Testing phosphanes in the palladium-catalysed allylation of secondary and primary amines

Article abstract of DOI:10.1002/ejic.200600592

The electronic nature of the ligand plays a crucial role in the palladium-catalysed allylation of amines with allylic alcohols. The better the ligand is as a π acceptor, the more active the catalyst. Experiments with a series with mono- and bidentate ligands featuring phosphanes and phospholes applied in the catalytic allylation of aniline clearly demonstrate this. Bolstered by DFT calculations, we have devised a new efficient catalyst for this process which carries the strong π acceptor 1,2,5-triphenylphosphole as a ligand. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Full text of DOI:10.1002/ejic.200600592

FULL PAPER
DOI: 10.1002/ejic.200600592
Testing Phosphanes in the Palladium-Catalysed Allylation of Secondary and
Primary Amines
Claire Thoumazet,[a] Hansjörg Grützmacher,[b] Bernard Deschamps,[a] Louis Ricard,[a] and
Pascal le Floch*[a]
Keywords: Allylation / Amines / Catalysis / Palladium / Phosphorus
The electronic nature of the ligand plays a crucial role in the
palladium-catalysed allylation of amines with allylic
alcohols. The better the ligand is as a π acceptor, the more
active the catalyst. Experiments with a series with mono- and
bidentate ligands featuring phosphanes and phospholes ap-
plied in the catalytic allylation of aniline clearly demonstrate
this. Bolstered by DFT calculations, we have devised a new
efficient catalyst for this process which carries the strong π
acceptor 1,2,5-triphenylphosphole as a ligand.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
that DPCB Pd(allyl) complexes (DPCB stands for diphos-
phanylidenecyclobutene ligands) efficiently catalyse the
coupling between aniline derivatives and allylic alcohols in
the presence of MgSO4 as a water scavenger to afford the
corresponding allylamines in good yields (Scheme 1).[4a–4d]
Recently, we showed that allyl palladium complexes of
mixed bidentate P-S ligands featuring a phosphabarrelene
moiety and a diphosphanyl sulfide pendant arm are ef-
ficient catalysts for the bis(allylation) of primary amines un-
der mild conditions.[5]
Introduction
Carbon–nitrogen bond formation is a major challenge in
organic synthesis for the preparation of nitrogen containing
molecules of biological and physiological interest.[1] Among
various metal promoted catalytic processes, the Tsuji–
Trost[1a,2] coupling reaction involving the reaction of a nu-
cleophile with a transient allyl palladium complex proves to
be one of the most straightforward routes towards allyl-
amines. Various nucleophiles and protected allylic alcohols
can be employed and this reaction usually proceeds with
good conversion under mild conditions.[3] However, as in
other allylic alkylation processes, the presence of a good
leaving group such as carboxylate, carbonate, phosphate or
other related derivatives on the allylic moiety is a prerequi-
site in most cases in order to obtain sufficient activity. From
a practical, economical and environmental point of view an
interesting goal consists of directly using allylic alcohols as
alkylating agents.[4] This approach has been explored by Ta-
maru as well as Ozawa and Yoshifuji in 2002. Tamaru et
al. showed that classical palladium(0) complexes, such as
Pd(PPh3)4 and Pd(OAc)2/PnBu3, could be employed as cat-
alysts for the allylation of primary and secondary amines
using a variable amount of BEt3 (between 0.3 and 2.4
equiv.) as a cocatalyst. The group of Ozawa demonstrated
Scheme 1. Allylation of primary amines by DPCB based com-
plexes.
[a] Laboratoire “Hétéroéléments et Coordination” UMR CNRS
7653, École Polytechnique,
Though the mechanism of this new catalytic process has
not been explored in detail, the experimental results suggest
that the π accepting capacity of the ligand likely plays a
decisive role in the outcome of the reaction. That is, the
stronger the π accepting capacity, the faster the process. In
this article we report on the use of mono- and bidentate
ligands in this allylation process and show through DFT
calculations that the electronic nature of the phosphane in-
deed plays a crucial role. As will be seen, these studies led
91128 Palaiseau Cedex, France
Fax: +33-1-69-33-39-90
E-mail: lefloch@poly.polytechnique.fr
[b] Department of Chemistry and Applied Biosciences (D-CHAB),
ETH Hönggerberg,
Wolfgang-Pauli Str., 8093 Zürich, Switzerland
Fax: +41-1-633-10.32
E-mail: gruetzmacher@inorg.chem.eth.ch
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
Eur. J. Inorg. Chem. 2006, 3911–3922
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C. Thoumazet, H. Grützmacher, B. Deschamps, L. Ricard, P. le Floch
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us to devise a new efficient catalyst featuring the easily
available 1,2,5-triphenylphosphole[6] as a ligand.
All cationic palladium complexes were conventionally
prepared by treating equimolar amounts of the ligand with
the [PdCl(allyl)]2 dimer in dichloromethane at room tem-
perature. After stirring for 5 min, the formation of the com-
plexes [Pd(allyl)(L2)]Cl (L2 = two monodentate ligands or
one bidentate ligand) was verified by 31P NMR spec-
troscopy (see the experimental section for 31P NMR spec-
troscopic data of the intermediary complexes). Sub-
sequently, a silver salt AgX (X = OTf or NTf2; Tf =
–SO3CF3) was added to exchange the chloride thereby af-
fording the expected cationic complexes 10a–17a (X = OTf)
or 10b–17b (X = NTf2) (see Scheme 3). Complexes 10a,b
were isolated as orange powders in excellent yields and their
structures are in accord with by NMR spectroscopy and
elemental analysis. Complex 10a was also structurally char-
acterised (X-ray crystal structure given in the available sup-
plementary material). Complexes 11a,b were characterised
by NMR spectroscopy and elemental analyses and their
NMR spectroscopic data were compared with those re-
ported in the literature for the [Pd(PPh3)2(allyl)][X] com-
plexes.[10] The dppe and dppp complexes 12a,b, and 13a,b
as well as the phosphole derivatives 14a,b and 15a,b were
synthesised by following the same experimental procedure
and isolated as colourless or pale-yellow powders (fully
characterised by NMR spectroscopy and elemental analy-
ses). X-ray analyses of single-crystals of complexes 11a (not
reported in this paper), 12b and 13a (given in the available
supplementary material) and of the phosphole complexes
14a and 15a were performed to elucidate their structures.
The structures of the latter are presented in Figure 1 and
Figure 2, respectively. Information concerning the data col-
Results and Discussion
Synthesis of Complexes
All experiments were carried out using cationic palladi-
um(allyl) complexes as precursors. As neutral donor li-
gands, various acyclic and cyclic phosphanes and one 1,4-
diazabutadiene ligand 1 (Ar = 2,6-diisopropylbenzene) were
tested as models for N–N chelating ligands (see Scheme 2
for a representation of all ligands employed in this study).
The classical triphenylphosphane ligand 2 was used as a
reference and its activity was compared with that of chelat-
ing ligands such as dppe 3 [dppe = 1,2-bis(diphenylphos-
phanyl)ethane] and dppp 4 [dppp = 1,3-bis(diphenylphos-
phanyl)propane] to assess the importance of the chelate ef-
fect. Furthermore, a series of phosphole based ligands was
investigated including the readily available 1,2,5-tri-
phenylphosphole 5 and the phenyldibenzophosphole 6[7] as
well as the chelate ligands 7 and 8[8] which are the phos-
pholyl counterparts of dppe and dppp, respectively. To
complete this series, we extended our study to the 1-di-
benzotropylidene-P-dibenzophosphole 9, a ligand which
has already proved to be very efficient in the Suzuki–
Miyaura cross coupling process allowing the synthesis of
arylboronic esters.[9] Note that it was shown previously that
this highly rigid phosphane alkene (PAL) acts as a firmly
binding bis(chelate) because of its well preorganised con-
cave shaped binding site.
Scheme 2. Ligands used in this study.
Scheme 3. Synthesis of cationic complexes 10–17a,b.
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Testing Phosphanes in the Palladium-Catalysed Allylation Amines
FULL PAPER
lection and refinement are given in Table 9 for both com- phosphole ligands point in opposite directions in order to
plexes. Selected bond lengths (Å) and angles (°) are listed minimise the steric congestion with the second phosphole
in Table 1 (complex 14a) and Table 2 (complex 15a), respec- ligand. No stacking interactions between the two phosphole
tively.
rings or their phenyl substituents can be observed. The P1–
Pd1 and P2–Pd1 bond lengths at 2.307(1) Å and 2.325(1) Å
are comparable with the corresponding Pd–P bonds in the
PPh3 complex (11a) [2.311(1) Å and 2.339(1) Å]. Similarly,
the Pd–Callyl bonds (see Table 1) fall in the same range
as those of the PPh3 complex [2.153(2), 2.174(4) and
2.236(8) Å]. Note that in the 1,4-diazabutadiene complex
10a, the Pd–Callyl bonds [2.107(3), 2.122(2) and 2.114(3) Å]
are significantly shorter than in the two phosphole com-
plexes indicating a stronger bond between the Pd atom and
the allyl group.
The structure of 15a is different and π stacking between
the planar dibenzophosphole ligands can be observed (dis-
tance between the two planes: 3.66 Å). Other metric param-
eters are close to those recorded for the structures of com-
plexes 11a and 14a. The bidentate ligands 7 and 8 have
already been synthesised by Neibecker et al. following the
classical procedure which consists of treating the 2,5-di-
phenylphospholide anion with 1,2-dibromoethane and 1,3-
dibromopropane.[8] Complexes 17a,b were straightfor-
wardly formed and isolated as dark-red powders and their
identities were ascertained by NMR spectroscopic studies
and elemental analyses (see Scheme 3). On the contrary, the
synthesis of complexes 16a,b failed. Whatever the experi-
mental conditions used, each attempt led to the formation
of dark solids that could not be dissolved in common or-
ganic solvents and despite many efforts, the insoluble mate-
rials could not be characterised.
Figure 1. A view of one molecule of complex 14a.
The synthesis of complexes 19a,b took a slightly different
reaction pathway. Specifically, the reaction of ligand 9 with
[Pd(allyl)Cl]2 did not yield a cationic complex with chloride
as the counter-anion but the neutral species 18 which results
from the breaking of the dimer, the chloride ligand remain-
ing coordinated to the palladium centre (see Scheme 4).
Complex 18 was characterised by 31P NMR spectroscopy
and its structure determined by an X-ray diffraction study.
Figure 2. A view of one molecule of complex 15a.
Table 1. Selected bond lengths [Å] and bond angles [°] for complex
14a.
P1–Pd1
P2–Pd1
Pd1–C45
Pd1–C46
Pd1–C47
P2–C1
2.3066(6)
2.3254(6)
2.143(2)
2.141(3)
2.202(3)
1.812(2)
1.348(3)
C2–C3
C3–C4
C4–P2
P1–Pd1–P2
C45–C46–C47
C4–P2–C1
P1–Pd1–C45
1.437(4)
1.360(3)
1.818(2)
102.4(2)
123.7(3)
107.6(2)
130.2(1)
C1–C2
Table 2. Selected bond lengths [Å] and bond angles [°] for complex
15a.
P1–Pd1
P2–Pd1
Pd1–C1
Pd1–C2
Pd1–C3
P2–C4
2.3096(7)
2.2882(7)
2.190(3)
2.176(3)
2.164(3)
1.804(3)
1.405(4)
C9–C10
C10–C15
C15–P1
P1–Pd1–P2
C1–C2–C3
C15–P1–C4
P1–Pd1–C3
1.465(4)
1.398(4)
1.824(3)
99.13(2)
121.0(3)
91.2(1)
C4–C9
67.5(1)
As displayed in Figure 1, complex 14a adopts the ex-
pected square-planar geometry. The two phenyl rings of the Scheme 4. Synthesis of cationic complexes 18 and 19a,b.
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C. Thoumazet, H. Grützmacher, B. Deschamps, L. Ricard, P. le Floch
FULL PAPER
Figure 3 shows the result and selected bond lengths and structure of complex 19b (Figure 4). Selected bonding pa-
angles are listed in Table 3. The structure of complex 18 rameters are listed in Table 4. Details concerning the crystal
shows that the 1-dibenzotropylidene-P-dibenzophosphole is data collection and refinement are given in Table 9.
coordinated to the metal centre by means of the phospho-
rus atom only, the C=Ctrop unit remaining uncoordinated.
Table 4. Selected bond lengths [Å] and bond angles [°] for complex
19b.
In order to minimise repulsive steric interactions, the tropy-
lidene and the allyl fragment point in opposite directions
with respect to the central plane through the Pd atom.
P1–Pd1
P1–C1
C1–C6
2.272(1)
1.815(4)
1.406(5)
1.468(6)
1.415(5)
1.788(4)
1.866(4)
2.135(4)
2.166(4)
Pd1–C30
Pd1–C13
Pd1–C14
C13–C14
C28–C29–C30 120.2(5)
C1–P1–C12 92.1(2)
C13–Pd1–C14 34.9(1)
2.214(4)
2.306(3)
2.293(3)
1.380(6)
C6–C7
C7–C12
C12–P1
P1–C21
Pd1–C28
Pd1–C29
P1–Pd1–C28
P1–Pd1–C30
99.0(1)
165.9(1)
The metric parameters of complex 19b are comparable
with those found in complex 15a. The C=Ctrop bond length
of the tropylidene unit [1.380(6) Å] is slightly lengthened
when compared with the uncoordinated C=Ctrop bond in
18 indicating π back donation from the metal fragment to
the ligand.
Figure 3. A view of one molecule of complex 18.
Catalytic Experiments
Table 3. Selected bond lengths [Å] and bond angles [°] for complex
18.
Having all these complexes at hand, we investigated their
performance in catalytic allylic aminations. The allylation
of aniline was chosen as a model reaction (Scheme 5). All
experiments were carried under the same experimental con-
ditions, that is, in THF or toluene at room temperature with
MgSO4 as a water scavenger using 1 mol-% of catalyst, two
equiv. of aniline and one equiv. of allylic alcohol. These
conditions are similar to those used by Ozawa et al. during
their studies with the above mentioned DPCB complexes.
The use of two equiv. of aniline disfavours the formation of
the bis(allylation) derivatives.
P1–Pd1
P1–C1
C1–C6
2.2822(6)
1.813(2)
1.407(3)
1.466(3)
1.403(3)
1.811(2)
1.875(2)
2.104(5)
Pd1–C29
Pd1–C30
Pd1–Cl1
C20–C21
2.170(4)
2.215(4)
2.3767(7)
1.337(4)
C6–C7
C7–C12
C12–P1
P1–C13
Pd1–C28
C28–C29–C30 120.5(7)
C1–P1–C12
P1–Pd1–C28
P1–Pd1–C30
91.6(1)
96.7(2)
164.0(2)
Treatment with one equivalent of AgX (X = OTf, NTf2)
yielded the expected cationic species 19a,b which were iso-
lated as very stable colourless powders (see Scheme 4). The
coordination of the double bond to the metal was ascer-
tained by NMR studies and is also seen in the solid-state
Scheme 5. Catalytic coupling of allyl alcohol with aniline using pal-
ladium allyl complexes 10a,b–19a,b as catalyst precursors.
A first series of experiments showed that the use of tolu-
ene or THF as solvent had no influence and gave similar
results. Therefore, all subsequent experiments were per-
formed in THF. As shown in Table 5, only catalysts 11a,b,
14a,b, 15a,b and 19b gave a complete or nearly complete
conversion (80 to 100%) after a reaction time of 24 h. In
the experiments with 11a,b–17a,b, the nature of counter-
anion did not have a significant influence on the catalytic
performance. However, under the reaction conditions used
in these experiments, a strong influence was seen with com-
plexes 19a,b, where the triflate derivative 19a gave only a
20% conversion (vide supra).
Figure 4. A view of one molecule of complex 19b.
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Testing Phosphanes in the Palladium-Catalysed Allylation Amines
FULL PAPER
Table 5. Conversion in the catalytic coupling of allyl alcohol with of catalyst). Methylallyl alcohol and trans-crotyl alcohol
aniline using palladium allyl complexes 10a,b–19a,b as catalyst pre-
cursors. (n.t. = not tested).
were also used as substrates. Introduction of a methyl group
at the alpha position of the alcohol resulted in a significant
Catalyst
24 h
1 h
Catalyst 24 h
1 h
decrease in the catalytic activity and, after 24 h at room
temp., only 40% of the substrate was converted. As pre-
viously observed by Ozawa and Yoshifuji, introduction of
a methyl group at the β position (trans-crotyl alcohol) leads
to a mixture of SN2 and SN2Ј products in a 71:12 ratio.
To complete this study, we then focused our efforts on
the bis(allylation) of primary amines as well as on the
monoallylation of secondary amines. This latter transfor-
mation is known, in particular, to be much more difficult to
achieve.[4c–4d,5] For the bis(allylation) process, catalyst 14b
(1 mol-%) was treated with one equiv. of amine and two or
three equiv. of the allylic alcohol in THF at room tempera-
ture with MgSO4. With two equiv. of alcohol a nearly com-
plete conversion was obtained after 39 h of stirring [92% of
bis(allylation), 8% of monoallylation]. With three equiv. a
complete conversion could be obtained after 14 h of reac-
tion (see Scheme 7).
10a
10b
11a
11b
12a
12b
13a
13b
0%
0%
100%
80%
20%
5%
n.t.
n.t.
47%
27%
n.t.
n.t.
n.t.
n.t.
14a
14b
15a
15b
17a
17b
19a
19b
100%
72%
100%
52%
34%
18%
13%
n.t.
100%
100%
85%
73%
69%
20%
98%
5%
2%
30%
Hard σ donor ligands such as the diazadiene ligand in
complexes 10a,b are not suited to the Pd-catalysed al-
lylation of aniline and no conversion was achieved. Com-
plexes such as 12a,b and 13a,b with bidentate ligands also
showed very low activities with conversions not exceeding
20%. The chelate complexes 17a,b carrying the bis(phos-
phole) ligand 8 gave better results but no complete conver-
sion was observed after 24 h.
In a second series of experiments, the most active cata-
lysts were selected and the reaction was stopped after 1 h.
As the results in Table 5 show, catalyst 14b proved to be
the most active (complete conversion) and, as previously
observed with 19a,b, this complex with the NTf2 counter-
anion was more active than its triflate counterpart 14a
(72%). However, complete conversion with 14a was
achieved after 2 h. The second best catalyst in terms of effi-
ciency is the dibenzophosphole based complex 15a which
Scheme 7. Bis(allylation) of primary amines with catalyst 14b.
Experiments to test the activity of 14b in the allylation
afforded a conversion of 52%. In this case, the NTf2 deriva- of secondary amines were conducted with 1 mol-% of cata-
tive 15b was less active (34%). The triphenylphosphane lyst, one equiv. of amine and two equiv. of allyl alcohol in
complex 11a (47% of conversion) ranks in third place. THF (at room temperature and 50 °C) in the presence of
Among the complexes which showed substantial conversion MgSO4. Three amines were tested: morpholine, dibenzyl-
after 1 h reaction time, complex 19b was the least efficient amine and N-methylaniline. A complete conversion was ob-
catalyst (30%). Note that in all these experiments the ad- tained after 24 h of heating at 50 °C with morpholine and
dition of MgSO4 is not necessary and the absence of this N-methylaniline as substrates. Note that 14b is therewith
water scavenger resulted only in a small decrease in the con- the most efficient catalyst reported to date for this transfor-
version yields (about 10%).
mation.[5] All the results are summarised in Table 6.
The results from the catalyses clearly demonstrate that
Having identified 14b as an efficient catalyst, some ad-
ditional experiments were also conducted with a lower the electronic nature of the phosphane plays a crucial role
loading of catalyst (0.5 and 0.1 mol-%) and by varying the for the activity. As previously observed, strong π acceptor
substitution scheme of the allyl alcohol. These results are ligands lead to higher TON (TON = turn over numbers).
presented in Scheme 6. Longer reaction times or heating Because diarylalkyl-substituted phosphanes such as dppe,
were needed to achieve a nearly complete conversion when dppp and ligand 8 show weaker π accepting capacities
a low loading of the catalyst was used (7 h at room temp. than triaryl phosphanes, the better performance of
with 0.5 mol-% of catalyst and 5 h at 70 °C with 0.1 mol-% [Pd(C3H5)(PPh3)2][X] 11a,b can be explained. However, the
Scheme 6. Reaction of aniline with methyl alcohol and trans-crotyl alcohol catalysed by complex 14b.
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Table 6. Conversion in the catalytic coupling of allyl alcohol with cator. Thus 5 (φ = 68°) would show a higher degree of aro-
secondary amines with 14b as a catalyst precursor.
maticity than 6 (φ = 72°). The significantly lower inversion
barrier at the phosphorus atom for 5 (16.9 kcalmol–1) than
Secondary amines
Temperature
Conversion
in 6 (26.2 kcalmol–1) supports this conclusion (see the sup-
porting information for a presentation and structure pa-
rameters of the transition states of the inversions calculated
at the same level of theory). Two explanations can be pro-
posed to rationalise the weaker inversion barrier in phos-
phole 5. First one may propose that the higher barrier for
6 is the result of significant overlap between the σ-P–R
bond and the π system of the butadienyl fragment (negative
hyperconjugation) which stabilises the ground state of this
less aromatic ring system. Note that the inversion barrier
for triphenylphosphane 2 was found to be equivalent to that
of 6, that is 26.2 kcalmol–1. A second possibility is to con-
sider that in the transition state the phosphole 5 is more
aromatic than 6 since in this fused system the π electrons
are delocalised into the two neighbouring six-membered
aromatic rings.[14] To confirm our findings further, the nu-
cleus independent chemical shifts (NICS) were calculated
for both phospholes and their transition states (noted TS5
and TS6, respectively). There is a good relationship be-
tween the NICS and other aromaticity criteria in phos-
pholes and the more negative the NICS the higher the aro-
matic character.[15] NICS calculations were performed with
the optimised structures at the RHF/6-311+G** level of
theory (measured at 1 Å above the plane defined by the
ring, opposite to the substituent at phosphorus). Table 8
shows that phosphole 5 is more aromatic than 6. Not sur-
prisingly, the presence of two fused benzene rings in 6 de-
creases the aromatic character of the central phosphole nu-
cleus. A similar phenomenon has already been reported by
Schleyer in the case of other fused structures such as phen-
anthrene.[15b] In 6, the NICS value of the peripheral ben-
zene rings (–10.3) is higher than that calculated for benzene
(–8.4) using the same method and basis set. NICS calcula-
tions were also performed on the two transitions states TS5
N-Methylaniline
Morpholine
Morpholine
Dibenzylamine
Dibenzylamine
room temp.
room temp.
50 °C
room temp.
50 °C
100%
28%
100%
11%
44%
explanation of the especially high activity of catalyst pre-
cursor 14 with the 2,5-diphenylphosphanylphosphole 5 as
ligand as compared with 15 with the dibenzophosphole de-
rivative 6 is less straightforward and requires a better under-
standing of the electronic nature of the ligands. Conse-
quently, a DFT study was carried out.
DFT Calculations
Calculations were carried out at the B3PW91/6-31G*
level of theory using the Gaussian 03 set of programs. Views
of the two calculated structures are shown in Figure 5 and
selected bond lengths and angles are listed in Table 7. The
agreement between the calculated and experimentally found
bonding parameters[11] is satisfactory. Because of the non-
planarity of the phosphorus atom, phospholes are weakly
aromatic.[12] The aromaticity of phospholes has been the
subject of many debates and several factors determine the
degree of aromaticity, such as the substitution pattern at
the carbon atoms, the pyramidalisation of the coordination
sphere at phosphorus and, most importantly, the nature of
the substituent at phosphorus which determines the ampli-
tude of the overlap between the π system of the C4-butadi-
enyl fragment and the P–R bond. This has been recently
demonstrated with a series of 1-R–P substituted phos-
pholes.[13] Both 5 and 6 carry a phenyl group as the substit-
uent, hence the degree of deviation φ of the P–C bond from
the ring plane can be used in first approximation as an indi-
Figure 5. Views of the optimised geometries of the two ligands 5 and 6 and TS5 and TS6 (hydrogens have been excluded).
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Testing Phosphanes in the Palladium-Catalysed Allylation Amines
FULL PAPER
and TS6, the structures of which are also presented in Fig-
ure 5. Both transition states are, as expected, more aromatic
than their respective precursors but the differences between
the NICS values are insignificant (NICS for TS5: –9.0;
NICS for TS6 = –8.9), that is, the degree of aromaticity
of the transition states is not the determining factor (see
Scheme 8).
Table 7. A comparison between calculated and experimental bond
lengths [Å] and angles [°] for ligands 5 and 6.
5
5[11a]
6
6[11b]
theoretical experimental theoretical experimental
Scheme 8. NICS values calculated at the RHF/6-311+G** level of
theory (measured at 1 Å above the plane defined by the ring, oppo-
site to the substituent at phosphorus) for 5, 6, TS5 and TS6.
P1–C2
C2–C3
C3–C4
P1–C6
C3–C2
P1–C5
1.822
1.368
1.441
1.839
114.8
1.821
1.822
1.348
1.440
1.822
116.1
1.822
1.832
1.412
1.469
1.848
110.0
1.832
1.812
1.385
1.465
1.841
110.2
1.818
Results of this CDA analysis are presented in Table 8,
further details are given in the experimental section. The
small residual term (∆) in all complexes shows that the elec-
tron density has been adequately partitioned into the repul-
sive term, r, and LǞM donor, d, as well as the MǞL back-
donating terms, b. Hence, the discussion of the data from
the CDA is meaningful.
The data given in Table 8 show that the ligands PPh3 and
dibenzophosphole 6 have similar electronic properties, that
is, they have similar donation/back-donation ratios, d/b, of
about 6.5. The triphenylphosphole 5 is a better acceptor, its
d/b ratio is significantly smaller (4.7).
Inspection of the MO’s involved in the bonding in com-
plexes II (HOMO-12 and HOMO-2, see Figure 7) and III
(HOMO-11 and HOMO-2) revealed that, as expected, the
most significant contribution to the bonding comes from
the orbital which describes the lone pair at phosphorus, i.e.
the HOMO-1 in 5 and the HOMO in 6. On the other hand,
the π back donation mainly results from the combination
Table 8. Sum of the bond angles around the P atoms, Σ° (P), devia-
tion φ of the P–C bond out the PC4 plane in the calculated struc-
tures of ligands 5 and 6. NICS values and data from CDA calcula-
tions for complexes I, II and III. b and d values are expressed in
electrons and d/b and b/d+b ratios are given in percent.
Ligands and com-
plexes
5
6
I
II
III
Σ° (P)
φ°
NICS (1 Å)
donation (d)
back-donation (b)
d/b
d/d+b
r
302
68
– 4.3
296
72
– 2.1
0.437
0.065
6.7
0.406
0.086
4.7
0.420
0.067
6.3
13.7
– 0.331
– 0.009
13
17.5
– 0.341
– 0.010
– 0.331
– 0.009
∆
The binding properties of 5 and 6 towards transition of a filled orbital of the Ni(CO)3 fragment with the
metal fragments were estimated by means of a charge de- LUMO+7 of 5 and 6 (σ* orbitals).
composition analysis (CDA) as developed by Frenking et
In summary, the results from the DFT calculations fully
al.[16] For simplicity, and in order to allow comparison with support the idea that the π accepting capacity of the ligand
previous work, we chose, as models, the Ni(CO)3 complexes governs the catalytic activity of the palladium complexes
I, II and III with triphenylphosphane 2, triphenylphosphole prepared from them: while [Pd(C3H6)(PPh3)2]X 10a,b and
5 and dibenzophosphole 6 as ligands, respectively (Fig- [Pd(C3H6)(6)]X 15a,b perform similarly, [Pd(C3H3)(5)]
ure 6).
14a,b stands out with its exceptional activity.
Figure 6. Views of the optimised geometries of the complexes I, II and III (hydrogen atoms have been excluded).
Eur. J. Inorg. Chem. 2006, 3911–3922
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3917

C. Thoumazet, H. Grützmacher, B. Deschamps, L. Ricard, P. le Floch
FULL PAPER
procedures. All other reagents and chemicals were obtained com-
mercially and used as received. The GC yields were determined on
a Varian Star 3400 gas chromatograph equipped with a CHROM-
PACK column (column type: WCOT FUSED SILICA, stationary
phase: CP-SIL 5 CB).
Theoretical Methods: The calculations were performed with the
GAUSSIAN 03 series of programs.[19] The geometries of com-
pounds 2 and 5 and 6 were optimised by using the B3PW91 func-
tional.[20] The standard 6-31G* basis set was used for all atoms (H,
C and P). NICS calculations were performed at the RHF/6-
311+G** level of theory using geometries calculated at the
RB3PW91/6-31G* level of theory. The Ni(CO)3 complexes I, II
and III were calculated with the B3PW91 functional using the 6-
31+G** basis set for P atoms, the 6-31G** basis set for the car-
bonyl groups and the 6-31G basis set for the H and C atoms. The
basis set for the metal was that associated with the pseudo poten-
tial, with a standard double-ζ LANL2DZ contraction. In each
case, harmonic frequencies were calculated at the same level of
theory to characterise the stationary points and to determine the
zero-point energies (ZPE). Intrinsic reaction coordinate calcula-
tions (IRC) were performed to ensure that transition states were
found for the inversion at the phosphorus atoms in the structures
of 5 and 6. All optimised structures reported here have only positive
Figure 7. Views of the two MO’s which describe the bonding in
complex II.
Conclusions
The performance of a series of catalysts with different
phosphane ligands and one complex with a diazabutadiene
ligand was evaluated in the palladium catalysed allylation
of primary and secondary amines. In this way, a new ef-
ficient catalyst carrying the 1,2,5-triphenylphosphole 5 as
a ligand (complexes 14a,b) was found which enables these eigenvalues of the Hessian matrix, i.e they are minima on the po-
tential energy surface. Inspection of ligand to metal donor-acceptor
interactions were performed using the charge-decomposition analy-
sis (CDA). In the CDA method the (canonical, natural or Kohn–
Sham) molecular orbitals of the complex are expressed in terms of
MO’s of appropriately chosen fragments. In the cases studied, the
Kohn–Sham orbitals of the calculations are formed in the CDA
procedure as a linear combination of the MO’s of the phosphorus
ligands 2, 5 and 6 and those of the remaining [Ni(CO)3] fragment.
In all cases, the ligands and the metal fragments were computed in
the geometry of the complex. The orbital contributions are divided
coupling reactions under mild conditions. DFT calculations
enabled a comparison of the electronic structures of the li-
gands which gave the most active catalysts and, in combina-
tion with calculations on simple model complexes, strongly
support the proposition that the best catalysts are obtained
with π accepting ligands. Further studies will now focus on
a systematic investigation of other strong π acceptor li-
gands, especially suitably substituted phospholes and phos-
phanes. Though significant progress has been achieved
through this study, the influence of the ligands and their into four parts: (i) the mixing of the occupied MO’s of the ligand
and the unoccupied MO’s of the metal fragment. This value (noted
d) represents the LǞM donation; (ii) the mixing of the unoccupied
MO’s of the ligand and the occupied MO’s of the metal fragment.
This value (noted b) accounts for the MǞL back donation; (iii)
the mixing of the occupied MO’s of the ligand and the occupied
MOs of the metal fragment. This term (noted r), which describes
the repulsive polarisation between the ligand and metal fragment,
is negative because electronic charge is removed from the overlap-
ping area of the occupied orbitals; (iv) the residual term (∆) which
results from the mixing of the unoccupied MO’s of the two respec-
tive fragments. Usually this term is very close to zero for closed-
shell interactions. This value constitutes an important probe for
determining whether the bonding studied can be really classified
as a donor-acceptor interaction following the Dewar–Chatt–
Duncansson model. Important deviations from ∆ = 0 imply that
the bond studied is more conventionally described as a normal co-
valent bond between two open shell fragments. A more detailed
presentation of the CDA method and the interpretation of the
results can be found in the literature. Compositions of molecular
orbitals, overlap populations between molecular fragments, bond
orders and density-of-states spectra were calculated by using the
AOMix program developed by I. Gorelski (version 6.23).[21]
related complexes on the mechanistic pathway has yet to be
precisely assessed as well as details on the stereochemical
course of the reaction. DFT calculations aimed at de-
termining the whole catalytic cycle of this important trans-
formation are currently underway and will be presented in
due course.
Experimental Section
General Remarks: All reactions were routinely performed under an
inert atmosphere of argon or nitrogen by using Schlenk and glove-
box techniques and dry deoxygenated solvents. Dry THF and hex-
anes were obtained by distillation from Na/benzophenone. Dry
dichloromethane was distilled from P2O5, dry toluene from Na and
dry acetonitrile from CaH2. NMR spectra were recorded on a
Bruker Avance 300 spectrometer operating at 300 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 an 85% H3PO4 ex-
ternal reference and coupling constants are expressed in Hertz. Ab-
breviations used: b broad, s singlet, d doublet, t triplet, m multiplet,
p pentuplet, sext sextuplet, sept septuplet, v virtual. Elemental
analyses were performed by the Service d’analyse du CNRS at Gif
sur Yvette, France. [Pd(COD)Cl2],[17] P-phenyldibenzophosphole
(6),[7] (dibenzo[a,d]cyclohepten-5-yl)dibenzophosphole (9),[9] tri-
phenylphosphole (5),[6] diazadiene (1)[18] and (2,5-diphenylphos-
phol-1-yl)alkanes 7 and 8[8] were prepared according to literature
X-ray Structure Data: Nonius KappaCCD diffractometer, φ and ω
scans, Mo-Kα radiation (λ = 0.71073 Å), graphite monochromator,
T = 150 K, structure solution with SIR97,[22] refinement against F2
in SHELXL97[23] with anisotropic thermal parameters for all non-
hydrogen atoms, calculated hydrogen positions with riding isotropic
thermal parameters (Table 9).
3918
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 3911–3922

Testing Phosphanes in the Palladium-Catalysed Allylation Amines
FULL PAPER
Table 9. Crystal data for complexes 14a, 15a, 18 and 19b.
14a
15a
18
19b
Empirical formula
Molecular mass [gmol–1
Crystal size [mm]
Crystal colour and shape
Crystal system
Temperature [K]
Space group
C47H39P2Pd, CF3O3S, CH2Cl2 C39H31P2Pd, CF3O3S C30H23ClPPd
C30H24PPd, C2F6NO4S2
802.05
0.22×0.16×0.16
colourless block
monoclinic
150.0(1)
]
1006.12
817.05
556.30
0.20×0.18×0.18
yellow block
monoclinic
150.0(1)
P21/n
0.23×0.20×0.03
light yellow plate
monoclinic
150.0(1)
0.20×0.18×0.18
yellow plate
monoclinic
150.0(1)
P21
P21
P21/c
a [Å]
b [Å]
c [Å]
12.2870(10)
22.1630(10)
16.1300(10)
93.9700(10)
4381.9(5)
4
11.6440(10)
11.8720(10)
13.8110(10)
110.7300(10)
1785.6(3)
2
9.4010(10)
13.9750(10)
10.0440(10)
115.3000(10)
1193.00(19)
2
44.9220(10)
14.9800(10)
18.8280(10)
97.6100(10)
12558.4(11)
16
β [°]
V [Å3]
Z
Density (calculated) [gcm–3
]
1.525
0.722
1.520
0.722
1.549
0.974
1.697
0.851
Absorbtion coefficient [mm–1
]
F(000)
θ max [°]
2048
30.03
828
27.45
562
30.03
6431
27.48
Reflections collected [I Ն 2σ(I)] 21134
8000
5637
45074
Independent reflections
Data/restraints/parameters
Gof on F2
12788 [Rint = 0.0208]
9168/16/550
1.039
0.0439, 0.1281
1.549(0.092)/
–0.986(0.092)
8000 [Rint = 0.0000]
7463/16/466
1.024
0.0293, 0.0730
0.633(0.057)/
–0.637(0.057)
5637 [Rint = 0.0000] 26730 [Rint = 0.0164]
5344/17/309
1.055
0.0252, 0.0636
0.509(0.067)/
–0.626(0.067)
20798/13/1558
1.042
0.0503, 0.1609
2.068(0.110)/
–0.757(0.110)
R(F), Rw(F2) [I Ն 2σ(I)]
Largest diff peak/hole [eÅ–3
]
CCDC-294689 to -294695 contain the crystallographic data for the
structures reported in this paper and have been deposited with the
Cambridge Crystallographic Data Centre. Copies of these data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
A2AЈ2XXЈ,
AAЈBBЈCXXЈ, ΣJ
Σ
J
=
99.5 Hz,
4
H, CH2PPh2), 3.39 (vddd,
=
24.8 Hz,
2
H, CHallyl), 4.86 (m,
AAЈBBЈCXXЈ, Σ J = 12.4 Hz, 2 H, CHallyl), 5.81 (vtt, AB2C2X2, Σ
J = 42.5 Hz, 1 H, CHallyl), 7.43–7.60 (m, 20 H, Ph) ppm. 13C NMR
(CDCl3, 25 °C): δ = 27.5 (vt, AXXЈ, Σ J = 46.0 Hz, CH2PPh), 71.4
(vt, AXXЈ, Σ J = 33.2 Hz, CH2allyl), 123.6 (vt, AXXЈ, Σ J =
12.2 Hz, CHallyl), 129.9–132.8 (Ph) ppm. C31H29F6NO4P2PdS2
(826.1): calcd. C 45.07, H 3.54; found C 44.85, H 3.53.
Synthesis of Complexes 10a,b [Pd(1)(η3-C3H5)][X]: To a solution
of glyoxal-bis(2,6-diisopropylphenyl)imine (100 mg, 0.26 mmol) in
dichloromethane (2 mL) was added [Pd(allyl)Cl]2 (48.6 mg,
0.13 mmol). After 5 min stirring, the silver salt AgX (0.26 mmol,
10a: 68.2 mg, 10b: 99.3 mg) was added and the pale-yellow solution
became orange. Filtration of AgCl on celite followed by evapora-
tion of the dichloromethane yielded the complexes as orange pow-
ders in very good yields (10a: 97%, 170 mg; 10b: 98%, 201 mg).
Single-crystals of 10a were obtained by slow diffusion of hexanes
into a solution of the complex in chloroform at room temperature.
1H NMR (CDCl3, 25 °C): δ = 1.32 (m, 24 H, CHCH3), 3.03 (m, 2
Synthesis of Complexes 13a,b [Pd(4)(η3-C3H5)][X]: To a solution of
1,2-bis(diphenylphosphanyl)propane (100 mg, 0.24 mmol) in
dichloromethane (2 mL) was added [Pd(allyl)Cl]2 (0.12 mmol,
44.5 mg). After 5 min stirring, the formation of a bidentate com-
plex was confirmed by 31P NMR (δ = 6.3 ppm). The silver salt
AgX was then added (0.24 mmol, 13a: 61.7 mg, 13b: 89.8 mg). Fil-
tration of AgCl on celite followed by evaporation of the dichloro-
methane yielded the complexes as white powders in very good
H, CHCH3), 3.17 (vd, AAЈBBЈC, Σ J = 12.8 Hz, 2 H, CHallyl), 3.25 yields (13a: 96%, 165 mg; 13b: 95%, 190 mg). Single-crystals of 13a
(m, 2 H, CHCH3), 3.59 (vd, AAЈBBЈC, Σ J = 7.0 Hz, 2 H, CHallyl),
5.56 (tt, J = 7.0 and 12.8 Hz Hz, 1 H, CHallyl), 7.26–7.40 (m, 6 H,
m-Ph), 8.61 (s, 2 H, CH=N) ppm. 13C NMR (CDCl3, 25 °C): δ =
23.0 (CHCH3), 23.7 (CH=N), 28.9 (CHCH3), 65.1 (CH2allyl), 120.1
(CHallyl), 124.1–128.8 (m-Ph), 138.1 (o-Ph), 146.1 (ipso-Ph), 170.0
(p-Ph) ppm. C30H41F3N2O3PdS (673.14): calcd. C 53.53, H 6.14;
found C 53.28, H 6.12.
were obtained by slow diffusion of hexanes into a solution of the
complex in dichloromethane at room temperature. 31P NMR
1
(CDCl3, 25 °C): δ = 6.8 ppm. H NMR (CDCl3, 25 °C): δ = 2.00
(m, A2M4X2, Σ J = 147.7 Hz, 2 H, CH2CH2PPh2), 2.76 (m,
A2AЈ2M2XXЈ, Σ J = 87.4 Hz, 4 H, CH2CH2PPH2), 3.28 (vddd,
AAЈBBЈCXXЈ,
Σ J = 25.6 Hz, 2 H, CHallyl), 3.95 (vddd,
AAЈBBЈCXXЈ, Σ J = 13.5 Hz, 2 H, CHallyl), 5.7 (vtt, AB2C2X2, Σ
J = 42.2 Hz, 1 H, CHallyl), 7.31–7.48 (m, 20 H, Ph) ppm. 13C NMR
(CDCl3, 25 °C): δ = 18.7 (s, CH2CH2PPh2), 25.3 (vt, AXXЈ, Σ J =
30.7 Hz, CH2CH2PPh2), 73.7 (vt, AXXЈ, Σ J = 32.5 Hz, CH2allyl),
123.0 (vt, AXXЈ, Σ J = 12.4 Hz, CHallyl), 128.9–132.8 (Ph) ppm.
C31H31F3O3P2PdS (709.0): calcd. C 52.51, H 4.41; found C 52.35,
H 4.40.
Synthesis of Complexes 12a,b [Pd(3)(η3-C3H5)][X]: To a solution of
1,2-bis(diphenylphosphanyl)ethane (100 mg, 0.25 mmol) in dichlo-
romethane (2 mL) was added [Pd(allyl)Cl]2 (0.13 mmol, 45.9 mg).
After stirring for 5 min, the formation of a bidentate complex was
confirmed by 31P NMR (δ = 51.2 ppm). The silver salt AgX was
then added (0.25 mmol, 12a: 64.5 mg, 12b: 93.9 mg). Filtration of
AgCl on celite followed by evaporation of the dichloromethane
yielded the complexes as white powders in very good yields (12a:
98%, 170 mg; 12b: 98%, 200 mg). Single-crystals of 12b were ob-
tained by slow diffusion of hexanes into a solution of the complex
in dichloromethane at room temperature. 31P NMR (CDCl3,
25 °C): δ = 51.4 ppm. 1H NMR (CDCl3, 25 °C): δ = 2.70 (m,
Synthesis of Complexes 14a,b [Pd(5)(η3-C3H5)][X]: To a solution of
[Pd(allyl)Cl]2 (0.16 mmol, 58.6 mg) in dichloromethane (2 mL) was
added triphenylphosphole (0.32 mmol, 100 mg). The formation of
the monophosphole complex was confirmed by 31P NMR (δ =
20.9 ppm). A second equiv. of triphenylphosphole (0.32 mmol,
100 mg) was added and after 5 min stirring, the formation of the
Eur. J. Inorg. Chem. 2006, 3911–3922
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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3919

C. Thoumazet, H. Grützmacher, B. Deschamps, L. Ricard, P. le Floch
FULL PAPER
bis(phosphole) complex was confirmed by 31P NMR (δ
11.0 ppm). The chloride was then abstracted with a silver salt AgX
(0.32 mmol, 14a: 83 mg, 14b: 120 mg). Filtration of AgCl on celite
followed by evaporation of the dichloromethane yielded the com-
plexes as yellow powders in very good yields (14a: 98%, 280 mg;
14b: 95%, 325 mg). Single-crystals of 14a were obtained by slow
diffusion of hexanes into a solution of the complex in dichloro-
methane at room temperature. 31P NMR (CD2Cl2, 25 °C): δ =
22.7 ppm. 1H NMR (CD2Cl2, 25 °C): δ = 3.61 (vdd, AAЈBBЈCXXЈ,
Σ J = 22.5 Hz, 2 H, CHallyl), 4.61 (vdd, AAЈBBЈCXXЈ, Σ J =
9.5 Hz, 2 H, CHallyl), 5.75 (vsept, AB2C2X2, Σ J = 41.9 Hz, 1 H,
CHallyl), 6.88 (m, A2AЈ2XXЈ, Σ J = 68.9 Hz, 4 H, Hβ), 7.03–7.32
(m, 30 H, HPh) ppm. 13C NMR (CD2Cl2, 25 °C): δ = 80.1 (vt,
AXXЈ, Σ J = 25.8 Hz, CH2allyl), 122.8 (vt, AXXЈ, Σ J = 9.9 Hz,
CHallyl), 126.7 (vt, AXXЈ, Σ J = 7.5 Hz, CHPh), 127.0 (vt, AXXЈ,
Σ J = 7.4 Hz, CHPh), 129.0 (s, CHPh), 129.1 (s, CHPh), 129.2 (s,
CHPh), 129.6 (vt, AXXЈ, Σ J = 10.9 Hz, CHPh), 131.9 (s, CHPh),
132.4 (vt, AXXЈ, Σ J = 11.6 Hz, CPh), 133.1 (vt, AXXЈ, Σ J =
14.4 Hz, CPh), 133.2 (vt, AXXЈ, Σ J = 14.4 Hz, CPh), 135.0 (vt,
AXXЈ, Σ J = 13.5 Hz, CHβ), 135.4 (vt, AXXЈ, Σ J = 13.4 Hz, CHβ),
142.6 (m, Σ J = 121.7 Hz, Cα) ppm. C48H39F3O3P2PdS (921.3):
calcd. C 62.58, H 4.27; found C 62.18, H 4.25.
=
AXXЈ, Σ J = 14.6 Hz, CHβ), 135.6 (vt, AXXЈ, Σ J = 14.8 Hz, CHβ),
144.9 (m, Σ J = 86.7 Hz, Cα) ppm. C41H35F3O3P2PdS (833.2):
calcd. C 59.11, H 4.23; found C 58.88, H 4.22.
Synthesis of Complexes 19a,b [Pd(9)(η3-C3H5)][X]: To a solution of
ligand (100 mg, 0.27 mmol) in dichloromethane (2 mL) was added
[Pd(allyl)Cl]2 (0.13 mmol, 48.8 mg). After stirring for 5 min, the
formation of the intermediate complex 18 was confirmed by 31P
NMR (δ = 49.5 ppm) and single-crystals of 18 were grown by slow
diffusion of hexanes into a solution in dichloromethane at room
temperature. The chloride was then abstracted with a silver salt
AgX (0.27 mmol, 19a: 68.6 mg, 19b 100 mg). Filtration of AgCl on
celite followed by evaporation of the dichloromethane yielded the
complexes as white powders in very good yields (19a: 97%, 175 mg;
19b: 96%, 205 mg). Single-crystals of 19b were obtained by slow
diffusion of hexanes into a solution of the complex in dichloro-
methane at room temperature.
Synthesis of Complexes 15a,b [Pd(6)(η3-C3H5)][X]: To a solution of
[Pd(allyl)Cl]2 (0.14 mmol, 50 mg) in dichloromethane (2 mL) was
added the 1-phenyl dibenzophosphole (0.27 mmol, 71 mg). The for-
mation the monophosphole complex was confirmed by 31P NMR
(δ = 15.8 ppm). A second equiv. of 1-phenyl dibenzophosphole
(0.27 mmol, 71 mg) was added and after 5 min stirring, the forma-
tion of the bis(phosphole) complex was confirmed by 31P NMR (δ
= 11.9 ppm). The chloride was then abstracted with a silver salt
AgX (0.27 mmol, 15a: 70 mg, 15b: 102 mg). Filtration of AgCl on
celite followed by evaporation of the dichloromethane yielded the
complexes as pale yellow powders in very good yields (15a: 98%,
217 mg; 15b: 97%, 245 mg). Single-crystals of 15a were obtained
by slow diffusion of hexanes into a solution of the complex in
dichloromethane at room temperature. 31P NMR (CD2Cl2, 25 °C):
δ = 13.9 ppm. 1H NMR (CD2Cl2, 25 °C): δ = 3.84 (br. s, 4 H,
CHallyl), 5.71 (vq, AB2C2X2, Σ J = 41.9 Hz, 1 H, CHallyl), 7.68–
7.21 (m, 26 H, Ph) ppm. 13C NMR (CD2Cl2, 25 °C): δ = 74.23 (br.
s, CH2allyl), 121.0 (br. s, CHallyl), 122.2 (d, JPH = 5.0 Hz, CHPh),
129.1 (d, JPH = 11.2 Hz, CHPh), 129.3 (d, JPH = 12.3 Hz, CHPh),
131.1 (br. s, CHPh), 131.3 (s, CHPh), 131.6 (vt, AXXЈ, Σ J =
31P NMR (CD2Cl2): δ = 55.8 ppm. 1H NMR (CD2Cl2): δ = 3.25
(m, 2 H, CHallyl), 4.10 (vdd, ABCDEX, Σ J = 23.4 Hz, 1 H,
CHallyl), 4.62 (d, JPH = 15.8 Hz, 1 H, H13), 5.43 (vt, ABCDEX, Σ
J = 13.6 Hz, 1 H, CHallyl), 5.77 (vsept, ABCDEX, Σ J = 41.9 Hz,
1 H, CHallyl), 6.08 (dd, JH,H = 7.5, JP,H = 7.5 Hz, 2 H, H5–H8),
7.01 (m, Σ J = 10.5 Hz, 2 H, H15–H26), 7.15 (m, Σ J = 21.3 Hz, 2
H, H3–H10), 7.53 (m, 6 H, H17–H24, H16–H25 and H4–H9), 7.66 (s,
2 H, H20–H21), 7.72 (m, Σ J = 8.9 Hz, 2 H, H18–H23), 7.95 (m, Σ
J = 9.6 Hz, 2 H, H2–H11) ppm. 13C NMR (CD2Cl2, 25 °C): δ =
54.8 (d, JP,C = 14.2 Hz, C13), 66.0 (s, CH2allyl), 85.9 (d, JPC
=
24.7 Hz, CH2allyl), 104.3 (s, C20–C21), 122.3 (d, JP,C = 6.1 Hz, C2–
C11), 124.9 (d, JP,C = 5.3 Hz, C3–C10), 129.0 (d, JP,C = 10.5 Hz C15–
C26), 129.5 (d, JP,C = 2.4 Hz, C4–C9), 130.8 (d, JP,C = 22.2 Hz, C5–
C8), 130.9 (d, JP,C = 2.7 Hz, C16–C25), 131.8 (d, JP,C = 45.9 Hz, C1–
C12), 131.9 (d, JP,C = 4.5 Hz, C18–C23), 132.9 (d, JP,C = 2.1 Hz, C17–
C24), 133.5 (d, JP,C = 9.2 Hz, C14–C27), 135.3 (d, JP,C = 2.8 Hz, C19–
11.9 Hz, CHPh), 142.7 (d, JPH
=
8.7 Hz, CPh) ppm.
C40H31F3O3P2PdS (817.1): calcd. C 58.80, H 3.82; found C 58.57,
H 3.82.
C22), 142.8 (d, JP,C = 9.6 Hz, C6–C7) ppm, missing CHallyl
.
Synthesis of Complexes 17a,b [Pd(8)(η3-C3H5)][X]: To a solution
of bis(2,5-diphenylphosphol-1-yl)propane (100 mg, 0.20 mmol) in
dichloromethane (2 mL) was added [Pd(allyl)Cl]2 (0.10 mmol,
35.7 mg). After 15 min stirring, the silver salt AgX was added
(0.10 mmol, 17a: 50.2 mg, 17b: 73 mg) and the formation of the
complexes were confirmed by 31P NMR (δ = 9.0 ppm). Filtration
of AgCl on celite followed by evaporation of the dichloromethane
yielded the complexes as dark-red powders in very good yields (17a:
95%, 150 mg; 17b: 96%, 174 mg). 31P NMR (CDCl3, 25 °C): δ =
C32H24F6NO4PPdS2 (802.1): calcd. C 47.92, H 3.02; found C 47.57,
H 3.01.
General Procedure for Catalytic Reactions: The catalyst (1 mol-%)
was placed in a Schlenck tube with MgSO4 (0.25 g) and THF
(1 mL). The Schlenck tube was then filled with aniline (182 µL,
2 mmol) and allyl alcohol (68 µL, 1 mmol). The mixture was stirred
at room temperature and the progress of the reaction was moni-
tored by GC. The mixture was filtered to remove the MgSO4 and
the solvent evaporated in vacuo. The product was then isolated by
column chromatography on alumina (hexanes).
1
9.0 ppm. H NMR (CDCl3, 25 °C): δ = 2.24 [m, 6 H, P(CH2)3P],
3.19 (vdt, AAЈBBЈCXXЈ, Σ J = 23.5 Hz, 2 H, CHallyl), 4.17 (vd
AAЈBBЈCXXЈ, Σ J = 7.0 Hz, 2 H, CHallyl), 5.58 (vsept, AB2C2X2,
Σ J = 41.1 Hz, 1 H, CHallyl), 7.15–7.45 (m, 24 H, Ph and Hβ) ppm.
13C NMR (CDCl3, 25 °C): δ = 19.1 (vt, AXXЈ, Σ J = 29.4 Hz,
CH2CH2P), 20.3 (s, CH2CH2P), 75.3 (vt, AXXЈ, Σ J = 25.6 Hz,
CH2allyl), 121.9 (vt, AXXЈ, Σ J = 9.1 Hz, CHallyl), 126.3 (m, CHPh),
128.0 (s, CHPh), 128.7 (vd, Σ J = 10.1 Hz, CHPh), 132.5 (vt, AXXЈ,
Σ J = 14.6, CPh), 132.9 (vt, AXXЈ, Σ J = 14.6, CPh), 134.9 (vt,
N-(2-Propenyl)aniline: See ref.[4a]
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Eur. J. Inorg. Chem. 2006, 3911–3922

Testing Phosphanes in the Palladium-Catalysed Allylation Amines
FULL PAPER
N,N-Bis(2-propenyl)aniline: See ref.[4a]
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1 H, H3), 4.97 (d, J = 1.0 Hz, 1 H, H3), 6.63 (AAЈBBЈC, Σ J =
8.5 Hz, 2 H, m-Ph), 6.71 (tt, AB2C2, Σ J = 16.8 Hz, 1 H, p-Ph),
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117.5 (s, p-Ph), 129.3 (s, o-Ph), 142.8 (s, C2), 148.2 (s, ipso-Ph) ppm.
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
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C. Thoumazet, H. Grützmacher, B. Deschamps, L. Ricard, P. le Floch
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Received: January 17, 2006
Published Online: August 7, 2006
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Eur. J. Inorg. Chem. 2006, 3911–3922