Enantiomerically pure phosphaalkene-oxazolines (PhAk-Ox): Synthesis, scope and copolymerization with styrene

Article abstract of DOI:10.1002/chem.201103887

The design of a synthetic route to a class of enantiomerically pure phosphaalkene-oxazolines (PhAk-Ox) is presented. The condensation of a lithium silylphosphide and a ketone (the phospha-Peterson reaction) was used as the P=C bond-forming step. Attempted condensation of PhC(=O)Ox (Ox=CNOCH(iPr)CH ₂) and MesP(SiMe₃)Li gave the unusual heterocycle (MesP)₂C(Ph)=CN-(S)-CH(iPr)CH₂O (3). However, PhAk-Ox (S,E)-MesP=C(Ph)CMe₂Ox (1 a) was successfully prepared by treating MesP(SiMe₃)Li with PhC(=O)CMe₂Ox (52 %). To demonstrate the modularity and tunability of the phospha-Peterson synthesis several other phosphaalkene-oxazolines were prepared in an analogous manner to 1 a: TripP=C(Ph)CMe₂Ox (1 b; Trip=2,4,6-triisopropylphenyl), 2-iPrC ₆H₄P=C(Ph)CMe₂Ox (1 c), 2-tBuC ₆H₄P=C(Ph)CMe₂Ox (1 d), MesP=C(4-MeOC ₆H₄)CMe₂Ox (1 e), MesP=C(Ph)C(CH ₂)₄Ox (1 f), and MesP=C(3,5-(CF₃) ₂C₆H₃)C(CH₂)₄Ox (1 g). To evaluate the PhAk-Ox compounds as prospective precursors to chiral phosphine polymers, monomer 1 a and styrene were subjected to radical-initiated copolymerization conditions to afford [{MesPC(Ph)(CMe₂Ox)} _x{CH₂CHPh}_y]_n (9 a: x=0.13n, y=0.87n; GPC: M_w=7400 g mol^-1, PDI=1.15). Copyright

Full text of DOI:10.1002/chem.201103887

FULL PAPER
DOI: 10.1002/chem.201103887
Enantiomerically Pure Phosphaalkene–Oxazolines (PhAk-Ox): Synthesis,
Scope and Copolymerization with Styrene
Julien Dugal-Tessier, Spencer C. Serin, Emmanuel B. Castillo-Contreras,
Eamonn D. Conrad, Gregory R. Dake,* and Derek P. Gates*[a]
Abstract: The design of a synthetic
route to a class of enantiomerically
MesP
G
(1c), 2-tBuC6H4P=C(Ph)CMe2Ox (1d),
MesP=C(4-MeOC6H4)CMe2Ox (1e),
MesP=C(Ph)C(CH2)4Ox (1 f), and
MesP=C(3,5-(CF3)2C6H3)C(CH2)4Ox
(1g). To evaluate the PhAk-Ox com-
pounds as prospective precursors to
chiral phosphine polymers, monomer
1a and styrene were subjected to radi-
cal-initiated copolymerization condi-
(52%). To demonstrate the modularity
and tunability of the phospha-Peterson
synthesis several other phosphaalkene–
oxazolines were prepared in an analo-
gous manner to 1a: TripP=C(Ph)-
CMe2Ox (1b; Trip=2,4,6-triisopropyl-
pure
phosphaalkene–oxazolines
ACHTUNGTRENNUNG
(PhAk-Ox) is presented. The conden-
sation of a lithium silylphosphide and
a ketone (the phospha-Peterson reac-
tion) was used as the P=C bond-form-
ing step. Attempted condensation of
PhC(=O)Ox (Ox= CNOCH(iPr)CH2)
G
G
ACHTUNGTRENNUNG
phenyl),
and MesP
heterocycle
CH(iPr)CH2O (3). However, PhAk-Ox
(S,E)-MesP=C(Ph)CMe2Ox (1a) was
successfully prepared by treating
G
tions to afford [{MesPC(Ph)ACHTUNGTRENNUNG(CMe2-
Keywords: asymmetric synthesis ·
inorganic polymers · main group
elements · phosphaalkenes · phos-
phorus · polymers
Ox)}xACHTNUGTRENG{UN CH2CHPh}y]n (9a: x=0.13n, y=
A
0.87n; GPC: Mw =7400 gmolꢀ1, PDI=
1.15).
Introduction
tain Lewis basic functional groups (Scheme 1). The key mo-
tivations were the potential applications of these compounds
as 1) ligands in enantioselective metal catalysis, and 2) mon-
omers for highly functionalized macromolecules. Previous
studies have demonstrated that phosphaalkenes can be em-
ployed as precursors to poly(methylenephosphine)s through
addition polymerization.[2,3] Therefore, the prospect of incor-
porating chiral moieties into phosphorus polymers is feasible
and may permit the construction of materials with attractive
properties.
Phosphaalkenes are a fascinating class of molecules contain-
ing a low-coordinate phosphorus atom and a (3p–2p)p
bond. Over the past decade, phosphaalkenes have evolved
from simply being intellectual curiosities to compounds with
potential applications ranging from polymer and materials
science to catalysis.[1,2] One of the continuing challenges in
the design of novel phosphaalkenes is the incorporation of
increased structural complexity and chemical functionality
in the face of a necessity to balance kinetic and thermody-
namic stabilization. To permit isolation, phosphaalkenes re-
quire structural features that slow kinetic reactivity and/or
increase p-bond stability through electronic delocalization.
Phosphaalkenes can also be stabilized to permit isolation by
protecting the P=C bond with sterically encumbering
groups, such as 2,4,6-tri-tert-butylphenyl (Mes*). Incorporat-
ing such structural features can facilitate the isolation and
characterization of what could otherwise be an intractable
functional group.
Scheme 1.
We were intrigued by the challenge of developing a previ-
ously unexplored class of chiral P=C compounds that con-
There is considerable interest in incorporating the P=C
bond motif into structurally complex molecules and poly-
mers with potential relevance in materials science.[4] In addi-
tion, phosphaalkenes containing metal-chelating functional
groups have been shown to be quite effective ligands for ap-
plication in catalysis (Scheme 2).[1b,c,e,2,5] Ligand classes that
have garnered the most attention include those based on the
diphosphinidenecyclobutene A (DPCB),[6] 1,3-diphospha-
[a] J. Dugal-Tessier, S. C. Serin, E. B. Castillo-Contreras,
Dr. E. D. Conrad, Prof. Dr. G. R. Dake, Prof. Dr. D. P. Gates
Department of Chemistry, University of British Columbia
2036 Main Mall, Vancouver, British Columbia, V6T 1Z1 (Canada)
Fax: (+1)604-822-2847
E-mail: gdake@chem.ubc.ca
dgates@chem.ubc.ca
Chem. Eur. J. 2012, 18, 6349 – 6359
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
6349

Results and Discussion
The underlying motivation behind these studies was the de-
velopment of a new class of chiral phosphaalkene for appli-
cation in asymmetric catalysis as monomers or polymers.
Given that catalyst optimization often requires subtle tailor-
ing of the ligands steric and electronic properties, our syn-
thetic methodology incorporates features such as conver-
gence and modularity. To achieve convergence, the final
step involves a phospha-Peterson reaction to form the P=C
bond from a ketone and a silylphosphine. This route was
chosen because of its high conversion and tolerance of P
substituents ranging from moderately sized (for example,
Mes) to very bulky groups.[10,18,19] Moreover, this strategy
also incorporates modularity since a small number of ke-
tones and silylphosphines permits the construction of a large
library of phosphaalkenes.
Scheme 2. Important classes of phosphaalkene ligands: a) A–E are che-
late ligands that have been employed in catalytic transformations; b) F
and G are known enantiomerically pure phosphaalkenes.
Another key feature of our ligand design involved the
choice of oxazoline as the chirality inducing group. This
choice was influenced by the successful phosphinooxazoline
(PHOX)[20] and bisoxazoline (box)[21] ligand systems. More-
over, the oxazoline-containing ketone precursors can readily
be constructed by using chiral pool amino acids as starting
materials. It must also be taken into consideration that the
ketone fragment requires a connection to the oxazoline
moiety. This so-called linker is of critical importance. It
must ensure that the ligating atoms of the oxazoline and the
phosphaalkene are appropriately placed to permit chelation
to a metal ion. At the same time, the linker must be adja-
cent to the P=C bond and therefore must assist in its kinetic
and thermodynamic stabilization. The next section will
clearly demonstrate the importance of the linker as it per-
tains to this latter point.
(1,3)-butadiene B,[7] phosphinidene-imine C,[8] and 2,6-bis-
(phosphaethenyl)pyridine D.[9] These ligands incorporate the
bulky Mes* substituent, and the effects of this large group
on mechanistic processes relevant to catalysis (ligand ex-
change, substrate binding, turnover, etc.) are not well under-
stood. We have previously shown that 2-pyridylphosphaal-
kene E can be prepared bearing the smaller 2,4,6-trimethyl-
phenyl (Mes) substituent.[10] The PdII complex of this phos-
phaalkene was an effective catalyst for the Overman–Clais-
en rearrangement.[11]
Despite their successful use in catalysis, it is surprising
that there is almost a complete absence of enantiomerically
pure phosphaalkenes for application in asymmetric catalysis.
We recently reported the isolation and characterization of
an enantiomerically pure free
Evaluating the linker—novel heterocycles rather than phos-
phaalkenes: Benzoyl oxazoline 2 was an attractive ketone
for phosphaalkene synthesis for the following reasons: a syn-
thetic route to 2 was available in the literature,[22] and the
resultant phosphaalkene would be expected to form a desir-
able five-membered chelate upon complexation. In the case
of 2, the linker is simply a covalent bond between the
ketone and oxazoline.
phosphaalkene (1a).[12] Al-
though chiral racemic phos-
phaalkenes were known in the
literature,[13] to our knowledge,
the
menthol–phosphaalkene
tungsten(0) complex F was the
only example of an enantiomer-
ically pure phosphaalkene de-
Ketone 2 was treated with MesPACTHUNGTERNNU(G SiMe3)Li (1 equiv) and
rivative prior to our investigations.[14] Since our initial
report, we have demonstrated that phosphaalkene–oxazo-
line (PhAk-Ox) ligands give high enantioselectivities in pal-
ladium(0)-catalyzed allylic alkylation reactions.[15] Concur-
rent to our work, Ozawa and co-workers reported a novel
planar chiral phosphaalkene G for use in asymmetric cataly-
subsequent analysis of the reaction mixture by 31P{1H} NMR
spectroscopy did not reveal any resonances attributable to
a phosphaalkene [that is, d
ACHTUNGTRENNUNG
major resonances (ca. 70% of the total) were consistent
with the formation of two phosphine-containing compounds,
each containing a P P single bond [d=32 (d, 1J
G
ꢀ
sis.[16] Given the success of heterocyclic P
N
202 Hz), 4 ppm (d, J
(P,P)=202 Hz), and d=32 (d, J
1
1
as phosphinines and phosphaferrocenes, in asymmetric catal-
ysis,[17] the prospects for chiral acyclic phosphaalkene ligands
are particularly exciting. Herein, we present the synthesis of
several enantiomerically pure phosphaalkene–oxazolines, in-
cluding the first copolymerization data for one of them.
196 Hz), 0 ppm (d, 1J
ACTHNGUTERNNU(G P,P)=196 Hz)]. Fortunately, crystals
of the major products suitable for crystallographic analysis
could be obtained from a saturated solution of the crude
product in hexanes. Surprisingly, the solid-state molecular
structure revealed that the product (3 and 3’) was composed
of an unusual fused bicyclic system containing a C2P2N het-
erocycle (Figure 1). We speculate that the desired phos-
6350
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2012, 18, 6349 – 6359

Enantiomerically Pure Phosphaalkene–Oxazolines (PhAk-Ox)
FULL PAPER
addition, the presence of addi-
tional methyl groups should
function to provide steric pro-
tection to the P=C bond. The
known oxazoline 4 was conven-
iently accessed in one step from
l-valinol.[26,27] Subsequent treat-
ment of
4 with sBuLi and
N,N,N’,N’-tetramethylethylene-
diamine (TMEDA) for one
hour at ꢀ788C formed the de-
sired carbanion.[28] Claisen-type
condensation of this anion with
ethyl benzoate afforded ketone
5 in 49% isolated yield. Importantly, these synthetic steps
were scalable to an approximately 20 g scale and purifica-
tion did not require flash column chromatography.
Having secured a supply of ketone 5, its phosphaolefina-
Figure 1. The molecular structure of 3 (one of two unique molecules,
50% probability ellipsoids). All hydrogen atoms (except H19) are omit-
tion was attempted. A solution of MesPACTHNGUETRNNU(G SiMe3)Li in THF
ꢀ
ted for clarity. Selected bond lengths [ꢁ] and angles [8]: C1 P1 1.834(4),
(ꢀ788C) was treated with a solution of 5 in THF and, subse-
quently, the reaction mixture was warmed slowly to room
temperature (1 h). An aliquot was removed from the reac-
ꢀ
ꢀ
ꢀ
ꢀ
C10 C11 1.447(5), C10 C17 1.343(5), C10 P1 1.810(4), C17 O1
ꢀ
ꢀ
ꢀ
ꢀ
1.341(4), C17 N1 1.354(5), C23 P2 1.824(4), N1 P2 1.727(3), P1 P2
2.213(1); C17-C10-P1 113.0(3), C11-C10-P1 120.6(3), O1-C17-C10
126.3(4), O1-C17-N1 110.1(3), C10-C17-N1 123.6(4), C10-P1-C1 108.0(2),
C10-P1-P2 93.2(1), N1-P2-C23 104.5(2), N1-P2-P1 92.0(1), C23-P2-P1
105.0(1).
phaalkene may be formed transiently and subsequently
a second MesP fragment is added. Clearly, a redox process
must take place to afford the cyclic products (3/3’), but the
details of this type of process are unknown. Phosphorus-con-
taining heterocycles similar to 3 are known, but are rare.[23]
tion mixture for analysis by 31P{1H} NMR spectroscopy. Im-
portantly, the signal assigned to MesP
ꢀ187 ppm] was entirely consumed and was replaced by
a new singlet resonance at d
(31P)=244 ppm, which is consis-
tent with that expected for phosphaalkene 1a [compare with
MesP=CPh2:
(31P)=233 ppm]. The presence of only
ACHUTGTNNERNUG(SiMe3)Li [dACHTUNGTRENNUNG
(31P)=
A bulky linker—isolation of an enantiomerically pure phos-
phaalkene: We hypothesized that the addition of a methyl-
ene linker between the ketone and the oxazoline would
permit phosphaalkene formation. Cognizant of the potential
AHCTUNGTRENNUNG
dACHTUNGTRENNUNG
ꢀ
ꢀ
tautomerization of RP=C CH2(Ox) to form RPH C=
CH(Ox),[24] the known ketone PhC(O)CH2(Ox) would not
be a suitable precursor.[25] Moreover, the presence of a CH2
moiety may not provide enough steric protection to the P=C
bond in MesP=C(Ph)CH2(Ox). Therefore, the gem-dimethyl
ketone 5, which has no enolizable protons, was prepared. In
a single signal suggests that a single diastereomer of 1a was
obtained (that is, E or Z). The crude product was recrystal-
lized from n-pentane to afford colorless crystals of 1a
(52%), which were characterized crystallographically. The
optical activity of the product was confirmed by polarimetry
and the Flack parameter [0.13(9)], determined crystallo-
Chem. Eur. J. 2012, 18, 6349 – 6359
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6351

D. P. Gates, G. R. Dake et al.
graphically, suggested that the S configuration of 1a was as-
signed correctly. Moreover, all of the compounds leading to
phosphaalkene 1a were similarly optically active. Together,
these observations suggest that, as expected, the enantio-
meric purity of l-valine was not lost during the synthetic se-
quence.
The molecular structure showing the E configuration of
the P=C bond and metrical parameters for 1a are given in
Figure 2. The P=C bond length in 1a [1.679(2) ꢁ] is in the
when solutions in CH2Cl2 or THF were saturated with water
or oxygen (about 1 h). These properties suggest that phos-
phaalkene 1a can be manipulated without the need for spe-
cial precautions, an advantageous property for its use in cat-
alysis. However, it should be noted that phosphaalkene 1a,
dissolved in either THF or CH2Cl2, rapidly degrades upon
treatment with aqueous acid (HCl) or in the presence of ox-
idizing agents, such as meta-chloroperoxybenzoic acid
(MCPBA) or H2O2. Nevertheless, the surprising air and
moisture stability of 1a is highly unexpected.
Modularity and tunability of the PhAk-Ox design: With the
isolation of enantiomerically pure phosphaalkene 1a, the
modularity of the synthetic route and the tunability of the
ligand architecture could be investigated. Three distinct
parts of the PhAk-Ox motif were modified: the P-aryl sub-
stituent, the C-aryl substituent, and the structure of the
linker. This facilitates the building of a small library of
PhAk-Ox compounds for future polymerization or catalyst
optimization studies.
Variation of the steric bulk of the P substituent: Due to its
close proximity to the metal-binding site, the steric proper-
ties of the P substituent are likely to significantly influence
catalytic performance. The incorporation of a 2,4,6-triisopro-
pylphenyl substituent within PhAk-Ox 1b was quite
straightforward. Treatment of a solution of in situ generated
Figure 2. The molecular structure of 1a (50% probability ellipsoids). All
hydrogen atoms are omitted for clarity. Selected bond lengths [ꢁ] and
ꢀ
ꢀ
ꢀ
ꢀ
angles [8]: C1 P1 1.826(2), C10 P1 1.679(2), C10 C11 1.485(3), C10 C17
ꢀ
ꢀ
ꢀ
1.529(3), C17 C20 1.511(3), C20 O1 1.356(3), C20 N1 1.248(3); C10-P1-
C1 105.3(1), C11-C10-P1 124.1(2), C17-C10-P1 119.2(2), C20-C17-C10
108.9(2), N1-C20-O1 118.6(2), N1-C20-C17 127.6(2), C25-C23-C24
110.5(2).
2,4,6-(iPr)3C6H2P
(SiMe3)Li (d=ꢀ205 ppm) in THF with
ketone
5 afforded 1b (d=248 ppm) quantitatively by
31P{1H} NMR spectroscopy.
normal range found in C-substituted phosphaalkenes (1.61–
1.71 ꢁ).[29] The P Mes bond in 1a [P(1) C(1)=1.826(2) ꢁ]
is also similar to those found in other mesityl-substituted
phosphaalkenes (ca. 1.83 ꢁ).[10] Interestingly, the Mes-P=C
bond angle in 1a [C(1)-P(1)-C(10)=105.3(1)8] is more acute
than that found in related P-mesityl phosphaalkenes (ca.
1088).[10] Presumably, this smaller angle is a consequence of
increased steric repulsion between the methyl groups of the
ꢀ
ꢀ
ꢀ
trans-configured CMe2 linker and the P Mes substituent in
1a. Of particular interest is the fact that the angle between
ꢀ
the best plane of the C Ph substituent and the plane of the
P=C bond in 1a (80.48) is greater than in other Mes-substi-
tuted phosphaalkenes (ca. 498).[10] Similarly, the dihedral
angle between the best plane of the Mes substituent and the
ꢀ
P=C bond (78.68) is also greater than in other related P
Mes phosphaalkenes (ca. 718).[10] In contrast to related phos-
phaalkenes, these large dihedral angles suggest that there is
little to no p-conjugation between the P=C p-bond and the
aromatic substituents in 1a.
Isolable phosphaalkenes traditionally contain substituents
in both the 2- and 6-positions of the P-aryl group to impart
steric protection above and below the P=C bond plane. Sub-
stitution at only one ortho-aryl position would differentiate
the face above from the face below the P=C bond plane
and, consequently, might lead to useful applications in asym-
metric catalysis. Isolable phosphaalkenes with mono-ortho-
substituted P-aryl groups are rare, with examples being lim-
It is quite remarkable that phosphaalkene 1a, bearing the
moderately sized Mes substituent, is stable to air and mois-
ture. Crystals of 1a were stored open to the atmosphere in
a well-lit laboratory for two months with no sign of decom-
position, as evaluated by 31P{1H} NMR spectroscopy. More-
over, the 31P{1H} NMR spectrum of 1a showed no change
when a solution in toluene was heated at reflux (12 h) or
6352
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2012, 18, 6349 – 6359

Enantiomerically Pure Phosphaalkene–Oxazolines (PhAk-Ox)
FULL PAPER
ited to 2-RC6H4P=CR’ACTHNURGTENNUG(OSiMe3) (R=Me3SiOAHCUTNGTREN(NGUN C=O) or
SiMe3 and R’=tBu, CMe2Et, 1-Ad)[30] and the RuII complex
of 3,3-diphenyl-3H-phosphindole, in which the P=C bond is
contained within a ring.[31] A previous attempt at generating
(2-MeC6H4)P=CPh2 led to uncharacterized material pre-
sumed to be a polymer.[32]
Although the stability of a mono-ortho-aryl phosphaal-
kene was uncertain, we moved ahead and attempted to pre-
[33]
pare new PhAk-Ox compounds from 2-iPrC6H4P
and 2-tBuC6H4P
ketone 5 with in situ generated 2-iPrC6H4P
ACHTUNGTRNE(NUNG SiMe3)2
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
ed phosphaalkene 1c (85%) in analytical purity after distil-
lation. The same procedure was repeated with in situ gener-
ated 2-tBuC6H4PACHTUNGTRENNUNG(SiMe3)Li, yielding 1d (83%). The spectro-
scopic data obtained for these novel phosphaalkenes include
1
31P{1H}, H and 13C{1H} NMR spectroscopy, mass spectrome-
try and optical rotations. These data fully support their for-
mulation as 1c and 1d. Remarkably, both mono-ortho-aryl
phosphaalkenes are stable at room temperature. These ex-
amples clearly demonstrate the power and generali-
ty of the phospha-Peterson route as a means to gen-
Table 1. Selected 31P{1H} and 13C{1H} NMR spectroscopic data for phosphaalkenes
1a–1g in CDCl3 solvent.
erate highly functionalized phosphaalkenes.
Variation of the C substituent and the linker: In ad-
dition to tuning the P substituent, the modification
of the C substituent and the linker group are of
considerable interest as a means to tune the donor–
acceptor properties of the PhAk-Ox ligand archi-
tecture. Consequently, simple modifications to the
electronic properties of the C substituent and the
linker group were undertaken. Of particular inter-
est was the potential to include electron-donating
and electron-withdrawing C substituents. Following
analogous procedures to those developed for the
formation of 5, three new ketones were synthesized
(6, 72%; 7, 70%; 8, 90%). Importantly, treatment
R1
R2
Ar
31P{1H} NMR
d [ppm]
13C{1H} NMR
dP [ppm]
=
C
(1J
ACHTUNGTRENNUNG(P,C) [Hz])
1a
1b
1c
1d
1e
1 f
1g
Me
Me
Me
Me
Me
Ph
Ph
Ph
Ph
Mes
244
248
245
254
245
243
254
203.3 (48)
201.3 (56)
204.9 (49)
196.7 (50)
203.2 (48)
200.8 (47)
196.9 (50)
2,4,6-(iPr)3C6H2
2-iPrC6H4
2-tBuC6H4
Mes
Mes
Mes
4-MeOC6H4
Ph
3,5-(CF3)2C6H3
G
A
of the appropriate ketone with MesP
ACHTUNGRTENUN(NG SiMe3)Li af-
forded phosphaalkenes 1e, 1 f, and 1g quantitative-
ly, according to 31P{1H} NMR spectroscopy. The new phos-
phaalkenes were isolated as liquids and purified by bulb-to-
bulb distillation in vacuo to afford analytically pure PhAk-
Ox compounds (1e, 50%; 1 f, 50%, 1g, 67%). In all cases,
only a single isomer was observed, as determined by
31P NMR spectroscopy.
[d
(13C)=203.3 ppm, J
R
1
that for MesP=CPh2 [d
G
ACHTUNGTRENNUNG
1
A
(13C)=203.3 ppm, J
ACHUTGTNRENNUG ACHUTTGNREN(NUGN P,C)=44 Hz].
AHCTUNGTRENNUNG
NMR spectroscopic parameters for PhAk-Ox compounds:
The synthesis of a small family of PhAk-Ox compounds fa-
cilitates a qualitative analysis of the effects of substitution
on the P=C bond. Selected NMR spectroscopic data for new
chiral phosphaalkenes 1a–1g are presented in Table 1. The
31P{1H} NMR signal for phosphaalkene 1a (d=244 ppm) is
downfield relative to those of related C-substituted phos-
phaalkenes. Since the best compound for comparison,
There are also minimal changes in the 13C{1H} NMR chemi-
cal shifts of the P=C carbon atoms. Consistent with the
structural data discussed earlier, this spectroscopic data sug-
gests that there is poor p-conjugation between the C-aryl
substituent and the P=C bond. This contrasts with previous
observations on the influence of p-donating substituents by
incorporating 4-MeOC6H4 as the C substituent on the P=C
bond.[10,35] The presence of an inductively withdrawing C
substituent results in a downfield shift in the 31P{1H} NMR
MesP=C
stituted MesP=CPh2 and C-tBu-substituted MesP=CH
(d
(31P)=233 and 224 ppm, respectively).[18,32,34] Similarly, the
13C{1H} NMR resonance of the P=C carbon atom in 1a
ACHTUNGTRENNUNG
G
resonances [that is, 1g vs. 1a, DdACTHNGUTERNNUG
(31P)=10 ppm].
ACHTUNGTRENNUNG
Chem. Eur. J. 2012, 18, 6349 – 6359
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6353

D. P. Gates, G. R. Dake et al.
Copolymerization of PhAk-Ox (1a) with styrene: PhAk-Ox
1a is an intriguing monomer for polymerization studies be-
cause of the fact that the resultant chiral polymer is expect-
ed to possess attractive properties. This type of chiral poly-
mer is of considerable interest as ligands for polymer-sup-
ported asymmetric catalysis and for their potential proper-
ties, such as helicity. In our attempts to purify 1a by vacuum
distillation (ca. 2008C), we occasionally noted the formation
of a viscous residue that was soluble in THF and from which
a small amount of polymer could be isolated after precipita-
tion with hexanes. Analysis of the polymer was consistent
phine moieties of the polymer. Similar patterns of signals
have been observed in random copolymers of MesP=CPh2
with styrene and have been attributed to the complex micro-
structure and regioirregularities within the copolymer.[3d]
Particularly informative is the 13C{1H} NMR spectrum of 9a,
which is shown in Figure 4b. For comparison, the spectra of
monomer 1a and polystyrene (Figure 4a and c, respectively)
are also given. Broad signals are detected that are consistent
with the functional groups expected for a copolymer with
the proposed formulation. Importantly, the doublet reso-
nance assigned to the P=C bond of 1a (d=203.3 ppm) is
absent in the copolymer. In addition, the characteristic sig-
nals assigned to the carbon atoms of the oxazoline ring are
present in the polymer and, as expected, are considerably
broader than those observed for 1a.
with
the
formation
of
poly(methylenephosphine)
(31P{1H} NMR: d=ꢀ13 ppm; GPC: Mw =21000 gmolꢀ1).
Despite our efforts, we have thus far been unable to repro-
ducibly obtain a homopolymer from 1a either thermally or
with radical initiators.
Analysis of a solution of copolymer 9a in THF by using
a gel permeation chromatograph (GPC) equipped with
a laser-light scattering (LLS) detector revealed a modest
weight-average molecular weight (Mw) of 7400 gmolꢀ1 with
a polydispersity index (PDI) of 1.15. The monomodal distri-
bution is consistent with the formulation as copolymer 9a
rather than a blend of polystyrene and poly-1a. Elemental
microanalysis of the polymer facilitated the estimation of
the composition of the polymer. In particular, the phospho-
rus analysis (2.83 wt%) suggests that approximately
13 mol% phosphaalkene is incorporated into the copolymer
(i.e. x=0.13n, y=0.87n). Although the tacticity and exact
microstructure of the copolymer is not known at this time,
an optical rotation was recorded on a 1.41 g per 100 mL so-
lution of 9a at 228C to give a specific rotation [a]2D2 of
ꢀ14.08. Therefore, it can be concluded that the polymer is
chiral. The details of the complex microstructure of 9a will
be the subject of future investigations.
As a consequence of the difficulties in homopolymerizing
1a, our attention shifted towards copolymerization of
PhAk-Ox with styrene in the presence of radical initiators.
When a mixture of monomers 1a and styrene (ca. 1:2 ratio)
was heated (1608C) in the presence of a diazo initiator
(VAZO 88; 1 mol%) the mixture exhibited an increase in
viscocity suggestive of polymerization. Dissolution of the
sample in THF and successive precipitation from hexanes af-
forded a yellow solid free of monomer 1a. Analysis of the
yellow solid by multinuclear NMR spectroscopy and ele-
mental microanalysis provided data that was consistent with
its formulation as poly(methylenephosphine-co-styrene) 9a.
The 31P{1H} NMR spectrum is shown in Figure 3 and dis-
plays a broad resonance at ꢀ7 ppm that is consistent with
polymerization through the P=C bond to afford a phos-
phine-containing polymer. The additional minor broad sig-
nals (about ꢀ25 and 5 ppm) are also consistent with phos-
Conclusion
We have developed and demonstrated a synthetic sequence
that enables a convergent and modular construction of
chiral, enantiomerically enriched, isolable phosphaalkenes
that feature oxazoline functional groups. Structural features
within these PhAk-Ox compounds can be readily modified.
In particular, this methodology permits the tuning of the
carbon backbone and the aryl substituents on either the
phosphorus or carbon atom of the phosphaalkene. We have
demonstrated that chiral phosphaalkenes can act as mono-
mers for radical-initiated copolymerization with styrene,
generating phosphine-functionalized copolymers. Function-
alized chiral copolymers such as these provide ample oppor-
tunities for the chemical exploration of coordination chemis-
try, asymmetric catalysis, and flow chemistry. In addition,
further exploration of these and structurally related phos-
phaalkenes as PACTHNUTRGNEUNG
(s2,l3) ligands in asymmetric catalysis is an
object of continuing investigation. Our results on these
topics will be presented in due course.
Figure 3. 31P{1H} NMR spectrum (162 MHz, 298 K) in CDCl3 of poly-
(methylenephosphine-co-styrene) copolymer 9a.
6354
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2012, 18, 6349 – 6359

Enantiomerically Pure Phosphaalkene–Oxazolines (PhAk-Ox)
FULL PAPER
were measured at a concentration in g
per 100 mL and their values (average
of 10 measurements) were obtained
on a Jasco P-1010 polarimeter.
A
(1a):
ACHTUNGTRENNUNG
(11.3 g, 38 mmol) in THF (25 mL).
The reaction mixture was heated at
558C for 1–2 h. 31P{1H} NMR analysis
of an aliquot removed from the reac-
tion mixture suggested quantitative
formation of MesPACHTNUGTRENUNG(SiMe3)Li (d=
ꢀ187 ppm). The reaction mixture was
cooled to ꢀ788C and treated with a so-
lution of oxazoline 5 (9.9 g, 38 mmol)
in THF (15 mL). After warming to
room temperature, analysis of an ali-
quot removed from the reaction mix-
ture by 31P{1H} NMR spectroscopy re-
vealed a singlet resonance, which is
consistent with phosphaalkene 1a (d=
244 ppm). The reaction mixture was
quenched
with
Me3SiCl
(4.1 g,
38 mmol), the solvent evaporated in
vacuo, and the product extracted into
hexanes (1ꢂ20 mL, 2ꢂ10 mL). After
filtration, the solvent was removed in
vacuo. The product was recrystallized
from n-pentane to give phosphaalkene
1b as
a colorless crystalline solid,
which was washed with cold n-pentane
(2ꢂ5 mL) and dried in vacuo (7.9 g,
52%). [a]2D2 =ꢀ65.8 (c=0.50 in
CDCl3);
CDCl3):
31P{1H} NMR
d=244 ppm;
(121 MHz,
1H NMR
Figure 4. 13C{1H} NMR spectra (75.5 MHz, 298 K) in CDCl3 of a) monomer 1a, b) poly(methylenephosphine-
co-styrene) 9a, and c) polystyrene. Assignments for monomer 1a were made with the aid of 1H–13C HMQC,
(400 MHz, CDCl3): d=7.00–6.50 (m,
7H), 4.23–4.18 (m, 1H), 3.99–3.95 (m,
1H), 3.88–3.82 (m, 1H), 2.26 (s, 3H),
2.21 (s, 3H), 2.09 (s, 3H), 1.75–1.66
1
1H–13C HMBC and H–1H COSY experiments (* indicates CDCl3).
(m, 1H), 1.67 (d, J
(P,H)=1 Hz, 3H), 0.90 (d, 3J
(H,H)=7 Hz, 3H), 0.81 ppm (d,
(H,H)=7 Hz, 3H); 13C{1H} NMR (100 MHz, CDCl3): d=203.3 (d,
(P,C)=48 Hz), 170.6 (d, 3J
(P,C)=6 Hz), 142.8 (d, J(P,C)=15 Hz), 140.0
(P,C)=7 Hz), 139.8 (d, J (P,C)=
(P,C)=6 Hz), 137.9, 135.9 (d, 1J
41 Hz), 128.0 (d, J(P,C)=4 Hz), 126.9, 126.7, 126.6, 126.3, 72.1, 70.0, 47.5
(d, 2J
(P,C)=25 Hz), 32.6, 28.2 (d, J(P,C)=9 Hz), 28.0 (d, J(P,C)=7 Hz),
22.6 (d, (P,C)=7 Hz), 22.5 (d, (P,C)=7 Hz), 21.1, 19.2, 18.0 ppm;
ACHTUNGTREN(NGNU P,H)=1 Hz, 3H),
Experimental Section
1.64 (d, J
ACHTUNGTRENNUNG
G
ACHTUNGTRENNUNG
3J
1J
General procedures: All manipulations of air- and/or water-sensitive
compounds were performed under a nitrogen atmosphere by using stan-
dard Schlenk or glovebox techniques. Hexanes and dichloromethane
(CH2Cl2) were deoxygenated with nitrogen and dried by passing through
T
N
ACHTUNGTRENNUNG
(d, J
A
R
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
U
E
ACHTUNGTRENNUNG
a
column containing activated alumina. Tetrahydrofuran (THF) was
J
N
JACHTUNGTRENNUNG
LRMS (EI): m/z (%): 394, 393 (4, 15) [M+], 380, 379, 378 (12, 74, 100)
dried over sodium and benzophenone. Ethyl benzoate, methyl 4-meth-
oxybenzoate, isobutyric acid, l-valine, cyclopentane carboxylic acid,
chlorotrimethylsilane, and xylenes were purchased from Aldrich and
used as received. sec-Butyllithium and methyllithium were purchased
from Aldrich and titrated by using N-benzylbenzamide.[36] N,N,N’,N’-
Tetramethylethylenediamine (TMEDA) was purchased from Aldrich and
distilled over sodium prior to use. 1,1’-Azobis(cyclohexanecarbonitrile)
(VAZO 88) was purchased from Aldrich and recrystallized from metha-
nol prior to use. Styrene was purchased from Aldrich and distilled from
[M+ꢀCH3], 275, 274 (5, 24) [M+ Mes]; elemental analysis calcd (%) for
ꢀ
C25H32NOP: C 76.31, H 8.20, N 3.56; found: C 76.56, H 8.17, N 3.56.
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
2.6 mmol) in THF (5 mL). The reaction mixture was heated at 558C for
1–2 h. 31P{1H} NMR analysis of an aliquot removed from the reaction
mixture suggested quantitative formation of 2,4,6-(iPr)3C6H2P(Li)ACHTUNGTRENNUNG(SiMe3)
(d=ꢀ205 ppm). The reaction mixture was cooled to ꢀ788C and treated
with a solution of oxazoline 5 (0.68 g, 2.6 mmol) in THF (5 mL). After
warming to room temperature, analysis of an aliquot removed from the
reaction mixture by 31P{1H} NMR spectroscopy revealed a singlet reso-
nance, which is consistent with phosphaalkene 1b (d=248 ppm). The re-
action mixture was quenched with Me3SiCl (0.29 g, 2.6 mmol), the solvent
evaporated in vacuo, and the product extracted into hexanes (1ꢂ10 mL,
2ꢂ5 mL). After filtration, the solvent was removed in vacuo to give
phosphaalkene 1b as a yellow oil (1.2 g, 93%). [a]1D8 =ꢀ32.9 (c=2.4 in
CH2Cl2); 31P{1H} NMR (121 MHz, CDCl3): d=248 ppm; 1H NMR
(400 MHz, CDCl3): d=7.00–6.62 (m, 7H), 4.25–4.16 (m, 1H), 4.01–3.94
ACTHNUTRGNEUNG
CaH2 prior to use. l-Valinol,[27] oxazoline 4,[26] MesP(SiMe3)2,[19] 2,4,6-
(iPr)3C6H2P
N
(SiMe3)2,[37]
2-iPrC6H4P
G
and
2-tBuC6H4P-
[33]
1
(SiMe3)2 were prepared according to literature procedures. H, 31P{1H},
and 13C{1H} NMR spectra were recorded at 258C on Bruker Avance 300
or 400 MHz spectrometers. H3PO4 (85%) was used as an external stan-
dard (d=0.0 ppm for 31P). 1H NMR spectra were referenced to residual
protonated solvent peaks and 13C{1H} NMR spectra were referenced to
the deuterated solvent. Infrared spectra were recorded on a Thermo
Nicolet 4700 FTIR spectrometer by using neat samples on NaCl plates.
Elemental analyses were performed in the University of British Colum-
bia Chemistry Microanalysis Facility. Mass spectra were recorded on
a Kratos MS 50 instrument in EI mode (70 eV). The optical rotations
(m, 1H), 3.92–3.83 (m, 1H), 3.40–3.25 (m, 2H), 2.68 (sept, 3J
7 Hz 1H), 1.76–1.58 (m, 1H), 1.67 (s, 3H), 1.65 (s, 3H), 1.28–1.06 (m,
ACHTUNGTRENNUNG(H,H)=
Chem. Eur. J. 2012, 18, 6349 – 6359
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6355

D. P. Gates, G. R. Dake et al.
18H), 0.90 (d, 3J
G
E
vacuo, and the product extracted into hexanes (1ꢂ20 mL, 2ꢂ10 mL).
After filtration, the solvent was removed in vacuo and the product was
bulb-to-bulb distilled (0.01 mmHg) to give phosphaalkene 1e as a yellow
oil (3.8 g, 50%). [a]D19 =ꢀ80.8 (c=1.1 in CH2Cl2); 31P{1H} NMR
(121 MHz, CDCl3): d=245 ppm; 1H NMR (400 MHz, CDCl3): d=6.73–
6.47 (m, 6H), 4.23–4.16 (m, 1H), 3.98–3.94 (m, 1H), 3.90–3.82 (m, 1H),
3.66 (s, 3H), 2.25 (s, 3H), 2.20 (s, 3H), 2.12 (s, 3H), 1.77–1.69 (m, 1H),
HRMS: m/z calcd for C31H44NOP: 477.3161; found: 477.3159; LRMS
(EI): 479, 478, 477 (1, 3, 10) [M+], 464, 463, 462 (6, 32, 100) [M+ꢀCH3],
275, 274 (7, 23) [M+ꢀ
ACHTUNGTRENNUNG(S,E)-2-iPrC6H4P=C(Ph)CMe2Ox (1c): MeLi in Et2O (1.5m, 2.25 mL,
3.3 mmol) was added to
3.3 mmol) in THF (10 mL). The reaction mixture was heated at 558C for
1–2 h. The solution was cooled to ꢀ788C and treated with a solution of
oxazoline 5 (0.86 g, 3.3 mmol) in THF (5 mL). After warming to room
temperature, analysis of an aliquot removed from the reaction mixture
by 31P{1H} NMR spectroscopy revealed a singlet resonance, which was as-
signed to be phosphaalkene 1c (d=245 ppm). The reaction mixture was
quenched with Me3SiCl (0.36 g, 3.3 mmol), the solvent evaporated in
vacuo and the product extracted into hexanes (3ꢂ10 mL). The solvent
was removed in vacuo and the phosphaalkene was purified by bulb-to-
bulb distillation (0.01 mmHg) to give phosphaalkene 1c as a yellow oil
(1.1 g, 85%). [a]2D7 =ꢀ88.2 (c=1.9 in CH2Cl2); 31P{1H} NMR (121 MHz,
CDCl3): d=245 ppm; 1H NMR (400 MHz, CDCl3): d=7.07–6.71 (m,
9H), 4.25–4.18 (m, 1H), 4.01–3.94 (m, 1H), 3.90–3.81 (m, 1H), 3.37–3.27
(m, 1H), 1.76–1.59 (m, 1H), 1.70 (s, 3H), 1.68 (s, 3H), 1.25–1.20 (m, 6H),
1.67 (s, 3H), 1.62 (s, 3H), 0.91 (d, 3J
A
3J
1J
ACHTUNGTRENNUNG
A
N
ACHTUNGTRENNUNG
139.8 (d,
J
N
ACHTUNGTRENNUNG
J
N
N
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
J
N
JACHTUNGTRENNUNG
HRMS: m/z calcd for C26H34NO2P: 423.2327; found: 423.2322; LRMS
(EI): m/z (%): 424, 423 (6, 8) [M+], 410, 409, 408 (6, 30, 100) [M+ꢀMe].
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
THF (10 mL). The reaction mixture was heated at 558C for 1–2 h.
31P{1H} NMR analysis of an aliquot removed from the reaction mixture
0.93 (d, 3J
13C{1H} NMR (100 MHz, CDCl3): d=204.9 (d, 1J
(P,C)=8 Hz), 151.4 (d, J(P,C)=9 Hz), 141.9 (d, J
(d, 1J
(P,C)=41 Hz), 133.5 (d, J(P,C)=5 Hz), 128.8, 128.5, 128.4, 127.0,
126.3, 125.0 (d, J (P,C)=25 Hz),
(P,C)=2 Hz), 124.5, 72.1, 70.0, 47.6 (d, 2J
32.8 (d, (P,C)=11 Hz), 32.6, 28.0, 27.8, 23.9, 23.8, 19.2, 18.1 ppm;
(H,H)=7 Hz, 3H), 0.84 ppm (d, 3J
(P,C)=49 Hz), 170.4 (d,
(P,C)=14 Hz), 139.0
revealed
AHCTUNGTRENNUNG
a
single resonance (d=ꢀ187 ppm) assigned to be MesP-
of oxazoline 7 (0.90 g, 3.2 mmol) in THF (5 mL). After warming to room
temperature, analysis of an aliquot removed from the reaction mixture
by 31P{1H} NMR spectroscopy revealed a singlet resonance that was as-
signed to be phosphaalkene 1 f (d=243 ppm). The reaction mixture was
quenched with Me3SiCl (0.34 g, 3.2 mmol), the solvent evaporated in
vacuo, and the product extracted into hexanes (3ꢂ10 mL). The solvent
was removed in vacuo and phosphaalkene 1 f was isolated as an impure
yellow oil [31P{1H} NMR (121 MHz, THF): d=243 ppm]. The solvent was
removed in vacuo and 1 f was purified by bulb-to-bulb distillation
(0.01 mmHg; 0.82 g, 50%). [a]1D8 =ꢀ41.0 (c=1.3 in CH2Cl2);
31P{1H} NMR (121 MHz, CDCl3): d=245 ppm; 1H NMR (400 MHz,
CDCl3): d=6.99–6.93 (m, 3H), 6.81–6.77 (m, 2H), 6.62–6.57 (m, 2H),
4.19–4.13 (m, 1H), 3.98–3.93 (m, 1H), 3.87–3.81 (m, 1H), 2.42–2.35 (m,
3H), 2.26 (s, 3H), 2.20 (s, 3H), 2.20–2.13 (m, 1H), 2.11 (s, 3H), 1.87–1.80
J
A
T
N
JACHTUNGTRENNUNG
HRMS: m/z calcd for C23H32NOP: 393.2222; found: 393.2220; LRMS
(EI): m/z (%): 394, 393 (5, 12) [M+], 380, 279, 378 (4, 27, 100) [M+ꢀMe];
elemental analysis calcd (%) for C25H32NOP: C 76.31, H 8.20, N 3.56;
found: C 76.62, H 8.34, N 3.66.
ACHTUNGTRENNUNG
3.2 mmol) in THF (10 mL). The reaction mixture was heated at 558C for
1–2 h. The solution was cooled to ꢀ788C and treated with a solution of
oxazoline 5 (0.86 g, 3.3 mmol) in THF (5 mL). After warming to room
temperature, analysis of an aliquot removed from the reaction mixture
by 31P{1H} NMR spectroscopy revealed a singlet resonance that was as-
signed to be a phosphaalkene (d=254 ppm). The reaction mixture was
quenched with Me3SiCl (0.35 g, 3.2 mmol), the solvent evaporated in
vacuo and the product extracted into hexanes (3ꢂ10 mL). The solvent
was removed in vacuo and the phosphaalkene was purified by bulb-to-
bulb distillation (0.01 mmHg) to afford phosphaalkene 1d as a yellow oil
(1.2 g, 83%). [a]2D7 =ꢀ64.5 (c=1.7 in CH2Cl2); 31P{1H} NMR (121 MHz,
CDCl3): d=254 ppm; 1H NMR (400 MHz, CDCl3): d=7.22–7.15 (m.
1H), 7.05–6.88 (m, 5H), 6.83–6.77 (m, 2H), 6.73–6.67 (m, 1H), 4.25–4.17
(m, 1H), 4.02–3.95 (m, 1H), 3.87–3.83 (m, 1H), 1.79–1.65 (m, 1H), 1.66
(m, 4H), 1.74–1.69 (m, 1H), 0.90 (d, 3J
ACHTUNGTRENNUNG
G
3J
1J
A
U
ACHTUNGTRENNUNG
(d,
J
N
J
N
JACHTUNGTRENNUNG
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
HRMS: m/z calcd for C27H34PNO: 419.2387; found: 419.2375; LRMS
(EI): m/z (%): 419, 418 (45, 5) [M+], 301, 300 (8, 33) [M+ꢀMes].
A
ACHTUNGTERNNU(NG 3,5-ACHUTNTRGEG(NNUN CF3)2C6H4)CACTUHNGTRENNUGN
AHCTUNGTRENNUNG
(d, J
3J(H,H)=7 Hz, 3H), 0.82 ppm (d, 3J
(100 MHz, CDCl3): d=196.7 (d, 1J(P,C)=50 Hz), 170.7 (d, 3J
8 Hz), 153.1 (d, (P,C)=9 Hz), 142.0 (d, (P,C)=14 Hz), 139.6 (d,
1J
(P,C)=52 Hz), 136.4, 128.6 (d, J(P,C)=8 Hz), 128.2, 126.9, 126.1, 125.2,
124.7, 72.1, 69.9, 47.3 (d, 2J
(P,C)=26 Hz), 37.0, 32.5 (d, J(P,C)=10 Hz),
28.1 (d, J(P,C)=6 Hz), 27.9 (d, J(P,C)=3 Hz), 19.2, 18.0 ppm; HRMS:
ACHTUNGTRENNUNG(P,H)=2 Hz, 3H), 1.63 (d, JCAHTUNGTRENNNUG
3.2 mmol) in THF (10 mL). The reaction mixture was heated at 558C for
T
1–2 h. 31P{1H} NMR analysis of an aliquot removed from the reaction
mixture revealed
a
single resonance (d=ꢀ187 ppm) assigned to be
MesP
AHCTUNGTRENNUNG
N
lution of oxazoline 8 (1.3 g, 3.1 mmol) in THF (5 mL). After warming to
room temperature, analysis of an aliquot removed from the reaction mix-
ture by 31P{1H} NMR spectroscopy revealed a singlet resonance that was
assigned to be phosphaalkene 1g (d=256 ppm). The reaction mixture
was quenched with Me3SiCl (0.34 g, 3.2 mmol), the solvent evaporated in
vacuo, and the product extracted into hexanes (3ꢂ10 mL). The solvent
was removed in vacuo and phosphaalkene 1g was isolated as an impure
yellow oil [31P{1H} NMR (121 MHz, THF): d=256 ppm]. The solvent was
removed in vacuo and the phosphaalkene was purified by bulb-to-bulb
distillation (0.01 mmHg; 1.2 g, 67%). [a]1D8 =ꢀ56.4 (c=1.6 in CH2Cl2);
31P{1H} NMR (121 MHz, CDCl3): d=254 ppm; 1H NMR (400 MHz,
CDCl3): d=7.45–7.40 (m, 1H), 7.24–7.19 (m, 2H), 6.63–6.56 (m, 1H),
6.55–6.51 (m, 1H), 4.23–4.18 (m, 1H), 3.97–3.92 (m, 1H), 3.88–3.78 (m,
1H), 2.48–2.33 (m, 3H), 2.22 (s, 3H), 2.13 (s, 3H), 2.12–2.09 (m, 1H),
N
m/z calcd for C26H34NOP: 407.2378; found: 407.2380; LRMS (EI): m/z
(%): 408, 407 (4, 7) [M+], 394, 393, 392 (5, 37, 100) [M+ꢀtBu], 275, 274
(7, 23) [M+ꢀtBu
ACHTUNGTRENNUNG(C6H4)]; elemental analysis calcd (%) for C26H34NOP: C
76.63, H 8.41, N 3.44; found: C 76.34, H 8.78, N 3.61.
A
ACHTUNGTRENNUNG
THF (25 mL). The reaction mixture was heated at 558C for 1–2 h.
31P{1H} NMR analysis of an aliquot removed from the reaction mixture
suggested quantitative formation of MesP
reaction mixture was cooled to ꢀ788C and treated with a solution of oxa-
zoline 6 (5.0 g, 18 mmol) in THF (15 mL). After warming to room tem-
perature, analysis of an aliquot removed from the reaction mixture by
31P{1H} NMR spectroscopy revealed a singlet resonance, which is consis-
tent with phosphaalkene 1e (d=245 ppm). The reaction mixture was
quenched with Me3SiCl (2.0 g, 18 mmol), the solvent evaporated in
2.08 (s, 3H), 1.89–1.80 (m, 4H), 1.67–1.58 (m, 1H), 0.89 (d, 3J
7 Hz, 3H), 0.79 ppm (d, 3J(H,H)=7 Hz, 3H); 13C{1H} NMR (100 MHz,
CDCl3): d=196.9 (d, 1J
(P,C)=50 Hz), 169.9 (d, J(P,C)=9 Hz), 144.9 (d,
(P,C)=14 Hz), 139.8 (d, J(P,C)=6 Hz), 139.5 (d, J(P,C)=5 Hz), 138.9,
ACHTUNGTRENNUNG(H,H)=
AHCTUNGTRENNUNG
A
ACHTUNGTRENNUNG
J
N
N
ACHTUNGTRENNUNG
6356
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2012, 18, 6349 – 6359

Enantiomerically Pure Phosphaalkene–Oxazolines (PhAk-Ox)
FULL PAPER
134.7 (d, J
126.8 (m), 123.4 (q, J
2J
(P,C)=21 Hz), 37.6 (d, J
37.3 (d, J(P,C)=20 Hz), 24.0, 23.9, 22.2 (d, J
(P,C)=8 Hz), 21.0, 19.0, 18.1 ppm; HRMS: m/z calcd for C29H32NOPF6:
G
E
32.5, 25.1, 25.0, 19.1, 18.2 ppm; IR (neat, NaCl): 2960, 2936, 2904, 2866,
1682, 1656, 1602, 1575, 1511 cmꢀ1; HRMS: m/z calcd for C17H24NO3:
290.1756; found: 290.1752.
(CH2)4Ox: A modified literature procedure was used.[26] Cyclo-
(S)-HCACHTUNGTRNEUNG
1
G
ACHTUNGTRENNUNG
R
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
pentane carboxylic acid was added (9.1 mL, 83 mmol) to a solution of l-
valinol (8.5 g, 83 mmol) in xylenes (0.5m) and the mixture was heated at
reflux by using a Dean–Stark apparatus for 44 h. The reaction mixture
was cooled and extracted with aqueous hydrochloric acid (10%) and the
aqueous layer was neutralized with aqueous sodium hydroxide (40%).
The aqueous layer was extracted with Et2O (3ꢂ60 mL) and the combined
organic extracts were dried by using Na2SO4. The solvent was removed
by rotary evaporation in vacuo, and the crude product was purified by
bulb-to-bulb distillation (958C, 0.4 mmHg) to give the product as a color-
less oil (8.3 g, 55%). Rf =0.39 (hexanes/EtOAc, 3:1); [a]2D2 =ꢀ62.5 (c=
0.607 in CHCl3); 1H NMR (CDCl3, 300 MHz): d=4.17–4.11 (m, 1H),
3.88–3.79 (m, 2H), 2.76–2.65 (m 1H), 1.88–1.83 (m, 2H), 1.77–1.70 (m,
555.2126; found: 555.2127; LRMS (EI): m/z (%): 557, 556, 555 (8, 29, 84)
[M+], 528, 527, 526 (5, 25, 72) [M+ꢀEt], 513, 512 (5, 15) [M+ꢀiPr], 488,
487, 486 (3, 7, 8) [M+ꢀCF3], 437, 436 (7, 29) [M+ꢀMes], 406, 405, 404
(18, 26, 100) [M+ꢀC9H12P].
(S)-(MesP)2C(Ph)=CNCH
ACHTUNGTRENNUNG
6.9 mmol) was added to a solution of MesPACHTUNGTRENNNUG
THF (20 mL). The reaction mixture was heated at 558C for 1–2 h.
31P{1H} NMR analysis of an aliquot removed from the reaction mixture
suggested quantitative formation of MesP
N
reaction mixture was cooled to ꢀ788C and treated with a solution of oxa-
zoline 2 (1.5 g, 6.9 mmol) in THF (20 mL). After warming to room tem-
perature, analysis of an aliquot removed from the reaction mixture by
31P{1H} NMR spectroscopy revealed multiple resonances (d=ꢀ40–
33 ppm). The solvent was evaporated in vacuo and the product extracted
into hexanes (1ꢂ20 mL, 2ꢂ10 mL). X-Ray crystallography quality crys-
tals were obtained from slow evaporation of the solvent. A mixture of 3
5H), 1.55–1.52 (m, 2H), 0.86 (d, 3J
3J(H,H)=7 Hz, 3H); 13C{1H} NMR (CDCl3, 75 MHz): d=170.7, 71.8,
ACHTUNGTNER(NUNG H,H)=7 Hz, 3H), 0.77 ppm (d,
AHCTUNGTRENNUNG
69.7, 38.4, 32.6, 30.7, 30.6, 25.9, 18.8, 17.8 ppm; IR (neat, NaCl): 2958,
2872, 1666 cmꢀ1; HRMS: m/z calcd for C11H20NO: 182.1545; found:
182.1540.
and 3’: 31P{1H} NMR (121 MHz, CDCl3): d=32 (d, 1J
(d, 1J(P,P)=196 Hz), 4 (d, 1J(P,P)=202 Hz), 0 ppm (d, 1J
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
(S)-PhC(=O)CACTHNUTRGNEUNG(CH2)4Ox (7): sBuLi (1.4m, 20.0 mL, 28.0 mmol) was
A
U
added to a solution of (S)-2-cyclopentyl-4-isopropyl-4,5-dihydrooxazole
(5.0 g, 28 mmol) and TMEDA (4.2 mL, 27.7 mmol) in THF (30 mL) at
ꢀ788C. The reaction mixture was stirred at ꢀ788C for 1 h, following
which cold ethyl benzoate (4.0 g, 27.5 mmol) in THF (15 mL) was added.
The reaction mixture was stirred for 1 h and then warmed to room tem-
perature, at which point it was quenched with a solution of saturated
aqueous NH4Cl (50 mL) and water (10 mL). The aqueous layer was ex-
tracted with Et2O (3ꢂ50 mL). The organic fractions were combined,
dried by using Na2SO4, and the solvent removed by rotary evaporation in
vacuo. The yellow oil was purified by flash column chromatography on
silica (hexanes/EtOAc, 95:5) to obtain ketone 7 as a colorless oil (5.5 g,
70%). Rf =0.48 (hexanes/EtOAc, 3:1); [a]2D2 =ꢀ19.9 (c=0.982 in CHCl3);
1H NMR (300 MHz, CDCl3): d=7.87–7.84 (m, 2H), 7.32–7.26 (m, 1H),
7.21–7.16 (m, 2H), 3.89–3.86 (m, 1H), 3.74–3.60 (m, 2H), 2.35–2.10 (m,
1H NMR (400 MHz, CDCl3): d=7.41–6.79 (m, 18H), 4.75–4.70 (m, 1H),
4.67–4.63 (m, 1H), 4.54–4.50 (m, 1H), 4.41–4.37 (m, 1H), 3.86–3.80 (m,
1H), 3.48–3.41 (m, 1H), 2.62 (s, 3H), 2.55–2.51 (m, 21H), 2.27 (s, 3H),
2.26 (s, 3H), 2.23 (s, 3H), 2.22 (s, 3H), 2.11–2.03 (m, 1H), 1.80–1.70 (m,
1H), 1.01 (d, 3J
G
ACHTUNGTRENNUNG ACHTUNGTRENNUNG
(H,H)=7 Hz, 3H), 0.95 (d, 3J
3
3J
(S)-PhC(=O)CMe2Ox (5): sBuLi (1.27m, 51 mL, 65 mmol) was added to
a cooled solution (ꢀ788C) of oxazoline 4 (10.0 g, 64 mmol) and TMEDA
(7.4 g, 64 mmol) in THF (1m). After 1 h at ꢀ788C, ethyl benzoate
(10.7 g, 71 mmol) was added to the reaction mixture. The solution was
warmed to room temperature and stirred for 30 min. Subsequently, water
(25 mL) and saturated aqueous ammonium chloride (25 mL) were added
to the yellow reaction mixture. The aqueous layer was extracted with di-
ethyl ether (3ꢂ150 mL). The organic fractions were combined, dried by
using sodium sulfate, and concentrated by rotary evaporation in vacuo.
The residue was purified by fractional distillation (155–1658C,
0.2 mmHg) by using a Kugelrohr to give ketone 5 as a colorless oil (8.2 g,
49%). [a]2D2 =ꢀ28.1 (c=0.13 in CHCl3); 1H NMR (400 MHz, CDCl3) d=
7.98–7.96 (m, 2H), 7.50–7.46 (m, 1H), 7.39–7.35 (m, 2H), 4.11–4.07 (m,
1H), 3.97–3.90 (m, 1H), 3.88–3.83 (m, 1H), 1.84–1.73 (m, 1H) 1.60 (s,
4H), 1.65–1.46 (m, 5H), 0.77 (d, 3J
3J(H,H)=7 Hz, 3H); 13C{1H} NMR (75 MHz, CDCl3): d=196.5, 169.3,
ACHTUNGTNER(NUNG H,H)=7 Hz, 3H), 0.68 ppm (d,
AHCTUNGTRENNUNG
135.2, 132.2, 128.7, 127.8, 71.5, 70.2, 58.2, 35.3, 35.2, 32.2, 25.7, 25.5, 18.5,
17.9 ppm; IR (neat, NaCl): 3059, 2958, 2872, 1689, 1659, 1598, 1573 cmꢀ1
;
HRMS: m/z calcd for C18H24NO2: 286.1807; found: 286.1800.
(S)-3,5-(CF3)2C6H3C(=O)CACHTNUTRGNEG(UN CH2)4Ox (8): sBuLi (1.0m, 2.0 mL, 2.0 mmol)
was added to a solution of oxazoline (S)-2-cyclopentyl-4-isopropyl-4,5-di-
hydrooxazole (0.34 g, 1.9 mmol) and TMEDA (0.3 mL, 1.8 mmol) in
THF (19 mL) at ꢀ788C . After stirring the reaction mixture at ꢀ788C for
1 h, a cold solution of N-methoxy-N-methyl-3,5-bis(trifluoromethyl)ben-
zamide (0.56 g, 1.88 mmol)[38] in THF (15 mL) was added. The reaction
mixture was stirred for 1 h and warmed to room temperature, at which
point it was quenched with a solution of saturated aqueous NH4Cl
(15 mL) and water (15 mL). The aqueous layer was extracted with Et2O
(3ꢂ25 mL). The organic fractions were combined, dried by using
Na2SO4, and the solvent removed by rotary evaporation in vacuo. The
yellow oil was purified by flash column chromatography with silica (hex-
anes/EtOAc, 95:5) to obtain ketone 8 as a colorless oil (0.71 g, 90%).
Rf =0.63 (hexanes/EtOAc, 3:1); [a]2D2 =ꢀ27.0 (c=1.04 in CHCl3);
1H NMR (300 MHz, CDCl3): d=8.46 (s, 2H), 8.00 (s, 1H), 4.15–4.06 (m,
1H), 3.87–3.77 (m, 2H), 2.51–2.23 (m, 4H), 1.91–1.52 (m, 5H), 0.92 (d,
3H), 1.58 (s, 3H), 0.97 (d, 3J(H,H)=7 Hz, 3H), 0.87 ppm (d, 3J
ACTHNUTRGENNUG AHCUTNGTREN(NUGN H,H)=
7 Hz, 3H); 13C{1H} NMR (100 MHz, CDCl3): d=199.0, 170.2, 135.8,
132.7, 128.9, 128.4, 72.1, 70.6, 48.3, 32.5, 25.0, 24.9, 19.1, 18.2 ppm; IR
(neat, NaCl): 1691, 1661, 1449 cmꢀ1; HRMS: m/z calcd for C16H21NO2Na:
282.1470; found: 282.1469; LRMS (ESI): m/z (%): 283, 282 (15, 100)
[M+Na+], 261, 260 (8, 38) [M+H+]; elemental analysis calcd (%) for
C16H21NO2: C 74.10, H 8.16, N 5.40; found: C 73.73, H 8.27, N 5.45.
(S)-4-OMeC6H4C(=O)CMe2Ox (6): sBuLi (1.24m, 38 mL, 47 mmol) was
added to a cooled solution (ꢀ788C) of oxazoline 4 (7.4 g, 47 mmol) and
TMEDA (7.2 mL, 47 mmol) in THF (50 mL). After stirring the reaction
mixture at ꢀ788C for 45 min, a cold solution of methyl 4-methoxyben-
zoate (8.0 g, 47 mmol) in THF (30 mL) was added and the reaction mix-
ture was stirred for 1 h and warmed to room temperature. The reaction
mixture was quenched with a solution of saturated aqueous NH4Cl
(25 mL) and water (25 mL). The aqueous layer was extracted with Et2O
(3ꢂ30 mL). The organic fractions were combined, dried by using
Na2SO4, and the solvent removed by rotary evaporation in vacuo. The
yellow oil was purified by bulb-to-bulb distillation under reduced pres-
sure to give ketone 6 (9.9 g, 72%) as a colorless oil. Rf =0.26 (hexanes/
EtOAc, 3:1); [a]2D1 =ꢀ33.9 (c=0.326 in CHCl3); 1H NMR (300 MHz,
3J
(75 MHz, CDCl3): d=194.8, 168.8, 137.4, 132.1 (q, J
(q, 3J(F,C)=4 Hz), 125.9 (quint, 3J(F,C)=4 Hz), 123.2 (q, 1J
ACHTUNGTRENNUNG
(H,H)=7 Hz, 3H), 0.81 ppm (d, 3J(H,H)=7 Hz, 3H); 13C{1H} NMR
ACHUTGTNRENNUG CAHTUNGTRENNUGN
2
AHCTUNGTRENNUNG
A
U
271 Hz), 72.5, 71.2, 58.8, 35.8, 35.6, 32.9, 26.2, 26.1, 19.1, 18.3 ppm; IR
(neat, NaCl): 3088, 2962, 2876, 1703, 1661, 1615 cmꢀ1; HRMS: m/z calcd
for C20H22F6NO2: 422.1555; found: 422.1547.
CDCl3): d=7.97 (d, 3J
4.08 (dd, 3J(H,H)=9, 3J
3H), 1.84–1.73 (m, 1H), 1.55 (s, 3H), 1.53 (s, 3H), 0.95 (d, 3J
7 Hz, 3H), 0.85 ppm (d, 3J(H,H)=7 Hz, 3H); 13C{1H} NMR (75 MHz,
CDCl3): d=197.1, 170.5, 163.1, 131.3, 128.4, 113.5, 72.0, 70.5, 55.5, 48.0,
A
R
Copolymer [{MesPC(Ph)ACHUTNERTG(GUNNN CMe2Ox)}xAHCTNURTGE{GUNNN CH2CHPh}y]n ACHTNGUTREN(NUGN 9a): Styrene (0.80 g,
A
U
7.7 mmol), phosphaalkene 1a (1.50 g, 3.8 mmol) and VAZO 88 (0.03 g,
0.12 mmol) were added to a pyrex tube. The tube was flame-sealed in
vacuo and, subsequently, heated at 1608C in an oven equipped with rock-
ing tray. Over a period of 14 h, the polymerization mixture became in-
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
Chem. Eur. J. 2012, 18, 6349 – 6359
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6357

D. P. Gates, G. R. Dake et al.
creasingly viscous. The tube was removed from the oven and cooled to
ambient temperature, at which point the sample was solid and broken in
a nitrogen filled glovebox. The contents were dissolved in THF (ca.
3 mL) in the glovebox and transferred to a Schlenk flask (10 mL). The
solution was concentrated in vacuo and precipitated with hexanes (5 mL)
to give a light yellow solid. This process was repeated four times to give
a light-yellow powder that was dried in vacuo for 24 h (0.25 g, 11%).
[a]2D2 =ꢀ14.0 (c=1.41 in CHCl3); 31P NMR (162 MHz, CDCl3): d=
ꢀ7 ppm (brs); 1H NMR (300 MHz, CDCl3): d=7.5–5.8 (brm; aryl H
from phosphaalkene and styrene), 4.1–3.3 (brs; methane CH from oxazo-
line), 3.0–0.5 ppm (brm; CH3 from phosphaalkene, CH, CH2 from sty-
rene); 13C{1H} NMR (75 MHz, CDCl3): d=172.3, 145.3, 140.2, 138.2,
129.8, 127.9, 125.6, 71.3, 69.2, 45.9, 40.3, 32.3, 25.1, 22.7, 21.0, 18.7,
17.5 ppm; GPC-LLS (THF): Mn =7400 gmolꢀ1; PDI=1.15; dn/dc=0.198;
elemental analysis found: C 87.00, H 8.14, N 1.19, P 2.83.
graduate scholarship to J.D.-T. We also thank Merck–Frosst Canada Ltd.
and Merck & Co. Inc. for support of this work. E.B.C.-C. acknowledges
the CONYCAF for a graduate fellowship.
[1] For reviews, see: a) K. B. Dillon, F. Mathey, J. F. Nixon, Phosphorus:
the Carbon Copy: From Organophosphorous to Phospha-Organic
Chemistry, Wiley, Chichester, 1998; b) P. Le Floch, Coord. Chem.
Rev. 2006, 250, 627; c) F. Ozawa, M. Yoshifuji, Dalton Trans. 2006,
4987; d) F. Mathey, Angew. Chem. 2003, 115, 1616; Angew. Chem.
Int. Ed. 2003, 42, 1578; e) L. Weber, Angew. Chem. 2002, 114, 583;
Angew. Chem. Int. Ed. 2002, 41, 563.
[2] J. I. Bates, J. Dugal-Tessier, D. P. Gates, Dalton Trans. 2010, 39,
3151.
[3] For addition polymerization of a P=C bond, see: a) K. J. T. Noonan,
D. P. Gates, Macromolecules 2008, 41, 1961; b) K. J. T. Noonan,
B. H. Gillon, V. Cappello, D. P. Gates, J. Am. Chem. Soc. 2008, 130,
12876; c) K. J. T. Noonan, D. P. Gates, Angew. Chem. 2006, 118,
7429; Angew. Chem. Int. Ed. 2006, 45, 7271; d) C. W. Tsang, B. Ba-
harloo, D. Riendl, M. Yam, D. P. Gates, Angew. Chem. 2004, 116,
5800; Angew. Chem. Int. Ed. 2004, 43, 5682; e) C. W. Tsang, M.
Yam, D. P. Gates, J. Am. Chem. Soc. 2003, 125, 1480.
X-ray crystallography: All single crystals were immersed in oil and
mounted on a glass fiber. Data were collected on a Bruker X8 APEX dif-
fractometer with graphite-monochromated MoKa radiation. Structures
were solved by direct methods and subsequent Fourier difference tech-
niques. All non-hydrogen atoms were refined anisotropically with hydro-
gen atoms being included in calculated positions but not refined. All data
sets were corrected Lorentz and polarization effects. All calculations
were performed by using the SHELXTL[39] crystallographic software
package from Bruker-AXS. Additional crystal data and details of the
data collection and structure refinement are given in Table 2. CCDC-
692226 (1a) and CCDC-857554 (3/3’) contain the supplementary crystal-
lographic data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.ccdc.cam.
ac.uk/data_request/cif.
[4] Phosphaalkene molecules and polymers possessing extended p-con-
jugation are attracting considerable attention for their potential
opto-electronic properties. For selected examples in polymer sci-
ence, see: a) V. A. Wright, B. O. Patrick, C. Schneider, D. P. Gates, J.
Am. Chem. Soc. 2006, 128, 8836; b) S. Kawasaki, J. Ujita, K. Toyota,
M. Yoshifuji, Chem. Lett. 2005, 34, 724; c) R. C. Smith, J. D. Prota-
siewicz, Eur. J. Inorg. Chem. 2004, 998; d) R. C. Smith, J. D. Prota-
siewicz, J. Am. Chem. Soc. 2004, 126, 2268; e) R. C. Smith, X. F.
Chen, J. D. Protasiewicz, Inorg. Chem. 2003, 42, 5468; f) V. A.
Wright, D. P. Gates, Angew. Chem. 2002, 114, 2495; Angew. Chem.
Int. Ed. 2002, 41, 2389; for selected examples in molecular chemis-
try, see: g) X. L. Geng, S. Ott, Chem. Eur. J. 2011, 17, 12153; h) E.
ꢃberg, X. L. Geng, M. P. Santoni, S. Ott, Org. Biomol. Chem. 2011,
9, 6246; i) M. P. Washington, V. B. Gudimetla, F. L. Laughlin, N. De-
ligonul, S. He, J. L. Payton, M. C. Simpson, J. D. Protasiewicz, J.
Am. Chem. Soc. 2010, 132, 4566; j) X. L. Geng, Q. Hu, B. Schꢄfer, S.
Ott, Org. Lett. 2010, 12, 692; k) V. B. Gudimetla, L. Ma, M. P. Wash-
ington, J. L. Payton, M. C. Simpson, J. D. Protasiewicz, Eur. J. Inorg.
Chem. 2010, 854; l) E. ꢃberg, B. Schꢄfer, X. L. Geng, J. Pettersson,
Q. Hu, M. Kritikos, T. Rasmussen, S. Ott, J. Org. Chem. 2009, 74,
9265; m) X. L. Geng, S. Ott, Chem. Commun. 2009, 7206; n) B.
Schꢄfer, E. ꢃberg, M. Kritikos, S. Ott, Angew. Chem. 2008, 120,
8352; Angew. Chem. Int. Ed. 2008, 47, 8228; o) C. Moser, A. Or-
thaber, M. Nieger, F. Belaj, R. Pietschnig, Dalton Trans. 2006, 3879;
p) S. M. Cornet, K. B. Dillon, A. E. Goeta, J. A. K. Howard, M. D.
Roden, A. L. Thompson, J. Organomet. Chem. 2005, 690, 3630.
[5] M. Doux, A. Moores, N. Mꢅzailles, L. Ricard, Y. Jean, P. Le Floch,
J. Organomet. Chem. 2005, 690, 2407.
[6] See, for example: a) Y. Nakajima, M. Nakatani, K. Hayashi, Y. Shir-
aishi, R. Takita, M. Okazaki, F. Ozawa, New J. Chem. 2010, 34,
1713; b) A. Hayashi, T. Yoshitomi, K. Umeda, M. Okazaki, F.
Ozawa, Organometallics 2008, 27, 2321; c) H. Murakami, Y. Matsui,
F. Ozawa, M. Yoshifuji, J. Organomet. Chem. 2006, 691, 3151;
d) A. S. Gajare, R. S. Jensen, K. Toyota, M. Yoshifuji, F. Ozawa,
Synlett 2005, 144; e) H. Katayama, M. Nagao, T. Nishimura, Y.
Matsui, K. Umeda, K. Akamatsu, T. Tsuruoka, H. Nawafune, F.
Ozawa, J. Am. Chem. Soc. 2005, 127, 4350; f) A. S. Gajare, K.
Toyota, M. Yoshifuji, F. Ozawa, J. Org. Chem. 2004, 69, 6504;
g) A. S. Gajare, K. Toyota, M. Yoshifuji, F. Ozawa, Chem. Commun.
2004, 1994; h) F. Ozawa, T. Ishiyama, S. Yamamoto, S. Kawagishi,
H. Murakami, M. Yoshifuji, Organometallics 2004, 23, 1698; i) F.
Ozawa, H. Okamoto, S. Kawagishi, S. Yamamoto, T. Minami, M.
Yoshifuji, J. Am. Chem. Soc. 2002, 124, 10968; j) T. Minami, H. Oka-
moto, S. Ikeda, R. Tanaka, F. Ozawa, M. Yoshifuji, Angew. Chem.
2001, 113, 4633; Angew. Chem. Int. Ed. 2001, 40, 4501; k) F. Ozawa,
S. Yamamoto, S. Kawagishi, M. Hiraoka, S. Ikeda, T. Minami, S. Ito,
M. Yoshifuji, Chem. Lett. 2001, 972; l) S. Ikeda, F. Ohhata, M.
Acknowledgements
We gratefully acknowledge the Natural Sciences and Engineering Re-
search Council (NSERC) of Canada for Discovery, Strategic, and Re-
search Tools and Instruments grants to G.R.D. and D.P.G. and for a post-
Table 2. X-ray data collection and refinement details
3/3’
1a
formula
Mr
crystal system
space group
color
a [ꢁ]
b [ꢁ]
c [ꢁ]
a [8]
2 ꢂ C31H37N1O1P2
1003.11
triclinic
P1
colorless
8.196(1)
10.656(1)
15.571(2)
101.997(9)
91.31(1)
96.89(1)
1319.4(3)
173
C25H32NOP
393.49
hexagonal
P61
colorless
8.697(1)
8.697(1)
50.627(8)
90
90
120
3316(6)
173
6
b [8]
g [8]
V [ꢁ3]
T [K]
Z
1
m
N
]
0.190
0.25ꢂ0.25ꢂ0.1
1.262
0.139
0.6ꢂ0.4ꢂ0.3
1.182
crystal size [mm3]
calcd density [Mgmꢀ3
2qmax [8]
]
56.8
56.4
no. of reflns
no. of unique data
Rint
21909
11052
0.0422
17.08
0.0431; I>2s(I)
0.1174
1.005
55634
5413
0.0704
20.82
0.0471; I>2s(I)
0.1010
1.082
refln/param. ratio
[a]
R1
wR2 (all data)[b]
GOF
2
[a] R1 =S||Fo|ꢀ|Fc|/S|F˙ [b] wR2(F2
ACHUTGTNREN[UNG all data])={S[wACTHUNGTRENNNUG
o
2
S[w
G
.
6358
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2012, 18, 6349 – 6359

Enantiomerically Pure Phosphaalkene–Oxazolines (PhAk-Ox)
FULL PAPER
Miyoshi, R. Tanaka, T. Minami, F. Ozawa, M. Yoshifuji, Angew.
Chem. 2000, 112, 4686; Angew. Chem. Int. Ed. 2000, 39, 4512.
[7] A. Ionkin, W. Marshall, Chem. Commun. 2003, 710.
[8] O. Daugulis, M. Brookhart, P. S. White, Organometallics 2002, 21,
5935.
[9] See, for example: a) Y. Nakajima, Y. Shiraishi, T. Tsuchimoto, F.
Ozawa, Chem. Commun. 2011, 47, 6332; b) A. Orthaber, F. Belaj, R.
Pietschnig, Inorg. Chim. Acta 2011, 374, 211; c) Y. Nakajima, Y.
Nakao, S. Sakaki, Y. Tamada, T. Ono, F. Ozawa, J. Am. Chem. Soc.
2010, 132, 9934; d) C. Mꢆller, E. A. Pidko, M. Lutz, A. L. Spek, D.
Vogt, Chem. Eur. J. 2008, 14, 8803; e) A. Hayashi, M. Okazaki, F.
Ozawa, R. Tanaka, Organometallics 2007, 26, 5246; f) A. S. Ionkin,
W. J. Marshall, Heteroat. Chem. 2002, 13, 662.
[10] M. Yam, J. H. Chong, C. W. Tsang, B. O. Patrick, A. E. Lam, D. P.
Gates, Inorg. Chem. 2006, 45, 5225.
[11] J. Dugal-Tessier, G. R. Dake, D. P. Gates, Organometallics 2007, 26,
6481.
[12] J. Dugal-Tessier, G. R. Dake, D. P. Gates, Angew. Chem. 2008, 120,
8184; Angew. Chem. Int. Ed. 2008, 47, 8064.
[13] For selected examples, see: a) A. S. Ionkin, W. J. Marshall, B. M.
Fish, M. F. Schiffhauer, F. Davidson, C. N. McEwen, D. E. Keys, Or-
ganometallics 2007, 26, 5050; b) S. B. Clendenning, P. B. Hitchcock,
M. F. Lappert, P. G. Merle, J. F. Nixon, L. Nyulꢇszi, Chem. Eur. J.
2007, 13, 7121; c) C. Fish, M. Green, J. C. Jeffery, R. J. Kilby, J. M.
Lynam, J. E. McGrady, D. A. Pantazis, C. A. Russell, C. E. Willans,
Angew. Chem. 2006, 118, 6837; Angew. Chem. Int. Ed. 2006, 45,
6685; d) C. Jones, M. Waugh, Dalton Trans. 2004, 1971; e) J. Renner,
U. Bergstrꢄsser, P. Binger, M. Regitz, Angew. Chem. 2003, 115,
1907; Angew. Chem. Int. Ed. 2003, 42, 1863; f) S. Ito, H. Sugiyama,
M. Yoshifuji, Chem. Commun. 2002, 1744; g) C. Peters, H. Distel-
dorf, E. Fuchs, S. Werner, S. Stutzmann, J. Bruckmann, C. Krꢆger, P.
Binger, H. Heydt, M. Regitz, Eur. J. Org. Chem. 2001, 3425;
h) M. J. M. Vlaar, A. W. Ehlers, M. Schakel, S. B. Clendenning, J. F.
Nixon, M. Lutz, A. L. Spek, K. Lammertsma, Chem. Eur. J. 2001, 7,
3545; i) M. Scheer, P. Kramkowski, K. Schuster, Organometallics
1999, 18, 2874; j) B. Geissler, S. Barth, U. Bergstrꢄsser, M. Slany, J.
Durkin, P. B. Hitchcock, M. Hofmann, P. Binger, J. F. Nixon,
P. von R. Schleyer, M. Regitz, Angew. Chem. 1995, 107, 485; Angew.
Chem. Int. Ed. Engl. 1995, 34, 484; k) O. Wagner, G. Maas, M.
Regitz, Angew. Chem. 1987, 99, 1328; Angew. Chem. Int. Ed. Engl.
1987, 26, 1257.
Soc. 2005, 127, 11244; j) R. Shintani, G. C. Fu, J. Am. Chem. Soc.
2003, 125, 10778; k) R. Shintani, G. C. Fu, Angew. Chem. 2003, 115,
4216; Angew. Chem. Int. Ed. 2003, 42, 4082; l) M. Ogasawara, K.
Yoshida, T. Hayashi, Organometallics 2003, 22, 1783; m) R. Shintani,
G. C. Fu, Org. Lett. 2002, 4, 3699; n) S. O. Agustsson, C. Hu, U. Eng-
lert, T. Marx, L. Wesemann, C. Ganter, Organometallics 2002, 21,
2993; o) K. Tanaka, S. Qiao, M. Tobisu, M. M. C. Lo, G. C. Fu, J.
Am. Chem. Soc. 2000, 122, 9870; p) R. Shintani, M. M. C. Lo, G. C.
Fu, Org. Lett. 2000, 2, 3695.
[18] J. I. Bates, B. O. Patrick, D. P. Gates, New J. Chem. 2010, 34, 1660.
[19] G. Becker, W. Uhl, H. J. Wessely, Z. Anorg. Allg. Chem. 1981, 479,
41.
[20] For a review, see: G. Helmchen, A. Pfaltz, Acc. Chem. Res. 2000, 33,
336; for initial publications, see: a) P. von Matt, A. Pfaltz, Angew.
Chem. 1993, 105, 614; Angew. Chem. Int. Ed. Engl. 1993, 32, 566;
b) J. Sprinz, G. Helmchen, Tetrahedron Lett. 1993, 34, 1769; c) G. J.
Dawson, C. G. Frost, J. M. J. Williams, S. J. Coote, Tetrahedron Lett.
1993, 34, 3149.
[21] J. S. Johnson, D. A. Evans, Acc. Chem. Res. 2000, 33, 325.
[22] C. Bolm, F. Schmidt, L. Zani, Tetrahedron: Asymmetry 2005, 16,
1367.
[23] P. B. Hitchcock, M. F. Lappert, J. E. Nycz, Chem. Commun. 2003,
1142.
[24] M. Yam, C. W. Tsang, D. P. Gates, Inorg. Chem. 2004, 43, 3719.
[25] Y. Tohda, T. Kawashima, M. Ariga, R. Akiyama, H. Shudoh, Y.
Mori, Bull. Chem. Soc. Jpn. 1984, 57, 2329.
[26] M. J. Kurth, O. H. W. Decker, H. Hope, M. D. Yanuck, J. Am.
Chem. Soc. 1985, 107, 443.
[27] M. J. Mckennon, A. I. Meyers, K. Drauz, M. Schwarm, J. Org.
Chem. 1993, 58, 3568.
[28] R. Luisi, V. Capriati, S. Florio, T. Vista, J. Org. Chem. 2003, 68,
9861.
[29] R. Appel in Multiple Bonds and Low Coordination in Phosphorus
Chemistry, (Eds.: M. Regitz, O. J. Scherer), Thieme, Stuttgart, 1990,
pp. 157.
[30] B. Breit, M. Regitz, Chem. Ber. 1993, 126, 1945.
[31] J. G. Cordaro, D. Stein, H. Grꢆtzmacher, J. Am. Chem. Soc. 2006,
128, 14962.
[32] T. C. Klebach, R. Lourens, F. Bickelhaupt, J. Am. Chem. Soc. 1978,
100, 4886.
[33] J. Dugal-Tessier, P. S. Kuhn, G. R. Dake, D. P. Gates, Heteroat.
Chem. 2010, 21, 355.
[14] R. De Vaumas, A. Marinetti, L. Ricard, F. Mathey, J. Am. Chem.
Soc. 1992, 114, 261.
[15] J. Dugal-Tessier, G. R. Dake, D. P. Gates, Org. Lett. 2010, 12, 4667.
[16] R. Takita, Y. Takada, R. S. Jensen, M. Okazaki, F. Ozawa, Organo-
metallics 2008, 27, 6279.
[34] M. Brym, C. Jones, M. Waugh, E. Hey-Hawkins, F. Majoumo, New
J. Chem. 2003, 27, 1614.
[35] T. van der Does, F. Bickelhaupt, Phosphorus Sulfur Silicon Relat.
Elem. 1987, 30, 515.
[17] See, for example: a) C. Mꢆller, E. A. Pidko, A. J. P. M. Staring, M.
Lutz, A. L. Spek, R. A. van Santen, D. Vogt, Chem. Eur. J. 2008, 14,
4899; b) C. Mꢆller, L. G. Lꢈpez, H. Kooijman, A. L. Spek, D. Vogt,
Tetrahedron Lett. 2006, 47, 2017; c) B. Breit, J. Mol. Catal. A: Chem.
1999, 143, 143; d) B. Breit, Chem. Commun. 1996, 2071; e) D. Car-
michael, J. Klankermayer, E. Muller, K. M. Pietrusiewicz, L. Ricard,
N. Seeboth, S. Sowa, M. Stankevic, Organometallics 2011, 30, 1804;
f) H. Willms, W. Frank, C. Ganter, Organometallics 2009, 28, 3049;
g) H. Willms, W. Frank, C. Ganter, Chem. Eur. J. 2008, 14, 2719;
h) M. Ogasawara, A. Ito, K. Yoshida, T. Hayashi, Organometallics
2006, 25, 2715; i) A. Suꢇrez, C. W. Downey, G. C. Fu, J. Am. Chem.
[36] A. F. Burchat, J. M. Chong, N. Nielsen, J. Organomet. Chem. 1997,
542, 281.
[37] Y. van den Winkel, H. M. M. Bastiaans, F. Bickelhaupt, J. Organo-
met. Chem. 1991, 405, 183.
[38] J. L. Krinsky, J. Arnold, R. G. Bergman, Organometallics 2007, 26,
897.
[39] SHELXTL, Version 5.1, Bruker ZSX, Madison, 1997.
Received: December 12, 2011
Revised: February 8, 2011
Published online: April 4, 2012
Chem. Eur. J. 2012, 18, 6349 – 6359
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6359