Synthesis of 1-phosphabarrelene phosphine sulfide substituted palladium(II) complexes: Application in the catalyzed suzuki cross-coupling process and in the allylation of secondary amines

Article abstract of DOI:10.1021/om0490278

The reactivity of 2-phosphine sulfide substituted phosphinines toward alkynes was examined. 2,6-bis(diphenylphosphine sulfide)-3,5-diphenylphosphinine 2 reacts with diphenylacetylene to yield the corresponding 1-phosphabarrelene derivative 3, resulting from the [4 + 2] cycloaddition. Compound 2 and 2-(diphenylphosphine sulfide)-3-methyl-5,6-diphenylphosphinine 1 react with dimethyl acetylenedicarboxylate in a similar fashion to yield the expected 1-phosphabarrelenes 4 and 5, respectively. Ligand 3 acts as a tridentate ligand in its reaction with [Pd(COD)Cl₂] to afford the expected cationic Pd-Cl complex 6. The reaction of [Pd(COD)Cl₂] and [Pd(η³-C₃H₅)Cl]₂ with ligand 5 yielded the corresponding complexes 7 and 8, in which the ligand behaves as a bidentate ligand. Complex 8 was isolated as a cationic derivative after chloride abstraction with AgOTf. DFT calculations, carried out at the B3LYP/6-311+G(d,p) level of theory, have shown that formation of 1-phosphabarrelenes is thermodynamically favored when dimethyl acetylenedicarboxylate is used as the alkyne. Complexes 6 and 8 proved to be very active catalysts in the Suzuki-Miyaura reaction, which allows the synthesis of functionalized biphenyl derivatives from the coupling of bromoarenes with phenylboronic acid (TON up to 7 × 10⁶ using complex 8 as catalyst). The cationic complex 8 also catalyzes the coupling between allyl alcohol and secondary amines to afford the corresponding N-allylamines in toluene at 70°C using 2% of the catalyst.

Full text of DOI:10.1021/om0490278

1204
Organometallics 2005, 24, 1204-1213
Synthesis of 1-Phosphabarrelene Phosphine Sulfide
Substituted Palladium(II) Complexes: Application in the
Catalyzed Suzuki Cross-Coupling Process and in the
Allylation of Secondary Amines
Olivier Piechaczyk, Marjolaine Doux, Louis Ricard, and Pascal le Floch*
Laboratoire “He´te´roe´le´ments et Coordination”, UMR CNRS 7653, Ecole Polytechnique,
91128 Palaiseau cedex, France
Received December 9, 2004
The reactivity of 2-phosphine sulfide substituted phosphinines toward alkynes was
examined. 2,6-bis(diphenylphosphine sulfide)-3,5-diphenylphosphinine 2 reacts with diphen-
ylacetylene to yield the corresponding 1-phosphabarrelene derivative 3, resulting from the
[4 + 2] cycloaddition. Compound 2 and 2-(diphenylphosphine sulfide)-3-methyl-5,6-diphen-
ylphosphinine 1 react with dimethyl acetylenedicarboxylate in a similar fashion to yield
the expected 1-phosphabarrelenes 4 and 5, respectively. Ligand 3 acts as a tridentate ligand
in its reaction with [Pd(COD)Cl2] to afford the expected cationic Pd-Cl complex 6. The
reaction of [Pd(COD)Cl2] and [Pd(η3-C3H5)Cl]2 with ligand 5 yielded the corresponding
complexes 7 and 8, in which the ligand behaves as a bidentate ligand. Complex 8 was isolated
as a cationic derivative after chloride abstraction with AgOTf. DFT calculations, carried
out at the B3LYP/6-311+G(d,p) level of theory, have shown that formation of 1-phospha-
barrelenes is thermodynamically favored when dimethyl acetylenedicarboxylate is used as
the alkyne. Complexes 6 and 8 proved to be very active catalysts in the Suzuki-Miyaura
reaction, which allows the synthesis of functionalized biphenyl derivatives from the coupling
of bromoarenes with phenylboronic acid (TON up to 7 × 106 using complex 8 as catalyst).
The cationic complex 8 also catalyzes the coupling between allyl alcohol and secondary amines
to afford the corresponding N-allylamines in toluene at 70 °C using 2% of the catalyst.
Introduction
η6 ligand at an Fe(0) center in the catalyzed cyclo-
trimerization of alkynes with nitriles to form functional
pyridines.4
Low-coordinated phosphorus ligands exhibit unique
electronic properties that make them very attractive for
catalytic purposes. Though the intrinsic high reactivity
of the PdC double-bonded systems means that only
kinetically or thermodynamically protected ligands can
be employed, very promising results have recently been
obtained with molecules such as phosphaferrocenes1 and
1,4-diphosphabutadienes.2 Though many synthetic routes
have been devised to produce polyfunctional phosphin-
ines, another important class of low-coordinated phos-
phorus ligands, these heterocycles have not found
numerous applications so far as ligands in catalysis.
This mainly results from the high electrophilicity of the
phosphorus atom as well as from the reactivity of the
aromatic π-system. So far, λ3-phosphinines have only
found application in two catalytic processes: Rh(I)
complexes in the hydroformylation of olefins3 and the
Two years ago, we launched an important synthetic
program aimed at exploiting the phosphinines as ligands
in catalysis. Indeed, though the ligand itself proves to
be too reactive to be employed in standard catalytic
transformations, its reactivity offers interesting struc-
tural possibilities. Thus, reactions with nucleophiles
yield λ4-phosphinine anions,5 which bind transition-
metal centers in an η1 (type A),6,7 η2 (type B),8 or η5
fashion (type C),9 depending on the substitution scheme
of the ring (Scheme 1). The first class of complex (type
A), incorporating a phosphino sulfide as ancillary ligand
and a λ4-phosphinine as the central subunit, exhibits
an interesting activity for the activation of several metal
(3) (a) Breit, B.; Winde, R.; Harms, K. J. Chem. Soc., Perkin Trans.
1 1997, 2681-2682. (b) Breit, B.; Winde, R.; Mackewitz, T.; Paciello,
R.; Harms, K. Chem. Eur. J. 2001, 7, 3106-3121.
(4) Knoch, F.; Kremer, F.; Schmidt, U.; Zenneck, U.; Le Floch, P.;
Mathey, F. Organometallics 1996, 15, 2713-2719.
(1) (a) Sava, X.; Ricard, L.; Mathey, F.; Le Floch, P. Organometallics
2000, 19, 4899-4903. (b) Shintani, R.; Fu, G. C. Org. Lett. 2002, 4,
3699-3702. Tanaka, K.; Fu, G. C. J. Org. Chem. 2001, 66, 8177-8186.
(c) Ogasawara, M.; Yoshida, K.; Hayashi, T. Organometallics 2001,
20, 3913-3917. (d) Shintani, R.; Lo, M. M. C.; Fu, G. C. Org. Lett.
2000, 2, 3695-3697. (e) Carmichael, D.; Klankermayer, J.; Ricard, L.;
Seeboth, N. Chem. Commun. 2004, 9, 1144-1145.
(2) (a) Minami, T.; Okamoto, H.; Ikeda, S.; Tanaka, R.; Ozawa, F.;
Yoshifuji, M. Angew. Chem., Int. Ed. 2001, 40, 4501-4503. (b) Ozawa,
F.; Okamoto, H.; Kawagishi, S.; Yamamoto, S.; Minami, T.; Yoshifuji,
M. J. Am. Chem. Soc. 2002, 124, 10968-10969. (c) Yoshifuji, M. J.
Synth. Org. Chem. Jpn. 2003, 61, 1116-1123.
(5) Moores, A.; Ricard, L.; Le Floch, P.; Me´zailles, N. Organometal-
lics 2003, 22, 1960-1966.
(6) (a) Doux, M.; Ricard, L.; Le Floch, P.; Me´zailles, N. Dalton 2004,
2593-2600. (b) Doux, M.; Ricard, L.; Mathey, F.; Le Floch, P.;
Me´zailles, N. Eur. J. Inorg. Chem. 2003, 687-698.
(7) Doux, M.; Bouet, C.; Me´zailles, N.; Ricard, L.; Le Floch, P.
Organometallics 2002, 21, 2785-2788.
(8) Moores, A.; Me´zailles, N.; Ricard, L.; Jean, Y.; le Floch, P.
Organometallics 2004, 23, 2870-2875.
(9) Doux, M.; Moores, A.; Me´zailles, N.; Ricard, L.; Jean, Y.; Le Floch,
P. J. Organomet. Chem. 2004, published on line Nov 10, 2004.
10.1021/om0490278 CCC: $30.25 © 2005 American Chemical Society
Publication on Web 02/16/2005

Palladium(II) 1-Phosphabarrelene Complexes
Organometallics, Vol. 24, No. 6, 2005 1205
Scheme 1
Chart 1
Scheme 2
centers and was employed, for example, with Rh(I)
complex to activate small molecules such as O2, CO2,
and CS2.10 On the other hand, palladium(II) complexes
showed a high catalytic activity in the Miyaura cross-
coupling reaction between bromoarenes and pinacolbo-
rane.11 Much more recently, we showed that η5 Rh(I)
complexes (type C) of these anions could be successfully
employed in the hydroformylation of olefins under mild
conditions.12
As explained above, a second interesting possibility
consists of taking advantage of the reactivity of the
π-system. It is well-known that phosphinines can be-
have as masked 1-cyclophosphabutadienes, and many
studies have focused on their use as dienes in [4 + 2]
cycloadditions with alkynes to form 1-phosphabar-
relenes. However, except in very rare cases when
activated alkynes are employed, these cycloadditions
occur when the ring has been activated by coordination13
or sulfurization14 of the lone pair at phosphorus. Only
a few examples of free barrelenes, obtained by the direct
[4 + 2] cycloaddition of phosphinines with alkynes, have
been reported so far.15 Thus, the use of 1-phosphabar-
relenes as ligands in homogeneous catalysis has hardly
been explored. Only Breit reported on the use of such
ligands in the Rh-catalyzed hydroformylation of ole-
fins.16 In this article, we report on the synthesis of mixed
bidentate P-S and tridentate S-P-S ligands featuring
a 1-phosphabarrelene moiety as ligand. As will be seen,
we also show that palladium(II) complexes of these new
ligands exhibit a significant catalytic activity in two
processes of synthetic importance, the Suzuki-Miyaura
cross-coupling reaction and the allylation of secondary
amines.
at the R-position of phosphorus enhanced the electro-
philicity of the phosphorus atom.7 When we initiated
this study, our initial aim was to evaluate the reactivity
of these mixed ligands as dienes toward alkynes in [4
+ 2] cycloaddition processes. All our experiments were
carried out with the 2-diphenylphosphine sulfide phos-
phinine 1 and the 2,6-bis(diphenylphosphine sulfide)
phosphinine 2 (Chart 1), which were prepared according
to reported procedures (see Experimental Section).
Reaction of 2 with diphenylacetylene proved to be
quite difficult to achieve, and heating for 10 days at 120
°C was necessary for complete conversion. Phosphabar-
relene 3, which was obtained in good yield after puri-
fication, was isolated as a very stable beige powder and
fully characterized by means of NMR and mass spec-
troscopy and elemental analyses. In 31P NMR, whereas
the chemical shift of the phosphine sulfide group
remains roughly unchanged (43.4 ppm in 2 vs 40.5 ppm
in 3), the formation of the bicyclic structure results in
a very important upfield shift of the ring phosphorus
atom (from 253.1 ppm in 2 vs -39.1 ppm in 3) (see
Scheme 2). The same reaction was attempted with the
P-S phosphinine 1, but no reaction occurred, despite a
prolonged reaction time (several weeks of heating at 120
°C).
Results and Discussion
In the course of our previous studies we have noticed
that the presence of diphenylphosphine sulfide ligands
More satisfactory results were obtained when dimeth-
yl acetylenedicarboxylate was used as the dienophile.
With the phosphinine 2, the Diels-Alder reaction takes
place at 80 °C and the phosphabarrelene 4 was isolated
in good yield after only 8 h of heating. Like its diphenyl
analogue 3, phosphabarrelene 4 is a very stable mol-
ecule which can be handled in air without oxidation of
the phosphorus atom, even after several days (see
Scheme 2).
Similarly, phosphinine 1 proved to be sufficiently
reactive to undergo the same reaction, but a longer
heating period was needed. Thus, heating for 18 h at
90 °C was necessary to convert 1 into phosphabarrelene
5, which was recovered as a very stable beige powder
(10) Doux, M.; Me´zailles, N.; Ricard, L.; Le Floch, P. Organometallics
2003, 22, 4624-4626.
(11) Doux, M.; Me´zailles, N.; Melaimi, M.; Ricard, L.; Le Floch, P.
Chem. Commun. 2002, 1566-1567.
(12) Moores, A.; Me´zailles, N.; Ricard, L.; Le Floch, P. Organome-
tallics 2005, 24, 508-513.
(13) (a) Alcaraz, J. M.; Mathey, F. Tetrahedron Lett. 1984, 25, 207-
210. (b) Markl, G.; Beckh, H. J. Tetrahedron Lett. 1987, 28, 3475-
3478. (c) Me´zailles, N.; Ricard, L.; Mathey, F.; Le Floch, P. Eur. J.
Inorg. Chem. 1999, 2233-2241. (d) Welfele´, S.; Me´zailles, N.; Maigrot,
N.; Ricard, L.; Mathey, F.; Le Floch, P. New J. Chem. 2001, 25, 1264-
1268.
(14) Alcaraz, J. M.; Mathey, F. J. Chem. Soc., Chem. Commun. 1984,
508-509.
(15) (a) Markl, G.; Lieb, F. Angew. Chem., Int. Ed. Engl. 1968, 7,
733. (b) Ashe, A. J.; Gordon, M. D. J. Am. Chem. Soc. 1972, 94, 7596-
7597.
(16) Breit, B.; Fuchs, E. Chem. Commun. 2004, 6, 694-695.

1206 Organometallics, Vol. 24, No. 6, 2005
Piechaczyk et al.
Scheme 3
and fully characterized by conventional techniques and
elemental analyses (Scheme 2).
Table 1. Calculated Enthalpies (ZPE corrected) of
Diels-Alder Reactions of Model Compounds Ia,
IIa, and IIIa with Acetylene and
The higher reactivity of phosphinine 2 can be ratio-
nalized on the basis of both kinetic and thermodynamic
arguments. Theoretical calculations were carried out
within the framework of DFT using the Gaussian 03
suite of programs. Computational details (functional and
basis sets used) are given in the Experimental Section.
Three reaction profiles were computed, those corre-
sponding to the reaction of the parent phosphinine
C5H5P Ia and the model compounds Ib and Ic with
acetylene. In Ib and Ic, the phenyl groups of the
diphenylphosphine sulfide groups and those grafted on
the phosphinine ring in 2 as well as the methyl group
in 1 were replaced by H atoms. The first interesting
piece of information is given by the examination of the
HOMO-LUMO gaps of the reactants. All these trans-
formations involve an inverse electron demand process,
the most important interaction occurring between the
LUMO of the phosphinine and the HOMO of acetylene.
Most importantly, these calculations show that forma-
tion of barrelene IIIa is only weakly exothermic (∆Hr
) -2.8 kcal mol-1), thus explaining why phosphinines
usually do not react with classical alkynes, even under
forced conditions. Model compounds Ib and Ic are
calculated to be much more reactive, and the formation
of barrelenes IIIb and IIIc is thermodynamically fa-
vored, in good agreement with experimental observa-
tions. Note, however, that they are not significantly
kinetically favored (enthalpies of transition states IIb
and IIc compare with that required to form IIIa) (see
Scheme 3). All of these values are reported in Table 1.
Nevertheless, no definitive conclusion can be drawn
from these results, since dimethyl acetyledicarboxylate
is a strongly activated alkyne for which acetylene is not
an optimal model. Therefore, the same calculations were
carried out using acetylenedicarboxylic acid as the
model. Whereas the formation of barrelenes Va and Vb
follows a normal electron demand process, the phosphi-
nine playing the role of the diene and the alkyne the
role of the dienophile, it is much more risky to conclude
Acetylenedicarboxylic Acida
transformation
II (TS)
III
IV(TS)
V
Ia to IIIa or Va
Ib to IIIb or Vb
Ic to IIIc or Vc
+31.7
+28.7
+25.7
-2.8
-6.7
-10.5
+26.3
+25.2
+23.9
-7.9
-10.4
-13.0
a Single point calculations were carried out at the B3LYP/6-
311+G(d,p) level of theory. TS denotes the transition state. All
energies are expressed in kcal/mol.
on the process involved in the case of Vc, since the
HOMO-LUMO gaps in the two processes (classical or
inverse electron demand) are quite similar (5.60 eV for
the classical process and 5.66 eV for the inverse electron
demand process). Nevertheless, here again, formation
of barrelenes Vb and Vc is more thermodynamically
favored than that of Va (see Table 1 for theoretical
data). This second set of data suggests that the reaction
of phosphinines with DMADC would probably be fa-
vored thermodynamically. So far, no systematic studies
on the reactivity of functionalized phosphinines toward
this activated alkyne have been reported. This point is
currently under investigation in our laboratories, and
results will be reported in due course. To conclude, one
could add that Diels-Alder reactions between alkynes
and phosphinines have been mostly studied with C4-
substituted (para position) compounds and it would be
of interest to assess the importance of the substitution
scheme in these transformations.
Having these new barrelenes at hand, we then
focused our study on their coordinating behavior toward
palladium(II) centers. The cationic monochloride com-
plex 6 (see eq 1) and neutral complex 7 (see eq 2) were
conventionally prepared by a displacement of the COD
(1,5-cyclooctadiene) ligand from [Pd(COD)Cl2] in dichlo-
romethane at room temperature. In the synthesis of 6
one chloride ligand is also displaced and acts as a
counteranion. In both cases the substitution of the
ligand was quantitative, yielding 6 as an orange powder

Palladium(II) 1-Phosphabarrelene Complexes
Organometallics, Vol. 24, No. 6, 2005 1207
Scheme 4
analogous systems featuring a similar PS chelate back-
bone. In complex 7, the two Pd-Cl bonds are different,
reflecting the difference between the σ-donor strengths
of the phosphorus and sulfur ligands (trans influence).
Thus, the Pd-Cl(1) distance (trans to P) is longer
(2.3570(8) Å) than the Pd-Cl(2) distance (trans to Pd
S) which falls at 2.3158(8) Å. This structural feature is
not unusual and appears to be relatively common in
similar complexes featuring an sp3-hybridized phospho-
rus atom. For example, in the [Cp2Fe(PPh2)(PPh2dS)-
PdCl2] complex the Pd-Cl bond length trans to the P
atom is longer (2.3696(7) Å) than that which is located
trans to the PdS ligand (2.3160(7) Å).17 From these data
one may conclude that the phosphabarrelene ligand in
7 exhibits electronic properties that are equivalent to
those of classical triarylphosphines. Interestingly, Ito
and Yoshifuji reported on the synthesis of a mixed P-S
ligand containing both a phosphaalkene and a PdS
ligand.18-20 Phosphaalkenes are known to act as poor
σ-donor ligands but generally exhibit a strong π-accept-
ing capacity, as low-coordinated phosphorus ligands in
general. Therefore, it is not surprising to note that the
Pd-Cl bond length which is located trans to the phos-
phaalkene ligand is short (2.319(3) Å) compared to the
above-mentioned complexes. Interestingly, we note that
in 7 the P-Pd bond distance is relatively short (2.1753-
(8) Å) compared to classical complexes (2.23 Å on
average) and is similar to that reported by Itoh and
Yoshifuji in their complex (2.186(3) Å).19 This would
suggest that the 1-phosphabarrelene ligand also dis-
plays a significant π-accepting capacity. Note that this
is expected from the substitution scheme of the phos-
phorus atom (three vinylic susbtituents, among which
one is substituted by two strong π-acceptor substitu-
ents). However, no direct comparison can be drawn
between 7 and this complex because of the difference
of hybridization of the two phosphorus atoms.
and 7 as a brown powder after the usual workup
(Scheme 4). Both complexes were fully characterized by
NMR techniques and elemental analyses. The sym-
metrical structure of complex 6 was ascertained by
NMR spectroscopy. Thus, in 31P NMR, 6 exhibits as a
classical AX2 spin system pattern: δA (CDCl3) 39.6 ppm
with 2J(AX) ) 83.6 Hz and δX (CDCl3) 50.2 ppm.
Definite proof of the structure of 7 was given by an X-ray
crystallographic study.
Suitable crystals of 7 were obtained by diffusing
hexanes into a dichloromethane solution of the complex
at room temperature. A view of one molecule of 7 is
presented in Figure 1, and the most significant bond
distances and bond angles are listed below. As can be
seen, the overall geometry around the palladium center
is square planar, as expected for a d8 complex. An
interesting comparison can be established between other
In pursuing our investigations on the coordination
chemistry of ligand 5, we found that the cationic
derivative [Pd(η3-C3H5)(5)][TfO] 8 could also be conven-
1
tionally prepared by reacting the ligand with /2 equiv
of the [Pd(η3-C3H5)Cl]2 precursor in the presence of
AgOTf as chloride abstractor. The presence of AgOTf
proved to be crucial, and no stable complex could be
isolated when the chloride ligand was left as the
counteranion. The presence of two diastereomeric com-
plexes, resulting from the orientation of the η3-allyl
ligand, was evidenced in 31P NMR, where 8 appears as
two different AB systems in a 45/55 ratio. No detailed
NMR studies have been undertaken to ascribe the
stereochemistry of these complexes. This complex was
isolated as a brown powder in 95% yield (eq 3) (only
one diastereomer is represented in eq 3).
Figure 1. ORTEP view of one molecule of complex 7.
Ellipsoids are scaled to enclose 50% of the electron density.
The phenyl groups at phosphorus atom P2 and at carbons
atoms C4 and C5 have been omitted for clarity. Relevant
distances (Å) and bond angles (deg): Pd-P1 ) 2.1753(8),
Pd-S1 ) 2.3070(8), Pd-Cl2 ) 2.3158(8), Pd-Cl1 ) 2.3570-
(8), S1-P2 ) 2.026(1), P1-C1 ) 1.823(3), P1-C6 ) 1.825-
(3), P1-C5 ) 1.831(3), P2-C1 ) 1.790(3), C2-C3 )
1.533(4), C3-C7 ) 1.522(4), C3-C4 ) 1.547(4) C4-C5 )
1.355(4) C6-C7 ) 1.328(4); P1-Pd-S1 ) 90.67(3), P1-
Pd-Cl2 ) 83.33(3), S1-Pd-Cl1 ) 88.47(3), Cl2-Pd-Cl1
) 97.26(3).
An X-ray crystallographic study was carried out on
suitable microcrystals obtained by diffusing hexanes

1208 Organometallics, Vol. 24, No. 6, 2005
Table 2. Crystal Data and Structural Refinement Details for 7, 8, and 10
Piechaczyk et al.
7
8
10
formula
Mr
cryst syst
space group
a (Å)
b (Å)
c (Å)
C
36H30Cl2O4P2PdS‚CH2Cl2
C39H35O4P2PdS(CF3O3S)
917.14
C28H27P2PdS(CF3O3S)
882.83
2851.86
orthorhombic
P212121
11.0880(10)
17.2800(10)
19.3660(10)
triclinic
orthorhombic
Pca21
15.5700(10)
9.2190(10)
20.3650(10)
P1h
9.8490(10)
11.2220(10)
19.0690(10)
92.4700(10)
101.4400(10)
109.4600(10)
1934.1(3)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
3710.5(4)
2923.2(4)
4
2
1
F (g cm-3
)
1.580
1.575
1.620
µ (cm-1
)
0.970
0.735
0.937
cryst size (mm)
F(000)
0.22 × 0.14 × 0.08
0.20 × 0.16 × 0.14
0.20 × 0.20 × 0.05
1784
932
1440
index ranges
-9 to + 15; -24 to +24;
-13 to +13; -15 to +15;
-26 to +25
30.03/I > 2σ(I)
529; 17
-18 to +21; -12 to +12;
-27 to +25
-28 to +23
2θmax (deg)/criterion
no. of params refined; data/param
no. of rflns collected
no. of indep rflns
no. of rflns used
wR2a
30.00/I > 2σ(I)
30.03/I > 2σ(I)
446; 19
362; 18
24 611
16 812
18 989
10 818
11 233
7658
8689
9303
6565
0.0903
0.0959
0.0850
R1b
0.0347
0.0342
0.0332
goodness of fit
1.008
1.030
1.012
largest diff peak/hole (e Å-3
)
0.610(0.093)/-0.525(0.093)
0.914(0.078)/-0.940(0.078)
1.065(0.076)/-0.776(0.076)
2
2
a wR2 ) (∑w||Fo| - |Fc|| /∑w|Fo| )1/2
.
b R1 ) ∑|Fo| - |Fc||/∑|Fo|.
into a solution of the complex in CDCl3. The two
diastereomeric complexes cocrystallize in the unit cell
in ratios of 2/3 to 1/3. A view of one molecule of one
diastereomer is presented in Figure 2, and the most
significant metric parameters are presented in the
corresponding caption. This structure does not display
a particular feature, and metric parameters within the
barrelene ligand are comparable with those of complex
7. As in 7, the Pd1-C8 bond length (trans to the P
ligand) is longer (2.229(7) Å) than the Pd1-C10 one
(2.13(1) Å), thus reflecting the stronger trans influence
of the phosphine ligand. These data compare with those
already reported for similar allylic complexes incorpo-
rating a five-membered palladacycle with PdS and P
ligands.19
To the best of our knowledge, if one excepts their
recent use in the hydroformylation of olefins,16 1-phos-
phabarrelenes have never been employed as ligands in
homogeneous catalysis. Therefore, to complete this
study, we launched a preliminary screening program
aimed at evaluating the catalytic activity of complexes
6 and 8. Our first attempt was to use these three
palladium(II) complexes in the well-known Suzuki-
Miyaura process,21 because it is now well established
that this type of coupling process requires bulky phos-
phines that combine both a good σ-donor strength and
π-accepting capacity.
Figure 2. ORTEP view of one molecule of complex 8
(cationic part). Ellipsoids are scaled to enclose 50% of the
electron density. The numbering is arbitrary and different
from that used in the assignment of NMR spectra. The
phenyl groups at phosphorus atom P2 and at carbons atoms
C4 and C5 have been omitted for clarity. Relevant distances
(Å) and bond angles (deg): Pd1-C8 ) 2.229(7), Pd1-C9
) 2.128(3), Pd1-C10 ) 2.13(1), Pd1-P1 ) 2.2541(5), Pd1-
S1 ) 2.3877(5), S1-P2 ) 2.0090(6), P1-C1 ) 1.826(2), P1-
C6 ) 1.828(2), P1-C5 ) 1.842(2), P2-C1 ) 1.793(2), C1-
C2 ) 1.338(2), C2-C3 ) 1.541(2), C3-C7 ) 1.523(3), C3-
C4 ) 1.545(2), C4-C5 ) 1.346(2), C6-C7 ) 1.336(2), C8-
C9 ) 1.441(7), C9-C10 ) 1.45(1); P1-Pd1-S1 ) 89.70(2),
C10-Pd1-C8 ) 69.9(3), C10-Pd1-P1 ) 102.5(3).
Complexes 6 and 8 proved to be very active, and
excellent conversion and TON were obtained (see Table
3). For example, biphenyl can be produced in 2 h in 90%
(17) Broussier, R.; Bentabet, E.; Laly, M.; Richard, P.; Kuz’mina,
L. G.; Serp, P.; Wheatley, N.; Kalck, P.; Gautheron, B. J. Organomet.
Chem. 2000, 613, 77-85.
(18) Ito, S.; Liang, H.; Yoshifuji, M. Chem. Commun. 2003, 398-
399.
(19) Liang, H. Z.; Ito, S.; Yoshifuji, M. Org. Lett. 2004, 6, 425-427.
(20) Liang, H.; Ito, S.; Yoshifuji, M. Org. Biomol. Chem. 2003, 1,
3054-3058.
yield using 10-5 equiv of complex 8 (TON ) 90 000) as
catalyst in toluene under reflux. A conversion of 70%
was obtained using 10-7 equiv of 8, although a longer
heating period was required (24 h; TON ) 7 × 106).
Finally, a conversion of 95% was obtained using 10-5

Palladium(II) 1-Phosphabarrelene Complexes
Organometallics, Vol. 24, No. 6, 2005 1209
Table 3. Cross-Coupling Reactions between Bromoarenes and Phenylboronic Acid using Complex 8 or 6 as
Catalysta
a All experiments were carried out in toluene using K2CO3 as a base.
equiv of complex 6 in 24 h (TON ) 95 000). Though
these results do not compare with those obtained by the
group of Buchwald using the di-tert-butylbiphenylphos-
phine, these catalysts do prove to be very efficient.22
These results, and the experimental conditions used,
also confirm that no metal poisoning results from the
presence of a sulfide group in the catalyst (eq 4).
the activation of the OH function through conversion
into a carboxylate, a carbonate, a phosphate, or other
related derivatives. Recently, the cationic Pd(allyl)
complex of a mixed 3-thioxo-1,3-diphosphapropene fea-
turing both a phosphaalkene and PdS group as ligands
was also successfully employed in this transformation.19
In the first series of experiments using Yoshifuji’s
conditions (toluene, room temperature in the presence
of MgSO4), we found that complex 8 proved to be less
reactive, but interestingly, we noted that the formation
of the desired monoallylation compound was always
accompanied by a non-negligible amount of the bis-
(allyl)amine. More satisfactory results in terms of
conversion were obtained using THF as solvent. Thus,
using 2% of catalyst 8, aniline was quantitatively
converted into allylaniline (60%) and bis(allyl)aniline
(40%) in 24 h at 70 °C. Whatever the experimental
conditions used, the formation of bis(allyl)aniline could
not be avoided. Importantly, we noted that the presence
of MgSO4 could be avoided, the presence of water not
being detrimental to the course of the reaction.
More interestingly, we found that complex 8 could
also be employed in the allylation of amines. This
coupling process, reported by Yoshifuji and Ozawa using
cationic allylpalladium complexes of a 1,4-diphospha-
butadiene (phosphorus analogues of 1,4-diazadienes),
was used to produce several allylic amines from the
reaction of allylic alcohols with primary amines.23,24
Importantly, in comparison to the classical Tsuji-Trost
process,25 this method does not require as a prerequisite
(21) (a) an der Heiden, M.; Plenio, H. Chem. Eur. J. 2004, 10, 1789-
1797. (b) Bedford, R. B.; Cazin, C. S. J.; Coles, S. J.; Gelbrich, T.;
Hursthouse, M. B.; Scordia, V. J. M. Dalton 2003, 3350-3356. (c)
Kondolff, I.; Doucet, H.; Santelli, M. Tetrahedron 2004, 60, 3813-3818.
(d) Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457-2483. (e)
Miyaura, N. Top. Curr. Chem. 2002, 219, 11-59. (f) Miyaura, N.
Angew. Chem., Int. Ed. 2004, 43, 2201-2203. (g) Navarro, O.; Kelly,
R. A.; Nolan, S. P. J. Am. Chem. Soc. 2003, 125, 16194-16195. (h)
Suzuki, A. J. Organomet. Chem. 1999, 576, 147-168. (i) Walker, S.
D.; Barder, T. E.; Martinelli, J. R.; Buchwald, S. L. Angew. Chem.,
Int. Ed. 2004, 43, 1871-1876.
This observation prompted us to investigate the
allylation of secondary amines, a transformation which
has not been studied in depth so far and apparently
remains difficult to catalyze. The monoallylation of
diethylamine was reported by Mortreux et al., using the
Ni(COD)2/dppb system (dppb ) 1,2-bis(diphenylphos-
phino)butane) as catalyst, in very good yields.26 In 2001,
Yang and co-workers reported on the use of [Pt(acac)2]/
PPh3 as a catalyst for the transformation of anilines (1
mol %), but the presence of a Lewis acid ([Ti(OiPr)4] (25
mol %) proved to be necessary to accelerate the trans-
formation.27 More recently, Kimura et al. also showed
that the allylation of secondary amines and the bis-
allylation of primary amines could be achieved using
(22) Wolfe, J. P.; Buchwald, S. L. Angew. Chem., Int. Ed. 1999, 38,
2413-2416.
(23) Ozawa, F.; Okamoto, H.; Kawagishi, S.; Yamamoto, S.; Minami,
T.; Yoshifuji, M. J. Am. Chem. Soc. 2002, 124, 10968-10969.
(24) Ozawa, F.; Ishiyama, T.; Yamamoto, S.; Kawagishi, S.; Mu-
rakami, H.; Yoshifuji, M. Organometallics 2004, 23, 1698-1707.
(25) (a) Tsuji, J. Transition Metal Reagents and Catalysts; Wiley:
New York, 2000. (b) Davis, J. A. In Comprehensive Organometallic
Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.;
Pergamon: Oxford, U.K., 1995; Vol. 9, p 291. (c) Godleski, S. A. In
Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.;
Pergamon Press: New York, 1991; Vol. 3, p 535. (d) Trost, B. M. Angew.
Chem., Int. Ed. Engl. 1995, 34, 259. (d) Trost, B. M. Science 1991,
254, 1471.
(26) Bricout, H.; Carpentier, J.-F.; Mortreux, A. J. Mol. Catal. A
1998, 136, 243-251.
(27) Yang, S.-C.; Tsai, Y.-C.; Shue, Y.-J. Organometallics 2001, 20,
5326-5330.

1210 Organometallics, Vol. 24, No. 6, 2005
Piechaczyk et al.
Table 4. Amination of Allylic Alcohol by
Secondary Amines Using Complex 8 as Catalysta
a All reactions were performed in THF as solvent with 2 equiv
of allyl alcohol.
[PdL4] complexes as catalyst (5 mol %) in the presence
of BEt3 as additive.28 As can be seen in Table 4, complex
8 is a very efficient catalyst for this transformation and
good conversion yields were obtained by heating allylic
alcohol with secondary amines in the presence of 2% of
catalyst without additive in THF at 70 °C for 24 h (see
eq 5).
Figure 3. ORTEP view of one molecule of complex 10
(cationic part). Ellipsoids are scaled to enclose 50% of the
electron density. The numbering is arbitrary and different
from that used in the assignment of NMR spectra. Relevant
distances (Å) and bond angles (deg): Pd1-C2 ) 2.115(3),
Pd1-C3 ) 2.155(4), Pd1-C4 ) 2.192(3), Pd1-P1 ) 2.2828-
(8), Pd1-S1 ) 2.364(1), S1-P2 ) 2.005(1), P1-C1 ) 1.854-
(3), P2-C1 ) 1.805(1); P1-Pd1-S1 ) 95.74(3), C2-Pd1-
C4 ) 67.9(2), C2-Pd1-P1 ) 98.3(1), C4-Pd1-S1 )
97.1(1).
obtained. This last result clearly suggests that the issue
of this allylation process is highly dependent on the
electronic nature of the phosphine ligand. The rigidity
of the ligand’s backbone very likely plays an important
role, as shown by the comparison between catalyst 8,
Yoshifuji’s systems, and complex 10. Suzuki cross-
coupling reactions were also carried out with bromoben-
zene and chlorobenzene under the same conditions,
using phenylboronic acid as reagent. The reaction with
chlorobenzene yielded no conversion like complex 8.
More interestingly, the reaction with bromobenzene
yielded a large amount of benzene (70% with 0.5 mol %
of 10) and no coupling product, showing that the
reactivities of 10 and 8 are very different.
On the basis of these different results, we logically
wondered about both the role played by the sulfur atom
in our catalyst and about the importance of the elec-
tronic nature of the phosphorus atom of the barrelene
ligand. To establish a comparison, the cationic pal-
ladium allyl complex of the dppm monosulfide ligand 9
was prepared. The procedure employed is in all points
identical with that used for the synthesis of complex 8.
Ligand 9 was reacted with [Pd(allyl)Cl]2 in dichlo-
romethane in the presence of AgOTf as chloride ab-
stractor. Formation of complex 10 immediately occurred
at room temperature, and a combination of NMR studies
and elemental analyses confirmed the proposed struc-
ture (eq 6).
Conclusion
In conclusion, we have shown that mono- and disub-
stituted diphenylphosphine sulfide phosphinines can be
used as convenient precursors for the synthesis of
bidentate P-S and tridentate S-P-S ligands featuring
a 1-phosphabarrelene unit as the central ligand. Inter-
estingly, the palladium allyl complex of the bidentate
P-S ligand presents a promising catalytic activity in
the Suzuki-Miyaura cross-coupling process and, more
importantly, in the allylation of secondary amines.
Investigation of the electronic properties of these bar-
relene ligands are currently underway in our laborato-
ries, as well as a systematic program aimed at gener-
alizing their use as ligands in catalysis. We will report
on these results in due course.
Additional evidence was given by an X-ray crystal-
lographic study, which was carried out on single crystals
obtained by diffusing hexanes into a solution of the
complex in THF. A view of one molecule of 10 is
presented in Figure 3, and the most significant metric
parameters are listed in the corresponding caption. This
structure deserves no particular comment and, as
previously discussed, the trans influence of the phos-
phine ligand is clearly visible upon examining Pd-C
bond distances: e.g., the Pd-C(4) distance (trans to P)
is longer (2.192(3) Å) than the Pd-C(2) distance (trans
to PdS) at 2.115(3) Å.
Experimental Section
All reactions were routinely performed under an inert
atmosphere of argon or nitrogen by using Schlenk and glovebox
techniques and dry deoxygenated solvents. Dry THF and
hexanes were obtained by distillation from Na/benzophenoe;
dry ether was obtained by distillation from CaCl2 and then
NaH and dry CH2Cl2 from P2O5 and dry toluene on metallic
Na. [Pd(η3-C3H5)Cl]2 was purchased from Strem Chemical and
Complex 10 was tested in the allylation of secondary
and primary amines, using the same experimental
conditions as those used above, but no conversion was
(28) Kimura, M.; Futamata, M.; Shibata, K.; Tamaru, Y. Chem.
Commun. 2003, 234-235.

Palladium(II) 1-Phosphabarrelene Complexes
Organometallics, Vol. 24, No. 6, 2005 1211
stored under nitrogen in the refrigerator. Nuclear magnetic
resonance spectra were recorded on a Bruker 300 Advance
spectrometer operating at 300.0 MHz for 1H, 75.5 MHz for 13C,
and 121.5 MHz for 31P. Solvent peaks were used as internal
references relative to Me4Si for 1H and 13C chemical shifts
(ppm); 31P chemical shifts are relative to a 85% H3PO4 external
reference. Coupling constants are given in hertz. The following
abbreviations are used: s, singlet; d, doublet; t, triplet; m,
multiplet. Phosphinines 111 and 2,29 Ph2PCH2PPh2(dS),30 and
[Pd(COD)Cl2]31 were prepared by following procedures de-
scribed in the literature. Amines were filtrated over alumina
before use. Elemental analyzes were performed by the “Service
d’analyses du CNRS” at Gif sur Yvette.
(m, CH of Ph), 133.4 (m, C), 133.5 (m, C), 133.8 (m, C), 138.1
(d, J(C-P) ) 27.6, C), 138.8 (d, J(C-P) ) 1.2, C), 144.1 (d,
2
J(C-P) ) 28.5, C), 151.3 (s, C), 151.8 (dd, J(C-P) ) 40.7, J(C-
P) ) 3.8, C), 154.6 (d, J(C-P) ) 2.2, C), 164.8 (s, C), 168.0 (d,
J(C-P) ) 26.3, CdO), 173.3 (dd, J(C-P) ) 8.2, J(C-P) ) 2.3,
CdO). MS: m/z+ 620 (M), 480 (M - dimethyl acetylenedicar-
boxylate). Anal. Calcd for C36H30O4P2S (620.1): C, 69.67; H,
4.87. Found: C, 69.3; H, 4.42.
Synthesis of Complex 6. To a mixture of 3 (100 mg, 0.12
mmol) and [Pd(COD)Cl2] (33.2 mg, 0.12 mmol) was added 3
mL of CH2Cl2. The formation of the complex was followed by
31P MNR. After 5 min, the solvent was removed under vacuum
and the solid obtained was washed with hexanes (3 × 2 mL)
and with ether (1 mL). Complex 6 was recovered as an orange
solid. Yield: 40% (48 mg, 0.05 mmol).
Synthesis of Phosphabarrelene 3. A solution of 2 (200
mg, 0.29 mmol) and diphenylacetylene (209.5 mg, 1.18 mmol)
in toluene (5 mL) was heated at 120 °C for 10 days. The
initially white and nonhomogeneous solution slowly turned
homogeneous and beige. After removal of the solvent under
vacuum, the solid was washed three times with Et2O (3 × 2
mL). Phosphabarrelene 3 was isolated as a brown-green solid.
Yield: 65% (156 mg, 0.19 mmol).
2
31P NMR (CDCl3): δ 39.6 (t, J(PA-PB) ) 84.0, PA bridge-
head), 50.2 (d, 2J(PA-PB) ) 84.0, PBPh2). 1H NMR (CDCl3): δ
6.07 (td, 1H, 4J(H-PB) ) 4.4, 4J(H-PA) ) 3.7, H4), 6.88-7.77
4
(m, 40H, H of Ph). 13C NMR (CDCl3): δ 75.3 (d, J(C-PB) )
23.4, C4H), 123.4 (s, C), 123.5 (d, J(C-P) ) 89.6, C), 124.4 (dd,
J(C-P) ) 84.4, J(C-P) ) 9.8, C), 126.6-131.8 (m, CH of Ph),
131.9 (s, C), 132.6 (m, CH of Ph), 133.4 (m, C), 134.8 (m, C),
134.9-135.3 (m, CH of Ph), 138.5 (d, J(C-P) ) 34.6, C), 154.7
(s, C), 178.7 (d, J(C-P) ) 5.4, C). Anal. Calcd for C55H41Cl2P3-
PdS2 (1034.0): C, 63.75; H, 3.99. Found: C, 63.28; H, 3.67.
Synthesis of Complex 7. To a solution of 5 (100 mg, 0.16
mmol) in dichloromethane (5 mL) was added [Pd(COD)(Cl)2]
(46 mg, 0.16 mmol). The formation of complex 7 was followed
by 31P NMR. After 5 min, the solvent was removed under
vacuum and the residue obtained was washed with hexanes
(3 × 2 mL) and Et2O (1 mL). 7 was obtained as a yellow solid.
Suitable crystals for X-ray diffraction were obtained by slow
diffusion of hexanes into a dichloromethane solution of the
complex at room temperature. Yield: 89% (113 mg, 0.14
mmol).
31P NMR (CDCl3): δ -38.1 (t, 2J(PA-PB) )106.9, PA bridge-
2
1
head), 41.5 (d, J(PA-PB) ) 106.9, PBPh2). H NMR (CDCl3):
4
δ 5.69 (t, 1H, J(H-PB) ) 3.4, H4), 6.87-7.85 (m, 40H, H of
Ph). 13C NMR (CDCl3): δ 80.1 (AB2X, dt, 3J(C-PB) ) 8.8, 3J(C-
PA) ) 3.4, C4H), 125.64-131.15 (m, CH of Ph), 132.45 (ABX,
1
3
dd, J(C-PB) ) 86.1, J(C-PA) ) 3.0, C of Ph), 132.4-132.5
1
3
(m, CH of Ph), 132.8 (ABX, dd, J(C-PB) ) 86.8, J(C-PA) )
3.0, C of Ph), 138.8 (d, J(C-P) ) 27.9, C), 138.8 (dd, J(C-P)
) 27.9, J(C-P) ) 3.0, C), 139.4 (d, J(C-P) ) 5.3, C), 139.9 (d,
J(C-P) ) 1.5, C), 147.1 (dd, J(C-P) ) 30.2, J(C-P) ) 3.0,
C2), 153.3 (q, J(C-P) ) 2.3, C), 172.6 (dd, J(C-P) ) 6.4, J(C-
P) ) 2.0, C). m/z+ ) 859 (M). Anal. Calcd for C55H41P3S2
(858.2): C, 76.90; H, 4.81. Found: C, 76.45; H, 4.51.
Synthesis of Phosphabarrelene 4. A solution of 2 (300
mg, 0.44 mmol) and dimethyl acetylenedicarboxylate (54 µL,
0.44 mmol) in toluene (10 mL) was heated at 80 °C for 12 h.
The solution, initially white and nonhomogeneous, slowly
turned brown and became homogeneous. After evaporation of
the solvent under vacuum, the solid obtained was washed with
Et2O (3 × 2 mL). Compound 4 was recovered as a yellow-brown
solid. Yield: 71% (257 mg, 0.31 mmol).
2
31P NMR (CDCl3): δ 19.7 (d, J(PA-PB) ) 90.9, PA bridge-
head), 48.0 (d, 2J(PA-PB) ) 90.9, PBPh2). 1H NMR (CDCl3): δ
1.95 (s, 3H, Me), 3.77 (s, 3H, Me of CO2Me), 3.91 (s, 3H, Me of
CO2Me), 5.94 (d, 4J(H-P) ) 2.9, 1H, H4), 7.12-7.15 (m, 20H,
3
3
CH of Ph). 13C NMR (CDCl3): δ 23.1 (vt, J(C-PA) ) J(C-
PB) ) 4.6, Me), 53.5 (s, Me of CO2Me), 53.8 (s, Me of CO2Me),
64.5 (dd, 3J(C-P) ) 20.2, 3J(C-P) ) 9.3, C4H), 124.1 (dd, J(C-
P) ) 86.8, J(C-P) ) 4.3, C),124.6 (dd, J(C-P) ) 84.4, J(C-P)
) 7.0, C), 128.2-132.6 (m, CH of Ph), 133.5 (d, J(C-P) ) 13.8,
C), 134.5 (d, J(C-P) ) 3.1, CH of Ph), 134.6 (d, J(C-P) ) 3.0,
CH of Ph), 134.8 (dd, J(C-P) ) 85.2, 3J(C-P) ) 22.7, C), 136.3
(d, J(C-P) ) 8.9, C), 137.4 (dd, J(C-P) ) 35.1, J(C-P) ) 1.1,
C), 144.8 (dd, J(C-P) ) 27.1, J(C-P) ) 2.5, C), 147.0 (dd, J(C-
P) ) 4.9, J(C-P) ) 1.8, C), 155.0 (vt, J(C-PA) ) J(C-PB) )
1.7, C), 162.7 (d, J(C-P) ) 9.7, C), 163.5 (d, J(C-P) ) 14.6,
C), 178.3 (vt, J(C-P) ) 4.2, C). Anal. Calcd for C36H30Cl2O4P2-
PdS (796.0): C, 54.19; H, 3.79. Found: C, 53.80; H, 3.42.
Synthesis of Complex 8. Dichloromethane (5 mL) was
added to a mixture of 5 (150 mg, 0.24 mmol), [Pd(η3-C3H5)-
(Cl)]2 (44.3 mg, 0.12 mmol), and silver trifluoroacetate (61.6
mg, 0.24 mmol) at room temperature. Formation of complex 8
was followed by 31P NMR and was almost instantaneous. 31P
NMR spectroscopy revealed the presence of the two diaster-
eomers 8a and 8b (in a 55:45 ratio). The solution was filtrated
through Celite, and then the solvent was removed under
vacuum, affording a brown powder. Yield: 95% (210 mg, 0.23
mmol). Crystals suitable for X-ray diffraction were obtained
by slow diffusion of hexanes into a solution of this complex in
CDCl3 at room temperature. Both diastereomers were present
in the unit cell. Anal. Calcd for C40H35F3O7P2PdS2 (916.0): C,
52.38; H, 3.85. Found: C, 51.89; H, 3.46.
31P NMR (CDCl3): δ -47.4 (t, 2J(PA-PB) ) 110.2, PA
bridgehead), 41.7 (d, 2J(PA-PB) ) 110.2, PBPh2). 1H NMR
4
(CDCl3): δ 3.78 (s, 3H, Me), 3.92 (s, 3H, Me), 6.00 (t, J(H-
PB) ) 3.0, 1H, H4), 6.87-7.78 (m, 30H, CH of Ph). 13C NMR
(CDCl3): δ 51.7 (d, J(C-PA) ) 3.8, Me), 52.2 (d, J(C-PA) )
3.8, Me), 71.1 (m, C4H), 126.8-131.0 (m, CH of Ph), 136.4 (m,
C of Ph), 137.0 (d, J(C-P) ) 5.3, C of Ph), 149.1 (m, C), 150.8
(m, C), 164.3 (s, C), 166.2 (d, J(C-P) ) 27.9, C), 170.6 (d, J(C-
P) ) 4.5, C). MS: m/z+ 822 (M). Anal. Calcd for C47H37O4P3S2
(822.1): C, 68.60; H, 4.53. Found: C, 68.53; H, 4.25.
Synthesis of Phosphabarrelene 5. To a solution of 1 (2
g, 4.2 mmol) in toluene (100 mL) was added dimethyl acety-
lenedicarboxylate (0.52 mL, 4.2 mmol). After 18 h of heating
at 90 °C, the solvent was removed under vacuum and the
residue obtained was washed with diethyl ether (3 × 4 mL). 5
was recovered as a beige solid. Yield: 50% (1.3 g, 2.1 mmol).
31P NMR (CDCl3): δ -43.5 (d, 2J(PA-PB) ) 106.3, PA
bridgehead), 40.3 (d, 2J(PA-PB) ) 106.3, PBPh2). 1H NMR
(CDCl3): δ 2.09 (s, 3H, Me), 3.76 (s, 3H, Me of CO2Me), 3.88
(s, 3H, Me of CO2Me), 5.68 (d, 4J(H-PB) ) 2.9, 1H, H4), 6.97-
2
7.85 (m, 20H, CH of Ph). 13C NMR (CDCl3): δ 23.9 (d, J(C-
P) ) 6.3, Me), 52.9 (s, Me of CO2Me), 53.4 (s, Me of CO2Me),
69.4 (dd, 3J(C-P) ) 9.7, 3J(C-P) ) 3.0, C4H), 127.4-132.3
(29) Dochnahl, M.; Doux, M.; Faillard, E.; Ricard, L.; Le Floch, P.
Eur. J. Inorg. Chem. 2005, 125-134.
Data for diastereomer 8a are as follows. 31P NMR (CD2-
Cl2): δ 12.7 (d, 2J(PA-PB) ) 116.7, PA bridgehead), 49.8 (d,
(30) Grim, S. O.; Mitchell, J. D. Synth. React. Inorg. Met.-Org. Chem.
1974, 4, 221-230.
1
2J(PA-PB) ) 116.7, PBPh2). H NMR (CD2Cl2): δ 1.92 (s, 3H,
Me), 2.01 (d, 1H, 3J(H-H) ) 12.6, H of CH2a allyl), 3.39-3.54
(m, 1H, H of CH2b allyl), 3.62-3.89 (m, 6H, Me of CO2Me),
(31) Drew, D.; Doyle, J. R. In Inorganic Syntheses; Angelici, R. J.,
Ed.; Wiley: New York, 1990; Vol. 28, pp 348-349.

1212 Organometallics, Vol. 24, No. 6, 2005
Piechaczyk et al.
4.14 (m, 1H, H of CH2a allyl), 4.92 (m, 1H, H of CH2b allyl),
5.34 (m, 1H, CH allyl), 5.98 (s, H, H4), 6.52 (m, 2H, H of Ph),
yields were determined by GC. After purification on silica gel
using hexanes as solvent, NMR spectra of all the functional
biphenyl derivatives prepared were compared with those of
the commercial compounds (Aldrich) 4-methylbiphenyl,32
4-methoxybiphenyl,32 and 4-acetylbiphenyl.33
7.07-7.23 (m, 10H, H of Ph), 7.47-7.69 (m, 8H, H of Ph). 13
C
NMR (CD2Cl2): δ 24.0 (m, Me), 53.6 (m, Me of CO2Me), 54.1
(m, Me of CO2Me), 65.5 (s, CH2a of allyl), 67.6 (vt, 3J(C-PA) )
3J(C-PB) ) 21.3, C4H), 78.1 (d, 2J(C-P) ) 32.2, CH2b of allyl),
General Procedure for Allylic Substitution of Second-
ary Amines. Methylaniline (129 µL, 1 mmol) and allyl alcohol
(136 µL, 2 mmol) were successively added to a solution of 8
(18.3 mg, 0.01 mmol) in dichloromethane (2 mL) at room
temperature. The solution was then stirred at 70 °C for 24 h.
The product yields were based on GC analysis of the resulting
solution. All allylamine derivatives prepared were then puri-
fied by chromatography on alumina using hexane as eluent.
NMR data of N-allylaniline and N,N-diallylaniline were
compared with those reported in the literature.23
2
119.1 (s, C), 119.9 (d, J(C-P) ) 6.6, CH of allyl), 126.0 (dd,
J(C-P) ) 87.0, J(C-P) ) 3.0, C), 128.4-134.8 (s, CH of Ph),
135.6 (d, J(C-P) ) 18.3, C), 136.0 (d, J(C-P) ) 7.0, C), 138.4
(d, J(C-P) ) 21.7, C), 144.4 (d, J(C-P) ) 11.4, C), 151.8 (m,
C), 156.7 (m, C), 163.6 (d, J(C-P) ) 6.8, C), 164.7 (d, J(C-P)
) 19.1, C), 178.8-179.1 (m, C). CF3 not seen.
Data for diastereomer 8b are as follows. 31P NMR (CD2-
Cl2): δ 12.1 (d, 2J(PA-PB) ) 115.6, PA bridgehead), 49.6 (d,
1
2J(PA-PB) ) 115.6, PBPh2). H NMR (CD2Cl2): δ 1.92 (s, 3H,
Me), 2.75 (d, 1H, 3J(H-H) ) 12.6, H of CH2a allyl), 3.39-3.54
(m, 2H, 1H of CH2a and 1H of CH2b allyl), 3.62-3.89 (m, 6H,
Me of CO2Me), 4.92 (m, 1H, H of CH2b allyl), 5.04 (m, 1H, CH
allyl), 5.98 (s, H, H4), 6.67 (m, 2H, H of Ph), 7.07-7.23 (m,
10H, H of Ph), 7.47-7.69 (m, 8H, H of Ph). 13C NMR (CD2-
Cl2): δ 24.0 (m, Me), 53.6 (m, Me of CO2Me), 54.1 (m, Me of
CO2Me), 65.5 (s, CH2a of allyl), 67.6 (vt, 3J(C-PA) ) 3J(C-PB)
) 20.9, C4H), 78.3 (d, 2J(C-P) ) 31.2, CH2b of allyl), 120.3 (d,
2J(C-P) ) 7.5, CH of allyl), 123.4 (s, C), 126.0 (dd, J(C-P) )
87.0, J(C-P) ) 3.0, C), 128.4-134.8 (s, CH of Ph), 135.3 (d,
J(C-P) ) 17.9, C), 136.0 (d, J(C-P) ) 7.0, C), 138.4 (d, J(C-
P) ) 21.7, C), 144.1 (d, J(C-P) ) 12.1, C), 151.3 (m, C), 156.5
(m, C), 163.3 (d, J(C-P) ) 7.6, C), 164.7 (d, J(C-P) ) 19.1,
C), 178.8-179.1 (m, C). CF3 not observed.
N-Allylmorpholine. 1H NMR (CDCl3): δ 2.45 (t, 3J(H-H)
) 4.4, 4H, H of CH2-N), 3.01 (dt, 3J(H-H) ) 6.6, 4J(H-H) )
3
1.2, 2H, H of NCH2CHdCH2), 3.72 (t, J(H-H) ) 4.4, 4H, H
of CH2O), 5.14-5.23 (m, 2H, H of CH2dCH-), 5.85 (ddt, 3J(H-
3
H) ) 10.1, J(H-H) ) 6.8, H of CH allyl). 13C NMR (CDCl3):
δ 53.6 (s, C of CH2N), 62.3 (s, C of NCH2CHdCH2), 67.1 (s, C
of CH2O), 118.5 (s, C of CH2dCH-), 134.6 (s, CH of allyl).
MS: m/z+ 128 (M + 1).
Theoretical Methods. All calculations were carried out
within the framework of density functional theory (DFT)34
using the Gaussian 03 suite of programs.35 Geometry optimi-
zations, single-point energy calculations, and populations were
carried out by means of a pure gradient-corrected exchange
functional and the Lee-Yang-Parr nonlocal correlation func-
tional B3LYP,36 as implemented in the Gaussian suite of
programs. The 6-311+G(d,p) basis set was systematically used
for all atoms (H, C, P, O). The stationary points (minima,
transition states) located at the DFT-B3LYP level were
characterized by frequency calculations (see the Supporting
Information). Transition states were located using the STQN
method, and reaction path calculations were carried out using
the IRC procedure to verify that a transition structure connects
the starting and ending structures proposed.
X-ray Structural Determination. Pale orange plates of
complex 7 were obtained by slow diffusion of hexanes into a
solution of this complex in dichloromethane at room temper-
ature. Pale yellow blocks of complex 8 were similarly obtained
from a CDCl3 solution and colorless plates of 10 from THF
solution. Data were collected at 150 K by ψ and ω scans on a
Nonius Kappa CCD diffractometer using a Mo KR (λ )
0.710 70 Å) X-ray source and a graphite monochromator.
Experimental details are described in Table 2. The crystal
structures were solved using SIR-9737 and Shelxl-97.38 ORTEP
Synthesis of Complex 10. Dichloromethane (5 mL) was
added to a mixture of 9 (150 mg, 0.36 mmol), [Pd(η3-C3H5)-
(Cl)]2 (65 mg, 0.18 mmol), and silver trifluoromethanesulfonate
(93 mg, 0.36 mmol) at room temperature. The formation of
complex 10 was followed by 31P NMR and was almost
instantaneous. The solution was then filtrated through Celite.
After evaporation of the solvent under vacuum, the powder
obtained was washed with hexanes (3 × 2 mL) and Et2O (2
mL). 10 was then recovered as a pale yellow powder. Yield:
82% (210 mg, 0.29 mmol). Crystals suitable for X-ray diffrac-
tion were obtained by slow diffusion of hexanes into a solution
of the complex in THF at room temperature.
31P NMR (CDCl3): δ 27.3 (d, 2J(PA-PB) ) 59.9, PA), 62.4 (d,
2J(PA-PB) ) 59.9, PBdS). 1H NMR (CDCl3): δ 3.14 (d, 1H,
3
3J(H-H) ) 12.4, H of CH2a allyl), 3.68 (dd, J(H-H) ) 13.8,
3J(H-P) ) 10.2, 1H, H of CH2b allyl), 4.21-4.48 (m, 3H, 2H of
3
3
PCH2P and 1H of CH2a allyl), 5.01 (vtd, J(P-H) ) J(H-H)
) 7.5, 4J(H-H) ) 2.0, 1H, H of CH2b allyl), 5.79 (vtt, 1H, 3J(H-
H) ) 13.8, 3J(H-H) ) 7.5, CH allyl), 7.20-7.58 (m, 16H, H of
Ph), 7.76-7.93 (m, 4H, H of Ph). 13C NMR (CDCl3): δ 37.1
1
1
2
(dd, J(C-P) ) 55.0, J(C-P) ) 20.8, PCH2P), 64.9 (d, J(C-
P) ) 3.0, CH2a allyl), 75.4 (dd, 2J(C-P) ) 29.6, 3J(C-P) ) 3.6,
CH2b allyl), 119.4 (d, 2J(C-P) ) 6.0, CH allyl), 126.0 (d, 1J(C-
(32) Old, D. W.; Wolfe, J. P.; Buchwald, S. L. J. Am. Chem. Soc.
1998, 120, 9722-9723.
(33) Ha¨felinger, G.; Beyer, M.; Burry, P.; Eberle, B.; Ritter, G.;
Westermayer, G.; Westermayer, M. Chem. Ber. 1984, 117, 895-903.
(34) Ziegler, T. Chem. Rev. 1991, 91, 651. Parr, R. G.; Yang, W.
Density Functional Theory of Atoms and Molecules; Oxford University
Press: Oxford, U.K., 1989.
1
P) ) 81.9, C of Ph), 126.1 (d, J(C-P) ) 82.0, C of Ph), 126.3
1
1
(d, J(C-P) ) 82.3, C of Ph), 126.4 (d, J(C-P) ) 82.2, C of
Ph), 129.1-133.4 (m, CH of Ph). CF3 not observed. Anal. Calcd
for C29H27F3O3P2PdS2 (712.0): C, 48.85; H, 3.82. Found: C,
48.47; H, 3.34.
(35) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.;
Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.;
Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson,
G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.;
Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai,
H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Adamo,
C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin,
A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma,
K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.;
Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.;
Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui,
Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.;
Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.;
Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challa-
combe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.;
Gonzalez, C.; Pople, J. A. Gaussian 03, revision B.01; Gaussian, Inc.:
Pittsburgh, PA, 2003.
Typical Procedure for Suzuki-Miyaura Cross-Cou-
pling Reactions (Described in the Preparation of Bi-
phenyl). A solution of 8 in toluene (10-5 mmol) was prepared
by multiple volumetric dilutions of a stock solution. Bromoben-
zene (102 µL, 1 mmol), phenylboronic acid (183 mg, 1.5 mmol),
and potassium carbonate (276 mg, 2 mmol) were successively
added at room temperature. The solution was then heated to
110 °C, stirred for 24 h, cooled, and quenched with HCl(aq) (2
M, 40 mL). The organic layer was removed, the aqueous layer
was extracted with toluene (3 × 50 mL), the combined organic
layers were washed with water, dried (MgSO4), and filtered,
and the solvent was removed under vacuum. The residue was
dissolved in toluene (6 mL), hexadecane (0.068 M in CH2Cl2,
1.00 mL, internal standard) was added, and the conversion
(36) (a) Perdew, J. P. Phys. Rev. B 1986, 33, 8822-8832. (b) Becke,
A. D. Phys. Rev. A 1988, 38, 3098-3108.

Palladium(II) 1-Phosphabarrelene Complexes
Organometallics, Vol. 24, No. 6, 2005 1213
drawings were made using ORTEP III for Windows.39 The files
CCDC-262187 to CCDC-262189 give additional crystallo-
graphic information. These data can be obtained free of charge
at www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cam-
bridge Crystallographic Data Centre, 12, Union Road, Cam-
bridge CB2 1EZ, U.K.; fax (internat.) +44-1223/336-033).
work. The use of computational facilities from the IDRIS
institute (University Paris XI, Orsay, France) is also
gratefully acknowledged.
Supporting Information Available: Tables of crystal
data, atomic coordinates and equivalent isotropic displacement
parameters, bond lengths and bond angles, anisotropic dis-
placement parameters and hydrogen coordinates for 7, 8, and
10 and figures and tables giving optimized geometries of Ia-
c, IIa-c, IIIa-c, IVa-c, Va-c, acetylene, and acetylenedi-
carboxylic acid; crystallographic data for 7, 8, and 10 are also
given as CIF files. This material is available free of charge
via the Internet at http://pubs.acs.org.
Acknowledgment. The CNRS, the Ecole Polytech-
nique, and the DGA are thanked for supporting this
(37) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G.; Giaco-
vazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.; Spagna, R.
SIR97, an Integrated Package of Computer Programs for the Solution
and Refinement of Crystal Structures using Single-Crystal Data;
Institute of Crystallography. Bari, Italy. 1998.
(38) Sheldrick, G. M. SHELXL-97; Universita¨t Go¨ttingen, Go¨ttingen,
Germany, 1997.
(39) Farrugia, L. J. ORTEP-3; Department of Chemistry, University
of Glasgow, Glasgow, Scotland.
OM0490278