Phosphiranes as ligands: Tungsten(0) and Palladium(0) complexes of phosphirano[1,2-c][1,2,3]diazaphospholes

Article abstract of DOI:10.1002/ejoc.201000102

Phosphirano[1,2-c][1,2,3]diazaphospholes 5, which feature a strongly pyramidalized phosphorus atom at a ring fusion position, were identified as a new type of phosphane ligands for transition metals. The derivatives 5a - c smoothly form W(CO)₅

Full text of DOI:10.1002/ejoc.201000102

FULL PAPER
DOI: 10.1002/ejoc.201000102
Phosphiranes as Ligands: Tungsten(0) and Palladium(0) Complexes of
Phosphirano[1,2-c][1,2,3]diazaphospholes
Stefan Maurer,[a] Christian Burkhart,[a] and Gerhard Maas*[a]
Keywords: Complexes / Palladium / Phosphiranes / Phosphorus heterocycles / Tungsten
Phosphirano[1,2-c][1,2,3]diazaphospholes 5, which feature a
strongly pyramidalized phosphorus atom at a ring fusion po-
sition, were identified as a new type of phosphane ligands
for transition metals. The derivatives 5a–c smoothly form
W(CO)5 complexes, which are thermally quite stable – in
dibenzylideneacetone]palladium(0)
complex
Pd2(dba)3·
CHCl3 to form the corresponding isolable complexes [(5a)2-
(dba)Pd] and [(5b)2(dba)Pd]. In agreement with the formation
of these complexes, it was found that 5a,b as ligands effec-
tively promote the Suzuki cross-coupling of 4-bromotoluene
contrast to the known lability of various carbonylmetal com- with benzeneboronic acid. The solid-state structure of bicy-
plexes of simple phosphiranes. In the temperature range
120–150 °C, they undergo a clean decomplexation in toluene
clic phosphirane 5b and of the complexes [(5a)(CO)5W], [(5b)2-
(dba)Pd] (pentane solvate) and [(5b)2(dba)Pd] (benzene solv-
solution. Bicyclic phosphiranes 5a and 5b, but not the ac- ate) were determined by X-ray diffraction analysis.
ceptor-substituted derivative 5c, readily react with the [(E,E)-
Introduction
Phosphiranes represent a class of phosphorus-containing
three-membered heterocycles, the chemistry of which is
nowadays widely explored.[1] In addition to the familiar
chemical reactivity of cyclopropanes, which includes one-
bond ring-opening, [2+1] cycloreversion and ring-expan-
sion processes, the possibility to alter the coordination
number and oxidation state of the σ3,λ3-phosphorus atom
characterize the chemical reactivity of the phosphiranes. In
the context of coordination chemistry, phosphiranes 1 (Fig-
ure 1) can be conceived as a particular subset of phosphane
ligands, which differs from common aryl- and/or alkyl-sub-
Figure 1. Selected phosphirane systems as potential ligands in tran-
sition-metal complexes.
stituted phosphanes in terms of electronic and steric ligand
properties. Incorporation of a phosphorus atom in a three-
membered ring is connected with a stronger pyramidaliz-
are of the type LM(CO)n (L = phosphirane; M = W, Mo,
ation and a change in hybridization, and as a result it is
Cr, Fe); [(cod)(1-substituted-2-phenylphosphirane)2Rh]-
expected that phosphiranes 1 behave as ligands with only
[7]
PF6 and cp*IrCl2(tert-butylphosphirane)[2] have to be
weak σ-donor but significant π-acceptor character.[2–4] On
named as so far rare examples of complexes with transition
the other hand, a theoretical charge decomposition analysis
metals important in contemporary homogeneous catalysis.
of platinum complexes of 1-aminophosphirane has revealed
It may be that the chemical reactivity and limited thermal
that these donor-substituted phosphiranes are relatively
stability of some phosphiranes and phosphirane complexes
good electron donors, but have electron-accepting proper-
prevents a broader application of phosphirane complexes
ties not much different from those of common phos-
in transition-metal catalysis. As a solution to this problem,
phanes.[5]
Grützmacher and co-workers have developed the so-called
A number of transition-metal complexes containing mo-
BABAR-Phos polycyclic phosphiranes 2.[3,5,9,10] Formation
nocyclic and P,C-fused bicyclic phosphiranes as two-elec-
of isolable complexes with several metals (CuI, RhI, Pt0 and
tron donor ligands are known.[1–4,6–8] Almost all of them
PtII) has been documented, some of which were found to
catalyze efficiently the hydrosilylation (Pt0)[3] and hydrobor-
ation (RhI)[10] of olefins. Streubel and co-workers have de-
[a] Institute for Organic Chemistry I, University of Ulm,
Albert-Einstein-Allee 11, 89081 Ulm, Germany
scribed the M(CO)5 complexes (M = Mo, W) of several
Fax: +49-731-5022803
E-mail: gerhard.maas@uni-ulm.de
2504
P,C-cage compounds containing phosphirane subunits.[11]
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 2504–2511

Phosphiranes as Ligands
Recently we became interested in the suitability of P,C-
fused phosphirano-heterophospholes such as 3–5 (Figure 1)
as potential ligands for transition metals. Phosphirano-
[1,2]thiaphospholes 3[12] and 4[13] are easily prepared from
1,2-thiaphospholes and diphenyldiazomethane or 9-diazo-
fluorene, respectively, and they smoothly form W(CO)5
complexes. However, these complexes are thermally quite
labile. Depending on the individual substitution pattern, the
phosphirane ligand in the complex undergoes different
isomerization reactions in the temperature range 25–80 °C.
When the spiro compounds 4 are heated in acetonitrile
solution at 80 °C, decomplexation reconstituting the free
phosphirane ligand is the major event. Due to the ca-
pricious behavior of 3 and 4 in the ligand sphere of the
W(CO)5 complexes, we did not pursue these investigations
with other transition metals.
We have now turned our attention to phosphirano[1,2-
c][1,2,3]diazaphospholes 5. Compounds of this type were
first prepared and investigated by Arbuzov and co-workers
during their occupation with the cycloaddition chemistry of
1,2,3-diazaphospholes.[14] We report now on the chemical
and structural characterization of W(CO)5 and Pd0 com-
plexes with bicyclic phosphiranes of type 5 as ligands.
Scheme 1. Formation of bicyclic phosphiranes 5 and their penta-
carbonyltungsten complexes 7.
which provided after purification the unchanged bicyclic
phosphiranes 5 in 72–92% yield.
Table 1 lists significant changes of the NMR spectro-
scopic data for the phosphirane ring atoms, which occur
on complexation of 5a–c. As it is often observed, the 31P
resonance suffers a shift to lower field, with ∆δ values of
42.9, 42.5 and 35.5 ppm, respectively. The 1J(31P,193W) cou-
pling constant is considered as a good measure for the elec-
tronic properties of the ligands; it increases with the elec-
tronegativity of the substituents at the phosphorus atom.[17]
The observed values – 287.0 Hz for 5a,b and 296.0 Hz for
the somewhat more electron-withdrawing N-acetyl-substi-
tuted phosphirane 5c – are a little larger than for Ph3P–
W(CO)5 (280 Hz[17a]) and at the lower end of the range of
(triaminophosphane)W(CO)5 complexes (290–320 Hz);[17]
furthermore, they are larger by some 10–30 Hz than those
of the W(CO)5 complexes of phosphirano[1,2]thiaphos-
pholes 3 and 4.[12,13] In (1-phenylphosphirane)W(CO)5
complexes, values around 260 Hz are typically observed.[18]
Table 1 also shows the characteristic[1a] diminution of the
1JP,C coupling constants when going from the free to the P-
complexed phosphirane.
Results and Discussion
Synthesis of Phosphirano-[1,2,3]diazaphospholes 5 and
Their Pentacarbonyltungsten Complexes 7
The bicyclic phosphiranes 5a–c are easily obtained in one
step from 1,2,3-diazaphospholes 6 and diphenyldiazometh-
ane (Scheme 1). Compounds 5a[15] and 5c[16] have already
been prepared in this manner by Arbuzov and co-workers.
We describe here the analogous synthesis of 5b from diaza-
phosphole 6b, which in turn is readily formed by cyclocon-
densation of p-methoxyacetophenone phenylhydrazone and
PCl3. In addition, since only an IR spectrum of 5a has been
published so far, we provide a full characterization by
NMR spectroscopy (see Exp. Sect.). The reaction of di-
phenyldiazomethane with the N-phenyl-substituted diaza-
phospholes 6a,b is much slower than with the more elec-
tron-deficient P=C bond of N-acetyl-substituted 6c. In the
case of 6b, complete conversion required heating at 75 °C
for 1 d, and a small excess of the diazo compound was nec-
essary to account for the competing pathways of its thermal
decomposition.
On treatment with W(CO)5(thf), the bicyclic phosphir-
anes 5a–c readily form the pentacarbonyltungsten com-
plexes 7a–c. After chromatographic purification, the latter
were obtained in 63–76% yield. These complexes are ther-
mally much more stable than the W(CO)5 complexes of
phosphirano-thiaphospholes 3 and 4 (see Introduction). No
isomerization of the bicyclic phosphirane ligand was ob-
served on heating, which corresponds to the thermal sta-
bility of the free phosphiranes 5 up to 150 °C (already re-
Table 1. Selected NMR spectroscopic data (chemical shifts δ [ppm]
and coupling constants J [Hz]) of the phosphirane ring atoms in
5a–c and their W(CO)5 complexes 7a–c.
Compound δ(C-5) 1JP, C(C-5) δ(C-6) 1JP, C(C-6)
δ(P)
1JP, W
5a
7a
5b
7b
5c
7c
50.3
44.8
50.4
44.8
50.4
44.9
38.1
11.0
37.3
10.2
36.6[a]
8.8
32.3
36.3
32.5
36.4
38.4
43.2
46.8
19.0
46.8
–75.9
–33.0
–76.8
–34.3
–92.9
–57.4
–
287.0
–
287.0
–
19.0
47.6[a]
21.2
296.0
[a] The J(P,C) coupling constants given in ref.[16b] are not correct.
In order to learn about the structural changes associated
ported for 5c[15]). Only when toluene solutions of 7 were with the P-complexation of bicyclic phosphiranes 5, we
heated in a thick-walled closed Schlenk tube at 120 °C (7c) have determined by X-ray diffraction analysis the structures
or 150 °C (7a,b) for 3 h, clean decomplexation took place, of phosphirane 5b and of 5a–W(CO)5 in the crystal [suit-
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S. Maurer, C. Burkhart, G. Maas
FULL PAPER
able crystals of 5b–W(CO)5 could not be obtained]. Mole-
cule plots are shown in Figures 2 and 3, respectively. In the
uncomplexed bicyclic phosphirane 5b, the P–C bond
lengths of the phosphirane ring (1.865, 1.878 Å) are within
the typical range (1.78–1.89 Å[1]). The geometrical data for
the phosphirane ring match perfectly with those determined
for a closely related compound (4-methyl-2,6,6-triphenyl-1-
phospha-2,3-diazabicyclo[3.1.0]hex-3-ene[16]). The phos-
phorus atom is more pyramidalized, as expressed by the
sum of bond angles around the phosphorus atom (234.0°),
than in the analogous W(CO)5 complex of phosphirano-
thiaphosphole 3 (Ar = Ph), where a value of 252.3° was
found;[12] much smaller Σ(PR3) values were reported for
phosphirane rings incorporated in a strained cage com-
pound (194.9°[11a]) or in a dibenzophosphasemibullvalene
(220.1°[6c]).
Figure 3. Molecular structure of pentacarbonyltungsten complex
7a in the crystal. Selected bond lengths [Å] and angles [°]: P–C(2)
1.839(4), P–C(3) 1.846(4), C(2)–C(3) 1.546(5), P–N(1) 1.721(3), W–
P 2.4645(10), W–C(29) 2.002(4), W–C(O)eq. 2.036(4) – 2.060(5);
C(2)–P–C(3) 49.60(16), C(2)–C(3)–P 64.9(2), C(3)–C(2)–P 65.5(2),
N(1)–P–C(3) 100.99(17), N(1)–P–C(2) 88.60(16), C(2)–P–W 127.91
(13), C(29)–W–P 175.29(12).
least-squares plane of the exo-phenyl ring is 59.6°). Similar
to arylcyclopropanes,[19] this change is likely to cause, too,
small bond-length changes in the three-membered ring. In
the octahedrally coordinated P–W(CO)5 fragment of 7a, the
W–C(O)ax bond (2.002 Å) is shortened compared to the W–
C(O)eq bonds due to the trans effect of the phosphirane
ligand. Interestingly, the W–C(O)ax bond length is virtually
the same as in the W(CO)5 complex of phosphirano-thia-
phosphole 3 (Ar = Ph),[12] and the P–W distances [2.465(1)
vs. 2.480(1) Å] are similar.
Figure 2. Molecular structure of bicyclic phosphirane 5b in the
crystal. Selected bond lengths [Å] and angles [°]: P(1)–C(2)
1.865(2), P(1)–C(3) 1.878(2), C(2)–C(3) 1.528(3), P(1)–N(1)
1.737(2); C(2)–P(1)–C(3) 48.19(9), C(2)–C(3)–P(1) 65.44(12), C(3)–
C(2)–P(1) 66.37(12), N(1)–P(1)–C(3) 98.54(9), N(1)–P(1)–C(2)
87.29(9). The compound crystallizes from CH2Cl2/n-pentane with
one CH2Cl2 molecule in the asymmetric unit. The dichloromethane
molecule (not shown here) maintains a hydrogen bond to the meth-
oxy oxygen atom of 5b, C29–H29A···O1 (–x, 1 – y, 1 – z): C–H
0.99 (H in calculated position), H···O 2.31, C···O 3.227(4) Å, angle
C–H···O 154°.
Palladium(0) Complexes 8
Phosphane ligands play a key role in various palladium-
catalyzed cross-coupling reactions.[20] In numerous transfor-
mations of this kind, a (dba)palladium(0) complex [dba =
(E,E)-dibenzylideneacetone] in combination with a trisub-
stituted phosphane is applied. The coordination equilibria
and the role of the dba ligand in these ligand mixtures have
In the W(CO)5 complex of 5a, the diminution of the elec- been investigated.[21] One of the first observations was the
tron density at the phosphorus atom leads to a significant formation of a heteroleptic Pd0 complex according to the
shortening of the P–C bonds (1.839, 1.846 Å) and a length- equation: Pd(dba)2 + 2 PPh3 Ǟ (PPh3)2(dba)Pd.[22,23] With
ening of the basal C–C bond (from 1.528 to 1.546 Å) of the (dppe)(dba)Pd [dppe = 1,2-bis(diphenylphosphanyl)eth-
three-membered ring. Simultaneously, the pyramidalization ane], Herrmann and co-workers[23] presented the first struc-
at the phosphorus atom is a little reduced, as the sum of tural characterization of a (benzylideneacetone)diphos-
bond angles around the phosphorus atom increases from phanepalladium(0) complex. Other 16-valence-electron
234.0 to 239.2°. These complexation-induced changes are complexes of the type L2(dba)Pd0 were prepared and struc-
typical for phosphiranes (see for example, polycyclic phos- turally characterized subsequently.[24] To the best of our
phiranes 2[5] and a closely related dibenzophosphasemi- knowledge, however, the literature holds no report on the
bullvalene[6c]). The complexation by the W(CO)5 fragment use of phosphiranes as ligands in such catalytic reactions
also causes a significant conformational change, as the exo- nor even on the existence of (phosphirane)palladium(0)
phenyl substituent at phosphirane ring atom C3 is rotated complexes.
from the bisecting conformation with respect to the phos-
When the bicyclic phosphiranes 5a,b and Pd2(dba)3·
phirane ring to an almost perpendicular orientation (the CHCl3 were combined in a molar ratio of 1:4 in [D1]chloro-
dihedral angle between the cyclopropane ring plane and the form, 31P NMR spectroscopy showed the clean formation
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Eur. J. Org. Chem. 2010, 2504–2511

Phosphiranes as Ligands
of an AB spin system [e.g. from 5b: δ = –30.8 and complexed bicyclic phosphirane 5a, relatively small differ-
–32.0 ppm; J(PA,PB) = 59.2 Hz]. In contrast, 5c did not re- ences are observed in the two phosphirane rings of the pal-
act at all with Pd2(dba)3, and the 31P NMR spectrum re- ladium complex: the numerical differences for the C–C
mained unchanged under the same conditions during sev- bond and the ring-fusing P–C bond are within the sum of
eral days. Obviously, the σ-donating power of N-acetyl-sub- the standard deviations, only the P–C(Ph2) bond is shorter
stituted phosphirane 5c is no longer sufficient to ligate with by ca. 0.03 Å. The sum of the N–P–C and C–P–C bond
the (dba)Pd complex. In the cases of 5a and 5b, the carriers angles is 238.8°, matching very well the value observed for
of the 31P{1H} NMR signals could be isolated as finely tungsten complex 7a.
crystalline solids, which started to separate from an acetoni-
trile solution of the precursors after 15 min. They were
identified as the 16-valence-electron complexes [(5a)2(dba)-
Pd] and [(5b)2(dba)Pd], respectively, by spectroscopic data
(NMR, IR) and elemental analyses (Scheme 2). These com-
plexes appear to be stable in the solid state, but their solu-
tions in CDCl3 show traces of decomposition already after
a short time. In the 1H NMR spectra, broad and little struc-
tured signals are observed for the olefinic protons of the
Pd-coordinated C=C bond of the dba ligand (the protons
of the noncoordinated double bond being superimposed by
the aromatic protons) and for the phosphirane proton 5-H
as well. The broadening of the dba olefinic proton signals
has been noted before by several authors; dynamic NMR
studies[24e,24f] have revealed the existence of several dynamic
processes, such as intramolecular interchange between the
coordinated and the noncoordinated double bonds, rota-
tional isomerism, and rotation around the Pd–alkene axis.
Figure 4. Molecular structure of palladium complex [(5b)2(dba)-
Pd]·0.5 C5H12 in the crystal. The pentane molecule has been omit-
ted for clarity. Selected bond lengths [Å] and angles [°]: P(1)–C(2)
1.853(5), P(1)–C(3) 1.847(5), C(2)–C(3) 1.524(5), P(1)–N(1)
1.717(4), P(2)–C(30) 1.857(4), P(2)–C(31) 1.841(5), C(30)–C(31)
1.535(6), P(2)–N(3) 1.712(4), Pd–P(1) 2.2572(13), Pd–P(2)
2.2548(13), Pd–C(57) 2.213(5), Pd–C(58) 2.160(4), C(57)–C(58)
1.389(6), C(59)–O(3) 1.219(6), C(60)–C(61) 1.328(6); C(2)–P(1)–
C(3) 48.66(17), C(2)–C(3)–P(1) 65.9(2), C(3)–C(2)–P(1) 65.5(2),
N(1)–P(1)–C(3) 101.58(19), N(1)–P(1)–C(2) 88.6(2), C(30)–P(2)–
C(31) 49.03(18), C(30)–C(31)–P(2) 66.0(2), C(31)–C(30)–P(2)
64.9(2), N(3)–P(2)–C(30) 88.4(2), N(3)–P(2)–C(31) 101.41(19),
P(1)–Pd–P(2) 97.58(4), C(57)–Pd–C(58) 37.00(16).
Complexes of the type [(R3P)2(dba)Pd] are known as pre-
Scheme 2. Complex formation from 5a,b and Pd2(dba)3.
catalysts in the Suzuki cross-coupling reaction leading to
The structure of the palladium(0) complexes was con- biaryls. We have therefore applied ligands 5a–c to the cross-
firmed by a crystal structure analysis of [(5b)2(dba)Pd] (Fig- coupling reaction of 4-bromotoluene and benzeneboronic
ure 4). Depending on the conditions of crystallization from acid to yield 4-methylbiphenyl by using a standard setup
benzene/n-pentane, crystals were obtained either as a pen- (Scheme 3).[25] The results are shown in Table 2. Bicyclic
tane solvate or a benzene solvate (see Exp. Sect.). In both phosphiranes 5a and 5b are well-suited ligands, whereas the
cases, the crystals have the same space group with similar less electron-donating 5c is little effective, in agreement with
unit-cell dimensions. As in other [L2(dba)Pd] com- its failure to form a stable complex with Pd2(dba)3 at room
plexes,[23,24] the palladium atom has a trigonal-planar coor- temperature (see above). On the other hand, 5a,b are not
dination geometry with the three ligands. The dba ligand able to promote the cross-coupling reaction of 4-chlorotolu-
has the s-trans,s-trans conformation at the bonds adjacent ene with PhB(OH)2. Assuming that a complex [(phosphir-
to the oxo group, and only one double bond is η-coordi- ane)2Pd] is the catalytically active species, a Pd0/ligand ratio
nated (Pd–C 2.213 and 2.160 Å). Both the Pd–P distances of 1:2 would be appropriate. A variation of the Pd0/5a ratio
(2.256 vs. 2.348 Å, mean values) and the P–Pd–P angle (Table 2, Entries 2–4) suggests, however, that a ratio less
(97.6 vs. 112.6°) are distinctly smaller than in a complex than 2 is more favorable. Fu and co-workers[25] found a Pd0/
with two triarylphosphane ligands, [{[Ph2(1-naphthyl)]- P(tBu)3 ratio of 1–1.5 as optimal, and they conluded that
P}2(dba)Pd].[24c] Compared to the bond lengths in the un- the catalytically active palladium species is in fact the
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S. Maurer, C. Burkhart, G. Maas
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δ = 77.00 ppm) NMR spectra, and to external 85% H3PO4 for 31P
NMR spectra. If necessary, signal assignments were based on
COSY, HMBC, and HSQC experiments. Mass spectra in the chem-
ical ionization mode (CI) were recorded with a Finnigan MAT SSQ
7000 spectrometer.
monophosphanepalladium complex. Should this also be the
case for a palladium complex bearing only one ligand of
5a,b, one would have to attribute it to the steric demand of
these ligands. In terms of their electronic properties, they
do not match the much more electron-rich P(tBu)3 ligands.
Starting Materials: Diphenyldiazomethane[26] was prepared by de-
hydrogenation of the corresponding hydrazone using a sixfold ex-
cess of activated MnO2. p-Methoxyacetophenone phenylhydra-
zone,[27] and 1-(4-methyl-6,6-diphenyl-2,3-diaza-1-phosphabicy-
clo[3.1.0]hex-3-en-2-yl)ethanone (5c)[16] were prepared by published
procedures.
Scheme 3. Suzuki cross-coupling reaction. See Table 2 for condi-
tions.
4-(4-Methoxyphenyl)-2-phenyl-2H-1,2,3-diazaphosphole (6b): PCl3
(4.00 mL, 45.7 mmol) was added carefully to a solution of p-meth-
oxyacetophenone phenylhydrazone (11.0 g, 45.7 mmol) in toluene
(100 mL), and the reaction mixture was heated at reflux for 48 h.
Addition of triethylamine (7.62 mL, 55.0 mmol) to the slightly yel-
low solution led to a voluminous precipitate, which was filtered off.
The filtrate was stirred with silica gel (5 g) for 5 min. After removal
of the silica gel, the filtrate was kept at –35 °C for 2 d to precipitate
6b. Further purification was achieved by Kugelrohr distillation
(1.5ϫ10–4 mbar/160 °C). The product was obtained as a colorless
Table 2. Suzuki cross-coupling reaction of 4-bromotoluene and
benzeneboronic acid to yield 4-methylbiphenyl: ligand screening.[a]
Entry
Ligand
Mol-% of Pd0 vs. ligand
Yield [%]
1
2
3
4
5
6
7
–
1.5, –
1.5, 3.0
1.5, 3.6
1.5, 2.25
1.5, 1.8
1.5, 3.0
1.5, 3.0
16
59
49
5a
5a
5a
5a
5b
5c
95
65–73[b]
90
38
solid (8.95 g, 73%), m.p. 99 °C. IR (KBr): ν = 1608 (s), 1592 (s),
˜
1523 (s), 1507 (m), 1490 (s), 1453 (m), 1438 (s), 1418 (s), 1363 (m),
1300 (m), 1287 (s), 1234 (s), 1176 (s), 1028 (s), 836 (s), 772 (s), 752
(s) cm–1. 1H NMR: δ = 3.87 (s, 3 H, CH3), 7.00 (d, 3JH,H = 8.8 Hz,
[a] Reagents and conditions: 4-bromotoluene (0.5 mmol), ben-
zeneboronic acid (0.75 mmol), Cs2CO3 (1.0 mmol), [Pd2(dba)3]·
CHCl3 (1.5 mol-%), ligand 5 (1.5–3 mol-%), 1,4-dioxane (1.5 mL),
80 °C, 48 h. [b] Reaction time: 5 h.
2 H, HPh), 7.31 (m, 1 H, HPh), 7.45 (m, 2 H, HPh), 7.89 (m, 4 H,
2
H
Ph), 8.18 (d, JP,H = 44.7 Hz, 1 H, 3-H) ppm. 13C{1H} NMR: δ
= 55.3 (s, CH3), 113.1, 113.6, 114.1, 119.9, 120.1, 126.8, 127.8,
2
1
129.2, 129.3, 134.2, 134.5 (d, JP,C = 8.8 Hz, C-5), 158.7 (d, JP,C
=
36.6 Hz, C-4), 159.9 ppm. 31P NMR: δ = 229.2 ppm. MS (CI =
100 eV): m/z (%) = 269 (100) [MH]+, 268 (50) [M]+. C15H13N2OP
(268.3): calcd. C 67.16, H 4.88, N 10.44; found C 67.13, H 5.13, N
10.17.
Conclusions
Phosphirano[1,2-c][1,2,3]diazaphospholes 5a,b, repre-
senting P,C-fused bicyclic phosphiranes, emerge as a class
of potentially useful phosphane ligands. In contrast to the
limited thermal stability of several substituted monocyclic
phosphiranes and their M(CO)n complexes, 5a,b and their
W(CO)5 complexes are thermally quite stable – the com-
plexes suffer dissociation only in toluene solution when
heated at around 120–150 °C. With [(5a)2(dba)Pd] and
[(5b)2(dba)Pd], the first palladium complexes of any phos-
2,4,6,6-Tetraphenyl-2,3-diaza-1-phosphabicyclo[3.1.0]hex-3-ene (5a):
Prepared as described below for 5b, from 2,5-diphenyl-2H-1,2,3-
diazaphosphole and diphenyldiazomethane. Pale yellow solid, m.p.
138 °C. 1H NMR: δ = 4.57 (d, 2JP,H = 19.5 Hz, 1 H, 5-H), 6.89 (m,
3
2 H, HPh), 6.98 (t, JH,H = 7.3 Hz, 1 H, HPh), 7.10–7.46 (m, 14 H,
HPh), 7.90 (dd, 3JH,H = 8.2, 1.4 Hz, 2 H, HPh) ppm. 13C{1H} NMR:
1
1
δ = 32.3 (d, JP,C = 46.8 Hz), 50.3 (d, JC,P = 38.1 Hz), 116.2 (d,
phirane could be isolated and structurally characterized. We JP,C = 10.2 Hz), 122.0, 125.6, 125.7, 126.7, 127.6, 128.5, 128.6,
128.8, 129.1, 132.1, 134.4, 134.9, 143.9 (d, JP,C = 15.4 Hz), 145.0
could show that, in agreement with the formation of these
complexes, the catalytic system Pd0/5a(b) effectively pro-
motes the Suzuki cross-coupling of 4-bromotoluene with
benzeneboronic acid. The unreactivity of 4-chlorotoluene in
this coupling reaction is not unexpected, since phosphiranes
5 have to be considered as only modest σ-donors.
(d, JP,C = 13.2 Hz), 151.1 ppm. 31P NMR: δ = –75.9 ppm.
4-(4-Methoxyphenyl)-2,6,6-triphenyl-2,3-diaza-1-phosphabicyclo-
[3.1.0]hex-3-ene (5b): A solution of 6b (2.66 g, 9.91 mmol) and di-
phenyldiazomethane (2.30 g, 11.8 mmol) in toluene (90 mL) was
heated at 75 °C, until the red color of the diazo compound had
disappeared (24 h). The solvent was partly removed in vacuo, sub-
sequent addition of methanol led to the precipitation of the prod-
uct. Recrystallization from dichloromethane/n-pentane gave 5b as
yellow crystals (3.42 g, 80%) containing 1 equiv. of CH2Cl2, which
Experimental Section
General Information: All reactions were carried out under argon by
using standard Schlenk techniques. Rigorously dried solvents were
used. Kugelrohr distillations were performed with a Büchi GKR
50 apparatus; oven temperatures are reported. Melting points were
measured on samples in open capillaries and are not calibrated.
Infrared spectra (IR) were recorded with a Bruker Vector 22 FTIR
can be removed in vacuo; m.p. (after drying) 131 °C. IR (KBr): ν
˜
= 1594 (s), 1512 (m), 1493 (s), 1443 (m), 1365 (m), 1306 (s), 1257
(s), 1176 (s), 751 (s), 699 (s) cm–1. 1H NMR: δ = 3.87 (s, 3 H, CH3),
2
3
4.51 (d, JP,H = 19.2 Hz, 1 H, 5-H), 6.87 (d, JH,H = 7.6 Hz, 2 H,
3
3
HPh), 6.94 (d, JH,H = 8.8 Hz, 2 H, HPh), 6.96 (t, JH,H = 8.8 Hz,
1 H, HPh), 7.11 (m, 3 H, HPh), 7.16 (m, 3 H, HPh), 7.27 (m, 4 H,
3
3
spectrometer by using KBr pellets. 1H (400.13 MHz), 13C HPh), 7.44 (d, JH,H = 8.1 Hz, 2 H, HPh), 7.84 (d, JH,H = 8.6 Hz,
(100.62 MHz) and 31P NMR (161.98 MHz) spectra were measured 2 H, HPh) ppm. 13C NMR: δ = 32.5 (d, JP,C = 46.8 Hz, C-6), 50.4
with a Bruker DRX 400 spectrometer. All NMR spectra were re-
corded in CDCl3 at 298 K. NMR chemical shifts were referenced
to the solvent peak for 1H (CHCl3: δ = 7.26 ppm) and 13C (CDCl3:
1
1
(d, JP,C = 37.3 Hz, C-5), 55.3 (s, CH3), 114.0, 116.0, 121.7, 125.3,
125.6, 127.3, 127.5, 128.2, 128.5, 129.0, 132.1, 134.9, 137.9, 144.1
2
(d, JP,C = 14.6 Hz, C-4), 145.1, 151.2, 160.3 ppm. 31P{1H} NMR:
2508
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© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 2504–2511

Phosphiranes as Ligands
δ = –76.8 ppm. MS (CI = 100 eV): m/z = 435 [MH]+. C28H23N2OP [M – 3 CO]+, 494 (5) [M – 5 CO]+, 309 (53) [M – W(CO)5]+.
(434.5) + 1.0 CH2Cl2: calcd. C 67.06, H 4.85, N 5.39; found C
67.14, H 4.83, N 5.38.
C23H17N2O6PW (632.2): calcd. C 43.70, H 2.71, N 4.43; found C
43.89, H 2.81, N 4.37.
Decomplexation of Complexes 7a–c: A solution of the complex
(0.130 mmol) in toluene (10 mL) was placed in a sealed tube and
heated at 120 °C (7c) or 150 °C (7a,b) for 3 h. The solvent was
removed in vacuo. For further purification, a solution of the resi-
due in toluene/cyclohexane (1:1) was passed through a short pad
of silica gel (5 g). Evaporation of the solvent furnished phosphir-
anes 5a [72% yield; m.p. 138 °C (dec.)], 5b [77% yield; m.p. 131 °C
(dec.)], and 5c [92% yield; m.p. 136 °C (dec.); ref.[16b] 132–135 °C],
respectively.
Pentacarbonyltungsten Complexes 7a–c. General Procedure: A solu-
tion of hexacarbonyltungsten (1.83 mmol) in tetrahydrofuran
(200 mL) was placed in a photolysis apparatus and irradiated by
using a 150 W medium-pressure mercury lamp for 60 min. The yel-
low solution of the formed complex W(CO)5(thf) was transferred
through a cannula to a flask containing the solid phosphirane 5
(1.60 mmol), and the mixture was stirred for 1 d. The solvent was
removed in vacuo, and the resulting oil was purified by column
chromatography on silica gel with toluene/cyclohexane (1:1) as elu-
ent.
[(5a)2(dba)Pd]: Pd2(dba)3·CHCl3 (12.9 mg, 12.5 µmol) and bicyclic
phosphirane 5a (20.2 mg, 50 µmol) were placed in a Schlenk tube
and dissolved in dry acetonitrile (1 mL). Separation of a finely crys-
talline lemon-colored precipitate started after 15 min. Stirring was
continued for another 75 min, and the yellow solid was isolated by
centrifugation in virtually quantitative yield. 1H NMR
(complex·CH3CN): δ = 2.00 (s, 3 H, CH3CN), 3.01 (br. d, 2 H,
phosphirane-H), 4.92 (br., 1 H, CHolefin dba), 5.42 (br., 1 H,
CHolefin dba), 6.22 (d, 1 H), 6.42–7.85 (all Haryl and CH=CH dba)
Pentacarbonyl(2,4,6,6-tetraphenyl-2,3-diaza-1-phosphabicyclo-
[3.1.0]hex-3-ene-κP)tungsten (7a): Synthesis according to the Gene-
ral Procedure from W(CO)6 (0.640 g, 1.83 mmol) and 5a (0.650 g,
1.60 mmol). Recrystallization from toluene gave 7a as yellow crys-
talline plates (0.730 g, 63%); m.p. 195 °C. IR (KBr): ν = 2079 (vs),
˜
1995 (s), 1938 (vs, br.), 1596 (m), 1491 (s), 1445 (m), 1360 (m), 1277
1
(m), 756 (s), 693 (s), 592 (s), 568 (s) cm–1. H NMR: δ = 4.90 (d,
3
2JP,H = 3.5 Hz, 1 H, 5-H), 7.10–7.56 (m, 18 H, HPh), 7.96 (d, JH,H
ppm. 31P{1H} NMR: δ = –30.3 and –31.4 (AB system, JP,P
=
1
= 6.8 Hz, 2 H, HPh) ppm. 13C{1H} NMR: δ = 36.3 (d, JP,C
=
1
60.4 Hz) ppm. C71H56N4OP2Pd·CH3CN (1149.61 + 41.05): calcd.
C 73.64, H 4.99, N 5.88; found C 73.95, H 5.06, N 5.36.
19.0 Hz, C-6), 44.8 (d, JP,C = 11.0 Hz, C-5), 122.0, 125.0, 126.6,
127.7, 127.9, 128.6, 128.7, 128.8, 129.0, 129.3, 129.3, 130.9, 133.8,
2
136.0, 138.6, 141.2, 150.9, 193.8 (d, JP,C = 8.1 Hz, COeq), 196.5
[(5b)2(dba)Pd]: Preparation as described above, but from 5b
(28.6 mg, 65.7 µmol) and 15.1 µg (14.5 mmol) of Pd2(dba)3·CHCl3.
2
(d, JP,C = 40.3 Hz, COax) ppm. 31P{1H} NMR: δ = –33.0 (1JP,W
=
287.0 Hz) ppm. MS (CI = 100 eV): m/z (%) = 728 (28) [M]+, 405
(100) [M – W(CO)5 + 1]+. C32H21N2O5PW (728.4): calcd. C 52.77,
H 2.91, N 3.85; found C 53.06, H 3.00, N 3.71.
Yield: 34.6 mg (98%). IR (KBr): ν = 1560 (m, C=O), 1596 (s), 1489
˜
1
(s), 760 (s), 696 (s) cm–1. H NMR (complex·CH3CN): δ = 2.00 (s,
3 H, CH3CN), 3.02 (br., 2 H, H phosphirane), 3.88 (s, 6 H, OCH3),
4.91 (br., 1 H, CHolefin dba), 5.38 (br., 1 H, CHolefin dba), 6.20 (d,
1 H), 6.41–7.85 (all Haryl and CH=CH dba) ppm. 31P{1H} NMR:
Pentacarbonyl{4-(4-methoxyphenyl)-2,6,6-triphenyl-2,3-diaza-1-
phosphabicyclo[3.1.0]hex-3-ene-κP}tungsten (7b): Synthesis accord-
ing to the General Procedure from W(CO)6 (0.640 g, 1.83 mmol)
and 5b (0.700 g, 1.60 mmol). Yellow solid (0.870 g, 72%); m.p.
δ
= –30.8 and –32.0 (AB system, JP,P = 59.2 Hz) ppm.
C73H60N4O3P2Pd·CH3CN (1209.67 + 41.05): calcd. C 73.64, H
4.99, N 5.88; found C 73.95, H 5.06, N 5.36. Crystals used for
X-ray structure determination: C73H60N4O3P2Pd·C5H12 (1209.67 +
72.15): calcd. C 73.09, H 5.66, N 4.37; found C 73.39, H 5.32, N
4.34.
190 °C. IR (KBr): ν = 2080 (vs), 1996 (s), 1941 (vs, br.), 1607 (m),
˜
1596 (m), 1513 (m), 1491 (m), 1446 (m), 1361 (s), 1306 (m), 1257
1
(s), 1176 (m), 1025 (m), 701 (s), 693 (s), 589 (s), 571 (s) cm–1. H
2
NMR: δ = 3.90 (s, 3 H, CH3), 4.89 (d, JP,H = 4.9 Hz, 1 H, 5-H),
3
7.03 (d, JH,H = 8.8 Hz, 2 H, HPh), 7.13–7.43 (m, 13 H, HPh), 7.53
Suzuki Cross-Coupling Reactions: The ligand 5a–c (3 mol-%), ben-
zeneboronic acid (0.75 mmol), Cs2CO3 (1.00 mmol) and [Pd2-
(dba)3]·CHCl3 (1.5 mol-%) were placed in a vial that could be
3
3
(d, JH,H = 8.1 Hz, 2 H, HPh), 7.93 (d, JH,H = 8.6 Hz, 2 H, HPh
)
ppm. 13C{1H} NMR: δ = 36.4 (d, JP,C = 19.0 Hz, C-6), 44.8 (d,
2JP,C = 10.2 Hz, C-5), 55.4 (s, CH3), 114.2, 121.9, 124.7, 125.3,
126.5, 127.6, 127.9, 128.6, 129.0, 129.2, 130.8, 135.9, 137.9, 138.7,
141.3, 150.8, 160.7, 193.9 (d, JP,C = 8.1 Hz, COeq), 196.5 (d, JP,C
= 40.0 Hz, COax) ppm. 31P NMR: δ = –34.3 (1JP,W = 287.0 Hz)
ppm. MS (CI = 100 eV): m/z (%) = 758 (13) [M]+, 435 (38) [M –
W(CO)5]+. C33H23N2O6PW (758.4): calcd. C 52.26, H 3.06, N 3.69;
found C 52.43, H 3.16, N 3.86.
1
closed with
a screw-cap. After addition of 4-bromotoluene
(0.50 mmol) and degassed 1,4-dioxane (1.5 mL) under an inert gas,
the reaction mixture was heated in a heating block at 80 °C. After
48 h, the reaction was stopped and the product ratio determined.
For this purpose, an aliquot was withdrawn from the reaction mix-
ture and analyzed unchanged (i.e. without evaporation of volatiles)
by NMR spectroscopy. The quoted yields are average yields ob-
tained from 2–4 independent runs.
2
2
Pentacarbonyl{1-(4-methyl-6,6-diphenyl-2,3-diaza-1-phosphabicyclo-
[3.1.0]hex-3-en-2-yl)ethanone-κP}tungsten (7c): Synthesis according Crystal Structure Determinations: Data collection was performed
to the General Procedure from W(CO)6 (0.640 g, 1.83 mmol) and with an image-plate diffractometer (Stoe IPDS) by using mono-
5c (0.490 g, 1.60 mmol). Yellow solid (0.770 g, 76%); m.p. 140 °C. chromated Mo-Kα radiation (λ = 0.71073 Å). The structures were
IR (KBr): ν = 2081 (s), 1969 (vs), 1949 (vs, br.), 1671 (s), 1447 (m),
solved by direct methods and refined by using a full-matrix least-
squares method. Hydrogen-atom positions were calculated geomet-
rically and treated as riding on their bond neighbors in the refine-
˜
1387 (m), 1337 (m), 757 (m), 706 (m), 693 (m), 571 (s) cm–1. 1H
2
NMR: δ = 2.01 (s, 3 H, CH3), 2.25 (s, 3 H, CH3), 3.98 (d, JP,H
=
6.3 Hz, 1 H, 5-H), 7.13–7.38 (m, 10 H, HPh) ppm. 13C{1H} NMR: ment procedure. For 5b and 7a, the phosphirane ring proton was
3
1
δ = 19.4 (d, JP,C = 2.2 Hz, CH3), 22.1 (s, CH3), 43.2 (d, JP,C
=
localized in a ∆F map and refined isotropically. Software for struc-
ture solution and refinement: SHELX-97;[28] molecule plots: OR-
TEP-3.[29] Further details are provided in Table 3. 5b: Crystals of
1
21.2 Hz, C-6), 44.9 (d, JP,C = 8.8 Hz, C-5), 128.0, 128.2, 128.5,
128.6, 128.9, 129.3, 130.7, 136.1, 137.3, 156.1 (d, 2JP,C = 2.9 Hz, C-
2
2
4), 173.9 (d, JP,C = 7.3 Hz, CH3CO), 194.0 (d, JP,C = 8.0 Hz, 5b·CH2Cl2 were obtained by crystallization from a dichlorometh-
COeq), 197.1 (d, JP,C = 43.9 Hz, COax) ppm. 31P{1H} NMR: δ = ane/n-pentane solution. The occupancy factor of the CH2Cl2 mole-
2
–57.4 (1JP,W = 296.0 Hz) ppm. MS (CI = 100 eV): m/z (%) = 633
cule was refined to be 0.974(3). 7a: Suitable crystals were obtained
(100) [MH]+, 604 (61) [M – CO]+, 577 (10) [M – 2 CO]+, 549 (4) by slow concentration of a diethyl ether solution. [(5b)2(dba)Pd]: A
Eur. J. Org. Chem. 2010, 2504–2511
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2509

S. Maurer, C. Burkhart, G. Maas
FULL PAPER
Table 3. Crystallographic data and details of data collection and structure refinement for 5b, 7a and [(5b)2(dba)Pd] (pentane solvate and
benzene solvate).[a]
5b
7a
[(5b)2(dba)Pd]
Pentane solvate
Benzene solvate
Empirical formula
Formula mass
Temperature [K]
Crystal size [mm]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
C28H23N2OP·CH2Cl2 C32H21N2O5PW C73H60N4O3P2Pd·0.5C5H12 C73H60N4O3P2Pd·C6H6
519.38
728.33
193(2)
1209.67 + 36.07
193(2)
1209.67 + 78.11
193(2)
0.31ϫ0.15ϫ0.08
monoclinic
P 21/n
193(2)
0.38ϫ0.27ϫ0.12
triclinic
0.46ϫ0.27ϫ0.12 0.27ϫ0.15ϫ0.04
monoclinic
P 21/n
monoclinic
P 21/n
¯
P1
10.6055(16)
11.2442(16)
12.0606(17)
63.898(15)
86.271(18)
86.892(18)
1288.3(3)
2
10.2133(12)
12.0170(10)
23.598(3)
90
96.389(15)
90
2878.3(5)
4
1.681
12.6691(15)
23.2646(19)
21.120(2)
90
99.355(13)
90
6142.2(11)
4
1.347
11.0142(13)
27.1081(19)
21.942(3)
90
100.974(14)
90
6431.5(12)
4
1.330
β [°]
γ [°]
Volume [Å3]
Z
Density [g cm–3]
µ(Mo-Kα) [mm–1]
F (000)
1.339
0.34
540
4.113
1424
0.408
2588
0.392
2672
θ range [°]
2.07–25.02
14588
4298 (0.0483)
94.3
–
–
4298/0/322
0.923
0.0398, 0.0905
0.0682, 0.0978
0.52, –0.39
2.10–25.98
10205
5429 (0.0264)
96.0
numerical
0.5676/0.3320
5429/0/374
0.991
0.0230, 0.0531
0.0309, 0.0635
0.71, –1.15
2.14–25.03
44282
10527 (0.1420)
97.0
–
–
10527/0/778
0.758
0.0446, 0.0633
0.1226, 0.0780
0.48, –0.83
2.03–25.95
47861
12009 (0.2079)
95.5
–
–
12009/0/804
0.812
0.0719, 0.0746
0.1460, 0.0906
0.64, –0.59
Reflections collected
Independent reflections (Rint
Completeness to θmax [%]
Absorption correction
Max/min transmission
Data/restraints/parameters[b]
Goodness-of-fit on F2
)
[b]
Final R indices [IϾ2σ(I)]: R1, wR2
[c]
R indices (all data): R1, wR2
Largest diff. peak, hole [e Å–3]
[a] CCDC-760810 (for 5b), -760809 (for 7a), -760811 {for [(5b)2(dba)Pd] (pentane solvate)}, and -760812 {for [(5b)2(dba)Pd] (benzene
solvate)} contain the supplementary crystallographic 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. [b] Refinement based on F2 values. [c] R1 = Σ||Fo| – |Fc|/Σ |Fo|;
wR2 = {Σ[w(Fo – Fc ) ]/Σw(Fo2)2}1/2
.
2
2 2
(Eds.: A. R. Katritzky, C. W. Rees, E. F. V. Scriven), Pergamon,
Oxford, 1996, vol. 1A (Ed.: A. Padwa), pp. 277–304; c) F. Ma-
they, M. Regitz, in Phosphorus-Carbon Heterocyclic Chemistry:
The Rise of a New Domain (Ed.: F. Mathey), Elsevier Science,
Amsterdam, 2001, pp. 17–55.
benzene solution of the complex was exposed to pentane vapors in
a closed vessel. At room temperature, crystals were formed as a
pentane solvate (C73H60N4O3P2Pd·C5H12), but crystallization at
5 °C furnished crystals containing one benzene molecule per asym-
metric unit (C73H60N4O3P2Pd·C6H6). In the crystal structure of the
former complex, the pentane molecules are positionally disordered:
The midpoint of the C3–C4 bond of the pentane molecule coin-
cides with a crystallographic inversion center, so that an n-hexane
molecule is simulated. However, when the molecule was refined as
an n-hexane molecule, the temperature factors of the methyl carbon
atom became unusually high. The disorder was not fully taken into
account in the refinement (the 2-methylene group in one pentane
molecule coincides with the terminal CH3 group of the pentane in
the inversion-related position). For the crystal structure of the ben-
zene solvate complex, large and strongly anisotropic amplitudes of
thermal vibration were found, but no efforts were made to intro-
duce any constraints in the refinement procedure.
[2] N. Mézailles, P. E. Fanwick, C. P. Kubiak, Organometallics
1997, 16, 1526–1530.
[3] J. Liedtke, S. Loss, C. Widauer, H. Grützmacher, Tetrahedron
2000, 56, 143–156.
[4] Recent calculcation showing the effect of the p-character of the
P lone pair (HOMO) and the HOMO/LUMO energies: E. P. A.
Couzijn, A. W. Ehlers, J. C. Slootweg, M. Schakel, S. Krill, M.
Lutz, A. L. Spek, K. Lammertsma, Chem. Eur. J. 2008, 14,
1499–1507.
[5] C. Laporte, G. Frison, H. Grützmacher, A. C. Hillier, W. Som-
mer, S. P. Nolan, Organometallics 2003, 22, 2202–2208.
[6] a) B. Deschamps, L. Ricard, F. Mathey, Polyhedron 1989, 8,
2671–2676; b) D. C. R. Hockless, Y. B. Kang, M. A. McDon-
ald, M. Pabel, A. C. Willis, S. B. Wild, Organometallics 1996,
15, 1301–1306; c) J. Geier, G. Frison, H. Grützmacher, Angew.
Chem. 2003, 115, 4085–4087; Angew. Chem. Int. Ed. 2003, 42,
3955–3957; d) M. L. G. Borst, N. van der Riet, R. H. Lem-
mens, F. J. J. de Kanter, M. Schakel, A. W. Ehlers, A. M. Mills,
M. Lutz, A. L. Spek, K. Lammertsma, Chem. Eur. J. 2005, 11,
3631–3642; e) J. C. Slootweg, F. J. J. de Kanter, M. Schakel, M.
Lutz, A. L. Spek, S. I. Kozhushkov, A. de Meijere, K. Lam-
mertsma, Chem. Eur. J. 2005, 11, 6982–6993; f) H. A. Tallis,
P. D. Newman, P. G. Edwards, L. Ooi, A. Stasch, Dalton Trans.
2008, 47–53.
Acknowledgments
S. M. thanks the Fonds der Chemischen Industrie for a scholarship.
We thank Ms. Emel Ay, summer student from the University of
Metz, France, for her experiments on the Suzuki cross-coupling
reactions.
[1] Reviews: a) F. Mathey, Chem. Rev. 1990, 90, 997–1025; b) F.
Mathey, M. Regitz in Comprehensive Heterocyclic Chemistry II
[7] A. Marinetti, F. Mathey, L. Ricard, Organometallics 1993, 12,
1207–1212.
2510
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© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 2504–2511

Phosphiranes as Ligands
[8] K. Lammertsma, M. J. M. Vlaar, Eur. J. Org. Chem. 2002,
1127–1138.
[20] M. Beller, C. Bolm (Eds.), Transition Metals for Organic Syn-
thesis, Wiley-VCH, Weinheim, 1998, vol. 1.
[21] Review: C. Amatore, A. Jutand, Coord. Chem. Rev. 1998, 178–
180, 511–528.
[22] C. Amatore, A. Jutand, F. Khalil, M. A. M’Barki, L. Mottier,
Organometallics 1993, 12, 3168.
[9] J. Liedtke, S. Loss, G. Alcaraz, V. Gramlich, J. Grützmacher,
Angew. Chem. 1999, 111, 1724–1727; Angew. Chem. Int. Ed.
1999, 38, 1623–1626.
[10] J. Liedtke, H. Rüegger, S. Loss, J. Grützmacher, Angew. Chem.
2000, 112, 2596–2599; Angew. Chem. Int. Ed. 2000, 39, 2478– [23] W. A. Herrmann, W. R. Thiel, C. Broßmer, K. Öfele, T. Pri-
2481.
ermeier, W. Scherer, J. Organomet. Chem. 1993, 461, 51–60.
[24] a) W. A. Herrmann, W. R. Thiel, T. Priermeier, E. Herdtweck,
J. Organomet. Chem. 1994, 481, 253–258; b) J. Fawcett,
R. D. W. Kemmitt, D. R. Russell, O. Serindag, J. Organomet.
Chem. 1995, 486, 171–176; c) A. D. Burrows, N. Choi, M.
McPartlin, D. M. P. Mingos, S. V. Tarlton, R. Vilar, J. Or-
ganomet. Chem. 1999, 573, 313–322; d) X. Bei, H. W. Turner,
W. H. Weinberg, A. S. Guram, J. L. Petersen, J. Org. Chem.
1999, 64, 6797–6803; e) S. M. Reid, J. T. Mague, M. J. Fink,
J. Organomet. Chem, 2000, 616, 10–18; f) F. A. Jalón, B. R.
Manzano, F. Gómez-de la Torre, A. M. López-Agenjo, A. M.
Rodríguez, W. Weissensteiner, T. Sturm, J. Mahía, M. Maestro,
J. Chem. Soc., Dalton Trans. 2001, 2417–2424.
[11] a) U. Rohde, F. Ruthe, P. G. Jones, R. Streubel, Angew. Chem.
1999, 111, 158–160; Angew. Chem. Int. Ed. 1999, 38, 215–217;
b) R. Streubel, U. Schiemann, N. Hoffmann, Y. Schiemann,
P. G. Jones, D. Gudat, Organometallics 2000, 19, 475–481; c)
R. Streubel, M. Bode, G. von Frantzius, C. Hrib, P. G. Jones,
A. Monsees, Organometallics 2007, 26, 1371–1375.
[12] T. Jikyo, G. Maas, Chem. Commun. 2003, 2794–2795.
[13] S. Maurer, T. Jikyo, G. Maas, Eur. J. Org. Chem. 2009, 2195–
2207.
[14] B. A. Arbuzov, E. N. Dianova, Phosphorus Sulfur Relat. Elem.
1986, 26, 203–251.
[15] B. A. Arbuzov, E. N. Dianova, E. Y. Zabotina, N. A. Chada-
eva, Zh. Obshch. Khim. 1983, 53, 835–838; engl. transl.: 733–
736.
[25] A. F. Littke, G. C. Fu, Angew. Chem. 1998, 110, 3586–3587;
Angew. Chem. Int. Ed. 1998, 37, 3387–3388.
[16] a) B. A. Arbuzov, E. N. Dianova, Y. Y. Samitov, Dokl. Akad.
Nauk SSSR 1979, 244, 1117–1121; engl. transl.: 59–62; b) see
also: X. Guo, L. Feng, Q. Wang, Z. Li, F. Tao, J. Heterocycl.
Chem. 2006, 43, 353–359.
[17] a) E. O. Fischer, L. Knauss, R. L. Keiter, J. G. Verkade, J. Or-
ganomet. Chem. 1972, 37, C7–C10; b) H. Schumann, J.-J.
Kroth, Z. Naturforsch., Teil B 1977, 32, 768–770; c) F. Mercier,
F. Mathey, C. A. Akpan, J. F. Nixon, J. Organomet. Chem.
1988, 348, 361–367.
[26] L. I. Smith, K. L. Howard, Org. Synth., Coll. Vol. 1955, 3, 351–
352.
[27] G. Palla, G. Predieri, P. Domiano, Tetrahedron 1986, 42, 3649–
3654.
[28] G. M. Sheldrick, SHELXS/L-97, Program for the Solution and
Refinement of Crystal Structures from Diffraction Data, Uni-
versity of Göttingen, Göttingen, 1997.
[29] L. J. Farrugia, ORTEP-3 for Windows, University of Glasgow,
Glasgow, 1998.
[18] A. Marinetti, F. Mathey, Organometallics 1984, 3, 456–461.
[19] F. A. Allen, Acta Crystallogr., Sect. B 1980, 36, 81–96.
Received: January 25, 2010
Published Online: March 23, 2010
Eur. J. Org. Chem. 2010, 2504–2511
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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