On the resolution of secondary phosphine oxides via diastereomeric complex formation: The case of tert-butylphenylphosphine oxide

Article abstract of DOI:10.1055/s-0029-1216811

The secondary phosphine oxide, t-BuPhHP=O, the most prominent chiral member of this compound class, has been resolved in high yield and with excellent ee. This resolution discloses an efficient route to enantiopure phosphorus compounds. Georg Thieme Verla

Full text of DOI:10.1055/s-0029-1216811

PAPER
2061
On the Resolution of Secondary Phosphine Oxides via Diastereomeric
Complex Formation: The Case of tert-Butylphenylphosphine Oxide
R
esolution
a
of tert-Bu
r
tylpheny
l
lphosp
e
hine
O
xide Holt,a,b,1 Anna M. Maj,c Ebe P. Schudde,b K. Michał Pietrusiewicz,*c Lełsaw Sieroꢀ,d Wanda Wieczorek,d
Thomas Jerphagnon,b Isabel W. C. E. Arends,a Ulf Hanefeld,a Adriaan J. Minnaard*b
a
Biocatalysis and Organic Chemistry, Department of Biotechnology, Delft University of Technology,
Julianalaan 136, 2628 BL Delft, The Netherlands
b
Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
Fax +48(81)5242134; E-mail: A.J.Minnaard@rug.nl
c
Department of Organic Chemistry, Maria Curie-Skłodowska University, ul. Gliniana 33, 20-614 Lublin, Poland
Fax +31(50)3634296; E-mail: kazimierz.pietrusiewicz@poczta.umcs.lublin.pl
d
Institute for General & Ecological Chemistry, Technical University of Łódꢁ, ꢂeromskiego 116, 90-924 Łódꢁ, Poland
Received 17 December 2008; revised 26 February 2009
times provides only one enantiomer of the auxiliary. The
resolution of tertiary phosphine oxides via diastereomeric
complex formation (classical resolution)6 has been report-
ed a number of times as well.
Abstract: The secondary phosphine oxide, t-BuPhHP=O, the most
prominent chiral member of this compound class, has been resolved
in high yield and with excellent ee. This resolution discloses an ef-
ficient route to enantiopure phosphorus compounds.
Key words: secondary phosphine oxide, phosphinous acid, asym- Secondary phosphine oxides,7 (or phosphinous acids,
metric catalysis, resolution, chiral ligand, P-chiral compounds
Scheme 1), are important ligands in nonasymmetric tran-
sition metal catalysis, especially in cross-coupling reac-
tions.3,8 This class of ligands combines excellent
coordinating properties with low oxidation sensitivity and
is easily prepared, often in one step. These properties also
make them in principle very good ligands in asymmetric
catalysis;9 secondary phosphine oxides have successfully
been used in iridium-catalyzed imine hydrogenation,10 iri-
dium- and rhodium-catalyzed alkene hydrogenation,11
palladium-catalyzed allylic substitution,12 and platinum-
catalyzed alkylidenecyclopropanation.13
Trivalent chiral phosphorus compounds are of tremen-
dous importance in organic chemistry, especially in asym-
metric synthesis2 and catalysis. Transition metal catalysis
uses phosphorus-based ligands extensively3 whereas
phosphorus-based catalysts also play an important role in
organocatalysis.4
The synthesis of enantiopure P-chiral compounds, with
chirality centered on phosphorus, is in general difficult to
achieve.5 Several successful approaches have neverthe-
less been developed over the years using chiral auxiliaries
such as menthol or ephedrine, or chiral bases such as
sparteine. These methods are frequently applied but re-
quire several synthetic steps, and the chiral pool some-
Chiral enantiopure secondary phosphine oxides are also
excellent starting materials for P-chiral phosphines and
other derivatives (Scheme 2).14 Alkylation of these com-
pounds takes place with retention of stereointegrity, lead-
ing to tertiary phosphine oxides.15 Subsequent
deoxygenation affords the corresponding chiral phos-
phines.16 The use of the corresponding borane complexes
in a variety of applications has recently been described.17
O
R1
OH
R1
P
P
H
The barrier in the application of chiral secondary phos-
phine oxides is the difficulty to obtain them enantiopure.
Several strategies have been developed for the preparation
of enantioenriched secondary phosphine oxides, mainly
R2
R2
Scheme 1 A secondary phosphine oxide (R1, R2 = alkyl or aryl) in
equilibrium with its phosphinous acid. For the free compound only
the phosphine oxide form is observed, but it tautomerizes to the phos-
phinous acid form upon complexation with a metal.
O
O
O
O
R
P
P
P
P
P
Br
OR
H
R
R = alkyl, aryl
R = alkyl, allyl, aryl
(R)-(+)-1
CH2COOMe, CH2OH
Scheme 2 Secondary phosphine oxide 1 as a starting material for chiral enantiopure phosphorus compounds
SYNTHESIS 2009, No. 12, pp 2061–2065
x
x.
x
x
.
2
0
0
9
Advanced online publication: 25.05.2009
DOI: 10.1055/s-0029-1216811; Art ID: T22208SS
© Georg Thieme Verlag Stuttgart · New York

2062
J. Holt et al.
PAPER
focusing on t-BuPhHP=O (1), the primus inter pares of A series of acidic resolving agents was selected for the
this class.
resolution of 1 in various solvents (Figure 1). The varying
results obtained using mandelic acid24 were confirmed, as
sometimes 1 crystallized from the solution, and some-
times complexes of 1 and mandelic acid were isolated
with varying ee and absolute configuration for 1. The use
of the phosphoric acids Phencyphos, Anicyphos, and
Chlocyphos28 did not lead to complex formation whereas
chalcone sulfonic acid29 in butanone gave 30% of a com-
plex with racemic 1.
Conversion of rac-1 into the corresponding thiophospho-
ric acid, followed by resolution via diastereomeric com-
plex formation and desulfurization has been developed on
preparative scale and affords enantiopure 1 in high ee.15,18
Preparative chiral HPLC of a series of secondary phos-
phine oxides has been successfully applied as well and
afforded gram quantities of 1.10 Reaction of racemic
t-BuPhPCl with (R)-a-methylbenzylamine led to diaste-
reomeric aminophosphines that could be separated by dis-
tillation and subsequently hydrolyzed to 1. However, the
hydrolysis led to some racemization.19 Recently, one of us
reported the preparation of enantioenriched 1 via resolu-
tion of its borane complex, that is, phosphinous acid bo-
rane.17 This work was followed by studies of the Buono
group who reported a flexible synthesis of chiral second-
ary phosphine oxides using either menthol20 or prolinol21
as a chiral auxiliary. The enatiomeric excesses were in
general excellent but did not exceed 91% for 1. Very re-
cently, the stereospecific alkylation of diastereomerically
pure menthyl phosphinates was reported, which affords 1
in 95% yield and 99% ee.22 Finally, the synthesis of enan-
tiopure ferrocenyl-based secondary phosphine oxide
ligands was recently reported in the patent literature using
the addition of Grignard reagents to enantiopure ferroce-
nyl-PCl2 derivatives followed by diastereoselective hy-
drolysis.23
R
O
OH
R
O
O
OH
P
O
OH
(S)-Mandelic acids
R = H, Br, MeO
(S)-Phencyphos, R = H
(R)-Chlocyphos, R = Cl
(S)-Anicyphos, R = OMe
R
R
O
SO3K
O
O
O
O
(R)-chalcone sulfonic acid
potassium salt
O
O
OH HO
(S,S)-Dibenzoyltartaric acid, R = H
(S,S)-Ditoluoyltartaric acid, R = Me
(S,S)-Dianisoyltartaric acid, R = OMe
Summarizing the literature, the conclusion is that the
routes to prepare enantiopure secondary phosphine oxides
require a number of steps and often do not lead to enan-
tiopure compounds, whereas racemic secondary phos-
phine oxides are readily available in one step. Therefore,
resolution via diastereomeric complex formation seems to
be a very attractive route to, for example, 1. Remarkably,
apart from one single example,24 and contrary to the reso-
lution of tertiary phosphine oxides, no reports on the res-
olution of secondary phosphine oxides via diastereomeric
complex formation could be found in the literature.25 In
the aforementioned report, the resolution of 1 using man-
delic acid was described. However, in later work,26 prob-
lems with this resolution were encountered (also vide
supra). The configuration and ee of 1 isolated in the com-
plex were unpredictable, pointing at kinetic phenomena
during the resolution.
Figure 1 The resolving agents used in this study
Next, the application of mixtures of resolving agents, the
so-called Dutch Resolution,30 was performed. However,
the M-mix (containing mandelic acid, p-bromomandelic
acid and p-methoxymandelic acid), the P-Mix (containing
the three aforementioned phosphoric acids) and the T-mix
(dibenzoyl, ditoluoyl, and dianisoyltartaric acid) all gave
oils in the resolution experiments or precipitated from the
solution.
Although dianisoyltartaric acid in butanone gave a com-
plex containing racemic 1, we were pleased to observe
that (R,R)-O,O-dibenzoyltartaric acid [(R,R)-DBTA] gave
20% yield and 12% ee when applied in water with a small
amount of acetonitrile. All the more so because both enan-
tiomers of DBTA are commercially available. The break-
through came when EtOAc or water–acetonitrile (1:1)
were used as the solvent, which led to 28% yield and 90%
ee. After some optimization, 32% yield of a complex con-
taining a 1:1 ratio of DBTA and 1 was obtained with an ee
for 1 of 97%! One recrystallization afforded the complex
with >99% ee, thereby excluding end-solid solution be-
havior.31 Performing the method of ‘half quantities’,25d
applying 0.6 equivalent of DBTA gave a small but signif-
icant improvement of the ee to 99%. Finally, using ben-
zene–acetone as the solvent, 35% yield was obtained with
an ee of >99.5%, making recrystallization unnecessary.
Liberation of 1 from the complex by washing a chloro-
form solution with aqueous NaHCO3 or 5% aqueous
NaOH afforded pure 1 without erosion of the ee.
As part of a program aiming at the preparation of P-stereo-
genic secondary phosphine oxides and phosphines we set
out reinvestigating the resolution of 1. We first optimized
the synthesis of racemic 1; the t-BuMgBr addition to
dichlorophenylphosphine (PhPCl2) followed by acidic hy-
drolysis, with a reported yield of 60%.27 By performing
the reaction at –10 °C to room temperature using an ex-
cess of Grignard reagent, and keeping a considerably
shorter reaction time, an excellent 96% isolated yield was
obtained on a preparative (0.4 mol) scale. The reaction af-
forded pure rac-1 according to melting point and NMR
spectrum.
Synthesis 2009, No. 12, 2061–2065 © Thieme Stuttgart · New York

PAPER
Resolution of tert-Butylphenylphosphine Oxide
2063
1) t-BuMgCl, excess
(R,R)-DBTA (1 equiv)
benzene–acetone
O
O
2) 25% aq H2SO4
96%
P
H
P
PCl2
H
(R)-1 DBTA complex, 35%
(R)-(+)-1, 31%, >99.5% ee
5% aq NaOH
CHCl3
O
mother liquor
P
H
(S)-1 DBTA complex, 34%
(S)-(–)-1, 31%, 97% ee
5% aq NaOH
CHCl3
Scheme 3 The resolution of rac-1 with (R,R)-DBTA
It is noteworthy that, contrary to most resolutions via di-
astereomeric complex formation, this procedure affords
large colorless crystals, with a diameter of up to 1 cm re-
gardless of the solvent. To assure that this resolution was
a thermodynamic and robust process, several control ex-
periments were carried out. The resolution was repro-
duced seven times, using both enantiomers of DBTA and
at two different locations, without any failure. In addition,
in one experiment the resulting suspension was stored for
several weeks, to conclude that the composition of the
precipitated complex did not change.
When the mother liquor of the crystallization in benzene–
acetone was concentrated in vacuo and dissolved in hot
benzene, the other diastereomer of the complex was ob-
tained in 34% yield and 97% ee for 1. So, both enantio-
mers of 1 were obtained in one resolution in high yield and
excellent ee without recrystallization. The developed res-
olution protocol is summarized in Scheme 3.
Figure 2 Hydrogen-bonded polymeric ribbons in A, running along
the [010] direction; hydrogen bonds are drawn as dashed lines
Finally, the resolutions were scaled up starting with 53 g
of rac-1 using benzene–acetone, and 1 equivalent of
(R,R)-DBTA [(R,R)-(–)-dibenzoyltartaric acid, (–)-2,3-
dibenzoyl-L-tartaric acid] affording, after liberation of 1
from the complex, 16 grams (31%) of (R)-1 with an ee of
>99.5% and after crystallization of the residue of the fil-
trate from benzene, 16 g (31%) of (S)-1 with an ee of 97%.
The resolution in EtOAc was carried out starting with 15
grams of rac-1 and 0.6 equivalent of (R,R)-DBTA; it af-
forded (R)-1 in 21% yield and 97% ee. Crystallization of
the residue obtained from the filtrate of the latter experi-
ment gave complexes with a considerable lower ee.
Figure 3 Hydrogen-bonded polymeric ribbons in B, running along
the [010] direction; hydrogen bonds are drawn as dashed lines
The melting points of the crystals obey the rule that the
less soluble complex has a higher melting point (176–
178 °C) than the more soluble complex (137 °C).25d In
both cases, the oxygen of 1 forms hydrogen bonds with
carboxylic acid residues of two DBTA molecules. The tet-
rahedral arrangement around phosphorus in both mole-
cules of 1 is deformed, the valency angles in complex A
and B ranging from 103(1) to 113.6(1)° and 100(2) to
112.9(2)°, respectively. The positions of the P=O bonds in
relation to the phenyl rings are identical in A and B. Over-
The use of (R,R)-DBTA afforded invariably crystals con-
taining (R)-(+)-1. This was deduced from the optical rota-
tion and chiral HPLC of liberated 1, as the absolute
configuration of 1 is known.26 To confirm this, and to get
insight into the interactions between DBTA and 1 in the
solid phase, single crystals of both the less soluble
[(R,R),R] complex (A) and the more soluble [(R,R),S]
complex (B) were obtained and subjected to X-ray dif-
fraction (Figures 2 and 3) (see experimental for details).
Synthesis 2009, No. 12, 2061–2065 © Thieme Stuttgart · New York

2064
J. Holt et al.
PAPER
was taken and solvents were removed under vacuum. After dissolu-
tion in hot benzene (500 mL), cooling down to r.t., and keeping for
24 h, the large white crystals formed were isolated by filtration and
washed with benzene (50 mL). After drying, 56 g (34%) of DBTA/
1 complex (B) was obtained; mp 137 °C; [a]D –87.8 (c = 2.5,
MeOH). The crystals were dissolved in CHCl3 (50 mL) and the so-
lution was washed with 5% aq NaOH (3 × 300 mL) followed by
H2O (200 mL). After drying (MgSO4) and evaporation of the sol-
vent, 16 g (31%) of (S)-1 was obtained; mp 48 °C; [a]D –40.4
(c = 2.5, MeOH); >97% ee. Spectral data were identical with those
in the literature.
all, the origin of the difference in solubility of A and B is
not clear from the X-ray structures alone.
Whereas secondary phosphine oxides tend to decompose
slowly at room temperature, the corresponding DBTA
complexes were found to be perfectly stable at room tem-
perature, a characteristic reminiscent to the method of Ne-
theton and Fu for the handling of air sensitive
phosphines.32
In conclusion, it has been shown that tert-butylphe-
nylphosphine oxide (1), the most prominent chiral sec-
ondary phosphine oxide, can be resolved via
diastereomeric complex formation. Enantiopure 1 has
been prepared in two steps, namely synthesis of the race-
mate in 96% yield and resolution with dibenzoyltartaric
acid in 31% yield (max. 50%), >99.5% ee for one enan-
tiomer and 31% yield, 97% ee for the other enantiomer.
The starting materials and the resolving agent are com-
mercially available, the procedure has been carried out on
preparative (>50 g) scale and recrystallization is not nec-
essary. As 1 is a versatile ligand itself and an excellent
starting material for the preparation of P-chiral phos-
phines and other phosphorus compounds, their prepara-
tion is strongly facilitated this way.
X-ray Crystal Structures of Compounds A and B33
Structures of the compounds A [DBTA/1 (R,R),R complex] and B
[DBTA/1 (R,R),S complex] were determined by single-crystal X-
ray diffraction at ambient temperature. Intensity data for the crystal
of A were collected using an Enraf-Nonius CAD4 diffractometer34
and graphite-monochromated Cu-Ka radiation (l = 1.54178 Å).
The measurements for B were performed on a Kuma KM-4 k-axis
diffractometer35 with graphite-monochromated Cu-Ka radiation
(l = 1.54178 Å). The structures were solved by direct methods us-
ing the SHELXS-97 program.35All non-hydrogen atoms were re-
fined anisotropically by full-matrix least-squares based on F2 using
the SHELXL-97 program,36 and the complete set of reflections. The
final geometrical calculations were carried out with the PLATON
program.37 Figures were drawn using the Mercury program.38 In A
and B, hydrogens attached to P1 atoms were located in a difference
Fourier map and their positions and displacement parameters were
refined freely. Remaining hydrogen atoms were placed in their cal-
culated positions, assigned isotropic thermal parameters (1.2 or 1.5
times that of the atom attached to) and allowed to ride on their re-
spective parent atoms.
PhPCl2, tert-butyl chloride and all resolving agents were used as re-
ceived. NMR spectra were recorded using CDCl3 as solvent. Opti-
cal rotations were measured on a Schmidt + Haensch polarimeter
(Polartronic MH8) with a 10 cm cell (c given in g/100 mL). The
enantiomeric excess of 1 was determined by HPLC on a Chiralpak
AD column (Daicel), solvent: n-heptane–propan-2-ol (90:10), flow:
0.5 mL/min, UV-detection: 216 nm, (S)-1 = 9.2 min, (R)-1 = 12.4
min, or was approximated by comparison of the optical rotation val-
ues.
Figures 2 and 3 show a stereoscopic view of the molecular packing
in the unit cell for complexes A and B. In both structures the mole-
cules are connected by O4–H4···O1 and O5–H5···O1 hydrogen
bonds, which run along the b axis of the unit cell, resulting in a
1
C2 (9) graph-set motif.39 The two O4–H4···O1 [–x + 1, y – 0.5, –z +
1] and O5–H5···O1[x + 1, y, z] hydrogen bonds in the complex A
are 1.81 and 1.82 Å with the angles O4–H4···O1 and O5–H5···O1
165 and 161°; distances O4···O1 and O5···O1 are 2.610(3) and
2.605(2) Å. Analogous hydrogen bonds are observed in the com-
plex B, where O4–H4···O1 [x, y – 1, z + 1] and O5–H5···O1 [–x, y
– 0.5, –z + 1] are 1.80 and 1.84 Å with the angles O4–H4···O1 and
O5–H5···O1 of 158 and 167°; distances O4···O1 and O5···O1 are
2.577(4) and 2.641(4) Å.
tert-Butylphenylphosphine Oxide (rac-1)
A 2 L round-bottomed flask equipped with a stirring bar, dropping
funnel, condenser, and thermometer was charged with Mg turnings
(38.8 g, 1.6 mol), a crystal of I2 and anhyd Et2O (200 mL). Under
N2, t-BuCl (148 g, 1.6 mol) was added dropwise over 5 h. Subse-
quently, the temperature was decreased and kept between –10 and
–15 °C. PhPCl2 (71.2 g, 0.4 mol) in anhyd Et2O (100 mL) was add-
ed dropwise and after 1 h at that temperature, stirring was continued
for 1 h at r.t. Subsequently, 25% aq H2SO4 (600 mL) was added
carefully. After phase separation, the aqueous layer was extracted
with CH2Cl2 (5 × 50 mL) and the combined organic layers were
dried (MgSO4). The solvents were removed under vacuum and the
crude product was distilled at 105–110 °C/0.1 mm Hg to give 70 g
(96%) of 1 as white crystals; mp 46 °C. NMR data were as reported
in the literature.18
Resolution of rac-1 in EtOAc
A round-bottomed flask was charged with (–)-(R,R)-dibenzoyltar-
taric acid monohydrate (18.61 g, 0.049 mol, 0.6 equiv), 1 (15 g,
0.082 mol, 1.0 equiv), and EtOAc (375 mL). The mixture was heat-
ed at reflux until complete dissolution, subsequently allowed to cool
down to r.t. and kept for 24 h. The mother liquor was decanted, the
crystals were washed with Et2O (50 mL) and dried to give 9.79 g
(22%) of the complex. To isolate 1, the crystals were suspended in
sat. aq NaHCO3 (200 mL) and Et2O (200 mL). After stirring for 20
min, the organic phase was separated and the aqueous phase extract-
ed with Et2O (4 × 200 mL). The combined organic phases were
dried (Na2SO4) and the solvent was evaporated under vacuum to
give 3.087 g (21%) of (R)-1 with an ee of 97%.
Resolution of rac-1 in Benzene–Acetone
To a round-bottomed flask containing benzene–acetone (4:1, 780
mL) at reflux was added 1 (53 g, 0.291 mol) and (–)-(R,R)-diben-
zoyltartaric acid (110.5 g, 0.291 mol). After complete dissolution,
the mixture was allowed to cool down to r.t. and kept for 17 h. The
large white crystals formed were isolated by filtration and washed
with benzene–acetone (4:1, 50 mL). After drying, 57 g (35%) of
DBTA/1 complex (A) was obtained; mp 176–178 °C; [a]D –66.6
(c = 2.5, MeOH). The crystals were dissolved in CHCl3 (50 mL)
and the solution was washed with 5% aq NaOH (3 × 300 mL) fol-
lowed by H2O (200 mL). After drying (MgSO4) and evaporation of
the solvent, 16 g (31%) of (R)-1 was obtained; mp 48 °C; [a]D +41.8
(c = 2.5, MeOH); >99.5% ee. Spectral data were identical with
those in the literature. The remaining filtrate of the crystallization
Acknowledgment
M. Leeman (Syncom BV) and Dr. C. Hedberg (Max Planck Insti-
tute, Dortmund) are thanked for useful discussions. Syncom BV is
kindly acknowledged for a gift of resolving agents. T. D. Tiemers-
ma is thanked for assistance with HPLC, and NRSC-Catalysis is
thanked for financial support.
Synthesis 2009, No. 12, 2061–2065 © Thieme Stuttgart · New York

PAPER
Resolution of tert-Butylphenylphosphine Oxide
2065
(19) (a) Grishkun, E. V.; Kolodyazhnaya, A. O.; Kolodyazhnyi,
O. I. Russ. J. Gen. Chem. 2003, 73, 1823.
References
(1) Present address: School of Chemistry, University of Leeds,
Leeds, LS2 9JT, UK.
(2) Enders, D.; Saint-Dizier, A.; Lannou, M.-I.; Lenzen, A. Eur.
J. Org. Chem. 2006, 29.
(3) Phosphorus Ligands in Asymmetric Catalysis: Synthesis and
Applications; Börner, A., Ed.; Wiley- VCH: Weinheim,
2008.
(4) Methot, J. L.; Roush, W. R. Adv. Synth. Catal. 2004, 346,
1035.
(5) This topic has been reviewed recently, see: (a) Grabulosa,
A.; Granell, J.; Muller, G. Coord. Chem. Rev. 2007, 251, 25.
(b) See also: Pietrusiewicz, K. M.; Zablocka, M. Chem. Rev.
1994, 94, 1375. For a recent dynamic kinetic resolution,
see: (c) Bergin, E.; O’Connor, C. T.; Robinson, S. B.;
McCarrigle, E. M.; O’Mahony, C. P.; Gilheany, D. G. J. Am.
Chem. Soc. 2007, 129, 9566.
(b) Kolodyazhnyi, O.; Andrushko, N. V.; Grishkun, E. V.
Russ. J. Gen. Chem. 2004, 74, 515.
(20) (a) Leyris, A.; Bigeault, J.; Nuel, D.; Giordano, L.; Buono,
G. Tetrahedron Lett. 2007, 48, 5247. (b) Moraleda, D.;
Gatineau, D.; Martin, D.; Giordano, L.; Buono, G. Chem.
Commun. 2008, 3031.
(21) Leyris, A.; Nuel, D.; Giordano, L.; Achard, M.; Buono, G.
Tetrahedron Lett. 2005, 46, 8673.
(22) Xu, Q.; Zhao, C.-Q.; Han, L.-B. J. Am. Chem. Soc. 2008,
130, 12648.
(23) Pfaltz, A.; Ribourdouille, Y.; Feng, X.; Ramalingam, B.;
Pugin, B.; Spindler, F. PCT Int. Appl. WO2007135179,
2007; Chem. Abstr. 2007, 148, 11345.
(24) Drabowicz, J.; Lyzwa, P.; Omelanczuk, J.; Pietrusiewicz, K.
M.; Mikolajczyk, M. Tetrahedron: Asymmetry 1999, 10,
2757.
(6) The resolution of tertiary phosphine oxides with backbone
chirality has been reported a number of times, see for
example: (a) Netscher, T.; Scalone, M.; Schmid, R.
Enantioselective Hydrogenation: Towards a Large Scale
Total Synthesis of (R,R,R)-a-Tocopherol, In Asymmetric
Catalysis on Industrial Scale; Blaser, H. U.; Schmidt, E.,
Eds.; Wiley-VCH: Weinheim, 2004. (b) Vandyck, K.;
Matthys, B.; Willen, M.; Robeyns, K.; Van Meervelt, L.;
Van der Eycken, J. Org. Lett. 2006, 8, 363. (c) Brunner, H.;
Muschiol, M.; Zabel, M. Synthesis 2008, 405. For recent
resolutions of P-stereogenic tertiary phosphine oxides, see:
(d) Novak, T.; Schindler, J.; Ujj, V.; Czugler, M.; Fogassy,
E.; Keglevich, G. Tetrahedron: Asymmetry 2006, 17, 2599.
(e) Novak, T.; Ujj, V.; Schindler, J.; Czugler, M.; Kubinyi,
M.; Mayer, Z. A.; Fogassy, E.; Keglevich, G. Tetrahedron:
Asymmetry 2007, 18, 2965.
(7) Berlin, K. D.; Butler, G. B. Chem. Rev. 1960, 60, 243.
(8) (a) Ackermann, L. Synthesis 2006, 1557. (b) Ackermann,
L.; Born, R.; Spatz, J. H.; Althammer, A.; Gschrei, C. J. Pure
Appl. Chem. 2006, 78, 209.
(9) Dubrovina, N. V.; Börner, A. Angew. Chem. Int. Ed. 2004,
43, 5883.
(10) Jiang, X.-b.; Minnaard, A. J.; Hessen, B.; Feringa, B. L.;
Duchateau, A. L. L.; Andrien, J. G. O.; Boogers, J. A. F.;
De Vries, J. G. Org. Lett. 2003, 5, 1503.
(11) (a) Jiang, X.-b.; Van den Berg, M.; Minnaard, A. J.; Feringa,
B. L.; De Vries, J. G. Tetrahedron: Asymmetry 2004, 15,
2223. (b) Galland, A.; Dobrota, C.; Toffano, M.; Fiaud, J.-C.
Tetrahedron: Asymmetry 2006, 17, 2354.
(25) The literature was scrutinized, but no examples of the
resolution of secondary phosphine oxides/phosphinous acids
via diastereomeric complex formation were found. See, next
to the Chemical Abstracts: (a) Handbook of Optical
Resolutions via Diastereomeric Salt Formation; Kozma, D.,
Ed.; CRC Press: Boca Raton, FL, 2002. (b) Wilen, S. H.
Tables of Resolving Agents and Optical Resolutions; Eliel,
E. L., Ed.; University of Notre Dame Press: Notre Dame, IN,
1972. (c) Newman, P. Optical Resolution Procedures for
Chemical Compounds, Vol 1-4; Optical Resolution
Information Center: New York, 1981-1993. (d) Jacques, J.;
Collet, A.; Wilen, S. H. Enantiomers, Racemates and
Resolutions; Wiley: New York, 1981.
(26) Wang, R.; Polavarapu, P. L.; Drabowicz, J.; Mikolajczyk,
M. J. Org. Chem. 2000, 65, 7561.
(27) (a) Ref. 15 (b) Hoffmann, H.; Schellenbeck, P. Chem. Ber.
1966, 99, 1134.
(28) Ten Hoeve, W.; Wynberg, H. J. Org. Chem. 1985, 50, 4508.
(29) Kellogg, R. M.; Nieuwenhuijzen, J. W.; Pouwer, K.; Vries,
T. R.; Broxterman, Q. B.; Grimbergen, R. F. P.; Kaptein, B.;
La Crois, R. M.; de Wever, E.; Zwaagstra, K.; van der Laan,
A. C. Synthesis 2003, 1626.
(30) Vries, T.; Wynberg, H.; van Echten, E.; Koek, J.; ten Hoeve,
W.; Kellogg, R. M.; Broxterman, Q. B.; Minnaard, A.;
Kaptein, B.; van der Sluis, S.; Hulshof, L.; Kooistra, J.
Angew. Chem. Int. Ed. 1998, 37, 2349.
(31) Jacques, J.; Collet, A.; Wilen, S. H. Enantiomers, Racemates
and Resolutions; Wiley: New York, 1981, 299.
(32) Netheton, M. R.; Fu, G. C. Org. Lett. 2001, 26, 4295.
(33) CCDC-719981 (A) and CCDC-719982 (B) contain the
supplementary crystallographic data for this paper. These
data can be obtained free of charge at www.ccdc.cam.ac.uk/
conts/retrieving.html [or from the Cambridge
(12) Dai, W.-M.; Yeung, K. K. Y.; Leung, W. H.; Haynes, R. K.
Tetrahedron: Asymmetry 2003, 14, 2821.
(13) Bigeault, J.; Giordano, L.; de Riggi, I.; Gimbert, Y.; Buono,
G. Org. Lett. 2007, 9, 3567.
(14) (a) Au-Yeung, T.-L.; Chan, K.-Y.; Haynes, R. K.; Williams,
I. D.; Yeung, L. L. Tetrahedron Lett. 2001, 42, 457. (b) Au-
Yeung, T.-L.; Chan, K.-Y.; Chan, W.-K.; Haynes, R. K.;
Williams, I. D.; Yeung, L. L. Tetrahedron Lett. 2001, 42,
453.
(15) Haynes, R. K.; Au-Yeung, T. L.; Chan, W. K.; Lam, W. L.;
Li, Z. Y.; Yeung, L. L.; Chan, A. C. S.; Li, P.; Koen, M.;
Mitchell, C. R.; Vonwiller, S. C. Eur. J. Org. Chem. 2000,
3205.
(16) Imamoto, T.; Kikuchi, S.; Miura, T.; Wada, T. Org. Lett.
2001, 3, 87; and references cited therein.
(17) Stankevič, M.; Pietrusiewicz, K. M. J. Org. Chem. 2007, 72,
816.
Crystallographic Data Centre, 12 Union Road, Cambridge
CB2 1EZ, UK; fax: +44(1223)336 033; E-mail:
deposit@ccdc.cam.ac.uk.
(34) Frenz, B. A. SDP-Structure Determination Package; Enraf-
Nonius: Delft Holland, 1984.
(35) KUMA KM-4 Software; Kuma Diffraction: Wrocław
Poland, 1992.
(36) Sheldrick, G. M. Acta Cryst. 2008, A64, 112.
(37) Spek, A. L. J. Appl. Cryst. 2003, 36, 7.
(38) Macrae, C. F.; Edgington, P. R.; McCabe, P.; Pidcock, E.;
Shields, G. P.; Taylor, R.; Towler, M.; van de Streek, J.
J. Appl. Cryst. 2006, 39, 453.
(39) Etter, M. C.; MacDonald, J. C.; Bernstein, J. Acta
Crystallogr., Sect. B 1990, 46, 256.
(18) Haynes, H. K.; Freeman, R. N.; Mitchell, C. R.; Vonwiller,
S. C. J. Org. Chem. 1994, 59, 2919.
Synthesis 2009, No. 12, 2061–2065 © Thieme Stuttgart · New York