A novel approach toward asymmetric synthesis of alcohol functionalized C-chiral diphosphines via two-stage hydrophosphination of terminal alkynols

Article abstract of DOI:10.1021/ic060937m

Alcohol functionalized diphosphine ligands with chirality residing on the carbon backbone were prepared using a novel two-stage asymmetric synthetic methodology from the corresponding terminal alkynols. Under mild conditions, the alkynols, 3-butyn-1-ol and 2-propyn-1-ol, were subjected to direct hydrophosphination to give the corresponding Markovnikov addition products. The phosphine functionalized alkenols thus obtained were subsequently subjected to a second-stage asymmetric hydrophosphination employing an organopalladium complex containing the ortho-metalated (R)-(1-(dimethylamino)ethyl)naphthalene as a chiral auxiliary and reaction promoter. In the reaction that involved 3-diphenylphosphanyl-but-3-en-1-ol, all four possible stereoisomeric products were generated stereoselectively in the ratio of 1:2:4:18. The major isomer was subsequently isolated in appreciable yield in its configurationally pure form and characterized by means of single-crystal X-ray crystallography. The naphthylamine auxiliary could be removed chemoselectively from the template product by treatment with concentrated hydrochloric acid to form the corresponding optically pure neutral complex. Subsequent ligand displacement from the palladium achieved using aqueous potassium cyanide generated the optically pure diphosphine ligand with chirality residing on the carbon backbone in appreciable yield. However, the similar asymmetric hydrophosphination reaction involving 2-diphenylphosphanyl-prop-2-en-1-ol did not exhibit appreciable selectivity.

Full text of DOI:10.1021/ic060937m

Inorg. Chem. 2006, 45, 7455−7463
A Novel Approach toward Asymmetric Synthesis of Alcohol
Functionalized C-Chiral Diphosphines via Two-Stage
Hydrophosphination of Terminal Alkynols
Sumod A. Pullarkat,† Ding Yi,† Yongxin Li,† Geok-Kheng Tan,‡ and Pak-Hing Leung*,†
DiVision of Chemistry and Biological Chemistry, Nanyang Technological UniVersity,
Nanyang Walk, Singapore 637616, and Department of Chemistry, National UniVersity of
Singapore, Kent Ridge, Singapore 119260
Received May 30, 2006
Alcohol functionalized diphosphine ligands with chirality residing on the carbon backbone were prepared using a
novel two-stage asymmetric synthetic methodology from the corresponding terminal alkynols. Under mild conditions,
the alkynols, 3-butyn-1-ol and 2-propyn-1-ol, were subjected to direct hydrophosphination to give the corresponding
Markovnikov addition products. The phosphine functionalized alkenols thus obtained were subsequently subjected
to a second-stage asymmetric hydrophosphination employing an organopalladium complex containing the ortho-
metalated (R)-(1-(dimethylamino)ethyl)naphthalene as a chiral auxiliary and reaction promoter. In the reaction that
involved 3-diphenylphosphanyl-but-3-en-1-ol, all four possible stereoisomeric products were generated stereoselectively
in the ratio of 1:2:4:18. The major isomer was subsequently isolated in appreciable yield in its configurationally
pure form and characterized by means of single-crystal X-ray crystallography. The naphthylamine auxiliary could
be removed chemoselectively from the template product by treatment with concentrated hydrochloric acid to form
the corresponding optically pure neutral complex. Subsequent ligand displacement from the palladium achieved
using aqueous potassium cyanide generated the optically pure diphosphine ligand with chirality residing on the
carbon backbone in appreciable yield. However, the similar asymmetric hydrophosphination reaction involving
2-diphenylphosphanyl-prop-2-en-1-ol did not exhibit appreciable selectivity.
Introduction
However, hydrophosphination processes involving function-
alized alkynes and alkenes have been reported sparingly
The asymmetric synthesis of functionalized optically active
phosphines, mainly using natural products as chirons, has
been extensively studied over many years. Among the
various approaches, the asymmetric synthesis of chiral
diphosphines via the addition of phosphorus-hydrogen
bonds to carbon-carbon multiple bonds continues to pose
considerable challenges. With free phosphines, addition onto
an unsaturated C-C bond requires strong bases,1 Brønsted
acids,2 radical initiators,3 or transition metal catalysis.4
(2) (a) Wolfsberger, W. Chem.-Ztg. 1988, 112, 53. (b) Dombek, B. D. J.
Org. Chem. 1978, 43, 3408.
(3) (a) Brandt, P. F.; Schubert, D. M.; Norman, A. D. Inorg. Chem. 1997,
36, 1728. (b) Robertson, A.; Bradaric, C.; Frampton, C. S.; McNulty,
J.; Capretta, A. Tetrahedron Lett. 2001, 42, 2609. (c) Ropartz, L.;
Morris, R. E.; Foster, D. F.; Cole-Hamilton, D. J. J. Mol. Catal. A:
Chem. 2002, 99, 182-183. (d) Wagner, K. H.; Mitchell, T. N. J.
Organomet. Chem. 1994, 468, 99. (e) Mitchell, T. N.; Heesche, K. J.
Organomet. Chem. 1991, 409, 163.
(4) For selected examples of transition metal catalyzed hydrophosphination
reactions, see: (a) Yorimitsu, H.; Oshima, K. Pure Appl. Chem. 2006,
78, 441. (b) Kovacik, I.; Scriban, C.; Glueck, D. S. Organometallics
2006, 25, 536. (c) Sadow, A. D.; Togni, A. J. Am. Chem. Soc. 2005,
127, 17012. (d) Ohmiya, H.; Yorimitsu, H.; Oshima, K. Angew. Chem.,
Int. Ed. 2005, 44, 2368. (e) Francisco, A.; Irina, P. B.; Miguel, Y.
Chem. ReV. 2004, 104, 3079. (f) Kazankova, M. A.; Efimova, I. V.;
Kochetkov, A. N.; Afanas’ev, V. V.; Beletskaya, I. P. Russ. J. Org.
Chem. 2002, 38, 1465. (g) Takaki, K.; Takeda, M.; Koshoji, G.;
Shishido, T.; Takehira, K. Tetrahedron Lett. 2001, 42, 6357. (h)
Douglass, M. R.; Marks, T. J. J. Am. Chem. Soc. 2001, 123, 10221.
(i) Kazankova, M. A.; Efimova, I. V.; Kochetkov, A. N.; Afanas’ev,
V. V.; Beletskaya, I. P.; Dixneuf, P. H. Synlett 2001, 497. (j) Douglass,
M. R.; Marks, T. J. J. Am. Chem. Soc. 2000, 122, 1824.
* To whom correspondence should be addressed. E-mail: pakhing@
ntu.edu.sg.
† Nanyang Technological University.
‡ National University of Singapore.
(1) (a) Bunlaksananusorn, T.; Knochel, P. Tetrahedron Lett. 2002, 43,
5817. (b) Gusarova, N. K.; Sukhov, B. G.; Malysheva, S. F.;
Kazantseva, T. I.; Smetannikov, Yu. V.; Tarasova, N. P.; Trofimov,
B. A. Russ. J. Gen. Chem. 2001, 71, 721. (c) Malysheva, S. F.; Sukhov,
B. G.; Larina, L. I.; Belogorova, N. A.; Gusarova, N. K.; Trofimov,
B. A. Russ. J. Gen. Chem. 2001, 71, 1907. (d) Bookham, J. L.;
Smithies, D. M. J. Organomet. Chem. 1999, 577, 305. (e) King, R.
B.; Kapoor, P. N. J. Am. Chem. Soc. 1969, 91, 5191.
10.1021/ic060937m CCC: $33.50
Published on Web 08/08/2006
© 2006 American Chemical Society
Inorganic Chemistry, Vol. 45, No. 18, 2006 7455

Pullarkat et al.
using these protocols.1a,4c,5 This is partly because of the harsh
reaction conditions employed, which do not tolerate most
of the functional groups. Our group recently has reported
the use of an organopalladium complex containing (R)- or
(S)-(1-(dimethylamino)ethyl)naphthalene as the chiral aux-
iliary to promote the asymmetric hydrophosphination reac-
tions.6 To extend this protocol to the hydrophosphination of
functionalized olefinic systems culminating in the synthesis
of functionalized chiral diphosphines, the hydrophosphination
of phosphine functionalized alkenols, 3-diphenylphosphanyl-
but-3-en-1-ol, and 2-diphenylphosphanyl-prop-2-en-1-ol, was
studied. The asymmetric hydrophosphination thus achieves
an alcohol functionalized derivative of 1-2-bis(diphenylphos-
phino)propane (PROPHOS).7 Literature review revealed that
the previous synthesis of these compounds, which involved
tedious organic manipulations extending to 14 steps as well
as provided access to one enantiomer as opposed to our
methodology,8was achieved from a chiral pool of substances
such as malic or L-ascorbic acid. To our knowledge, no
example of metal complex activated hydrophosphination of
functionalized alkenes has been reported despite its potential
for a new, direct route to a wide range of functionalized chiral
diphosphine ligands. It is noteworthy that this is a second-
stage hydrophosphination on the hydroxyl functionalized
olefinic system, because the compounds themselves were
prepared by a regioselective hydrophosphination of the parent
alkynols, 3-butyn-1-ol and 2-propyn-1-ol, albeit not involving
the metal template complex, which resulted in a Markovni-
kov addition of appreciable selectivity. This body of work
assumes significance because alkenylphosphines and their
functionalized derivatives, such as in the present case, are
attractive candidates to control the activation of various
substrates within their transition metal complexes. They also
have the potential to provide access to a variety of functional
ligands by modification of their carbon-carbon bond includ-
ing via enantioselective catalysis.
Scheme 1
and depending on the conditions employed, one of the
isomers was predominate. Reversal of regioselectivity was
achieved in the case of Pd-catalyzed hydrophosphination of
alkynes using diphenylphosphane oxide in the presence of
phosphonic acid and with the palladium-catalyzed addition
of triphenylphosphine and methanesulfonic acid to alkynes
wherein the Markovnikov product was formed as the major
product.9 For functionalized alkynes, the predominant Mark-
ovnikov product was achieved with the use of secondary
phosphine-boranes as hydrophosphinating agents under
metal catalyst and thermal activation conditions.10 No reports
involving reversal of regioselectivity were found in the
literature involving noncatalytic addition of diphenylphos-
phine to functionalized alkynes under mild conditions.
The hydrophosphination product obtained by regioselective
phosphine attack on the internal carbon of the terminal
alkynol (Markovnikov mode) was the targeted product,
because unlike the case of the anti-Markovnikov product,
the newly generated chiral center was adjacent to the
coordinated phosphorus of the alkenol substrate during the
course of the second-stage hydrophospination reaction. This
allowed us to study the directing influence of the chiral metal
template on the steroselectivity of the hydrophosphination
reaction in a more effective manner.
The synthetic protocol followed for the synthesis of
3-diphenylphosphanyl-but-3-en-1-ol is shown in Scheme 1.
It is important to note that the hydroxyl group on the alkynol
is susceptible to nucleophilic attack by the phosphide ion.
Therefore, it is necessary to protect the functional group,
which possesses an exchangeable proton that can quench the
phosphide ion. Instead of using traditional protecting groups
such as silyl ether to mask the hydroxyl group, it was
deprotonated prior to the hydrophosphination so as to prevent
it from quenching the phosphide ion. The recovery of the
hydroxyl group from its alkoxide is technically very simple.
The 31P{1H} NMR spectrum (CDCl3) of the crude reaction
product showed the presence of three singlets at δ -3.4,
-22.3, and -31.0 in the ratio 5:1:1.2 for the R-adduct and
the E- and Z- isomers, respectively. The structural assignment
for the three isomeric products could be achieved simply
based on the spectroscopic principles employed for similar
reactions involving free radical addition of diphenylphos-
phine to alkynes.11 Purification and separation of the isomeric
products were achieved by means of silica gel chromatog-
Results and Discussion
Regioselective Hydrophosphination of Terminal
Alkynols. Regioselective addition of diphenylphosphine to
alkynes was previously reported under free radical, metal
catalyzed, and basic addition conditions.1d,3d,e,5f In most cases,
E/Z isomer mixtures were formed (anti-Markovnikov mode),
(5) (a) Shulyupin, M. O.; Trostyanskaya, I. G.; Kazankova, M. A.;
Beletskaya, I. P. Russ. J. Org. Chem. 2006, 42, 17. (b) Join, B.;
Delacroix, O.; Gaumont, A. C. Synlett 2005, 12, 1881. (c) Sugiura,
J.; Kakizawa, T.; Hashimoto, H.; Tobita, H.; Ogino, H. Organome-
tallics 2005, 24, 1099. (d) Han, L. B.; Zhao, C. Q. J. Org. Chem.
2005, 70, 10121. (e) Kazankova, M. A.; Shulyupin, M. O.; Beletskaya,
I. P. Synlett 2003, 14, 2155. (f) Jerome, F.; Monnier, F.; Lawicka, H.;
Derien, S.; Dixneuf, P. H. Chem. Commun. 2003, 6, 696. (g) Malisch,
W.; Klupfel, B.; Schumacher, D.; Neiger, M. J. Organomet. Chem.
2002, 661, 95.
(6) (a) Yeo, W. C.; Tang, L.; Yan, B.; Tee, S. Y.; Koh, L. L.; Geok, K.;
Leung, P. H. Organometallics 2005, 24, 5581. (b) Yeo, W. C.; Tee,
S. Y.; Hun, B.; Koh, L. L.; Geok, K.; Leung, P. H. Inorg. Chem.
2004, 43, 8102.
(7) Fryzuk, M. D.; Bosnich, B. J. Am. Chem. Soc. 1978, 100, 5491.
(8) (a) Borner, A.; Kless, A.; Rhett, K.; Heller, D.; Holtz, J.; Baumann,
W. Chem. Ber. 1995, 128, 767. (b) Borner, A.; Ward, J.; Ruth, W.;
Holz, J.; Kless, A.; Heller, D.; Kagan, H. B. Tetrahedron 1994, 50,
10419.
(9) (a) Mieko, A.; Yamaguchi, M. J. Am. Chem. Soc. 2000, 122, 2387.
(b) Han, L. B.; Hua, R.; Tanaka, M. Angew. Chem., Int. Ed. 1998,
37, 94.
(10) David, M.; Gaumont, A. C. J. Org. Chem. 2003, 68, 7016.
7456 Inorganic Chemistry, Vol. 45, No. 18, 2006

Synthesis of Alcohol Functionalized C-Chiral Diphosphines
Scheme 2
Scheme 4
Scheme 3
raphy under inert conditions that yielded the desired Mark-
ovnikov product 1 as a colorless oil in 43% yield. The E-
and Z- isomers were formed as minor products and were
not isolated.
The hydrophosphination of propargyl alcohol was carried
out using the same method as that employed for 3-butyn-
1-ol discussed earlier (Scheme 2). The reaction was moni-
tored by means of 31P{1H} NMR spectroscopy and was found
to be complete in 3 days. Unlike the case of 3-butyn-1-ol,
only the Markovnikov product was selectively formed in the
hydrophosphination reaction. The 31P NMR spectrum of the
crude reaction mixture in CDCl3 showed only one singlet at
δ -9.2. Purification of the product using silica gel column
chromatography yielded pure 2 as a colorless oil in 73%
yield.
Asymmetric Hydrophosphination of 3-Diphenylphos-
phanyl-but-3-en-1-ol. The 3-diphenylphosphanyl-but-3-en-
1-ol ligand 1 was allowed to coordinate to the palladium
complex (Rc)-3 in dichloromethane yielding the neutral
monomeric complex (Rc)-4 as a yellow solid in 70% yield
(Scheme 3). The 31P{1H} NMR spectrum of the complex in
CDCl3 showed a singlet at δ 40.6. The coordination shift
(∆ ) 44.0 ppm) is consistent with the formation of (Rc)-4.
It was well established that the chloro ligand that is trans to
the ortho-metalated aromatic carbon in (Rc)-3 is inert to
displacement by incoming monodentate phosphine ligands.12,13
Therefore, the terminal chloro ligand in (Rc)-4 was subse-
quently replaced by a weakly coordinated perchlorato
counterpart through treatment of (Rc)-4 in dichloromethane
with excess aqueous silver perchlorate.
doublets at δ (31.4, 66.4), (39.8, 77.0), (47.5, 52.6), and
(48.0, 50.4) with the relative intensities of 2:18:1:4, respec-
tively. These signals indicated that all of the four possible
isomeric products were generated in the hydrophosphination
reaction. Subsequently, the major isomer (Rc,Rc)-7a was
separated by means of fractional crystallization as pale yellow
crystals from dichloromethane-diethyl ether in 63% yield.
The 31P{1H} NMR spectrum of pure (Rc,Rc)-7a in CDCl3
showed a pair of doublets at δ 39.8 and 77.0 (JPP ) 22.7
Hz).
The single-crystal X-ray diffraction analysis of the isolated
pure isomer (Rc,Rc)-7a revealed that the expected five-
membered diphosphine chelate was formed stereoselectively
(Figure 1). The newly formed stereogenic center at C(16)
adopts the R configuration. The geometry at the Pd center
is distorted square planar with angles of 80.4(2)-101.5(1)°
and 173.8(1)-177.6(1)°. The five-membered diphosphine
chelate adopts the λ ring configuration with the CH2CH2-
OHsubstituentatC(16)inthepreferredequatorialdisposition.14,6b
Selected bond lengths and angles are given in Table 1. Note
that in the absence of the metal ion, the alkenol shows no
reactivity with diphenylphosphine under ambient conditions.
Furthermore, the four-membered ring was formed by the
attack of diphenylphosphine on the R carbon of the alkenol.
A solution of (Rc,Rc)-7a in dichloromethane was subse-
quently treated with concentrated hydrochloric acid to
remove the naphthylamine auxiliary chemoselectively (Scheme
The perchlorato complex (Rc)-5 in dichloromethane then
was reacted with an equivalent of diphenylphosphine at -78
°C to yield the hydrophosphination products as shown in
Scheme 4. The reaction temperature was maintained at -78
°C for 10 h and subsequently stirred at room temperature
for 1 day. In CDCl3, the 31P{1H} NMR spectrum of the crude
reaction mixture showed the presence of four pairs of
(11) (a) Wagner, K. H.; Mitchell, T. N. J. Organomet. Chem. 1994, 468,
99-106. (b) Grim, S. O.; Molenda, R. P.; Mitchell, J. D. J. Org. Chem.
1980, 45, 250.
(12) (a) Leung, P. H. Acc. Chem. Res. 2004, 37, 169. (b) Aw, B. H.; Hor,
T. S. A.; Selvaratnam, S.; Mok, K. F.; White, A. J. P.; Williams, D.
J.; Rees, N. H.; McFarlane, W.; Leung, P. H. Inorg. Chem. 1997, 36,
2138.
(14) (a) MacNeil, P. A.; Roberts, N. K.; Bosnich, B. J. Am. Chem. Soc.
1981, 103, 2273. (b) Fryzuk, M. D.; Bosnich, B. J. J. Am. Chem. Soc.
1977, 99, 6262. (c) Corey, E. J.; Bailar, J. C., Jr. J. Am. Chem. Soc.
1959, 81, 2620.
(13) Dunina, V. V.; Golovan, E. B.; Gulyukina, N. S.; Buyevich, A. V.
Tetrahedron: Asymmetry 1995, 6, 2731.
Inorganic Chemistry, Vol. 45, No. 18, 2006 7457

Pullarkat et al.
Scheme 5
Scheme 6
mixture and are assigned to the regioisomeric product of
(Rc,Rc)-7a, that is, (Rc,Rc)-6a. Formation of regioisomers
during the recoordination of unsymmetrical diphosphine
ligands to the naphthylamine auxiliary is well established.
Previous studies on similar isomeric systems have shown
that for a pair of regioisomers such as (Rc,Sc)-6a and (Rc,Sc)-
7a formed on the naphthylamine chiral auxiliary system the
separation in 31P{1H} resonance signals will be significantly
larger than that observed for diastereomeric complexes such
as (Rc,Rc)-7a and (Rc,Sc)-7b.6,12a,15
Figure 1. Molecular structure and absolute stereochemistry of (Rc,Rc)-
7a.
Table 1. Selected Bond Lengths (Å) and Angles (deg) for (Rc,Rc)-7a
Pd(1)-C(1)
2.053(4)
2.250(1)
1.862(5)
1.434(10)
1.536(6)
80.4(2)
173.8(1)
101.5(1)
110.6(3)
115.1(4)
112.5(5)
Pd(1)-N(1)
2.140(3)
2.355(1)
1.829(5)
1.546(7)
1.500(8)
93.6(1)
177.6(1)
84.5(4)
110.5(4)
109.7(3)
113.5(6)
Pd(1)-P(1)
Pd(1)-P(2)
P(1)-C(16)
P(2)-C(15)
O(1)-C(18)
C(15)-C(16)
C(16)-C(17)
C(17)-C(18)
As further confirmation of the optical purity of (Rc)-9, the
recomplexation reaction of the diphosphine to the equally
accessible enantiomeric complex (Sc)-10 gave distinct dou-
blets at δ 31.4 (JPP ) 30.4 Hz), 47.5 (JPP ) 34.2 Hz), 52.6
(JPP ) 34.2 Hz), and 66.4 (JPP ) 30.4 Hz). These signals
are consistent with (Rc,Sc)-6b and (Rc,Sc)-7b, which are
diastereomers of (Rc,Rc)-6a and (Rc,Rc)-7a, respectively. The
coupling constants of the two pairs of signals are important
spectroscopic handles for pairing the resonances of the minor
isomers. Comparison of the signals to those of (Rc,Rc)-6a
and (Rc,Rc)-7a clearly indicates that the signals at δ 31.4
(JPP ) 30.4 Hz) and 66.4 (JPP ) 30.4 Hz) are caused by the
diastereomer of (Rc,Rc)-6a, that is, (Rc,Sc)-6b. Accordingly,
signals at δ 47.5 (JPP ) 34.2 Hz) and 52.6 (JPP ) 34.2 Hz)
can be assigned to the diastereomer of (Rc,Rc)-7a, that is,
(Sc, Rc)-7b. Thus, the recomplexation reactions identified that
all four isomers, (Rc,Rc)-6a, (Rc,Sc)-6b, (Rc,Rc)-7a, and
(Rc,Sc)-7b, were generated in the asymmetric hydrophosphi-
nation reaction in the ratio of 4:1:18:2, respectively.
Hydrophosphination of 2-Diphenylphosphanyl-prop-
2-en-1-ol. The 2-diphenylphosphanyl-prop-2-en-1-ol ligand
obtained by hydrophosphination of propargyl alcohol was
coordinated to the dimeric ortho-metalated palladium com-
plex (Rc-3) as shown in Scheme 8. The 121 MHz 31P{1H}
NMR spectrum of the crude complex showed a singlet signal
at δ 40.6 in CDCl3.
C(1)-Pd(1)-N(1)
N(1)-Pd(1)-P(1)
N(1)-Pd(1)-P(2)
C(16)-C(15)-P(2)
C(17)-C(16)-P(1)
C(18)-C(17)-C(16)
C(1)-Pd(1)-P(1)
C(1)-Pd(1)-P(2)
P(1)-Pd(1)-P(2)
C(17)-C(16)-C(15)
C(15)-C(16)-P(1)
O(1)-C(18)-C(17)
5). The 31P{1H} NMR spectrum of the dichloro complex in
CDCl3 showed a pair of doublets at δ 51.1 and 71.3 (JPP
)
7.5 Hz). The neutral dichloro complex (Rc)-8 crystallized
from the dichloromethane-n-hexanes as pale yellow prisms.
Note that the optically active diphosphine ligand (Rc)-9
could be stereospecifically liberated from (Rc)-8 ([R]D
)
+37.5 (c 0.2, CH2Cl2)) by treatment of the dichloro complex
with aqueous potassium cyanide at room temperature for 2
h (Scheme 6). The liberated optically pure ligand was
obtained as a pale yellow oil. The 31P{1H} NMR (CDCl3)
spectrum of (Rc)-9 showed a pair of doublet resonances at δ
19.31 and -0.2. Because of the potential air sensitivity of
the noncoordinated phosphorus atoms, liberated (Rc)-9 was
not stored in its pure form but was recomplexed to the bis-
(acetonitrile) complex (Rc)-10 (Scheme 7). The recoordina-
tion process is also a means of verifying the optical purity
of the released ligand and to establish the identity of the
minor isomers that were generated in the original hydro-
phosphination reaction.6 The recomplexation of the released
ligand (Rc)-9 to the bis(acetonitrile) complex (Rc)-10 was
monitored by 31P{1H} NMR spectroscopy (CDCl3), which
Crystallization of the crude product from acetonitrile-
diethyl ether gave yellow prisms of (Rc)-13. The monophos-
exhibited doublets at δ 39.8 (JPP ) 22.7 Hz), 47.5 (JPP
)
30.4 Hz), 52.6 (JPP ) 30.4 Hz), and 77.0 (JPP ) 22.7 Hz).
The resonance signals at δ 39.8 and 77.0 are identical to
those observed for the major product (Rc,Rc)-7a in the
original hydrophosphination reaction. The signals at δ 47.5
and 52.6 match signals detected in the original reaction
(15) (a) Bookham, J. L.; McFarlane, W. J. Chem. Soc., Chem. Commun.
1993, 1352. (b) Aw, B. H.; Leung, P. H. Tetrahedron: Asymmetry
1994, 5, 1167. (c) Leitch, J.; Salem, G.; Hockless, D. C. R. J. Chem.
Soc., Dalton Trans. 1995, 649. (d) He, G. S.; Mok, K. F.; Leung, P.
H. Organometallics 1999, 18, 4027. (e) Chatterjee, S.; George, M.
D.; Salem, G.; Willis, A. C. J. Chem. Soc., Dalton Trans. 2001, 1890.
7458 Inorganic Chemistry, Vol. 45, No. 18, 2006

Synthesis of Alcohol Functionalized C-Chiral Diphosphines
Scheme 7
Scheme 8
Scheme 9
Table 2. Selected Bond Lengths (Å) and Bond Angles (deg) of (Rc)-13
Pd(1)-C(1)
2.005(4)
2.251(1)
1.380(7)
1.490(8)
80.6(2)
Pd(1)-N(1)
Pd(1)-Cl(1)
C(15)-C(17)
2.126(4)
2.413(1)
1.306(7)
Pd(1)-P(1)
O(1)-C(16)
C(15)-C(16)
C(1)-Pd(1)-N(1)
N(1)-Pd(1)-P(1)
N(1)-Pd(1)-Cl(1)
C(1)-Pd(1)-P(1)
C(1)-Pd(1)-Cl(1)
P(1)-Pd(1)-Cl(1)
93.9(1)
171.2(1)
93.3(5)
173.4(1)
92.5(1)
phine complex formed was characterized by means of single-
crystal X-ray diffraction analysis (Figure 2). Selected bond
angles and bond lengths are given in Table 2. The X-ray
structure confirmed that the monodentate phosphine was
indeed the Markovnikov product obtained from the first-
stage hydrophosphination reaction of propargyl alcohol. The
coordination around the metal center is a distorted square
planar with angles at palladium in the range of 80.6(2)-
93.9(1) and 171.2(1)-173.4(1)°. The chloro complex (Rc)-
13 was subsequently converted to the perchlorato species
by treatment with aqueous silver perchlorate as shown in
Scheme 9. The perchlorato complex (Rc)-14 was dissolved
in dichloromethane and reacted with diphenylphosphine at
-78 °C. The 31P{1H} spectrum (CDCl3) of the crude reaction
mixture exhibited four pairs of doublets in the ratio 1:2.4:
5.3:7.8.
Attempted fractional crystallization using dichloromethane-
n-hexanes gave yellow prisms suitable for single-crystal
X-ray diffraction analysis. Preliminary 31P{1H} NMR (CD2-
Cl2) spectroscopic studies of the crystallized products,
however, indicated the presence of two isomers because four
doublet signals were observed at δ 41.6 (JPP ) 30.4 Hz),
42.0 (JPP ) 30.4 Hz), 50.0(JPP ) 30.4 Hz), and 51.5 (JPP
)
30.4 Hz).
A single-crystal X-ray diffraction analysis of the yellow
prisms obtained from the hydrophosphination reaction mix-
ture confirmed that the two diastereomers (Rc,Rc)-15a and
Figure 2. Molecular structure of (Rc)-13.
Inorganic Chemistry, Vol. 45, No. 18, 2006 7459

Pullarkat et al.
Table 3. Selected Bond Lengths (Å) and Angles (deg) of (Rc,Rc)-15a
and (Rc,Sc)-15b
(Rc,Rc)-15a
(Rc,Sc)-15b
Pd(1)-C(1)
2.059(7)
2.141(6)
2.245(2)
2.350(2)
1.835(8)
1.843(8)
1.497(11)
1.518(13)
1.366(14)
80.4(3)
Pd(2)-C(42)
2.059(7)
2.140(6)
2.257(1)
2.394(1)
1.853(8)
1.828(8)
1.537(11)
1.491(12)
1.447(12)
79.8(3)
Pd(1)-N(1)
Pd(2)-N(2)
Pd(1)-P(2)
Pd(2)-P(4)
Pd(1)-P(1)
Pd(2)-P(3)
P(1)-C(15)
P(3)-C(56)
P(2)-C(16)
P(4)-C(57)
C(15)-C(16)
C(56)-C(57)
C(15)-C(17)
C(56)-C(58)
O(1)-C(17)
O(2)-C(58)
C(1)-Pd(1)-N(1)
C(1)-Pd(1)-P(2)
N(1)-Pd(1)-P(2)
C(1)-Pd(1)-P(1)
N(1)-Pd(1)-P(1)
P(2)-Pd(1)-P(1)
C(42)-Pd(2)-N(2)
C(42)-Pd(2)-P(4)
N(2)-Pd(2)-P(4)
C(42)-Pd(2)-P(3)
N(2)-Pd(2)-P(3)
P(4)-Pd(2)-P(3)
95.7(2)
93.3(2)
175.1(2)
174.0(2)
99.4(2)
172.8(2)
175.6(2)
101.7(2)
85.1(7)
84.8(7)
Scheme 10
Figure 3. Molecular structure and absolute configuration of (Rc,Rc)-15a.
doublets at δ 53.3 and 66.2 (JPP ) 7.6 Hz) when monitored
by 31P{1H} NMR spectroscopy in CD2Cl2. The reaction
mixture was concentrated, and diethyl ether was added that
resulted in the formation of pale yellow crystals that were
analyzed by means of single-crystal X-ray diffraction analysis
(Figure 5). As was expected, the single-crystal X-ray
diffraction analysis showed that two enantiomers (Rc)-17a
and (Sc)-17b co-crystallized out in the same unit cell (Table
4).
Figure 4. Molecular structure and absolute configuration of (Rc,Sc)-15b.
(Rc,Sc)-15b have co-crystallized out (Figures 3 and 4).
Selected bond lengths and bond angles for the two diaster-
eomers are given in Table 3. The single-crystal X-ray
diffraction data revealed that the two diastereomers differ
in the chirality at C(15) and C(56). For (Rc,Sc)-15a the
chirality at C(15) is S whereas in the case of (Rc,Rc)-15b the
chiral carbon C(56) adopts the R configuration. Both
diastereomers show a similar coordination pattern with the
geometry at the Pd metal center being distorted square planar.
The angles formed by the diphosphine chelate and the
naphthylamine template at the Pd metal center were in the
range of 80.4(3)-99.4(2) and 174.0(2)-175.1(2)° for (Rc,Rc)-
15a. The diastereomer (Rc,Sc)-15b showed a slightly elevated
strain with angles at the metal center being in the range of
79.8(3)-101.7(2) and 172.9(2)-175.6(2)°.
Regio- and Sterochemical Observations. In principle,
the hydrophosphination reaction between diphenylphosphine
and alcohol functionalized alkenols may generate up to four
possible stereoisomeric products. In the case of the hydro-
phosphination reaction involving 3-diphenylphosphanyl-but-
3-en-1-ol and diphenylphosphine, the four possible isomers
were formed in the ratio 1:2:4:18. The major isomer has the
phosphorus of the alcohol moiety coordinated cis to the
ortho-metalated aromatic carbon once the five-membered
chelate is formed during the course of the hydrophosphina-
tion reaction. This was in contrast to what was observed for
the hydrophosphination of 2-diphenylphosphanyl-prop-2-en-
1-ol. Single-crystal X-ray analysis of the co-crystallized
major isomers revealed that they were cis-trans regiosiomers
The two diastereomers (Rc,Rc)-15a and (Rc,Sc)-15b that
co-crystallized out were converted to their dichloro species
(Scheme 10). The crude reaction mixture showed two
7460 Inorganic Chemistry, Vol. 45, No. 18, 2006

Synthesis of Alcohol Functionalized C-Chiral Diphosphines
membered diphosphine chelate with the phosphine function-
alized alcoholic entity occupying the position trans to the
NMe2 group of the chiral template. In the major isomers
(isolated as a racemic mixture) of the hydrophosphination
reaction involving 2-diphenylphosphanyl-prop-2-en-1-ol, the
phosphine functionalized alcohol entity occupied a position
cis to the NMe2 group. This is believed to be because of the
steric factor involved in the case of 3-diphenylphosphanyl-
but-3-en-1-ol in which the CH2CH2OH entity on the chiral
carbon extends into the metal coordination sphere to have
effective Pd-O interactions and, therefore, is sterically
hindered by the presence of the NMe2 group of the
naphthylamine auxiliary. Therefore, the phosphine function-
alized alcoholic entity prefers to occupy the position trans
to the NMe2 group. The shorter CH2OH group of the
2-diphenylphosphanyl-prop-2-en-1-ol does not have an ap-
preciable steric impact and, therefore, can afford to occupy
the position trans to the C of the chiral metal template.
In conclusion, the synthesis of alcohol functionalized chiral
diphosphines via a novel two-stage asymmetric hydrophos-
phination protocol was demonstrated. The hydrophosphina-
tion proceeded with high regio- and steroselectivites for the
case of 3-butyn-1-ol substrate under mild conditions. Further
investigations on the regio- and stereochemical considerations
involved are currently underway to provide a facile method
for the synthesis of P-stereogenic phosphines with selected
functionalities.
Figure 5. Molecular structure of 17.
Table 4. Selected Bond Lengths (Å) and Bond Angles (deg) of 17
Pd(1)-P(1)
2.225(2)
2.341(1)
1.859(9)
1.530(8)
1.462(7)
86.3(6)
Pd(1)-P(2)
Pd(1)-Cl(2)
P(2)-C(2)
C(1)-C(3)
2.228(2)
2.364(2)
1.843(6)
1.520(11)
Pd(1)-Cl(1)
P(1)-C(1)
C(1)-C(2)
O(1)-C(3)
P(1)-Pd(1)-P(2)
P(2)-Pd(1)-Cl(1)
P(2)-Pd(1)-Cl(2)
P(1)-Pd(1)-Cl(1)
P(1)-Pd(1)-Cl(2)
Cl(1)-Pd(1)-Cl(2)
90.3(6)
175.7(6)
93.5(6)
175.9(6)
90.1(6)
Experimental Section
All reactions and manipulations of air-sensitive compounds were
carried out under a positive pressure of dry, oxygen-free nitrogen
on a high-vacuum line or on a standard Schlenk line. Solvents were
dried and freshly distilled according to standard procedures and
with the phosphorus of the alcohol moiety coordinated trans
to the ortho-metalated carbon of the chiral template and
differed in the chirality of the stereogenic carbon chiral
center.
1
degassed prior to use when necessary. The 1-D H and 31P{1H}
A possible explanation for the observed difference in
stereoselectivity can be found by analyzing the structure of
the complex obtained upon coordination of the phosphanyl-
ene entity of the 2-diphenylphosphanyl-prop-2-en-1-ol to the
chiral template complex (Rc)-3 (Figure 2). It was observed
from the crystallographic data that the oxygen atom of the
-OH group was oriented in such a way that it was in close
proximity to the Pd metal center. This indicated significant
Pd-O interactions, which also should exist in nonpolar
solvents. In the case of 2-diphenylphosphanyl-prop-2-en-1-
ol, the chelating diphosphine adduct was formed upon
hydrophosphination, and the rigidity imposed by the forma-
tion of the five-membered chelate ring did not allow the
Pd-O interactions to occur. Therefore, two different con-
figurations for the newly generated carbon centers in (Rc,
Rc)-15a and (Rc, Sc)-15b were allowed. In contrast, the
flexibility available by virtue of the longer chain length of
the CH2CH2OH moiety for the product formed by the
hydrophosphination of 3-diphenylphosphanyl-but-3-en-1-ol
allowed these interactions to occur even upon formation of
the diphosphine chelate, thus influencing the chirality at the
sterogenic carbon center.
NMR spectra were measured on a Bruker ACF 300 spectrometer
operating at 300.1 and 121.5 MHz, respectively. Optical rotations
were measured on the specified solutions in a 1-cm cell at 25 °C
using a Perkin-Elmer model 341 polarimeter. Melting points were
determined using a Bu¨chi B-545 automatic melting point apparatus.
Elemental analyses were performed by the Elemental Analysis
laboratory of the Department of Chemistry at the National
University of Singapore.
Both enantiomerically pure forms of the complexes (Rc)-1,16 (Rc)-
10, and (Sc)-1017 were prepared as previously reported. Solvents
were distilled, dried, and degassed by standard procedures where
necessary. Column chromatography was performed using silica gel
60.
Caution: Perchlorate salts of metal complexes are potentially
explosiVe compounds and should be handled with care.18
3-Diphenylphosphanyl-but-3-en-1-ol. Diphenylphosphide ion
was generated by the addition of diphenylphosphine (2.79 g, 0.016
mol) with stirring to a Schlenk flask containing sodium metal (0.37
g, 0.016 mol) in THF (100 mL). The mixture was left to stir
overnight. A solution of n-butyllithium in hexane (15% in hexane,
(16) (a) Allen, D. G.; McLaughlin, G. M.; Robertson, G. B.; Stefen, W.
L.; Salem, G.; Wild, S. B. Inorg. Chem. 1982, 21, 1007. (b) Hockless,
D. C. R.; Gugger, P. A.; Leung, P. H.; Mayadunne, R. C.; Pabel, M.;
Wild, S. B. Tetrahedron 1997, 53, 4083.
(17) Chooi, S. Y. M.; Leung, P. H.; Lim, C. C.; Mok, K. F.; Quek, G. H.;
Sim, K. Y.; Tan, M. K. Tetrahedron: Asymmetry 1992, 3, 529.
(18) Wolsey, W. C. J. Chem. Educ. 1973, 50, A335.
The difference in regiochemistry observed for the two
reactions also should be noted. In the case of 3-diphe-
nylphosphanyl-but-3-en-1-ol, the major product was the five-
Inorganic Chemistry, Vol. 45, No. 18, 2006 7461

Pullarkat et al.
10.11 mL, 0.0162 mol) was added to 3-butyn-1-ol (1.22 mL, 0.0162
mol) in THF with stirring. The diphenylphosphide solution gener-
ated previously then was added to this solution dropwise with
vigorous stirring at 0 °C. The reaction mixture was allowed to reach
room temperature and was stirred for 5 days. The solvent was then
distilled off to leave a dark brown slurry to which brine (150 mL)
was added. The mixture was subsequently extracted with dichlo-
romethane (3 × 100 mL). The organic layer then was dried with
magnesium sulfate, and the solvent was removed by distillation to
give a dark yellow oil. The crude product was purified by means
of silica gel column chromatography using 20% ethyl acetate in
hexane under purified nitrogen. The product was collected as the
first fraction, which gave a yellow oil on removal of eluents (1.78
g, 43.2%). 31P{1H} NMR (CDCl3, δ): -3.36 (s).
2-Diphenylphosphanyl-prop-2-en-1-ol. Sodium metal (0.37 g,
0.016 mol) was placed in a 250 mL Schlenk flask containing THF
(100 mL). This was followed by the addition of diphenylphosphine
(2.79 g, 0.016 mol) with stirring. The mixture was stirred overnight
and was observed to turn a deep,red color, which was characteristic
of the diphenylphosphide ion. Propargyl alcohol (0.94 mL, 0.016
mol) then was placed in a 500 mL Schlenk flask with THF (100
mL). To this solution, n-butyllithium (15% solution in hexane)
(0.01618 mol, 9.86 mL) was added with stirring. The sodium
diphenylphosphide generated then was transferred dropwise into
the Schlenk flask with stirring at 0 °C. The reaction mixture was
allowed to reach room temperature and continued to be stirred over
3 days. Most of the THF then was distilled off and followed by
the addition of brine (150 mL) to the residue. The mixture was
extracted three times using 100 mL of dichloromethane each time.
The organic layer was subsequently extracted and dried with
magnesium sulfate, and the solvent was removed via distillation
leaving a highly viscous dark red oil. The crude product was purified
via elution through a silica gel column using 20% v/v ethyl acetate:
n-hexanes as eluent under an inert atmosphere. The recovered
product was a pale yellow oxygen-sensitive oil (2.87 g, 73.4%).
31P NMR (CDCl3, δ): -9.20.
dichloromethane-diethyl ether (1.2 g, 63.0%). [R]D ) -8.9 (c 1.4,
CH2Cl2), mp 229-231 °C (decomp). Anal. Calcd for C43H46Cl3-
NO5P2Pd: C, 55.5; H, 4.9; N, 1.5. Found: C, 55.7; H, 5.2; N, 1.4.
31P{1H} NMR (CDCl3, δ): 39.8 (d, 1P, JPP ) 22.7 Hz), 77.0 (d,
1P, JPP ) 22.7 Hz). 1H NMR (CDCl3, δ): 1.15 (m, 1H,
3
Ph2P1CH′HCH), 1.38 (m, 1H, Ph2P1CH′HCH), 2.09 (d, 3H, JHH
) 6.4 Hz, CHMe), 2.41 (s, 3H, NMe), 2.71 (s, 3H, NMe), 2.91 (m,
1H, P2CHCH2), 3.07 (ddd, 2H, 3JHH ) 3.2 Hz, 3JHH ) 11.05, 3JPH
3
) 17.55), 3.53 (m, 2H, CH2CH2OH), 4.52 (qn, 1H, JHH ) 4JPH
) 6.0 Hz, CHMe), 6.81-8.47 (m, 26H, aromatics).
Dichloro[(R)3,4-bis(diphenylphosphino)butan-1-ol]palladium-
(II), (Rc)-8. A solution of the complex (Rc,Rc)-7a (0.99 g, 0.001
mols) in dichloromethane was stirred with concentrated hydrochloric
acid (5 mL) for 8 h. The excess acid then was removed by washing
with water (3 × 20 mL), and the organic layer was dried using
magnesium sulfate. Upon removal of the solvent, a pale yellow
solid was obtained. Crystallization from dichloromethane-n-
hexanes yielded pale yellow needles (0.62 g, 86.1%). [R]D ) +37.5
(c 0.2, CH2Cl2), mp 214-217 °C. Anal. Calcd for C29H30Cl4OP2-
Pd: C, 49.4; H, 4.3. Found: C, 49.9; H, 4.7. 31P{1H} NMR (CDCl3,
1
δ): 51.1 (d, 1P, JPP ) 7.5 Hz), 71.3 (d, 1P, JPP ) 7.5 Hz). H
NMR (CD2Cl2, δ): 0.86 (m, 1H, P1CHH′), 0.94 (m, 1H, P1CHH′),
3
3
3
2.87 (ddd, JHH ) 4.8 Hz, JHH ) 12.4 Hz, JPH ) 14.7 Hz).
Decomplexation of (R)-3,4-bis(Diphenylphosphino)butan-1-
ol, (Rc)-9. A solution of the complex (Rc)-8 (0.03 g, 0.05 mmol) in
dichloromethane was stirred vigorously with aqueous potassium
cyanide (0.16 g, 0.24 mmol) for 2 h. The organic layer was
separated and washed with water (3 × 10 mL) and then was dried
with magnesium sulfate. A pale yellow oil was obtained on removal
of the solvents under reduced pressure (0.01 g, 57.2%). [R]D
)
3
+64.9 (c 0.2, CH2Cl2). 31P{1H} NMR (CDCl3, δ): -19.3 (d, JPP
3
) 19.0 Hz), -0.2 (d, JPP ) 19.0 Hz).
Chloro[(R)-1-[1-(dimethylamino)ethyl]-2-naphthalenyl-C,N]-
[2-(diphenylphosphino)prop-2-en-1-ol], (Rc)-13. To a solution of
complex (Rc)-3 in dichloromethane (2.04 g, 0.003 mols), 2-dipe-
nylphosphanyl-prop-2-en-1-ol (1.45 g, 0.006 mols) in dichlo-
romethane was added dropwise with stirring. The reaction was
allowed to stir for 8 h, and then the solvent was removed under
reduced pressure to give a yellow solid. Crystallization using
acetonitrile-diethyl ether gave yellow prisms (1.87 g, 93.0%). [R]D
) -38.7 (c 0.3, CH2Cl2), mp 211-213 °C. Anal. Calcd for C29H31-
ClNOPPd: C, 59.8; H, 5.3; N, 2.4. Found: C, 60.0; H, 4.9; N, 2.5.
31P{1H} NMR (CDCl3, δ): 38.7 (s). 1H NMR (CDCl3, δ): 2.02 (d,
3H, 2JHH ) 6.4 Hz, CHMe), 2.80 (s, 3H, NMe), 2.98 (s, 3H, NMe),
4.12 (m, 2H, CH2OH), 4.37 (qn, 1H, 3JHH ) 4JPH ) 6.0 Hz, CHMe),
Chloro[(R)-1-[1-(dimethylamino)ethyl]-2-naphthalenyl-C,N]-
[3-(diphenylphosphino)but-3-en-1-ol], (Rc)-4. To a solution of the
complex (Rc)-3 in dichloromethane (1.88 g, 0.003 mols), 3-diphe-
nylphosphanyl-but-3-yn-1-ol (1.41 g, 0.005 mols) in dichlo-
romethane was added dropwise with stirring. The reaction mixture
was allowed to stir for 8 h, and then the solvent was removed under
reduced pressure to give a yellow solid (1.95 g, 95.6%) m.p: 220-
223 °C. Anal. Calcd for C30H33NClPOPd: C, 60.4; H, 5.5; N, 2.4.
Found: C, 60.4, H, 5.9, N, 2.4. 31P{1H} NMR (CDCl3, δ): 40.6
1
2
3
3
(s). H NMR (CDCl3, δ): 2.07 (d, 3H, JHH ) 6.4 Hz, CHMe),
2.72 (s, 3H, NMe), 2.98 (s, 3H, NMe), 3.98 (m, 2H, CH2CH2OH),
5.16 (d, 1H, JPH ) 16.9 Hz, cis-PCdCH2), 6.02 (d, 1H, JPH
33.7 Hz, trans-PCdCH2), 6.56-8.12 (m, 16H, aromatics).
)
3
4
4.09 (m, 2H, CH2CH2OH), 4.37 (qn, 1H, JHH ) JPH ) 6.0 Hz,
CHMe), 5.39 (d, 1H, JPH ) 17.2 Hz, cis-PCdCH2), 5.91 (d, 1H,
[(R)-1-[1-(Dimethylamino)ethyl]-2-naphthalenyl-C,N][2,3-bis-
(diphenylphosphino)propan-1-ol]palladium(II) Perchlorate,
(Rc,Rc)-15a and (Rc,Sc)-15b. To a solution of the complex (Rc)-13
(1.57 g, 0.003 mols) in dichloromethane, silver perchlorate (0.83
g, 0.004 mols) in water (4 mL) was added and stirred for 30 min
at room temperature. The reaction mixture then was washed with
water (3 × 20 mL) and was dried with magnesium sulfate to yield
the perchlorato complex (Rc)-14 (1.82 g, 94.3%). A solution of the
perchlorato complex in dichloromethane (1.82 g, 0.003 mols) was
cooled to -78 °C and subsequently treated with diphenylphosphine
(0.52 g, 0.003 mols). The temperature was maintained for 10 h,
and then the solution was stirred at room temperature for an
additional 48 h to give a dark red solid upon removal of the solvents
under reduced pressure. Crystallization employing dichloromethane-
n-hexane gave yellow prisms (0.99 g, 39%). Anal. Calcd for C41H42-
ClNO5P2Pd: C, 59.2; H, 5.0; N, 1.7. Found: C, 58.9; H, 4.9; N,
3
3JPH ) 35.3 Hz, trans-PCdCH2), 6.54-8.17 (m, 16H, aromatics).
[(R)-1-[1-(Dimethylamino)ethyl]-2-naphthalenyl-C,N][(R)3,4-
bis(diphenylphosphino)butan-1-ol]palladium(II) Perchlorate,
(Rc,Rc)-7a. A solution of the complex (Rc)-4 (1.56 g, 0.002 mols)
in dichloromethane was treated with aqueous silver perchlorate (0.63
g, 0.003 mols) for 30 min. The reaction mixture was subsequently
washed with water (3 × 20 mL), and the organic layer was dried
using magnesium sulfate. Upon removal of the solvent, perchlorato
complex (Rc)-5 was obtained as a yellow solid (1.39 g, 94.5%). To
(Rc)-5 (1.39 g, 0.002 mol) in dichloromethane, diphenylphosphine
(0.35 g, 0.002 mol) was added with stirring at -78 °C. The
temperature was maintained for 10 h then stirred at room temper-
ature for 24 h to obtain a dark red solid upon solvent removal.
Pale yellow crystals were obtained upon crystallization using
7462 Inorganic Chemistry, Vol. 45, No. 18, 2006

Synthesis of Alcohol Functionalized C-Chiral Diphosphines
Table 5. Crystallographic Data for Complexes (Rc,Rc)-7a, (Rc)-13, 15, and 17
(Rc,Rc)-7a
(Rc)-13
15
17
formula
M
C43H46Cl3NO5P2Pd
931.50
C29H31ClNOPPd
582.37
C415H43Cl2NO5P2Pd
875.01
C28H28Cl4OP2Pd
690.64
space group
crystal system
a/Å
b/Å
P2(1)2(1)2(1)
orthorhombic
10.093(1)
19.017(2)
22.489(2)
4316.5(8)
4
P2(1)2(1)2(1)
orthorhombic
12.200(5)
13.360(6)
16.791(8)
2737.0(2)
4
P1
P2(1)/c
triclinic
9.727(4)
10.935(5)
19.975(9)
2017.8(2)
2
monoclinic
19.514(5)
8.547(2)
17.987(4)
2865.3(1)
4
c/Å
V/Å3
Z
T/K
223(2)
223(2)
295(2)
223(2)
λ/Å
0.71073
0.734
0.0487
0.1235
0.71073
0.855
0.0523
0.0877
0.03(3)
0.71073
0.716
0.0569
0.1238
0.02(3)
0.71073
1.154
0.0698
µ/mm-1
R1 (obs. data)a
wR2 (obs. data)b
Flack parameter
0.1387
-0.01(3)
a R1 ) ∑||Fo| - |Fc||/∑|Fo|. b wR2 ) {∑[w(F0 - Fc )2]/∑[w(F0 )2]}1/2, w-1 ) σ2(F0)2 + (aP)2 + bP.
2
2
2
1.7. 31P{1H}NMR (CD2Cl2, δ): 41.6 (d, 1P, 3JPP ) 30.4 Hz), 42.0
Diffraction data were collected at the National University of
Singapore using a Siemens SMART CCD diffractometer with Mo-
KR radiation (graphite monochromator) using ω-scans. SADABS
absorption corrections were applied. All non-hydrogen atoms were
refined anisotropically. Hydrogen atoms were introduced at a fixed
distance from the carbon and nitrogen atoms and were assigned
fixed thermal parameters. The absolute configurations of all chiral
complexes were determined unambiguously using the Flack pa-
rameter.19
(d, 1P, 3JPP ) 30.4), 50.0 (d, 1P, 3JPP ) 30.4), 51.5 (d, 1P, 3JPP
)
30.4).
Dichloro[2,3-bis(diphenylphosphino)propan-1-ol]palladium-
(II), (Rc)-17a and (Rc)-17b. A mixture of complexes (Rc,Rc)-15a
and (Rc,Sc)-15b (0.85 g, 0.001 mol) in dichloromethane was treated
with concentrated hydrochloric acid (4 mL) and was left to stir for
8 h. The excess acid then was removed by means of washing with
water (3 × 20 mL), and the organic layer was extracted and dried
using magnesium sulfate. The reaction mixture was concentrated
and n-hexanes were added. Yellow prisms were obtained upon
standing (0.52 g, 84.5%). 31P{1H} NMR (CD2Cl2, δ): 53.3 (d. 1P,
Supporting Information Available: For (Rc,Rc)-7a, (Rc)-13,
(Rc,Rc)-15a, (Rc,Sc)-15b, and 17. Tables of crystal data, data
collection, solution and refinement, final positional parameters, bond
distances and angles, thermal parameters of non-hydrogen atoms,
and calculated hydrogen parameters. This material is available free
of charge via the Internet at http://pubs.acs.org.
1
JPP ) 7.6 Hz), 66.2 (d, 1P, JPP ) 7.6 Hz). H NMR (CD2Cl2, δ):
2.29-2.47 (m, 2H, CHCH2OH), 2.66-2.77 (m. 1H, PCHH′), 2.88-
3
3
2.98 (m, 1H, PCHH′), 3.62 (dd, 2H, JPH ) 10.4 Hz, JHH ) 5.2
Hz, CH2OH), 7.50-8.08 (m, 20H, aromatics).
Crystal Structure Determination of (Rc,Rc)-7a, (Rc)-13, (Rc,Rc)-
15a, (Rc,Sc)-15b and 17. Crystal data for all four complexes and a
summary of the crystallographic analyses are given in Table 5.
IC060937M
(19) Flack, H. D. Acta Crystallogr. 1983, A39, 876.
Inorganic Chemistry, Vol. 45, No. 18, 2006 7463