala-Tyr(OPPh2)-OMe]2PtCl2 (13)
[Boc-Ser(OPPh2)-OMe]2PdCl2 (14)
[Boc-Tyr(OPPh2)-OMe]2PdCl2 (15)
[Boc-Thr(OPPh2)-OMe]2PdCl2 (16)
[Z-b-Ala-Tyr(OPPh2)-OMe]2PdCl2 (17)
84.8
86.1
4100
4220
4100
3760
˚
2.2278(13) A,
clarity. Selected bond distances and angles: PtÃ
/
P(1)ꢃ
/
˚
˚
PtÃ
2.3592(13) A, P(2)Ã
P(1)ÃPtÃCl(2)ꢃ173.13(5)8, P(2)Ã
Cl(1)ꢃ88.17(4)8, Cl(2)ÃPtÃCl(1)ꢃ
/
P(2)ꢃ
/
2.2235(12) A, PtÃ
/
Cl(1)ꢃ
95.80(5)8, P(2)Ã
PtÃCl(1)ꢃ174.31(5)8, P(1)Ã
86.33(5)8.
/
2.3663(12) A, PtÃ
PtÃCl(2)ꢃ89.98(4)8,
PtÃ
/
Cl(2)ꢃ
/
76.4
86.0
˚
/
PtÃ
/
P(1)ꢃ
/
/
/
/
/
/
/
/
/
/
/
/
112.6
111.7
103.9
111.5
/
/
/
/
those reported by Cesarotti for PdÃ/P, indicating stron-
ger bonding and potentially a lower ability of the
phosphinite ligand to dissociate from the metal center.
Interestingly, recrystallization of complex 16 in air
from dichloromethane/petroleum ether gave yellow
plates after 2 weeks. The 31P-NMR of the crystals
shows a singlet at d 78.8. The 1H-NMR spectrum shows
the absence of any signals due to the tyrosine group,
indicating the presence of the hydrolysis product. A
single crystal diffraction study showed the structure to
be that of di-m-chlorobis[hydrogen bis(diphenylphosphi-
nito)(1-)-P,P?] dipalladium, reported before by Parkins
and co-workers [16]. This is an important result
indicating a potential limit on the utility of tyrosine-
based phosphinites and its lability towards hydrolysis.
In order to investigate the influence of the metal
precursor on the stereochemistry of the complex the
following experiments were carried out. Metal com-
plexes were prepared starting from two different pre-
cursors, (COD)MCl2 and (PhCN)2MCl2. The latter
allows for the rearrangement of the complex during
the reaction to the thermodynamically most favorable
geometry, which presumably will have the ligands in a
trans configuration. Our experiments show that the
reaction of serine phosphinite ligand 5, 8 and 9 with
(COD)PtCl2 result exclusively in the formation of the cis
isomer. In contrast, the reaction of (PhCN)2PtCl2 with
the tyrosin phosphinite 8 and dipeptide phosphinite 9
gives a mixture of cis and trans products. Our results
compare well with earlier reports showing that product
chloride ligands. The IR for 10 exhibits two absorptions
at 330 and at 297 cmꢂ1. The related peptide complex 13
also exhibits two PtÃ
/
Cl vibrations at 360 and 319 cmꢂ1
.
These IR signals compare well with those reported for
(COD)PtCl2, cis-[(PhO)3P]2PtCl2 and cis-(styre-
ne)(PhH2Si)PtCl2 [14]. For the palladium reactions,
strong upfield shifts were observed for serine and
threonine-based complexes 14 and 16, respectively.
The tyrosine-complexes 15 and 17 showed virtually no
chemical shift differences compared to the free ligand.
However, the fragmentation pattern of the complexes
clearly indicate coordination of the ligand to the metal
centers.
Compound 10 crystallizes from chloroform/hexanes
as colorless needles. Its molecular structure was deter-
mined by a single-crystal X-ray diffraction study, a view
of which is presented in Fig. 1 together with selected
bond lengths and angles. As expected for platinum(II),
the coordination geometry around the Pt center is close
to square planar having the two phosphinito amino
acids ligands cis to each other. The structure compares
well with other known Pd(II) and Pt(II) phosphinite
structures [15]. The metalꢀphosphorus distances are
/
similar to those found in for other M-phosphinite
complexes reported in the literature.
˚
The PtÃ
/
P bond lengths of 2.2278(13) A for PtÃ
/
P(1)
P(2) are slightly shorter that
˚
and 2.2235(12) A for PtÃ
/

P.W. Galka, H.-B. Kraatz / Journal of Organometallic Chemistry 674 (2003) 24ꢀ
/31
27
distribution is greatly influenced by the nature of the
metal precursor [17].
the TLC showed the consumption of the starting
materials. The reaction mixture was washed with
saturated solutions of sodium bicarbonate, followed by
10% citric acid, saturated solution of sodium bicarbo-
nate, and finally distilled water. The organic phase was
dried over MgSO4, which was followed by the removal
of the solvent in vacuo. The desired product was
obtained as a white solid after purification by flash
In summary, we have prepared a series of novel
phosphinito amino acids and one phosphinito peptide
and prepared the corresponding Pd and Pt complexes.
The complexes exhibit the expected square planar
coordination environment about the metal center. We
are now investigating the reactivity of these complexes
and their potential to act as catalyst in catalytic
reactions and hope to compare them to related amino
acid and peptide phosphine complexes [18].
column
85:10:5 Rfꢃ
m/z (relative intensity): 401 ([Mꢁ
(26), 91 (55), 70 (42), 54 (100). HRMS of C21H25N2O6
Calc. [Mꢁ
H]ꢁ 401.1712, Found [Mꢁ1]ꢁ 401.1711.
1H-NMR (d, CDCl3): 7.83 (1H, br s, OH), 7.31 (5H, s,
CHar Z), 6.90 (2H, d, Jꢃ8.3 Hz, CHar Tyr), 6.72 (2H, d,
Jꢃ8.3 Hz, CHar Tyr), 6.66 (1H, d, Jꢃ7.8 Hz, NH Tyr),
chromatography
0.21). Yield 1.36 g (68%). LRMS (FAB),
1]ꢁ 17), 149 (16), 95
(CHCl3/hexanes/MeOH
/
/
/
/
3. Experimental
/
3.1. General
/
/
5.66 (1H, m, NH Ala), 5.07 (2H, s, CH2), 4.79 (1H, m,
CH Tyr), 3.67 (3H, s, OCH3), 3.36 (2H, m, CH2 Ala),
3.00 (2H, m, CH2 Tyr), 2.33 (2H, m, CH2 Ala).
All manipulations of air moisture sensitive materials
were conducted in an argon atmosphere using common
Schlenk techniques. All solvents were distilled prior to
use form appropriate drying agents: triethylamine was
distilled from potassium hydroxide; dichloromethane
was distilled from CaH2. Diphenylphosphine chloride
was redistilled before use. Unless otherwise noted,
chemicals were used as received from Aldrich. Flash
chromatography column was carried out on Merck
13C{1H}-NMR (d, CDCl3): 172.2 (CÄ
O), 156.8 (CÄOZ), 155.7 (CarÃ
/
O), 171.6 (CÄ
/
/
/
OH), 136.3 (Car Z),
130.2 (Car Tyr), 128.0 (Car Z), 127.9 (Car Z), 126.9
(Car), 115.6 (Car Tyr) 66.7 (CH2 Z), 53.6 (Car Tyr), 52.3
(OCH3), 37.2, 36.9, 35.8 (CH2).
3.3. General procedure for phosphinito ligands
Kieselgel 60 (200ꢀ400 mesh) silica. All thin layer
/
chromatography was performed using pre-coated TLC
plates with Silica Gel 60 F254. The spots were detected
To a flask containing the N,C-protected hydroxy-
amino acid and dichloromethane (20 ml), three equiva-
lents of triethylamine and catalytic amounts of DMAP
(10 mol%) were added. An amount of diphenylpho-
sphine chloride equimolar to the amino acid amount
was added dropwise using 1-ml Hamilton syringe. The
mixture was stirred overnight and then the solution was
filtered through basic alumina. After removal of the
solvent under reduced pressure, the desired phosphinito-
product was obtained.
1
using iodine. H, 13C{1H} and 31P{1H}-NMR spectra
were recorded on a Bruker AMX-300 spectrometer at
300.13, 75.48 and 121.49 MHz, respectively. Chemical
shifts (d) were measured relative to SiMe4 and were
referenced to the residual signal of CHCl3 (d 7.27) for
1H and the CDCl3 signal (d 77.23) for 13C{1H}. For
31P{1H} 85% H3PO4 was used as an external reference.
Mass spectra were obtained with VG Analytical 70/20
VSE chromatograph. GC MS analyses were performed
on Fision 8060, 8000 series optical rotations were
measured using Rudolph instruments DigiPol DP781
3.4. Boc-Ser(OPPh2)-OMe (5)
at 589 nm (cꢃ
CH2Cl2, unless specified otherwise). The mass of
compounds (15 mgꢀ5 g) were reported with an accuracy
of 91 mg.
/
0.01 g 1.00 mlꢂ1, dꢃ
/100.00 mm, in
Boc-Ser(OH)-OMe (4.6 mmol, 1.00 g), triethylamine
(13.7 mmol, 1.90 ml), DMAP (0.056 g), diphenylpho-
sphine chloride (4.5 mmol, 0.82 ml). Product: white
solid. Yield 1.09 g (60%). Anal. Calc. for C21H26NO5P:
C 62.52, H 6.50, N 3.47; Found: C 62.57, H 6.41, N
/
/
3.2. Preparation of Z-b-Ala-Tyr-OMe
3.35%. LRMS (FAB), m/z (relative intensity): 404 ([Mꢁ
1]ꢁ 8), 219 (40), 203 (100), 201 (28), 154 (23), 136 (21),
57 (65). HRMS of C21H27NO5P Calc. [Mꢁ
H]ꢁ
25
/
Z-b-Ala-OH (2.0 mmol, 0.45 g) was dissolved in 20 ml
of dry CH2Cl2 and cooled to 0 8C. Then solid HOBt (2.2
mmol, 0.30 g) and EDC (2.2 mmol, 0.42 g) were added.
/
404.1627 found [Mꢁ
/
H]ꢁ 404.1625. [a]D25
ꢃ
/
ꢁ
/
[10ꢂ1 8 cm2 gꢂ1]. 31P{1H}-NMR (d, CDCl3): 118.3
1
(s). H-NMR (d, CDCl3): 7.42 (5H, m, Har), 7.09 (5H,
H-Tyr-OMe×
/
HCl (2.2 mmol, 0.51 g) was placed in
second flask. CH2Cl2 (20 ml) and NEt3 (1.5 ml) were
added via syringe, until all solid starting material
dissolved. This solution was added to the mixture of
Z-b-Ala-OH and HOBt, EDC. Reaction was allowed to
warm up to room temperature and stirred for 24 h until
m, Har), 5.31 (1H, d, Jꢃ9.0 Hz, NH), 4.51 (1H, m, CH),
/
4.25 (1H, m, CH2), 4.10 (1H, m, CH2), 3.68 (3H, s
OCH3), 1.45 (3H, s, CH3). 13C{1H}-NMR (d, CDCl3):
170.9 (CÄ
/
O), 155.4 (CÄ
/
O), 141.4 (d, JCÃP
ꢃ
/
17.8 Hz, CÃ
/
P), 130.8 (m, Car), 130.4, 129.8, 128.7 (Car), 80.2 (CÃ
/
O),

28
P.W. Galka, H.-B. Kraatz / Journal of Organometallic Chemistry 674 (2003) 24ꢀ31
/
70.2 (d, JCÃP
28.5 (CH3).
ꢃ
/
20.0 Hz, Cb), 55.2 (Ca), 55.1 (OCH3),
17.9 Hz CÃ
/
OÃ
/
P), 136.3 (CZ), 130.7, 130.4, 129.8, 128.8,
20.2 Hz,
128.7, 128.5, 128.4, 128.3 (Car), 70.1 (d, JCÃP
ꢃ
/
CH2 Ser), 67.2 (CH2 Z), 55.5 (Ca), 52.7 (OCH3).
3.5. Boc-Thr(OPPh2)-OMe (6)
Boc-Thr(OH)-OMe (5.9 mmol, 1.37 g), triethylamine
(18.0 mmol, 2.5 ml), DMAP (0.072 g), diphenylpho-
sphine chloride (6.0 mmol, 1.0 ml). Product: oil. Yield
0.74 g (30%). 31P{1H}-NMR (d, CDCl3): 113.3 (s).
3.8. Z-b-Ala-Tyr(OPPh2)-OMe (9)
Z-b-Ala-Tyr(OH)-OMe (2.0 mmol, 0.86 g), triethyla-
mine (4.0 mmol, 0.6 ml), DMAP (0.025 g), diphenylpho-
sphine chloride (2.0 mmol, 0.36 ml). Product: colourless
oil. Yield 0.70 g ( 60%). 31P{1H}-NMR (d, CDCl3):
111.5 (s). LRMS (FAB), m/z (relative intensity): 585
LRMS (FAB), m/z (relative intensity): 418 ([Mꢁ
22), 219 (27), 203 (100), 160 (17), 57 (40). HRMS of
C22H29NO5P Calc. [Mꢁ
H]ꢁ 418.1783 found [Mꢁ1]ꢁ
418.1790. 1H-NMR (d, CDCl3): 7.43ꢀ
7.33 (10H, m,
Har), 5.34 (1H, d, Jꢃ9.9 Hz, NH), 4.65 (1H, m, CHa),
4.43 (1H, d, Jꢃ9.9 Hz, CHb), 3.41 (3H, s, OCH3), 1.48
(3H, s, CH3), 1.36 (3H, d, Jꢃ
6.0 Hz, CH3). 13C{1H}-
NMR (d, CDCl3): 171.2 (CÄO), 156.3 (CÄO), 142.5 (d,
JCÃP 15.8 Hz, CÃP), 141.8 (d, JCÃP 17.3 Hz, CÃP),
131.0, 130.3, 129.6, 128.5 (Car), 80.2 (CÃO), 77.2 (d,
JCÃP 21.1 Hz, CH2b), 59.1 (Ca), 52.3 (OCH3), 28.5
/
1]ꢁ,
/
/
([Mꢁ
(43), 91 (46), 73 (100). HRMS of C33H34N2O6P Calc.
[Mꢁ
H]ꢁ 585.2154, Found [Mꢁ1]ꢁ 585.2153.
[a]D25
30 [10ꢂ1 8 cm2 gꢂ1]. H-NMR (d, CDCl3):
7.58 (5H, m, Har), 7.40 (10H, m, Har), 7.04 (4H, m, Har),
6.02 (1H, d, Jꢃ7.4 Hz, NH), 5.42 (1H, m, NH), 5.09
/
1]ꢁ, 17), 201 (20), 185 (20), 154 (25), 147 (60), 136
/
/
/
/
/
1
/
ꢃ
/
ꢁ
/
/
/
ꢃ
/
/
ꢃ
/
/
/
/
(2H, s, CH2), 4.81 (1H, m, CHa), 3.71 (3H, s, OCH3),
3.45 (2H, m, CH2), 3.06 (2H, m, CH2), 2.41 (2H, m,
ꢃ
/
CH2). 13C{1H}-NMR (d, CDCl3): 172.1 (CÄ
/
O), 171.5
17.6 Hz, CÃOÃ
P), 130.4, 129.9, 129.8,
(CH3), 19.2 (CH3).
(CÄ
/
O), 156.9 (CÄ
/
OZ), 140.3 (d, JCÃP
7.2 Hz, CÃ
ꢃ
/
/
/
3.6. Boc-Tyr(OPPh2)-OMe (7)
P), 135.5 (d, JCÃP
ꢃ
/
/
128.2, 119.2 (Car), 66.8 (CH2Z), 53.4 (Ca), 52.6 (OCH3),
37.2, 36.0 (CH2).
Boc-Tyr(OH)-OMe (5.6 mmol, 1.67 g), triethylamine
(16.8 mmol, 2.3 ml), DMAP (0.068 g), diphenylpho-
sphine chloride (5.6 mmol, 1.0 ml). Product: colourless
oil. Yield 1.07 g (40%). 31P{1H}-NMR (d, CDCl3):
111.1 (s). LRMS (FAB), m/z (relative intensity): 480
3.9. General procedure for phosphiniteꢀmetal complexes
/
([Mꢁ
(100), 107 (27), 57 (82). HRMS of C27H31NO5P Calc.
[Mꢁ
H]ꢁ 480.1940 found [Mꢁ1]ꢁ 480.1938. 1H-NMR
(d, CDCl3): 7.63 (4H, m, Har), 7.40 (6H, m, Har), 7.07
(4H, m, Har), 5.06 (1H, d, Jꢃ8.0 Hz, NH), 4.58 (1H, m,
CHa), 3.70 (3H, s, OCH3), 3.06 (2H, m, CH2b), 1.44
(3H, s, CH3). 13C{1H}-NMR (d, CDCl3): 172.2 (CÄ
O),
156.2 (d, JCÃP 10.0 Hz, CÃOÃP), 155.1 (CÄO Boc),
140.7 (d, JCÃP 17.6 Hz, CÃP), 135.3 (d, JCÃP 6.9 Hz,
Car), 130.5, 130.3, 130.2 (Car), 130.1 (Car), 129.7 (Car),
118.8 (d, JCÃP O), 54.5 (Ca),
/
1]ꢁ, 20), 440 (82), 387 (61), 336 (25), 201 (87), 133
To the suspension of the metal precursor
(Cl2Pt(COD), Cl2Pt(PhCN)2 or Cl2Pd(PhCN)2) in
CH2Cl2 (10 ml), a solution of the phosphinito-ligand
(two equivalents) in CH2Cl2 (10 ml) was added drop-
wise. The mixture was stirred for 24 h at room
temperature. After evaporation of the solvent in vacuo
/
/
/
/
the corresponding phosphinitoꢀmetal complexes were
/
ꢃ
/
/
/
/
obtained as colorless to slightly yellow solids in nearly
quantitative yields.
ꢃ
/
/
ꢃ
/
ꢃ
/
10.7 Hz, Car), 79.6 (CÃ
/
52.0 (OCH3), 37.3 (CH2), 28.2 (CH3).
3.10. [Boc-Ser(OPPh2)-OMe]2PtCl2 (10)
3.7. Z-Ser(OPPh2)-OMe (8)
Cl2Pt(COD) (0.06 mmol, 0.022 g), Boc-Ser(OPPh2)-
OMe (0.12 mmol, 0.050 g). Elem. Anal. Calc for
C42H52Cl2N2O10P2Pt: C 46.14, H 4.89, N 2.61; Found:
C 46.45, H 4.99, N 2.35%. IR (CsI, disk) n(PtÃCl) 297, 330
Z-Ser(OH)-OMe (3.9 mmol, 1.00 g), triethylamine (12
mmol, 1.7 ml), DMAP (0.047 g), diphenylphosphine
chloride (3.9 mmol, 0.71 ml). Product: oil. Yield 0.68 g
(40%). LRMS (FAB), m/z (relative intensity): 438 ([Mꢁ
1]ꢁ, (18), 387 (5), 309 (7), 203 (11), 91 (100). HRMS of
C24H25NO5P Calc. [Mꢁ
H]ꢁ 438.1471 Found [Mꢁ1]ꢁ
438.1474. [a]D25
13 [10ꢂ1 8 cm2 gꢂ1]. 31P{1H}-
NMR (d, CDCl3): 118.3 (s). 1H-NMR (d, CDCl3):
7.36 (15H, m, Har), 5.63 (1H, d, Jꢃ8.3 Hz, NH), 5.13
/
cmꢂ1
.
31P{1H}-NMR (d, CDCl3): 84.8 (s), JPtÃP
ꢃ
/
4103
Hz. LRMS (FAB), m/z (relative intensity): 1037 ([Mꢂ
Clꢁ
1]ꢁ 82), 1000 (20), 900 (40), 826 (30), 800 (100). 1H-
NMR (d, CDCl3): 7.69ꢀ7.39 (20H, br m, CHar), 5.43
(2H, d, Jꢃ6.0 Hz, NH), 4.27 (2H, br m, CHa), 4.00
(4H, br m, CH2), 3.51 (6H, s, OCH3), 1.46 (18H, s,
CH3). 13C{1H}-NMR (d, CDCl3): 169.9 (CÄ
O), 155.2
(CÄO), 132.7, 132.3, 132.1, 128.9, 128.4 (m, Car), 80.9
(CÃO), 68.2 (CH2), 53.8 (Ca), 52.8 (OCH3), 28.5 (CH3).
/
/
/
/
ꢃ
/
ꢁ
/
/
/
/
(2H, s, CH2), 4.61 (1H, m, CHa), 4.30 (1H, m, CH2),
/
4.15 (1H, m, CH2), 3.64 (3H, s, OCH3). 13C{1H}-NMR
/
(d, CDCl3): 170.5 (CÄ
/
O), 155.9 (CÄ
/
O), 141.3 (d, JCÃP
ꢃ
/
/

P.W. Galka, H.-B. Kraatz / Journal of Organometallic Chemistry 674 (2003) 24ꢀ
/31
29
3.11. [Boc-Tyr(OPPh2)-OMe]2PtCl2 (11)
112.6 (s). LRMS (FAB), m/z (relative intensity): 949
([MꢂClꢁ
2]ꢁ, 5), 911(10), 302 (46), 154 (80), 136 (73),
73 (40), 57 (100). 1H-NMR (d, CDCl3): 7.68ꢀ
7.50 (20H,
m, Har), 5.36 (2H, d, Jꢃ9.4 Hz, NH), 4.22 (2H, br m,
CHa), 3.94 (4H, br m, CH2), 3.70 (6H, s, OCH3), 1.45
(18H, s, CH3). 13C{1H}-NMR (d, CDCl3): 169.8 (CÄ
O),
155.2 (CÄO), 133.0, 132.9, 132.5, 132.4, 129.3, 129.0,
128.6 (Car), 80.8 (CÃO), 68.5 (CH2), 54.0 (Ca), 52.8
(OCH3), 28.5 (CH3).
/
/
Cl2Pt(COD) (0.05 mmol, 0.019 g), Boc-Tyr(OPPh2)-
OMe (0.1 mmol, 0.050 g). Elem. Anal. Calc for
C54H60Cl2N2O10P2Pt: C 52.95, H 4.94, N 2.29; Found:
C 53.40, H 5.21, N 1.86%. 31P{1H}-NMR (d, CDCl3):
/
/
/
86.1 (s, JPÃPt
intensity): 1152 [Mꢂ
952 (64), 892 (23), 802 (100), 599 (92) HRMS of
ꢃ
/
4223 Hz). LRMS (FAB), m/z (relative
/
/
2Clꢂ
/
1]ꢁ, 25), 1096 (48), 1053 (16),
/
C54H59N2O10P2Pt Calc. [Mꢂ
/
2Clꢂ
1]ꢁ 1152.3293,
/
Found [M-2Cl-1]ꢁ 1152.3298. 1H-NMR (d, CDCl3):
7.60 (10H, m, Har), 7.42 (7H, m, Har), 7.30 (13H, m,
Har), 6.85 (4H, m, Har), 6.47 (4H, m, Har), 4.94 (2H, d,
3.15. [Boc-Tyr(OPPh2)-OMe]2PdCl2 (15)
Cl2Pd(PhCN)2 (0.05 mmol, 0.019 g), Boc-
Tyr(OPPh2)-OMe (0.1 mmol, 0.050 g). 31P{1H}-NMR
(d, CDCl3): 111.7 (s). LRMS (FAB), m/z (relative
Jꢃ
OCH3), 3.01 (4H, m, CH2), 1.43 (18H, s, CH3).
13C{1H}-NMR (d, CDCl3): 172.2 (CÄ
O), 155.2 (CÄ
O), 152.1 (CÃOÃP), 133.0, 132.0, 130.4, 128.1, 128.0,
121,3 (Car), 80.3 (CÃO), 54.5 (Ca), 52.5 (OCH3), 37.8
(CH2), 28.2 (CH3).
/
8.2 Hz, NH), 4.52 (2H, m, CHa), 3.69 (6H, s,
/
/
intensity): 1101 ([Mꢂ
514 (47), 291 (920), 147 (20), 91 (20), 57 (100). HRMS of
C54H60ClN2O10P2Pd Calc.[Mꢂ
Cl]ꢁ 1099.2447, Found
Cl]ꢁ 1099.2487. H-NMR (d, CDCl3): 7.65 (10H,
m, Har), 7.46, 7.32 (20H, m, Har), 6.84 (4H, m, Har), 6.45
(4H, m, Har), 4.93 (2H, d, Jꢃ7.8 Hz, NH), 4.51 (2H, m,
CHa), 3.68 (6H, s, OCH3), 2.99 (4H, m, CH2), 1.42
(18H, s, CH3). 13C{1H}-NMR, CDCl3): 172.2 (CÄO),
155.2 (CÄO), 152.1 (CÃOÃP), 133.1, 133.0, 132.1, 130.5,
128.2, 121.1 (Car), 80.3 (CÃO), 54.5 (Ca), 52.5 (OCH3),
37.7 (CH2), 28.5 (CH3).
/
Clꢁ
/
2]ꢁ, 7), 1065 (7), 556 (50),
/
/
/
/
1
[Mꢂ
/
3.12. [Boc-Thr(OPPh2)-OMe]2PtCl2 (12)
/
Cl2Pt(COD) (0.06 mmol, 0.022 g), Boc-Thr(OPPh2)-
OMe (0.12 mmol, 0.050 g). 31P{1H}-NMR (d, CDCl3):
/
/
/
/
76.4 (s, JPÃPt
intensity): 1065 ([Mꢂ
7.59ꢀ7.27 (20H, m, Har), 5.58 (2H, m, NH), 5.16 (2H,
m, CHa), 4.39 (2H, d, Jꢃ7.9 Hz, CHb), 3.60 (6H, s,
OCH3), 1.53 (6H, d Jꢃ5.9 Hz, CH3), 1.47 (18H, s,
CH3). 13C{1H}-NMR (d, CDCl3): 170.7 (CÄ
O), 155.7
(CÄO), 134.8, 133.8 (CÃP), 132.2, 131.5, 131.3, 128.8,
O), 76.8 (Cb), 58.3 (Ca), 52.6
ꢃ
/
4100 Hz). LRMS (FAB), m/z(relative
/
1
/
Clꢁ
1]ꢁ). H-NMR (d, CDCl3):
/
/
/
3.16. [Boc-Thr(OPPh2)-OMe]2PdCl2 (16)
/
/
Cl2Pd(PhCN)2 (0.06 mmol, 0.023 g), Boc-
Thr(OPPh2)-OMe (0.12 mmol, 0.050 g). 31P{1H}-
NMR (d, CDCl3): 103.9 (s). LRMS (FAB), m/z (relative
/
/
128.2 (Car), 80.6 (CÃ
/
(OCH3), 28.5 (CH3), 19.0 (CH3).
intensity): 975 [Mꢂ
/
Clꢂ
2]. H-NMR (d, CDCl3): 7.65, 7.46 (20H,
m, Har), 5.56 (2H, m, CHa), 5.52 (2H, d Jꢃ9.7 Hz,
NH), 4.46 (2H, d Jꢃ9.4 Hz, CHb), 3.54 (6H, s, OCH3),
1.53 (6H, d Jꢃ6.3 Hz, CH3), 1.45 (18H, s, CH3).
13C{1H}-NMR (d, CDCl3): 171.0 (CÄ
O), 156.3 (CÄO),
133.7 (CÃP), 132.4, 131.3, 129.3, 128.2, 128.1, 128.0
O), 78.2 (Cb), 58.8 (Ca), 52.8 (OCH3),
/
1]ꢁ, 939 [Mꢂ
/
2Clꢂ
/
2]ꢁ, 877
1
[Mꢂ
/
OCH3ꢂ
/
3.13. [Z-b-Ala-Tyr(OPPh2)-OMe]2PtCl2 (13)
/
/
Cl2Pt(COD) (0.06 mmol, 0.022 g), Z-b-Ala-
/
Tyr(OPPh2)-OMe (0.12 mmol, 0.060 g). 31P{1H}-
/
/
NMR (d, CDCl3): 86.0 (s, JPÃPt
(FAB), m/z (relative intensity): 1435 ([Mꢁ
ꢃ
/
3755 Hz). LRMS
/
/
2]ꢁ, 32),
1399 (37), 1363 (100), 1017 (22), 980 (40), 778 (31), 670
(Car), 80.3 (CÃ
/
28.5 (CH3), 19.6 (CH3).
1
(29), 598 (32). H-NMR (d, CDCl3): 7.58 7.38 (38H, br
m, Har), 6.47 (2H, d, Jꢃ/5.8 Hz, NH), 5.59 (1H, m,
3.17. [Z-b-Ala-Tyr(OPPh2)-OMe]2PdCl2 (17)
NH), 5.06 (2H, s, CH2), 4.76 (1H, m, CHa), 3.67 (3H, s,
OCH3), 3.40 (2H, m, CH2), 3.04 (2H, m, CH2), 2.37 (2H,
Cl2Pd(PhCN)2 (0.06 mmol, 0.023 g), Z-b-Ala-
Tyr(OPPh2)-OMe (0.12 mmol, 0.060 g). 31P{1H}-
NMR (d, CDCl3): 111.5 (s). LRMS (FAB), m/z (relative
m, CH2). 13C{1H}-NMR (d, CDCl3): 171.8 (CÄ
/O),
171.3 (CÄ
/
O), 156.6 (CÄ
/
O), 136.7 (CÃ
/
OÃ
/
P), 132.8 (CÃ
/
P), 131.8, 130.5, 129.8, 128.7, 128.2, 121.4 (Car), 66.8
(CH2Z), 53.5 (Ca), 52.6 (OCH3), 37.2, 36.0 (CH2).
intensity): 1273 ([Mꢂ
/
2Clꢂ
1]ꢁ, 11), 891 (30), 801 (20),
689 (100), 661 (30), 594 (29), 585 (35), 550 (90), 535 (57),
/
522 (83), 506 (47). 1H-NMR (d, CDCl3): 7.60 7.33 (30H,
3.14. [Boc-Ser(OPPh2)-OMe]2PdCl2 (14)
m, Har), 6.87 6.87 (8H, m, Har), 6.46 (2H, d, Jꢃ7.8 Hz,
/
NH), 5.59 (1H, m, NH), 5.06 (2H, s, CH2), 4.77 (1H, m,
CHa), 3.67 (3H, s, OCH3), 3.39 (2H, m, CH2), 2.99 (2H,
m, CH2), 2.36 (2H, m, CH2). 13C{1H}-NMR (d,
Cl2Pd(PhCN)2 (0.06 mmol, 0.023 g), Boc-Ser(OPPh2)-
OMe (0.12 mmol, 0.050 g). Elem. Anal. Calc for
C42H52Cl2N2O10P2Pd: C 51.26, H 5.33, N 2.85; Found:
C 51.72, H 5.87, N 2.39%. 31P{1H}-NMR (d, CDCl3):
CDCl3): 171.8 (CÄ
/
O), 171.4 (CÄ
/
O), 156.6 (CÄ
/
O),
P), 131.8, 130.4, 129.7,
136.6 (CÃOÃP), 134.3 (CÃ
/
/
/

30
P.W. Galka, H.-B. Kraatz / Journal of Organometallic Chemistry 674 (2003) 24ꢀ31
/
Table 3
Crystal data and structure refinement for of [Boc-Ser(OPPh2)-
OMe]2PtCl2 (10)
email: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
Empirical formula
Formula weight
Temperature (K)
C45H55Cl11N2O10P2Pt
430.89
Acknowledgements
193(2)
0.71073
˚
Wavelength (A)
The authors wish to thank NSERC for financial
support. H-B.K. is the Canadian Research Chair in
Biomaterials and also wishes to express his gratitude to
PetroCanada for a PetroCanada Young Innovator
Award. We thank Bob McDonald, University of
Alberta, Canada, for the data collection of compound
10.
Crystal system
Space group
Unit cell dimensions
Orthorhombic
P212121
˚
a (A)
9.8067(12)
17.130(2)
35.040(4)
5886.4(12)
4
˚
b (A)
˚
c (A)
3
Volume (A )
˚
Z
Density (calculated) (g mꢂ3
)
1.615
2.990
2856
Absorption coefficient (mmꢂ1
F(0 0 0)
)
References
Crystal size (mm)
u range for data collection (8)
Limiting indices
0.43ꢄ
1.32ꢀ26.45
12Bh B
21Bk B
16Bl B43
/
0.39ꢄ
/
0.09
/
ꢂ
/
/
/
12,
21,
[1] E.N. Jacobsen, A. Pfaltz, H. Yamamoto, Comprehensive Asym-
ꢂ
/
/
/
metric Catalysis, vol. 1ꢀ3, Springer, New York, 1999.
/
ꢂ/
/
/
[2] H.B. Kagan, M. Sasaki, in: F.R. Hartley (Ed.), The Chemistry of
Organophosphorus Compounds, vol. 1, Wiley, New York, 1990,
p. 52.
Reflections collected
12 078
11 458
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F2
11 458/0/640
1.132
[3] H.B. Kagan, M. Sasaki, Transition Metals for Organic Synthesis,
Wiley-VCH, Weinheim, 1998.
Final R indices [Iꢀ
R indices (all data)
Abs. structure parameter
Largest diff. peak and hole (e A
/
2s(I)]
Rꢃ
Rꢃ
0.006(5)
0.85 and ꢂ1.01
/
0.0358, wRꢃ
/
0.0812
0.0819
[4] R.H. Crabtree, The Organometallic Chemistry of the Transition
Metals, Wiley-Interscience, New York, 2001.
[5] R. Noyori, Asymmetric Catalysis in Organic Synthesis, Wiley,
New York, 1994.
/
0.0382, wRꢃ
/
ꢂ3
˚
)
/
[6] (a) M. Petit, A. Mortreux, F. Petit, G. Buono, G. Peiffer, New J.
Chem. 7 (1983) 593;
(b) J.W. Scott, Top. Stereochem. 19 (1989) 209.
[7] (a) T.V. RajanBabu, T.A. Ayers, G.A. Halliday, K.K. You, J.C.
Calabrese, J. Org. Chem. 62 (1997) 6012;
129.2, 126.8, 121.7 (Car), 66.7 (CH2Z), 53.5 (Ca), 52.5
(OCH3), 37.2, 35.9 (CH2).
(b) S. Shin, T.V. RajanBabu, Org. Lett. 1 (1999) 1229;
(c) T.V. RajanBabu, T.A. Ayers, A.L. Casalnuovo, J. Am. Chem.
Soc. 116 (1994) 4101;
3.18. X-ray crystallography
(d) T.V. RajanBabu, T.A. Ayers, Tetrahedron Lett. 35 (1994)
4295;
Suitable crystals of 10 were obtained by layering a
CH2Cl2 solution of 10 with ether. Colorless needles
suitable for X-ray crystallography were deposited after 2
days. Data for 10 were measured using a Siemens Smart
(e) A.L. Casalnuovo, T.V. RajanBabu, T.A. Ayers, T.H. Warren,
J. Am. Chem. Soc. 116 (1994) 9869;
(f) R. Selke, J. Organomet. Chem. 370 (1989) 249;
(g) Y. Chen, X. Li, S. Tong, M. Choi, A. Chan, Tertahedron Lett.
40 (1999) 957;
CCD diffractometer using MoꢀKa radiation (graphite
/
(h) K. Yonehara, T. Hashizume, K. Mori, K. Ohe, S. Uemura, J.
Org. Chem. 64 (1999) 5593;
monochromated) with v scans. The structures was
solved using direct methods. All non-hydrogen atoms
were refined anisotropically using full-matrix least-
(i) K. Yonehara, M. Mori, T. Hashizume, K.-G. Chung, K. Ohe,
S. Uemura, J. Organomet. Chem. 603 (2000) 40.
[8] C. Pasquier, S. Naili, A. Mortreux, F. Agbossou, L. Pelinski, J.
Brocard, J. Eilers, I. Reiners, V. Peper, J. Martens Organome-
tallics 19 (2000) 5723.
squares on F2. The final R value for 10 was Rꢃ
/
0.0358 and wRꢃ
/
0.0812 for 11458 reflection with I ꢀ
/
2s(I) (12078 total reflections). Crystallographic details
have been summarized in Table 3.
[9] F. Agbossou, J.-F. Carpentier, C. Hatat, N. Kokel, A. Mortreux,
Organometallics 14 (1995) 2480.
[10] A. Roucoux, L. Thieffry, J.-F. Carpentier, M. Devocelle, C.
Meliet, F. Agbossou, A. Mortreux, Organometallics 15 (1996)
2440.
4. Supplemental material
[11] D.G. Gorenstein, Phosphorus-31 NMR Principles and Applica-
tions, AcademicPress, Inc, Chicago, 1984.
[12] (a) E. Hauptman, R. Shapiro, W. Marshall, Organometallics 17
(1998) 4976;
Crystallographic data excluding structure factors
have been deposited at the Cambridge Crystallographic
Data Centre (CCDC no. 202084). This material can be
obtained upon request to CCDC, 12 Union Road,
(b) W. Xu, J.P. Rourke, J.J. Vittal, R.J. Puddephatt, Inorg.
Chem. 34 (1995) 323;
(c) D. Morales-Morales, R. Redon, C. Yung, C.M. Jensen, Chem.
Commun. (2000) 1619.
Cambridge, CB2 1EZ, UK (Fax: ꢁ44-1223-336033;
/

P.W. Galka, H.-B. Kraatz / Journal of Organometallic Chemistry 674 (2003) 24ꢀ
/31
31
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Wardell, J. Chem. Soc. Perkin Trans (1996) 809;
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(c) E. Cesarotti, M. Grassi, L. Prati, F. Demartin, J. Chem. Soc.
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